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WW2 American Prototypes WW2 British Prototypes

The Bechhold Tank

Light tank – Single partial prototype and design. (1938-41)
United Kingdom – None built

Introduction

Many people interested in tanks have likely heard the name Walter Christie and are aware that he produced several prototype tanks during the period between WW1 and WW2. Whilst his vehicles had some good features, overall they were not a commercial success for Christie, who had amassed a lot of debt in developing and building them. The result was that some of his assets, his tank prototypes included, ended up being used to pay off his debts and his ‘high-speed tank’ was one of them.

Sold to pay off Christie’s debts, this vehicle ended up in the hands of a German-born American businessman, Siegfried Bechold. This new owner rebranded the tank, had some additional design changes made and then, at the start of WW2, tried to sell the ‘new’ design to both the Belgians and the British.

The Belgians needed tanks urgently but this design would come too late to help them. The British expressed interest as the light weight of the machine was suited to their need for a tank for airborne operations, and by 1940 the British Purchasing Commission was actively considering the vehicle for production. Nonetheless, the idea was over by 1941, when British attention switched to a vehicle with more armor and firepower than the ‘Bechold’ tank. Even so, this early design and the consideration of it adds to the story of how the British were trying to develop their own ideas for a new kind of mobile warfare and airborne operations.

The enigmatic Mr. Bechhold

The name Siegfried Bechhold means very little even to the most ardent tank enthusiast. However, just prior to WW2 and into its first years, Bechhold was one of the most prominent men involved in tank design and production in America, despite never having produced any tanks. This peculiar state of affairs takes some digging to get to the bottom of, as does the man himself, not helped by his name appearing variously as Bechhold, Bechold, and Buchhold.

Siegfried Bechhold appears to have been born in Bavaria, Germany in 1900, although a newspaper article from January 1941 puts his birthplace as Holland. This is likely one of those situations where people de-Germanized themselves to try and disguise their German ancestry, something which was a common occurrence at the time, especially with the switch from ‘Deutsch’ to ‘Dutch’ in terms of self-description. Another account of his early life (from April 1941) stated that he was born in Bavaria and lived in Germany until he was 11 – so maybe his family moved to Holland or maybe he was just hiding his background.

Bechhold recounted his story that, at the age of 16 (so ~1916), he was, like tens of thousands of other German boys, drafted into the German Army during World War One, although it is not known if he saw any active service or not. By 1922, with WW1 behind him but in a country ravaged by economic and social problems, he managed to make the transatlantic voyage to the United States, arriving in New York with just US$40 to his name.

His first jobs were very poorly paid but, by the late 1920’s, he was living as a tenant at 34 East 62nd Street between Madison and Park Avenues (this house was demolished in an explosion in July 2006). He had been learning English at night school and had managed to get a job as a salesman, which proved very successful for him. So successful was it, that this man, who had arrived in the USA just a few years before, could now afford to travel back and forth to Europe. He would later claim that he used these trips to pass on information about German rearmament efforts during the early 1930’s and that he believed that Germany was far ahead of other countries in weapons development, although this sounds more like his sales-speak for selling tanks than the serious recollections of an international spy.

What is known though is that during this time, he, like many others, saw the tanks of Walter Christie. These were very well covered in the newspapers and newsreels of the age with Christie’s penchant for publicity stunts. Seeing a potential business opportunity, Bechhold was interested in these tanks which were significantly faster than other tanks of the age, and in many ways the most advanced tanks in the USA at the time.

Bechhold later reported that he was encouraged in his interests by Congressman Ross Collins of Mississippi, although how these two men knew each other is unknown. It was, according to Bechhold, Collins who encouraged him to produce tanks in the United States but Bechhold was not a technical man nor an engineer despite being Vice President of the Bethlehem Engineering Export Corporation of Wall Street, New York. He was skilled in salesmanship and finance. He was, however, despite his lack of engineering skills, to be credited in the US press as coming up with the idea of putting lightweight aircraft engines into tanks in place of ordinary diesel or petrol engines, although this too sounds more like the pitch of a salesman, as Christie had already done this years beforehand.

As an aside to his tank work and to give a flavour of the way in which Bechold was trying to avoid being labelled as anything other than as a patriot, he embarked on a vigorous self-justification campaign in the media, making sure no one was in any doubt as to his loyalties. As a result, in June 1941, it was reported that Bechhold, a naturalized citizen and “intense” patriot, had refused to sell his tanks to the Russians at the time of the War against Finland. Furthermore, it was claimed that, in the new war against Hitler, he would only sell them when the Russians went to war with Hitler, even though there seems to be no evidence whatsoever for this claim.

The Tank Company

By the end of the 1930’s, Bechhold had his opportunity. Walter Christie, a man of undoubted technical gifts, was running short of investors who wanted to keep losing money on his tanks. One vehicle of his, a “high-speed tank”, had to be handed over to the partners of the Hempsted Welding Company of New York, William and Alfred Christ, as a lien against unpaid debts owed to them by Christie. Exactly which of Christie’s vehicles this was in unclear but as the M.1938 was later presented by a Mr. Bigley with some involvement from Christie suggests that Bechhold got hold of the M.1937 high speed tank from Christie as the basis of his design. However, whilst exactly which vehicle may not be known, Christie’s creditors were to be appeased with a tank available for purchase to pay his debts.

Bechhold had, through Bethlehem Engineering Co. been engaged in a commercial contract with Christie which started on 9th August 1938 whereby Bechhold and his company were granted exclusive rights to sell and manufacture the design from Christie for the princely sum of US$5,000 (just over US$91,000 in 2020 values). The idea of the partnership was simple. For this initial outlay of cash to Christie, Bethem Engineering would take the full blueprints of the design, market them globally and grant manufacturing licences for US$50,000 to each national licensee. This US$50,000 (US$915,000 in 2020 values) would be split 50:50 between Bethlehem Engineering and Christie for which the licence got not only the blueprints but also a master mechanic or draughtsman from Christie. This agreement simply fell apart not least in part to how appallingly badly written and complicated it was. In the words of the New York Second Circuit of Appeals in July 1939 ruling on whether to grant an injunction against Christie for breach of his contract:

“This contract is so obscure, and, strictly taken, so incoherent, that nobody can be sure of its meaning, but so far as we can spell it out, this is what it was. The defendants made the plaintiff its exclusive agent to sell licenses to prospective manufacturers of their tank in foreign countries — perhaps also in this country as well, though apparently it was not included. The plaintiff was not free to sell such licenses generally, but only for those countries where the parties thought it “practical” to do so. The minimum license fee was to be $50,000, but the plaintiff was to try to get more, and the parties were to discuss the amount in advance: probably this implied that they should agree upon it.”
105.F.2d 933 (2nd Cir. 1939)

With the case between them ending in confused acrimony, Christie and Bethlehem Engineering’s relationship was over. Christie had won that case due not least in part to how confusing the agreement was between them over rights and whilst he had retained his rights over his design he was also financially crippled.
Bechhold too had moved on and was no longer involved with the Bethlehem Engineering Expert Company and, instead, on 25th July 1939 (just 2 weeks after the ruling), formed the Armored Tank Corporation (A.T.C.), incorporated in New York. Initially, this company had just 100 shares of stock (30 Class A, and 70 Class B) at a value of US$50 each (Total nominal value US$5,000).

The purpose of the company was to acquire the Walter Christie high-speed tank from William and Alfred Christ. On 31st July 1939, this tank was purchased for an undisclosed sum along with 34 shares (Value US$1,700) in the new company (6 more were given to the attorney for their legal services). The Armored Tank Corporation (A.T.C.) of New York was now in possession of the Christie High-Speed Tank, the rights over which had fractured the relationship between Christie and Bethlehem Engineering. Bechhold now had the vehicle and also the more difficult task of making money from it.

Belgians

Within a few months of formation of the company and the purchase of this High-Speed tank, Bechhold was recruiting a draughtsman. Between December 1939 and January 1940, A.T.C.’s draughtsman prepared blueprints and drawings of this Christie tank with some modifications. During this time, a license agreement for the production of this modified Christie high-speed tank was acquired in Belgium. The Belgium firm, Ateliers de Construction de Familleureux, paid an advance royalty of US$10,000 for this license. Whatever plans there were in Belgium for this vehicle though are unknown, as the nation was overrun by the Germans in May 1940, with no Christie tanks produced.

Super Tanks

By the end of 1940, the first glimpse of what A.T.C. was working on can be seen. In November-December that year, it was advertising ‘Super-Tanks’ in the US Army Ordnance Magazine as being “built in all weights” by the Armored Tank Corporation at 30 Church Street, New York. This was formerly the location of numerous businesses such as the National Manufacturing Company, American Locomotive Sales Corporation, and the New York Railway Club (close to the site of the World Trade Center Complex today and now the location of the Century 21 Department Store). The same advert appeared that same month as being constructed by the Pressed Steel Car Co. as well.

Image of a Bechhold Tank
Image of a Bechhold Tank dated 1940, published November/December 1940. Source: Army Ordnance Magazine

Although the tank was never built as shown, there is some information available from contemporary press reports too. Also, bearing in mind that the vehicle was based on the Christie design (purchased in 1939), and that it was advertised as being “Built in all weights”, a brief analysis of the vehicle shown is possible.

Advert for Bechold’s Armored Tank Corporation of New York.
Advert for Bechold’s Armored Tank Corporation of New York. Source: Army Ordnance Magazine

In December 1940, Bechhold was reported to have been producing ‘Medium Tanks’ for the British and had also submitted a design for an airborne tank. This tank was at the time being reported in the press as weighing 10 tons (9.1 tonnes), 14 ½ feet (4.42 m) long, fitted with armor one-inch (25 mm) thick with a single 37 mm gun and a machine gun. Also noted was that it would carry two sub-machine guns, suggesting a crew of just 2 or 3. A final note is that it was designed to be carried under “a Douglas plane”.

This description is immediately reminiscent of the Christie promotional idea of an underslung high-speed tank from 1936. In that artwork, a 3-wheel Christie turretless high-speed tank was pictured being carried under an Air Corps bomber.

The idea for the rapid deployment of tanks by aircraft
The idea for the rapid deployment of tanks by aircraft appeared in Christie designs as early as 1936. Source: Popular Mechanics. May 1936.

An idea of quite how a system for carrying a tank in this manner under a plane would work can be found in a May 1941 Patent. This was filed by Alfred Anderson, assignor to the Armored Tank Corporation for a ‘Hook-on-and-Release-Mechanism for Fighting Tanks’. This invention describes an invention for attaching tanks to aircraft, specifically slung below the plane, and for dropping the tank when in flight. This is a different system to the one from Christie – that one used a pair of scissor arms to grab and retract the tank.

Instead, four upside-down triangular fittings would be attached on the underside of the fuselage of the aircraft. Each held a hydraulically controlled actuator with a large stud pushed out on a spring. When hydraulic pressure was applied, this spring would compress withdrawing the stud back inside the actuator. This would release the tank, as these four studs were attached via holes into the body of the tank. These would not be disengaged simultaneously, but in pairs. The rear pair would disengage first, allowing the bottom of the tank to hang down as the carrying plane swooped in suicidally low over the ground. At a suitable point, the front studs would also then be disengaged releasing the front of the tank. The back end of the tank was then supposed to hit the ground first from a lower height, with the front end following. This method was intended to overcome the turning effect on the vehicle. The dangers to the vehicle crew and to the aircraft performing this maneuver cannot be overstated; this was really a system designed to get the plane and its tank shot down. Even if it did work and the tank was deposited safely to the ground, one wonders how long it would take the crew to become operational after such an experience.

Hook on and Release Mechanism for a Fighting Tank.
Hook on and Release Mechanism for a Fighting Tank. US Patent US2310887 of 1941
Christie M-1950
A depiction of the gantry arrangement on top of what is supposed to be the ‘Christie M-1950’ (albeit with a different number of road wheels). The gantry could not only attach a tank, but also raise it within the fuselage of the aircraft. Source: Steel Steeds Christie

The vehicle shown in that 1936 promotion art for Christie is different from the vehicle in the 1940 ATC advert though. For sure, ATC got a Christie High-Speed Tank but its vehicle is much closer to a vehicle the size of the M3 Stuart or even the M1 Combat Car. What can be seen from the advertising image is that it was a small tank with a distinctive rounded back end to the hull running on four closely-spaced Christie type wheels (and presumably Christie spring suspension too). No track guards or mud guards at all are shown. The track itself is very similar to the flat plate track of the Christie tanks.

The nose lacks any indication of the pointedness of the earlier Christie High-Speed tanks but is uniformly rounded leading to a long glacis sloping up to a slightly inclined driver’s plate. Where the glacis meets the driver’s plate, there are two structures that appear to be mounts for fixed hull machine guns. In 1940, it should have been obvious that fixed, forward-firing machine guns were utterly useless but it was an easy way to add what was thought of as additional firepower to a design and many tanks subsequent and independent of this one retained this feature, including the M3 Grant, M4 Sherman, and Canadian Ram.

The driver’s plate featured two rectangular hatches, each with a vision slit. Out of the front of the left hand hatch was what appears to be a heavy machine gun. From the position of the hatches and hull weapons, it would appear to have had a driver mounted on the right and hull machine gunner on the left. A third man, the commander, would most likely occupy the turret. The turret itself, as drawn, is very unusual, looking like an overturned cooking pot. On the roof was a full size (it occupies the entire roof) hatch in two parts, each opening sideways. A series of slits were placed around the exterior of the turret and at least two machine guns, one forwards and one to the left. In total, the firepower for this vehicle as drawn was 4 machine guns and one heavy machine gun.

Presumably, the part about being built in ‘all weights’ was to mean that different options in terms of fittings, armor, and weapons were potentially on offer. Certainly, the specifications and look of the vehicle were very up to date given the parlous state of US tank development at the time. The T4 medium tank, for example, from 1935/1936, was a very promising design but was 13.5 tons and capable of just 35 mph with 3 machine guns. The Bechhold tank was, at least on paper, better armed, better armored, smaller (about 50 cm shorter), and faster. No surprise then that it was an interesting prospect for investors interested in lucrative future army orders.

The 13.5 ton Medium Tank T4
The 13.5-ton Medium Tank T4 – at 13.5 tons (12.2 tonnes) this tank was armed only with machine guns and was not adopted. Source: Wiki

Investment

The potential of the A.T.C. tanks from Bechhold’s company had indeed gained attention. In June 1940, a British Purchasing Commission had arrived in the USA to look at the possibility of producing and purchasing tanks for the war effort. Great Britain had, of course, been at war since September 1939, and June 1940 was just after the evacuation of Dunkirk, a time when a lot of British armor had already been lost on the continent with the fall of France. Great Britain and its Empire now stood resolute against the Axis of Germany and Italy but it desperately needed tanks and arms to fight the war.

The same month, Bechhold managed to interest John MacEnulty, the President of the Pressed Steel Car Company, in tank production and a five-year contract (renewable for up to 2 years) was signed on 23rd July 1940. Under the terms of this contract, Pressed Steel would gain exclusive rights to the production of tanks from A.T.C. (notwithstanding that a non-exclusive Belgian production license had already been signed). Under the terms of the contract, Pressed Steel would pay A.T.C. a royalty of $750 for each vehicle of A.T.C.’s design ordered for production by the US or Foreign Governments at Pressed Steel. A.T.C. was to provide plans, drawings, technical advice and, if required, a skilled engineer to assist in production.

 John F. MacEnulty, President of Pressed Steel Car Company
John F. MacEnulty, President of Pressed Steel Car Company from 1937. Source: Railway Engineering and Maintenance Vol.34

On 25th October 1940. Pressed Steel entered into an agreement with the British Purchasing Commission for the production and delivery of 501 M3 Medium tanks. These were not tanks designed by A.T.C. but Bechhold did assist in the completion of the contract arrangement and the British sent an advance of US$500,000 to Pressed Steel. The next month, November 1940, Pressed Steel paid A.T.C. US$75,000 under the terms of the July 1940 contract with US$300,000 remaining to be paid.

It is not clear though why Pressed Steel paid this commission to A.T.C. as the vehicles being produced were Grant tanks and not the Christie-based tank design from A.T.C. Despite the huge sum paid to ATC, it was in trouble. Bechhold had finagled matters so that after October 1940, only he held all of the Class A shares in the company, and therefore had exclusive voting rights for A.T.C. He had also increased the number of shares available from 100 to 10,000 (3000 Class A and 7000 Class B) with a reduced value of just US$1 each.

British Interest

The desperate need for tanks meant that the British were rapidly building their own in industries repurposed from civilian work to war work, but they were also looking for American production too, as this would not be affected by the manpower shortage in Britain or by German bombing. As well as the order for the M3 tanks from Pressed Steel, various other options were being considered and the work of the Purchasing Commission continued into 1941.

One particular type of vehicle that the British were interested in was an airborne tank,namely a tank which could accompany parachute or glider-borne troops. The lightweight and compact Bechhold tank was obviously of specific interest. On 27th February 1941, on behalf of the British committee in charge of evaluating tank designs, a telegram was sent to the Consul General in New York regarding the tank situation. The British were clear on what they needed from an airborne tank:

3 man crew
37 mm gun and .30 calibre Browning in a 360 degree rotating turret (quite why a 37 mm gun was specified in preference to the 2 pounder which was already an excellent gun and fielded on the A.17 Tetrarch is unknown but it is probably to do with the 37 mm being easier to produce in the USA)
Space for a wireless
Maximum Speed 40 mph (64 km/h)
Radius of Action 200 miles (320 km)
Armor basis ‘preferably’ 40-50 mm on the front and turret. 30 mm thick sides
Weight about 9 tons (9.1 tonnes) (anything under 9 tons was felt to lack the fighting qualities required) (for reference: the A.17 Tetrarch weighed just 7.6 tonnes)
“Not very interested in dropping Tank from a height of two feet”

In other words, the idea of dropping the tank from a plane was not wanted at all. Either it had to be landed directly (some various schemes for adding wings to tanks were considered), or it had to be unloaded from an aircraft. Dropping it from underneath a plane was, quite rightly, seen as a terrible idea. These requirements exceeded those of the Bechhold tank from A.T.C. That vehicle lacked the armor and firepower required and was inferior to the available A.17 Tetrarch when what was wanted by the British was basically a better armored version of the Tetrarch. The British were also anxious to get an airborne tank as soon as possible and were hoping for interest from the USA in manufacturing the vehicle. The Bechhold tank was, therefore, not suitable for their needs as it was noted that a pilot model had not yet been built.

By the end of March 1941, British plans for “the Bechold [sic: Bechhold] Project” were over. Having analyzed the tank, the British reported that: “The tank will not have the essential fighting qualities for the operations in view” and would also divert production from heavy bombers. The matter was left in the hands of American authorities to pursue and oversee its development. In its place came consideration of a 9-ton (9.1 tonnes) tank to be carried by towed glider. A final comment on the matter, from 30th April 1941, was that it had become clear to the British that the “American War Department feel they have no capacity to devote to the development of air-borne tanks”. As the decision was that Bechhold’s tanks should be overseen in America rather than from Britain it was decided that no action be taken on the Bechhold tanks.

Sold Off

The British had not been convinced by Bechhold’s salesmanship. They had, after all, already been down the Christie suspension vehicle route with the purchase of a Christie M.1931 which became the A.13E1 in 1936/7 and they had extensive experience with light Cruiser type tanks already. They also had plenty of small light tank designs including the A.17 Tetrarch. They had been clear on what they wanted but Bechhold was either unable or unwilling to comply, or simply could not produce a prototype, which was required before a decision could be taken. With the British unconvinced and an already lucrative deal with Pressed Steel in place, Bechhold had other plans.

Shenanigans and Taxes

In February 1941, A.T.C. sold its original Christie tank for just US$3,500, (Bechhold had bought it for US$5,000 in 1939) and on 18th August that year, A.T.C. incorporated as a corporation in Delaware to avoid payment of New York franchise taxes. This was completed on 20th August and the shares changed to just 100 Class A and 9,900 Class B shares with Bechhold, of course, retaining all the Class A shares and the voting rights that went with them (he also held 6,400 of the Class B shares too). Between 2nd and 4th September 1941, A.T.C. signed over all assets and the July 1940 contract (with Pressed Steel) to a newly incorporated body in Delaware, meaning the New York ATC effectively disappeared, although it was not formally dissolved until 11th September 1941. Mr. MacEnulty of Pressed Steel wrote to Bechhold on 4th September 1941 informing him that the July 1940 contract was now canceled due to alleged misrepresentations by Bechhold and a legal fight ensued.

Bechhold was insistent that he was owed money from Pressed Steel and, despite being offered US$300,000 (the remaining balance from the British Purchasing Commission contract), Bechhold refused due to the tax liability involved. His counter-offer was US$1.5m and this was immediately rejected. Instead, Pressed Steel suggested it should buy all of the remaining shares of ATC for US$50 per share (10,000 shares at US$50 would mean a US$500,000 payday). This would mean the end of Delaware A.T.C, which would have to surrender all its designs including an “aero” (airborne) tank concept, a full size model of the hook and release mechanism for releasing a tank from an airplane, designs of various other tanks and flamethrowers, and cash. This offer was considered and changed on 3rd October 1941 with a value of US$37.50 per share (US$375,000), but this would be only the existing July 1940 contract, no other plans or designs. This was agreed to by the voting members of Delaware A.T.C., which was just Bechhold, who of course approved of this arrangement.

In order to facilitate this transaction, the Delaware incorporated A.T.C. was changed from any mention or use of Armored Tank Corporation to the ‘Illinois Tank Corporation’ (I.T.C.) on 14th October 1941. On this day, just as Armored Tank Corporation (Delaware) was bought out by Pressed Steel and changed to Illinois Tank Corporation, Bechhold started a new company in Delaware. He called this new company the ‘Armored Tank Company’ once more receiving all of the assets from the original A.T.C., other than the contract, which had now gone to I.T.C. The next day, the new A.T.C. handed over all of its shares to I.T.C. which was then distributed to the stockholders, which also included Bechhold.

From these corporate shenanigans, Bechhold netted himself a cool 100 Class A shares (100% of the voting power), and 6,400 Class B shares valued at US$243,750 in total. This 15th October 1941 payment of US$375,000 (tax year 1941-1942) was to have serious consequences for Bechhold and his creative accounting.

Following this 15th October takeover though, the original July 1940 contract was finished. Bechhold probably felt he had made enough money and the entire business of the Illinois Tank Company was wound up suggesting that what assets in terms of tank designs it might have had leftover had little to no value. I.T.C. formally dissolved on 22nd November 1941.

Certainty

The substantial pay-off which Bechhold had received was classed as personal income. He, and the other stakeholders, were found to be personally liable for taxes of this income. If there is one certainty greater than death and taxes, then it is taxation in time of war. Taken to court for non-payment of taxes, Armored Tank Corporation admitted an error in its tax liabilities and was assessed to be liable for the sum of US$390,144.91 (including US$78,028.98 in tax penalties on top of its original 80% tax liability of US$312,115.93).

This was not the end of it either, for the individual shareholders of the Armored Tank Corporation/Illinois Tank Corporation were also found personally liable for back taxes and penalties. Stockholders Philip Steckler and Hamilton Allen were found liable for US$33,750, and US$22,500 respectively, and Max and Siegfried Bechhold were found liable for US$243,750 and US$45,000 respectively. A massive combined penalty of US$735,144.91 (over US$12.8m in 2019 dollars) for not paying taxes on that US$375,000 (US$6.5m in 2019 dollars) income demonstrated the danger of trying to dodge taxes in wartime.

Accessories

A.T.C. did not just produce a tank design. One of the more unusual things it designed and produced was a trailer for vehicles. This design appears in a letter dated 19th May 1942 from the Office of the Chief of Ordnance to the Commanding General of Aberdeen Proving Grounds (A.P.G.). Confusingly though, the product in question was produced by the ‘Armored Tank Corporation’ of Jersey City, New Jersey, suggesting that Bechhold kept working on designs incorporated in a different state. It is unlikely to be a mistake as A.T.C. (NY) had ended in September 1941 and I.T.C. (DE) ended November 1941. It is undoubtedly the same firm reborn, however, as the person providing information to A.P.G. on behalf of A.T.C. (NJ) was none other than ’Mr. Bechhold’ himself.

Rota-Trailer Model 4
A.T.C.(NJ) Rota-Trailer Model 4 during testing at A.P.G., Summer 1941, hitched to the rear of a half-track. The tests did not go well. Source: The_Chieftain – WoT forum

The proposal to the military was not this time a tank, but a trailer capable of being used for hauling supplies, equipment, or fuel. According to Mr. Bechhold, the British were interested in this trailer and the report recommended that APG experiment with it over a 250 mile (402 km) course to assess its viability, showing it off to the army and British representatives respectively.

This trailer was known as the ‘ROTA-TRAILER’ and the name stenciled on the side during trials stated this was the ‘Model 4’, suggesting the other 3 models or designs were less well refined. This Model 4 trailer consisted of two large hollow wheels fitted with a 40 inch (101.6cm) rubber tire 5 inches (12.7cm) wide. The wheels were unsprung but could hold up to 60 imperial gallons (272.8 liters) of fuel, either petrol or diesel, and were covered in rubber to provide a ‘self-sealing’ effect if the wheel hub were punctured by ammunition up to .50 caliber. Between the two wheels was a large rectangular cargo compartment made from ⅛” thick (3.175 mm) thick welded steel. This large space inside could be fitted with an ammunition rack for tank or artillery shells (34 rounds of 75 mm or 108 rounds of 37 mm), small arms ammunition boxes, ration boxes, water or fuel cans, or other items that were required. A second, smaller compartment below this was specifically designed to hold four boxes of .30 ammunition.

Top-down view of the Rota-Trailer Model 4
Top-down view of the Rota-Trailer Model 4 from A.T.C. (NJ) with top cover open. It contained 3 specimen shells in a rack, two 5-US gallon (18.9 liter) ‘flimsies’ and three boxes of rations. Source: The_Chieftain – WoT forum

At the back of the trailer lay a third compartment, smaller than the first, and which contained a hand-operated fuel pump and supply hose long enough to feed the towing vehicle. Below this compartment lay a fourth compartment (just like the one at the front) which held stowage space for tools.

A.T.C.(NJ) Rota-Trailer Model 4
A.T.C.(NJ) Rota-Trailer Model 4 pictured during testing at A.P.G. Summer 1941. Source: The_Chieftain – WoT forum

Overall, the trailer was very complex containing many bespoke parts that made for complicated maintenance. The doors to access the items inside were fitted with wing nuts (butterfly nuts) but were overly laborious to unscrew to access the contents. This is something that could easily have been rectified in a production model.

Rear view of the Rota-Trailer Model 4
Rearview of the Rota-Trailer Model 4 from A.T.C. (NJ) with hand pump (top) and toolbox (bottom) open for inspection. Between the two is a towing hook for additional trailers. The narrow tires and very wide wheel hubs are apparent in this image. Source: The_Chieftain – WoT forum

The Rota-Trailer not only had these internal compartments for stowage but also the ability to have a multitude of items carried on top. A special frame was fitted which held three 5-US gallon (18.9 liter) oil cans, and various tie-downs allowed other accessories such as nets or tarpaulins or other stores to be lashed to the top of the trailer.

Testing

Despite looking good on paper, capable of extending the fighting range of a tank, the trailer had serious problems. It was tested by an M4 Sherman and two different half-tracks over a 26 mile (42 km) cross country course and 250 miles (400 km) of gravel roads and, whilst it was on a flat surface, like a road, it worked well with little bouncing. The trailer was heavy too: each wheel weighed 400 lbs (180 kg) empty and 800 lbs (360 kg) when full in addition to the weight of the other material carried. The weight of the trailer placed additional strain on the drivetrain of the towing vehicle and, during rough travel off-road, the stress and strain on the trailer risked serious damage. On top of this, the trailer reduced the maximum speed of the vehicle towing it because the instability of the load caused by the sloshing liquid in the wheels threatened to result in sideways skids at high speeds.

Even as it was, the semi-rough terrain traversed ended up with all of the cans of water inside or on top of the trailer becoming deformed and leaky but the trailer did at least provide self-floatation in mud due to the width of the fuel cells. Another downside was that the lower front compartment, just 8.75 inches (222 mm) from the ground had a tendency to become filled with mud which was forced into it.

A final problem with the trailer was that it made reversing more difficult. During testing with an M4, the trailer skewed to one side and the stress caused damage to the towing arm and the tank tracks rubbing against the trailer body.

Model 4 from A.T.C. (NJ) after testing, the twisted tow arm
View of the Rota-Trailer Model 4 from A.T.C. (NJ) after testing, the twisted tow arm and torn section of the front having been caused by contacting the tracks of the tank. Source: The_Chieftain – WoT forum

Overall, the tests of this A.T.C. product were a failure and the vehicle was not recommended for use. Its main faults were:
Difficult to reverse
Additional strain on the drivetrain of the towing vehicle
Reduces maximum possible speed of the towing vehicle
Too heavy to move easily by hand
Too little ground clearance
No suspension
Steel body is not resistant to small arms fire

None of these faults were to stop further ideas, designs, and experimentation with trailers for hauling fuel or stores by tanks, but the work from A.T.C. (NJ) on this matter was effectively dead. No more is known of A.T.C. after this time; possibly Bechhold’s resources had simply run out and this venture failed, although it is noteworthy that on 1st February 1943, despite the failings of the Rotatrailer, the British still ordered 600 of them anyway, although how many were finished or delivered is less clear.

In the Army

Siegfried Bechhold, aged 42, in October 1942 joined his second Army. His first was a German one in WW1, his second, an American one in WW2. He served as a private being sent to Camp Lee in Virginia. He is not believed to have been sent overseas.

Re-born once more?

The back end of the hull of the Bechhold Tank seen in the November/December 1940 advert is very similar to the vehicle shown to the US Army Ordnance Department in May 1942 known as the Bigley Gun Motor Carriage suggesting a possible link to that vehicle. Was, in fact, the Bigley GMC the M.1938 High-Speed tank from Christie, bought and modified by A.T.C. and then sold off, redeveloped and re-submitted by another firm? Or is it in fact the other Christie tank, the M.1937 sold off by his creditors to Mr. Becchold. On the balance of the evidence, the former case appears to be correct.

Bigley GMC seen in May 1942
Bigley GMC seen in May 1942. Source: US Army Ordnance

By the end of WW2, Bechhold had left the field of tanks and the complications of military work. By 1948, he was living in Florida where he headed the Ribbonwriter Corporation of America, selling parts for typewriters. Siegfried Bechhold died in California in 1956.

A rendition of Bechhold’s tank, as shown in the ad published in the November/December 1940 issue of the Army Ordnance Magazine. Illustration by Adrielcz, funded by our Patreon campaign.

Sources

Army Ordnance. (November-December 1940). Super Tanks. Vol. XXI.
The Camden News. (27th June 1941). Russians now seek to buy tank designs refused them during Finnish War. Arkansas, USA
Cypher Telegram. (8th March 1941). No.1456 Supply to the Consul General in New York. For Dewar from Burton T-59.
Gray, C. (16th July 2006). A Notable Block with a Hole in its Heart. New York Times, New York, USA
Second Circuit of Appeals. (10th July 1939). Bethlehem Engineering Export Company v Christie 105.F.2d 933 (2d Cir. 1939)
Indianapolis Star. (26th January 1941). U.S. Help Brings Joy to Greeks. Indianapolis, USA
The Jewish Floridian. (24th December 1948). New Typewriter Device Produced by Dania Firm.
Keough, F. (November 1918). Contents. American Industries: The Manufacturers’ Magazine. Vol. XIX, No.4.
Nielsen, K. (2012). Pressed Steel!. Author House Publishing
Ogden Standard Examiner. (1st June 1941). Flying Tanks. Utah, USA
Pearson, D., Back, R. (9th August 1941). The Washington Merry Go-Round. Nevada State Journal.
Popular Mechanics. (May 1936). Fast-Tank and Plane Latest War Machine.
Pinedale Roundup. (29th October 1942). No Cellophane Commission. Wyoming, USA
Railway Age. (2nd December 1939). Meetings and Conventions. Railway Age, Vol.107, No.23.
Railway Engineering and Maintenance. (January 1938). Supply Trade News.
San Bernadino Sun. (13th April 1941). Breaking Nazi Morale. Volume 46, 1941.
San Francisco Examiner. (8th February 1956). Siegfried Bechhold dies in Santa Rosa Hospital. San Francisco, USA
Strausbaugh, J. (2018). Victory City: A History of New York and New Yorkers during World War II. Twelve Publishing.
United States. (1949). Reports of the Tax Court of the United States, Volume 11. US Government Printing Office
Office of the Chief of Ordnance, Bigley Tank, OCE, Washington D.C., USA
United States Tax Court. (20th October 1948). Armored Tank Corporation v. Commissioner. Docket No. 9786, 9769, 9770, 9771, 9772, 11916, 1919, 11920, 11927
US Patent US2310887(A). Hook-on-and-release mechanism for fighting tanks. Filed 6th May 1941. Granted 9th February 1943.
Weir J. D.G. Mech. E. (24th March 1941). Memo to Sir James Lithgow.
Weir J. D.G. Mech. E. (24th March 1941). Memo to Air Marshall Dawson.
Weir, J. D.G. Mech. E. (30th April 1941). Memo to A.R. 2 War Office via DAFV.
Wrynn, C. Major. (1st February 1943). Rota Trailers – Memo.. 1/Rel/ Equip Armd/1
The Chieftain’s Hatch 28th March 2014. Trailer, Ammunition and Fuel Part 1. 
Christie, J. (1985). Steel Steeds Christie. Sunflower University Press, Kansas, USA

Categories
WW2 American Prototypes

Light Tank T3

USA (1936) Light Tank – 1 prototype

Light Tanks T3 Source: AGF

The Light Tank T3, made in the late 1930s, occupies a period of time in US tank development history best described not so much as a dark age but more of a grey age. Lots of failed and somewhat obscure ‘T’ number designs were being developed to fulfill an unclear and poorly considered set of strategic goals at a time when an isolationist America was unprepared to wage a modern war.

This relatively unknown and obsolete-before-it-was-even-finished tank is remarkable only for its unremarkableness, and that it was inferior in almost every way to tanks of other nations such as Italy, whose 2-man turretless light tanks were also identified as having serious failings in combat. Perhaps, the only thing to distinguish the Light Tank T3 is that it marks one small step in the process of development which eventually led to one of the most successful light tanks of WW2, the Stuart.

The design

The US Light Tank T3 started life in 1936 as an idea by Rock Island Arsenal (RIA) to produce a tank lighter than the Light Tank T2, which was due to go into mass production that fiscal year. At this time, weight was king. The US Secretary of State for War had decreed in the Spring of 1933 that 7.5 US tons (6.8 tonnes) was the maximum weight allowable for a light tank, so the goal was to keep the weight as low as possible. RIA had already dropped the British Vickers 6-ton-style suspension in favor of a double-wheel volute spring bogie from the Combat Car T5 for the Light Tank T2 in 1934. Thus, the suspension which was to form the basis of numerous American designs for the next several years had already been selected when the Light Tank T3 came along. With an attempt to be less than half the fully laden weight of the already light Light Tank T2 (weighing just 7.5 US tons to 9.7 US tons/6.8 to 8.8 tonnes depending on the variant), severe design compromises would have to be made.

The most obvious of these changes was the removal of the turret, followed by a significant overall reduction in size and the switch to a crew of just two instead of four on the Light Tank T2. The two crew were simply the driver on the front left of the hull, and the commander on the front right. The commander also had to operate the sole armament. In an effort to further reduce weight, some aluminum components were also used inside. Finished in March 1936, the vehicle was shipped to Aberdeen Proving Ground (APG) in Maryland in April that year. Here, on 23rd April, the Light Tank T3 was unveiled for comparative testing with the pilot model Combat Car T5 (a tank in all but name).

Pilot model of the Light Tank T2 (no armament fitted) Source: Hunnicutt
The 7.5 US ton (6.8 tonnes) Pilot Combat Car T5 (no armament fitted) Source: Hunnicutt

Engine

The Light Tank T3 was powered by a single V8 Ford car engine. Capable of delivering 83 hp at 3,800 rpm, with differential steering and a 4-speed transmission, the Light Tank T3 could manage a credible 35 mph (56 km/h) on a road.

This Ford V8 was later replaced with a Menasco air-cooled engine and as such was renamed Light Tank T3E1.

Suspension

The Light Tank T3 used a pair of dual-wheel bogies with rubber volute springs of a very similar style fitted to a whole generation of US tanks in WW2. These volute spring units, however, were the result of comparative testing with an experimental rubber torsion suspension. Details on what that suspension actually looked like are unclear but it is known that it failed repeatedly during testing and would need redesigning to be usable. It was not and was abandoned. When the Light Tank T3 was upgraded with a Menasco engine as the Light Tank T3E1, the volute springs were finally selected as the preferred suspension.

The Armament

The Light Tank T3 was very poorly armed, just a single .30 caliber (7.62 mm) machine gun located in the front right of the hull. Mounted in a ball, the range of motion was acceptable but still ultimately as limited as other vehicles such as the Italian CV.3, it faced forwards so could not fire to the sides or rear.

Armor

As might be imagined in such a small and light vehicle, the armor was woeful. No part of the Light Tank T3 was thicker than ⅜” (9.5 mm), with most of the armor being just 3/16” (4.8 mm) thick, enough to protect against small arms from the front but vulnerable to even a burst from a machine gun or shot from an anti-tank rifle. With such poor armor, it is no surprise that an idea was floated to increase the armor thickness to an unspecified value in another variant known as the Light Tank T3E2, with the issuing of the tank to the National Guard in mind. This was never completed and the Light Tank T3E2 was never built. There was also a T3E3 version that got as far as a study but it is not known exactly what the study was about and whether it was armor or automotive related or something else.

US Light Tank T3 pictured during trials on 13th March 1936. No armament is fitted but it does have a very shiny single front headlamp on the glacis nose and what appears to be some kind of siren on the mudguard. Source: Hunnicutt

Variants

T3E1: upgraded T3 with a Menasco engine. 1 converted.
T3E2: T3 project with increased armor. None built.
T3E3: unknown study project

Conclusion

When the Light Tank T3E1 was abandoned, it was not wasted. Instead, the remaining vehicle was stripped of its armament and converted into an experimental tracked carrier named the Cross-Country Carrier T5. The sole contribution of the Light Tank T3 is perhaps to show the futility of a two-man tank armed with just a single machine gun. The cost of the vehicle and the poor combat potential meant that, despite moderately good mobility, it was still a failure. Of the variants attempted, the Light Tank T3E1 was at least an improvement with a better engine but the E2 with more armor was dropped before it began. The Light Tank Tank T3E3 got as far as a design study but how far and quite what they were even trying to study is not clear. The concept was a dead end. The vehicle was converted to a tracked utility carrier and quite rightly consigned to the dustbin of US tank design.

With a soldier for scale, the tiny Light Tank T3 shows really just how small it was. Source: Hunnicutt
The T3 light tank was tiny, armed with just a single machine-gun and seating two crew members in the front compartment. The rear rounded compartment housed the engine. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

Specifications

Dimensions 11.25’ x 6.75’ x 4.5’ (3.43 x 2.06 x 1.37 m)
Weight 3.54 US tons / (3.21 tonnes)
Crew 2 (Commander/gunner, and driver/radio operator)
Engine Ford V8 Petrol (T3), Menasco air-cooled (T3E1)
Max. speed 35 mph (56 km/h)
Armament 1 x .30 caliber machine gun
Armor ¼” to ⅜” (6.35 to 9.53 mm) (T3), slightly heavier armor (T3E2)

Sources

AFV Data Series
Crimson, F. (1992). US Military Tracked Vehicles. Crestline, USA
United States Army. The General Staff: Its Origins and Powers
AGF Board. (1947). Development of Armored Vehicles Vol.1: Tanks.
Hunnicutt, R. (1992). Stuart: A History of the American Light Tank. Presidio Press, USA

Categories
WW2 American Prototypes

T21 Light Tank

U.S.A. (1942-1943)
Light Tank Design – None built

Introduction

When the US joined the war in 1941, their primary light tank was the M3 Stuart and, while this vehicle was acceptable for that time, there was an interest in a new light tank. In January 1941, the US Army started the T7 Light Tank program, however, by August 6th, 1942, this tank had grown in weight and size and was now reclassified as the M7 Medium Tank. With no replacement for the Light Tank M3 in progress, the T21 Light Tank project was started.

While no T21 mockup would ever be made, this mockup of the T20 shows roughly what the T21 would have looked like. (Photo: Stuart)

Development

With the need for a new light tank, representatives of the Ordnance Department and the Armored Force held a conference at Fort Knox on August 18th, 1942. where it was decided that they should use the new T20 medium tank as a basis for the light tank. It would mount the M3 75 mm gun and feature armor capable of holding up against .50 caliber rounds while being within a 20-ton limit. It was decided that, if possible, the M3 75 mm gun would be replaced with a 76 mm higher velocity gun. It was proposed that it could use the Medium Tank M7’s suspension.

Following this conference and additional studies, an Ordinance Committee Minutes (OCM) was issued in February 1943 detailing the new light tank. It would have a crew of 5, mount a stabilized 76 mm gun, and would have a top speed of 45 mph (72 km/h). However, at this stage, the engine, suspension, and various other aspects were not finalized and its weight had been increased to 47,000 lbs (21,300 kg) or 21 long tons. Final layout drawings were finished during March and submitted. By this time the weight had been increased to 51,000 lbs (23,100 kg) or 22.8 long tons, with the new top speed being intended as 50 mph (80 km/h).

There was also a second variant which existed for a short time called the T21E1. This variant was to weigh 22 tons, later increased to 23 tons, and would have thicker armor than the normal T21 while being able to manage 50 mph (80 km/h). It seems likely that the T21E1 program was accepted as the new T21, as later sheets state the T21 as having almost the same figures as the T21E1.

T20 Pilot 1
T20 Pilot 1; the T21 with VVSS would have been almost identical to this. (Photo: Pershing)

Armor

The initial armor for this tank was designed to only resist .50 caliber fire, being 1 1/8th inch (2.85 cm) on the hull’s front and 1.5 inches (3.81 cm) on the turret face. The hull’s side and rear armor was 1 inch (2.5 cm) and 3/4th (1.9 cm) of an inch, respectively, the turret’s side and rear armor were 1 1/8th inch (2.85 cm). At a later point, the armor on the T21 increased to be the same armor basis as on the M5 Stuart. The T21E1 project was to have the same armor as the M5 Stuart as well.

Firepower

The T21 was to mount the 76 mm M1E1 or M1E2 gun – the primary difference between these 2 guns being that one had a tighter rifling twist rate than the other. The rounds used by that gun included M62 Armor Piercing Capped (APC) and M79 Armor Piercing (AP), additional rounds including High Explosive and White Phosphorus. The gun was to have elevation and depression limits of +25 and -10 degrees respectively, as well as being gyro-stabilized. It also was to mount two .30 caliber machine guns, one co-axially to the main gun and another in a bow mount in the hull.

Suspension and Tracks

While it was initially proposed in August 1942 to use the M7 Medium Tanks Vertical Volute Spring Suspension or VVSS, it was later decided to utilize torsion bar suspension instead. The tracks that were intended for it were the 18 inch T49 type. Whilst the exact layout is unknown, the T21 would have had, it can be assumed that due to it being just a lighter T20, it would have been the same or very similar as on the T20E3. The T20E3’s suspension had a torsion bar and initially had 3 track return rollers per side, however later on, 2 additional ones were added, bringing the total to 5 per side. an idler wheel was attached to the front wheel to compensate for slack in the track.

T20E3 Pilot
T20E3 Pilot, externally, the T21’s suspension would have been almost identical. Note the 3 return rollers (Photo: Pershing)

Engine and Transmission

The engine for both the T21 and T21E1 was to be the Ford GAN, which produced 500 bhp at 2600 RPM. The transmission for both was the same 5-speed manual transmission utilized in the M4A3. The location for the engine and transmission is unknown, but again, due to it being just a lighter T20, it is likely that it would have been in the same position as on the T20, in the rear of the tank.

Fate

In March 1943, the design and layout were presented at Fort Knox to the Armored Force. They came to the realization, from their experience with the M7 Medium Tank, that the T21’s weight would continue to increase in the future, resulting in another under-armored medium tank. They then suggested that the T21 project be terminated and Ordinance replied in July 1943 by killing the project. Up to this point, no mockup or pilot vehicles had even been started. The fate of the T21E1 is unknown, but it was almost certainly canceled along with the T21 if it was still in development at that time.

T20E3 showing the later change to 5 return rollers
T20E3 showing the later change to 5 return rollers. (Photo: Pershing)

Conclusion

This design, like many before it, was a good idea on paper, but operational realities and desires soon lead to a situation where, like the M7 before, it was doomed to become too heavy to fulfill the light tank role and too light to fulfill the medium tank role. The discontinuation of the T21 program in March 1943 was met with the start of a new project, the T24, which would not be deployed until 1944, which in turn forced the US to continue having to field the M3 and M5 Stuarts up until the end of the war, despite their growing inferiority.

The T21 Light Tank was very similar to the T20 Medium Tank from which it was derived. Illustration by Andrei “Octo10” Kirushkin, funded by our Patreon campaign.

T21 Light Tank Specifications

Dimensions (L-W-H) 5.76 m x 2.98 m x 2.48 m
Total weight, battle ready 20.98 tons (47,000lbs gross)(21.31 tonnes)
Crew Five (Driver, Co-Driver, Commander, Gunner, Loader)
Propulsion Ford GAN
Maximum speed 45mph (72kph) on road
25mph(40kph) on 3% grade
12mph(19kph) on 10% grade
Suspensions Torsion bar
Range 1150 miles at 25mph (40kph) on roads
Main Armament Gyro Stabilized 76mm M1E1 or M1E2 gun with 70 rounds
Secondary Armament Two .30 Browning M1919 machine guns with 6000 rounds
Armor 1 inch (25mm) to 1.5 inches (38mm)
Production None

Sources

Pershing: A History of the Medium Tank T20 Series, R.P Hunnicutt.
Stuart: A History of the American Light Tank, R.P Hunnicutt.
R.A.C British Army Staff (AFV) Situation Report No. 5,7,9

Categories
WW2 American Prototypes

Barnes Two-Man Heavy Tank

U.S.A. (1938)
Heavy Tank Design – None Built

Lt. Colonel Gladeon M. Barnes from the US Army’s Ordnance Department casts a long shadow over tank development in the USA in the period around the start of WW2. Barnes was an interesting man, but some of his ideas and designs were demonstrative of a disconnect between his thinking and military reality.

One such example came in 1938 with the idea for a small heavy tank armed with a single machine gun. Quite what role such a vehicle was meant to fulfill is hard to imagine years after other users of such vehicles had already accepted the serious inherent limitations of a similar type of vehicle.

Inspiration

Somewhat oddly, the inspiration for this idea came from the Spanish Civil War. Section G-2 (the department responsible for Intelligence in the US Army) examined that conflict for lessons in a report titled ‘Tank Lessons from the Spanish Civil War’. They concluded that tanks were too poorly armored, used in too few numbers, and that they were not maneuverable enough.
In that war, the primary tanks being used were the German-supplied Panzer I, the Italian CV.3 series light tank, and the Soviet-supplied T-26 light tank. During that war, as G-2 correctly pointed out, tanks tended to be used in small numbers or alone and both the CV.3 series and T-26 had thin armor, around 14 to 15 mm maximum, meaning both were just bulletproof.

The T-26 had an advantage over the CV.3 in the addition of a turret-mounted weapon, whilst the CV.3 was stuck with its only armament in a mounting on the front left of the hull facing forwards. Neither tank was able to demonstrate much speed even though the CV.3 was faster, just under 30 miles per hour (48 km/h) compared to just under 20 miles per hour (32 km/h) for the T-26, although the overall effect was slight. Both tanks were too slow, both suffered from narrow tracks and a relatively underpowered engine. Any reasonable and objective assessment of the use of tanks in the Spanish Civil War would reflect this.

The Italians, for example, understood from the conflict the severe limitations of the CV.3 for tank vs tank combat and undertook work on turreted light tanks with some urgency. The Germans and Soviets likewise looked and learned. Why then did the US see a solution lying in a vehicle with the same sort of layout as the CV.3 but with less armament is difficult to comprehend.

The outline of Barnes’ concept for a 2-man heavy tank.(Source: Armor Magazine)

The design

Barnes’ concept was for a small light tank, just 7 US tons (6.35 tonnes) or so and just 11 feet (3.35 m) long. For reference, the Italian CV.3 was less than half the weight, shorter, narrower, and lower, and the Soviet T-26 was heavier and slightly longer, wider, and taller.

With a crew of just two, both men would have their work cut out for them. One man had to drive the tank and operate its radio, almost certainly sat on the left just like on the Light Tank T3. The other crew member would have to both command the tank and operate the armament and would sit on the right, alongside the other man. This is a very similar arrangement to the Italian CV.3, except the crew position/roles were reversed. It could be considered that these reductions in size and capability were, in fact, simply the means to get the most tank possible for the least money. However, here Barnes trips-up once more. He provided a cost estimate of US$20,000. In 1938, US$20,000 was a huge sum of money, equivalent to over US$350,000 in 2020 values, or roughly half the cost of a far more potent and useful Sherman tank.

Comparison between Barnes’ design and the primary Spanish Civil War Tanks

The 2-man heavy German Pz.I Italian CV.3 Soviet T-26
Crew 2 2 2 2
Armament 1 x 37 mm / 1 x .30 cal MG 2 x 7.92 mm machine guns 2 x 6 mm machine guns 1 x 45 mm & 1 x 7.62 mm MG
Dimensions
L / W / H
11’ x 6.5’ x 4.5’
(3.35m x 1.98m x 1.37m)
4.02 x 2.06 x 1.72
(meters)
3.03 x 1.4 x 1.2
(meters)
4.65 x 2.44 x 2.24
(meters)
Weight 7 tons (US)
(6.35 tonnes)
5.4 tonnes ~3 tonnes 9.6 tonnes
Speed
(off road/on road)
20 mph / 35 mph
(32 km/h / 56 km/h)
25 km/h / 37 km/h 42 km/h 42 km/h
Armour
F / S / R
1.5”
(38 mm)
7 – 13 mm 14 / 8 / 8
(mm)
15 / 15 / 15
(mm)
Note No turret Turreted No turret Turreted

The Armament

The drawing of Barnes’ vehicle shows a single machine gun and the annotation states this to be a single .30 caliber (7.62 mm) weapon with 60 degrees of traverse, presumably 30 degrees to each side. An alternative armament was also proposed, a 37 mm gun. Once more, this was to be mounted in the front, seriously limiting its potential effectiveness. On top of this failing, operating a gun is a lot of work to load, aim and fire and, perhaps because of this, Barnes did propose that it could be automatically fed. Thus, the commander would have to ‘only’ command the tank, aim and fire the gun. Even so, the tank, limited by the traverse of its gun, would still be inferior to the Soviet T-26.

Armor

If the CV.3 and T-26 were unsuitable, with armor only 15 mm at most, then the goal would be to have more, presumably to make the tank protected against automatic cannon fire such as the potent 20 mm Breda cannon which was a proven armor-killer in Spain. It would also mean anti-tank rifles would be less useful against tanks, so more armor was not an unreasonable goal. Barnes wanted up to 1.5 inches (38 mm) of armor on this small heavy tank. For the purposes of reference, the Czech LT vz. 35 (better known as the Panzer 35(t) in German service in WW2), a tank which is possibly the preeminent and most modern turreted tank of the era, had just 25 mm across the whole front. What Barnes was indeed proposing was a tank the size of the diminutive American Light Tank T3, a little larger than the Italian CV.3 light tank, but with armor heavier than most of the tanks then in European service. All that, just to carry a single and rather limited machine gun, a task the even smaller CV.3 did more effectively with two machine guns mounted together.

tiny Light Tank T3
With a soldier for scale, the tiny Light Tank T3 shows really just how small it was. (Source: Hunnicutt)

Maneuverability

The speed and agility of the vehicles in the Spanish Civil War were seen as a failure because they were insufficient. Therefore, Barnes should have been looking for a vehicle able to exceed the speed of the CV.3. Instead, he managed to make a vehicle which even under ideal circumstances was larger, heavier, and slower.

The power to weight ratio of this design was to be 20 to 25 horsepower per ton and, with an estimated 7-ton (6.35 tonnes) weight, that would mean an engine of 140 to 175 hp. Ideally, this would mean a top speed of 20 mph (32 km/h) on a slight slope and 35 mph (56 km/h) on a road. On paper, this all sounded good, but paper-designs are like that and a magic engine can be produced from thin air with imaginary performance. When the design meets reality, things change and this is exemplified by the Light Tank T3.

Although Barnes did not specify which engine was going to be used, the Light Tank T3, produced two years earlier in 1936 gives a good idea of the problems. Both vehicles clearly use a pair of volute-sprung bogies, each with two wheels and a front-mounted drive sprocket meaning the transmission was in the front. The Light Tank T3 is very similar in size, suspensions, armament, and appearance to Barnes’ idea and was fitted with a 221 cubic inch (3.62 litre) Ford V-8 engine. Despite being slightly over 3.54 US tons (3.21 tonnes), this vehicle had half of the armor Barnes was proposing and yet had the same top speed. The Light Tank T3 was the same size as Barnes’ idea, with half the armor and half the weight, and yet the same desired performance meaning whatever engine Barnes was considering would have to be significantly more powerful and yet fit in the same space as available in the T3. This was no small order, although the Combat Car T5 of 1933 had managed to cram a 235 hp air-cooled Continental R-670 radial petrol engine inside, all for 6.29 US tons (5.71 tonnes), albeit with armor around just ½” to ⅝” thick (12.7 to 16 mm).

US Light Tank T3 of 1936
US Light Tank T3 of 1936. (Source: AGF)

The closest vehicle, perhaps to Barnes’ idea, was not the Light Tank T3, but the Light Tank T6. Built in 1939, one year after Barnes’s 1938 concept, the Light Tank T6 departed from the suspension of the Light Tank T3, using just a single 2-wheel bogey with a volute spring and the large on-ground trailing wheel at the back along with a separately sprung half-bogey. Once more, the driver was to be on the left in another two-man tank but this vehicle was not armed at all. With armor up to 1” (25 mm) thick and weighing in at 9.75 US tons (8.85 tonnes), the Light Tank T6 was roughly the same size and gives a good idea of a potential power plant for Barnes’s tank, namely a pair of 8-cylinder Buick petrol engines. However, even so, it was more than 2 tons heavier and still had armor no thicker than 1” (25 mm) and, importantly, no armament. Comparing Barnes’ idea to both Light Tanks T3 and T6 shows how unrealistic it really was.

US Light Tank T6
US Light Tank T6. (Source: AGF)

Comparison between Barnes’ design and the Light Tanks T3 and T6

Light Tank T3 The 2-man heavy Light Tank T6
Date 1936 1938 1939
Crew 2 2 2
Armament 1 x .30 cal MG 1 x 37 mm / 1 x .30 cal MG unarmed
Dimensions
L / W / H
11.25’ x 6.75’ x 4.5’
(3.43m x 2.06m x 1.37m)
11’ x 6.5’ x 4.5’
(3.35m x 1.98m x 1.37m
Approx. 11.25’ x 6.75’ x 4.5’
(3.43m x 2.06m x 1.37m)
Weight 3.54 tons (US)
(3.21 tonnes)
7 tons (US)
(6.35 tonnes)
9.75 tons (US)
(8.85 tonnes)
Engine Ford V8 Petrol unstated Twin Buick 8-cylinder Petrol
Speed
(off road / on road)
? mph / 35 mph
(? km/h / 56 km/h)
20 mph / 35 mph
(32 km/h / 56 km/h)
? mph / 30 mph
(? km/h / 48 km/h)
Armour
F / S / R
¼” to ⅜”
(6.35 to 9.53 mm)
1.5”
(38 mm)
⅜” to 1”
(9.53 to 25 mm)
Note No turret No turret No turret

Conclusion

It is hard to see any merit in Barnes’ idea. The armor certainly would have provided excellent protection from the relatively small caliber weapons then in service on a lot of tanks, but those were the previous generation. Against a 37 mm anti-tank gun, like the type used in numbers in Spain to good effect, even 38 mm of armor was not going to be much help, although it would certainly have made the little tank impervious to infantry which did not have access to a cannon. What then was Barnes’ really proposing? A small lightly armed and heavily armored tank may have some utility against infantry but, with the only armament in the front it would, as the Italians found to their cost, prove untenable. If, however, Barnes was really considering a small tank destroyer then why bother with the armor at all. Concealment and maneuverability would have been of far more use and he could reasonably have mounted the gun on top in an open-setting for a wider arc of fire and more space to carry ammunition.

Both ideas were also stymied by the selection of just two crew. There was simply too much for two men to do in combat, so a slightly larger chassis would also have allowed a third or fourth man to operate the gun, but would also have severely increased the weight and decreased the mobility.

Finally, Barnes’ concept of mobility was flawed. There was no way he was going to get even more armor and an automatic 37 mm anti-tank gun into a vehicle no bigger than the 9-ton Light Tank T6, along with a larger engine and still have the same performance. Likewise, he could not have allowed the weight to go over 7.5 tons (6.8 tonnes), as this was the limit set in 1933 by the Secretary of War for light tanks, suggesting a reason behind the ‘heavy’ part of the name, and that is before the eye-watering price-tag for the vehicle was considered.

Illustration of Barnes Two-Man Heavy Tank illustrated by Yuvnashva Sharma and funded by our Patreon campaign.

Barnes 2-man Heavy Tank specifications

Weight 7 tons (6.35 tonnes).
Crew 2 (Commander/gunner, and driver/radio operator)
Propulsion Type unknown, 140-175 hp desired
Desired Speed 20 mph off-road / 35 mph on road (32 km/h / 56 km/h)
Trench Crossing 4 feet (1.22 m)
Armament 37 mm gun or .30 caliber machine gun
Armor up to 1.5 inches (38 mm)
Total production None

Sources

Bellinger, J. American Hetzer. AFV news Magazine 37(2)
AFV Data Series
Crimson, F. (1992). US Military Tracked Vehicles. Crestline, USA
United States Army. The General Staff: Its Origins and Powers
Christie, J. (1985). Steel Steeds Christie. Sunflower University Press, Kansas, USA
AGF Board. (1947). Development of Armored Vehicles Vol.1: Tanks.
Hunnicutt, R. (1992). Stuart. Presidio Press, USA

Categories
WW2 American Prototypes

G-3 Light Tank Destroyer

G-3 Light Tank USA 1941-1942
None Built – Plans Only

The G-3 Light Tank Destroyer was the product of the disorganized state of US tank design at the start of WW2. The United States of America formally declared war on Japan, one of the three main Axis powers, on 8th December 1941, following the attack of the US naval base at Pearl Harbor, Hawaii the day before. This was followed, on 11th December, by a declaration of war against Nazi Germany and Italy. The US had been selling arms to the United Kingdom for some time before this though and had started its own military build-up as well, increasing its army strength from just over ¼ million men in 1940 to nearly 1.5 million by the time of entering the war. Nonetheless, it would be some time before the American war machine was in full swing and it had squandered the honeymoon period from the war’s beginning in 1939 to do exactly the development work it needed to deliver an effective tank destroyer. The G-3 Light Tank Destroyer is emblematic of this failure by the US military as the design fails to accommodate the needs of the Army in a new era of tank warfare.

The Americans entered WW2 with a serious shortage of armor, just 8 battalions of tanks for the entire Army in 1940. The Army had been hamstrung by the determination that tanks were only there to support the infantry in tackling machine guns, leading to a lack of attention to the actual problems associated with knocking out enemy tanks with their own tanks. The speed of the German advance and destruction of the most powerful tank force in the world, France, in 1940 came as a further body blow to the US military, which realized it had a serious shortfall in capability to overcome. The US Army needed large numbers of powerful anti-tank guns quickly and this was a problem considering the main anti-tank weapon in service was the 37 mm towed gun which had only entered service in 1939. The Army, in fact, had not even started work on a dedicated anti-tank gun until 1936, and despite men like General McNair having pushed for mobile anti-tank battalions within Infantry Divisions, little had actually been done.

The Start

With little done in the run-up to declaring war and despite the bad news from France in 1940, it was not until April/May 1941 that General Marshall (Chief of Staff of the US Army) decided that a solution was needed to meet the shortfall in anti-tank capability. He instructed the Army’s G-3 Section, responsible for Operations and Training, with this task and, within G-3, this responsibility fell onto the shoulders of Lt. Col. Andrew Bruce. Specifically, Lt. Col. Bruce was tasked with dealing with “such unsolved problems as measures against armored force action”. This was the start of the tank destroyer branch and, at this time, nearly 6 months into the war, there were simply no vehicles for it. The most powerful gun on a tank at the time was mounted in the sponson of the M3 Medium Lee, the 75 mm M2 gun, a less than ideal solution.

The Requirement

G-3 quickly developed a list of requirements for a lightweight tracked vehicle. Fast and maneuverable, these vehicles were to be able to respond to actions where enemy tanks were encountered and then engage them. This required speed, but also a powerful gun. The one thing which was not a particular need was armor. Protection would be sacrificed to the need to bring a gun to the battle faster.

The Fast Tank

How do you get a tank to go quickly? – by taking away all unnecessary weight, such as all but the bare minimum of armor, just bulletproof would have to suffice. The turret could also go if necessary, saving a lot of weight directly, as it would not need turret traverse motors or a turret ring, but also indirectly as the gun could use mounts in the hull and be substantially lower, meaning a smaller vehicle. Maneuverability also meant the vehicle would need a powerful engine, and all of this would have to be carried on a suspension system capable of traveling quickly over rough ground. In 1940/41, there was a clear leader in this regard in the US, the ‘Christie’ system.

The essential elements of the Christie-type system relied upon large diameter wheels carried on a short arm connected to a large coil spring. It was already in extensive use by the British on their Cruiser tanks and by the Soviets on the BT series of tanks. The US, however, had said no. They had already closely examined and rejected the Christie design several years beforehand in favor of volute springs.

Volute springs had two large advantages over the Christie system. Firstly, they were more compact, and secondly, they removed the need to deal with the obnoxious Mr. Christie. So bad, in fact, was Christie’s reputation within US armor circles that, despite his designs having several advantageous features, the Army simply would not consider the vehicles. This attitude persisted even after Christie had divested himself of his designs, selling the rights off to a man named Bechold, who, in turn, would later sell them on to a man named Bigley. Both of those men (Bechold and Bigley) would learn the sting that Christie’s work carried with it and found no success either.

This need for a fast tank-destroyer though, meant a re-appraisal of the Christie system was needed regardless of the previous history between the establishment and the man. The volute-spring system worked but was simply not capable of dealing with the speeds that G-3 wanted. What this meant was that, by December 1941, G-3, through Lt. Col. Tharp, a G-3 General Staff Officer and strong advocate for the Christie-suspension tank destroyer concept, had managed to gain a small amount of interest in it, sending G-4 (responsible for supplies) their recommendation.

This recommendation was for a fast tank using Christie-suspension and carrying a 37 mm anti-tank gun. That vehicle would see development on the old Christie tank chassis owned by William Bigley. By the start of 1942, Tharp’s pressure had led G-3 to develop their own ideas for a fast tank-destroyer based on the now ‘Bigley’ chassis.

With the US entry into the war, the development of armored fighting vehicles required coordination and, to this end, a board was set up to manage things. This board, known as the Armored Vehicle Board (A.V.B) was chaired by Brigadier General William Palmer and often simply referred to as the ‘Palmer Board’. By October/December 1942, the Palmer Board was considering 15 different designs for tank destroyers, amongst them this design using the Bigley chassis. Of note is that one of the competing designs was what became the T49 from Buick.

Christie Airborne Gun Carrier Chassis
Difficult to read, the label says ‘Christie Airborne Gun Carrier Chassis’. Source: Armor Magazine

Engine

No engine is mentioned on the plans. It may be assumed that the engine inside was the same one that had originally been used in the Christie design, the 750 hp Hispano Suiza V12. With this engine the tank could, in theory, manage up to 60 mph (97 km/h) fully laden on a good road, although this would be lower off-road and also a dangerous and impractical speed to consider ‘the norm’. Nonetheless, the speed of the Christie design was undeniable and would likely be reflected within the thinking behind this G-3 concept.

Armament

The initial recommendation was to use the standard Army 37 mm anti-tank gun, but by the time the development work had begun on the Bigley chassis, the move towards a bigger gun was already underway.

By way of illustration, one of the rival designs, which went through a series of substantial changes, ended up as the T42. Even that vehicle did not meet requirements and was then redesigned once more (and redesignated as T49) by April 1942. When it did so, it was being considered for it to mount an American-made British 57 mm gun (6 pounder) instead of the original 37 mm gun considered suitable for anti-tank warfare at the start of the process. That decision was followed in July 1942 by the selection of an American 75 mm gun instead for the T49, ready for assessment in October/December that year. The T49 was later redesignated as T67.

As a turreted vehicle, the T42 (T49) mounting a 6 pounder or 75 mm gun was substantially more effective than the 37 mm proposed on the Bigley chassis and the result was obvious. The Bigley idea was shelved and the only known remaining drawing of the vehicle concept clearly shows it with a small-caliber gun. Whether the armament planned for the T42 was being mirrored by ideas to uparm the Bigley to match it is simply not known. If it was not changed, then it can be speculated that the Bigley tank-destroyer idea was dead sometime in the middle of 1942, when there was the switch to the British 6-pounder. Indeed, this would match with the death of the parallel idea, that of utilizing the Christie suspension taken from the Combat Car T4 to re-equip the T9 Light Tank chassis during the development of the 37 mm-armed GMC T42 in April 1942. That, in turn, had led to an unsuccessful Christie trailing-arm suspension concept for the first pilot model T49, although that too was dead by October, along with a myriad of other proposals to fill this fast tank destroyer role.

Even if heavier armament options had been considered for this G-3 concept, all hope for the Bigley was definitely over by the end of 1942 with the approval of the far more capable T49 platform. And, if any doubt remained, the selection of a 75 mm gun as the weapon of choice in January 1943 for the project put the final nail in the coffin.

Name Confusion

With all of the talk of Christie, Bechold, G-3, and Bigley, it is understandable how hard it is to keep track of what the actual name of the vehicle was. If that is not hard enough, the book ‘Steel Steeds Christie’ by Walter Christie’s son J. Edward Christie makes the matter worse. Here, a suspiciously similar tank using the hull shape of the tank (albeit with 5 return rollers) is being referred to as the ‘M-1943 Christie Tank’ and also as the ‘M-1950’, which is recorded in US Archives as the Bigley Motor Carriage when it had the 4 large road wheels.

The 'M-1943 Christie Tank'
The ‘M-1943 Christie Tank’ also known as the ‘M-1950’ as shown in Steel Steeds Christie by J. Edward Christie.
comparison between G-3 vehicle and M-1943
Reverse (from L to R, to R to L) image allows for a straightforward comparison between the vehicle considered by G-3 and the vehicle claimed by Christie as the M-1943
M-1936 Modified into Christie Tank M-1938
With its unmistakably similar lines, this vehicle is recorded by US Archives as the Bigley Gun Motor Carriage yet by ‘Steel Steeds Christie’ as the ‘M-1936 Modified into Christie Tank M-1938’: Armor Magazine

Comparing the vehicles it is clear that they share several common features such as the lines of the hull indicating a connection between the designs. However, the caption on the G-3 drawing shows Christie’s level of involvement with the name sticking with the suspension rather than the designer of this vehicle per se, despite the efforts of J. Edward Christie to postscript claim the design as his own.

Suspension

A real question mark though has to be considered as to what the final G-3 proposal was even to look like. Clearly, the suspension is the same type of angled ‘Christie’ units with a wheel on an arm controlled by an angled cylinder with a spring. Undoubtedly, this was a very good suspension system but was not without its faults either. Primarily, the problem with the suspension was that the springs took up valuable width on the vehicle. Four of the wheels, each relatively small, were on these arms and a fifth wheel at the back was attached in the reverse-position to the same axis as the drive sprocket. On top of this was a second balanced arm connected to the rearmost return roller which also served to feed the track at the correct angle to the drive sprocket whilst simultaneously pushing up on the track to keep it tight.
One additional note on the return rollers is that the lead-most roller is also drawn as if it was meant to be able to move. There is no springing or return arrangement for it to move back into its original position but a sprung return roller would also assist in keeping the track tight. The mechanism by which it was to do this is, however, not clear.

The sprocket too was a Christie-design leftover. This was not the normal kind of tank sprocket with a toothed wheel pulling a track around via gaps in the end connector of the track plates. This was actually patented by Christie in January 1937 in conjunction with Morris Commercial Cars of Birmingham, England and used a series of rollers mounted on a sprocket. These would draw the track by means of the central guides on the track plates and also move with them as the track is drawn over them to reduce wear.

A further arm was fitted to the front of the tank and appears to be connected to a short arm connected to a central pivot about which the arm could rotate. On each end of this arm was a bearing with a roadwheel. This arrangement was clearly sprung, but only on the top part of the arm. The spring was yet another of the cylindrical springs and was angled back just as sharply as the other ones. This arrangement was perhaps best considered to be in the manner of a see-saw (teeter-totter) where, as one side moves up or down, the arm rotates and the other side moves in the other direction. Balanced by a coil-spring to the top part of this arrangement it meant that regardless of the position of the arm and wheels relative to each other, that they would remain in contact with the track and help keep it taut.

 


Drive Sprocket and Double ArmsAngular Sprung Suspension Unit

Left: The unusual and ingenious system of drive sprocket and double arms with one arm for a sprung road wheel, and the other for a sprung-tensioning return roller. Right: An angular sprung cylinder suspension unit for a road wheel. Source: Steel Steeds Christie

Roller-Type Drive SprocketTrack Plates Designed by Christie

The roller-type drive sprocket and track plates designed by christie. Source: UK Patent GB474714 of January 1937

Layout

The basic hull shape was the same as the original Christie machine, that much is clear but the rest is not. The drawing from G-3 clearly shows some kind of superstructure on top. The superstructure would certainly increase the profile of the vehicle, but it doesn’t appear to be part of the actual tank itself. Instead, this frame appears to be part of a gantry system as used to attach the tank slung underneath or drawn up inside an aircraft, a particularly favorite pastime of Christie to suggest.

Gantry Arrangement on Top of Vehicle
Depicting the gantry arrangement on top of what is supposed to be the ‘Christie M-1950’, (albeit with a different number of road wheels). The gantry allowed not only to attach a tank but also to raise it within the fuselage of the aircraft. Source: Steel Steeds Christie

The small size of the wheels and the spacing between them would seem to indicate this was going to be a very light vehicle too, with the engine and transmission in the rear. Crew-wise there is little information other than that which can be inferred from the design. In the raised section on the hull, there was originally just a small raised cupola from which the commander/driver could observe the surroundings. There would also be space for a second man, presumably to operate the gun. There would still be sufficient space, albeit maybe not very comfortable considering ammunition storage and the breech of the gun, for another crew member, meaning a crew of 2 to 3 men.

Armor

Like all of Christie’s designs, armor was secondary to speed. In fact, for Christie, almost everything was secondary for speed. His designs were either bulletproof or barely bulletproof. In its original form, before being sold off to Mr. Bechold, the hull is reported to have been just ¼ (6.35 mm) to ½” (12.7 mm) thick. Speed, not armor, was to be the protection for the G-3 Tank Destroyer if it kept the same armor values.

Conclusion

It is not hard to see why this G-3 concept failed. It was not a future-looking design but a quick glance back to a past image of a tank in which the figure of Walter Christie loomed large. Undoubtedly, the Christie suspension was innovative with many desirable features but a barely-bulletproof, casemate-gun-mounting tank-destroyer armed with a 37 mm gun was hardly a reasonable competitor to a vehicle as capable as the T49 with a 75 mm gun. It would not be until July 1943 that the first actual descendants of this process, the M18 Hellcat started to roll off the production lines – the product of an unnecessarily long process started too late.

Illustration of the G-3 light tank destroyer, showing the very small size and the odd running gear. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon Campaign

G-3 Light Tank Destroyer Specifications

Crew 2-3
Dimensions
Armor bulletproof (roughly 0.25″-0.5″ or 6.35mm-12.7mm)
Armament 37mm gun
Engine Possibly Hispano Suiza V12 750 hp petrol
Speed Theoretically 60mph (97 km/h)

References

UK Patent GB474714 ‘Improvements Relating to Track Laying Vehicles’, filed 7th January 1937, granted 5th November 1937
Armor Magazine, November-December 1991. Christie’s last hurrah.
Armor Magazine, March-April 1992. The Origins of Torsion Bar Suspension.
Gabel, C. (1992). The US Army GHQ Maneuvers of 1941. Center of Military History, United States Army, Washington D.C., USA
United States Army. The General Staff: Its Origins and Powers
Christie, J. (1985). Steel Steeds Christie. Sunflower University Press, Kansas, USA

Categories
WW2 American Prototypes

Chrysler’s Improved Suspension M4A4

USA (1942)
Medium Tank – Blueprints Only

The Medium Tank M4A4 Sherman was an improved variant of the M4A3. The goal of the tank was to increase the speed of production of the M4 by using a new multibank engine and with a hull made from 5 pieces instead of seven. The longer and more complex engine would mean an increased length of track on the ground for improved performance of the M4A4 on soft ground, yet despite this, the M4A4 was not adopted by the US Army for use overseas. Early in the development of the M4A4, consideration was given to making us of the longer hull to improve the suspension. This led to the idea of using the ‘Christie’-style suspension from the T4 Medium Tank on this new Sherman. Whilst the M4A4 was built in large numbers and saw extensive service during World War 2 and later, the idea of using this ‘big-wheel’ suspension never left the drawing board.

M4A4 Sherman with the Vertical Volute Suspension System (VVSS) which Chrysler were investigating the replacement of with an improved big-wheel form. Photo: Mark Nash

Development

The design of the M4A4 began in February 1942. This new Sherman was going to be more mobile than the M4A3 by using the 435 hp Chrysler A57 multibank petrol engine. The selection of what was actually 5 engines fitted together created a crowded space within the engine bay, which necessitated a slightly longer hull than the M4A3. This was considered a tradeoff that could add a large number of tank engines into the supply chain which would aid in meeting their production targets. Further, the hull of the M4A4 was simplified, as it was made in fewer parts than the M4A3 (5 instead of 7), and featured a 3-piece final drive housing on the front instead of the single-piece final drive housing on the M4A3. This would improve the speed of repairs and maintenance on the tank although, initially, the complex engine arrangement had been unreliable.

Lengthening the hull by 11 inches (279 mm) in order to accommodate the engine also meant that the suspension would have to be lengthened. The M4A3 had used three pairs of volute spring suspension (Vertically Volute Suspension System – VVSS) and these could be spread out more along the slightly longer sides of the M4A4 or a new suspension system could be considered instead. This prompted a very short study by Chrysler, the design agent for the M4A4, to try and improve the performance of the tank by way of an improved suspension system. The system to be investigated was a modified version of that trialled on the T4 Medium Tank.

Rather than refit the three VVSS units, spaced out along the side, the idea was now to use five large road wheels connected on horizontal crank arms. Springing for the wheels was delivered by means of vertical coil springs mounted on the outside of the lower hull. This has been described variously online as being a ‘Christie Sherman’ or ‘Christie suspension’ but it really is not. The Christie patent for his system had already been sold off by then as well as licensed off to countries like Great Britain and the Soviet Union. One of the dominant features of Christie’s suspension design was the suspension springs operated within a double-wall cavity along each side of the tank. This system was adopted and adapted for use in tanks such as the British A.13 and Soviet BT-5 and remained in use on some tanks through to the end of World War 2. The British Comet, for example, was the last British tank to use a version of this system. This was not the case for this M4A4. Here, the springs would be mounted externally.

Christie, by February 1942, was almost a dirty word in US armor circles and had no formal involvement with the US Army. His last official contact had been with the Ordnance Department in March 1939 and ended when he had stormed out of a meeting in a tantrum when his demand for large orders for his tanks was rejected. He had stomped off saying he would go and see President Roosevelt and with that had ended any prospect of formal consulting work.

Consequently, attributing his name to this design would be incorrect. If there is any doubt on the matter, the somewhat awful book ‘Steel Steeds Christie’ published in 1985 by his son Edward and which makes numerous fallacious claims, makes no claim to this design. The T4 suspension design was certainly based on the work of Christie, but the first conceptualized drawings for a sprung suspension-arm suspension for the M4, prepared by the Ordnance Office in February 1942, had already departed from this arrangement.

T4

The T4 Medium Tank, built by Rock Island Arsenal in 1935 and 1936, weighed just 13.5 tons (12.2 tonnes). Different versions of the T4 were trialed between 1935 and 1940 when it was declared obsolete, but the key feature of the design was the four large road wheels on each side. The suspension of the T4 was certainly based on the suspension designs from Christie, but it did not use Christie’s patents. The track for the T4 was also a short-pitch type track 12 inches (305 mm) wide.

Medium Tank T4 showing the 4 large road wheel design with no return rollers. Source: Hunnicutt

The T4 weighed just 13.5 tons (12.2 tonnes), whereas the M4A4 would weigh 34.9 tonnes (31.6 tonnes), more than double the weight of the T4, so using the same suspension required changes. The T4 used just 4 wheels on each side, which would be inadequate for the extra weight of the M4. Thanks to the longer hull of the M4A4 though, 5 of these large-diameter wheels could be fitted on each side. The second change came about after the initial drawings from the Ordnance Board. Those drawings had shown the five, closely positioned wheels, each mounted on an individual arm with a corresponding spring cylinder angled forwards. To meet the increased weight of the M4, these springs had to be changed too. The solution here was to adopt heavier coil springs and to mount these vertically along the outside of the lower hull of the tank under the sponsons.


First plans for a T4 Medium tank-style suspension on the M4 Sherman, circa February 1942. Note the suspension springs are angled forwards rather than vertical. Source: Hunnicutt

Tracks

The adoption of the T4 style wheels was also met with the choice of a wider version of the T4 track. This single-pin track was 18.5 inches (470 mm) wide, wider than the standard M4A4 track and the original T4 track, and used a center guide to prevent lateral slippage. With 93 track links per side (compared to 85 on the T4) and the larger, heavier wheel, this new M4A4 was significantly heavier than the original volute-suspension M4A4 by 3,080 pounds (1,397 kg).

The volute-suspension M4A4 used either the T48 or T51 83-link 16.56 inch (421 mm) wide track with a ground contact length of 160 inches (4,064 mm), which was substantially longer than the M4A3 at 147 inches (3,734 mm). Using this T4 style suspension, the track length on the ground was only fractionally longer than that of the M4A3, at just 148 inches (3,759 mm), yet despite this shorter length of track in contact with the ground than the volute-suspensioned M4A4, the wider track made up for this and kept ground pressure to just 14 psi (96.5 kPa).

Front view of the Chrysler sprung swing-arm suspension M4A4 shows the width of the external springs on the sides of the outer lower hull (left), and with the additional width of the spring highlighted in pink (right). Source: Hunnicutt and Author respectively

With the new spring system fitted to the outside of the lower hull, this meant a lot of space was taken up under the sponson on each side. Consequently, the tracks and wheels would be further out than they would be if it had retained the VVSS system. This would have posed some additional issues regarding the transportation of the tank due to its increased width, about 450-470 mm wider than the M4A3 due to the projections of the track and the lack of space in which to add grousers to the inside of the track.

With the new spring system fitted to the outside of the lower hull, this meant a lot of space was taken up under the sponson on each side. Consequently, the tracks and wheels would be further out than they would be if it had retained the VVSS system. This would have posed some additional issues regarding the transportation of the tank due to its increased width, about 450-470 mm wider than the M4A3 due to the projections of the track and the lack of space in which to add grousers to the inside of the track.

M4A4 with VVSS (left) compared to M4A4 with T4 Style Suspension (right) showing the additional width of the M4A4 (not to scale). Source: Hunnicutt
M4A4 with VVSS (top) compared to M4A4 with T4 Style Suspension (bottom) (not to scale). Source: Hunnicutt

One final note of difference between the suspension systems on the M4A4 are the return rollers. Easily overlooked, the VVSS system used a small return roller angled back from the suspension bogie which served to hold the track off from fouling on the top of the bogies. No such rollers were drawn on the T4 suspension units to support the track. The angle of the track, as it descended from the front sprocket to the rear idler, would likely contact the top of the last roadwheel but other than that it was unsupported .

The final product. Five large diameter T4-style road wheels and vertical coil spring suspension on the M4A4. Note that the mantlet is misdrawn and should be further back, towards the turret front. Source: Hunnicutt

Conclusion

Despite the fact that the T4-style suspension was found by engineers at Chrysler to be workable, it was not pursued. The volute system was not ideal but it was simple and reliable. In the short-term, the volute-spring system was retained, although work on improved suspension for the M4 continued. No versions of the Chrysler vertical coiled spring suspension M4 were ever built. Despite 7,499 M4A4s being built, it only saw limited service with the US Army anyway, restricted mainly to training duties. It did, however, find extensive use overseas particularly with the British, where it was known as the Sherman V.



Illustration of Chrysler’s improved suspension M4A4. Illustration by Andrei Kirushkin, funded by our Patreon Campaign.

Specifications

Dimensions 6.06 m x 2.62 m (hull, 3.07 m to 3.09 m wide over tracks) x 2.74 m
Total weight, battle ready 72,780 pounds (36.29 US tons) (33 tonnes)
Crew 5 (commander, driver, co-driver, gunner and loader)
Propulsion 435 hp Chrysler A57 multibank petrol engine
Speed (road) 35 mph (56 km/h)
Armament M3 75 mm gun in M34 mounting
.50 calibre M2 AA machine gun
2 x .30 calibre M1919A4 machine guns
Armor 1.5 inches (38.1 mm) – 3 inches (76.2 mm) – 107.95mm

Sources

Armor Magazine, November-December 1991. Christie’s last hurrah.
Christie, E. (1985). Steel Steeds Christie. Sunflower University Press, USA
Gabel, C. (1992). The US Army GHQ Maneuvers of 1941. Center of Military History, United States Army, Washington D.C., USA
Hunnicutt, R. (1977). Sherman – A History of the American Medium Tank. Presidio Press, USA
Icks, R. (1969). The Fighting Tanks 1916-1933. We Inc. USA


Categories
WW2 American Prototypes

Heavy Tank T29

USA (1944-48)
Heavy Tank – 10 Built

The U.S. Army did not prioritize addressing the need for heavily armored tanks until very late in World War II, when the losses of Allied armor were increasing due to enemy anti–tank guns. The M4A3E2, a makeshift assault tank developed from the M4A3 Sherman, was only produced as a stopgap measure until the T26E3 Pershing was available for reinforcement. Unfortunately, these heavy tanks were still not considered enough.

The T29 was developed to solve this problem. Armed with a long-barreled 105 mm T5E1 gun in a heavily armored turret, and weighing over 66 tons (60 tonnes), it was intended to directly engage with any opposition, from fortified bunkers to heavily armored tanks. Over a thousand were planned for production, with the first tank being completed in July 1945, too late to see action against Germany in Europe. The production would continue for a planned invasion of Japan, Operation Downfall, until its cancellation after the nuclear bombing of Hiroshima and Nagasaki, followed by the surrender of Japan, ending the war in Pacific.

Even after WWII, experiences gained from the war were carried over to the T29 and the design underwent numerous experiments for postwar development studies, which led to the production of the 120mm Gun Tank M103.

T29 heavy tank at the Aberdeen Proving Ground on 31 October 1947. Source: Firepower

Prelude

The development of a new heavy tank was first requested by the Chief of Research and Engineering of the Ordnance Department, General Gladeon M. Barnes, on 1 August 1944. He called General John B. Waldron, the Assistant Deputy Commissary of the Ordnance, about an Ordnance Committee Minute for a new heavy tank project. Gen. Waldron told Gen. Barnes that the project must be considered before such a vehicle could be passed for production. The inspection of the tank details took place at the Detroit Arsenal on the following day by the Ordnance Board and the Armored Center. It was expected that the new vehicle would be armed with a 105 mm cannon.

On 14 September 1944, OCM 25117C specified that, in order for a tank of greater firepower to be developed to meet potential operational requirements against fortifications and heavily armored enemy combat vehicles, it was considered imperative that the development of such a vehicle should be initiated immediately. Preliminary studies had been made for the installation of a 105 mm cannon in a tank with cross-drive transmission, torsion bar suspension and center-guided tracks, all powered by a 750 hp Ford petrol engine.

These studies had indicated the feasibility of this project. It was recommended:

  • That four pilot vehicles in general accordance with the characteristics outlined in this item be procured for test. Two to be fitted with 105 mm gun and two with 155 mm gun.
  • That the vehicles with the 105 mm gun be designated as Heavy Tank, T29.
  • That the vehicles with the 155 mm gun be designated as Heavy Tank, T30.
  • That these projects be considered confidential.
Schematics of T29 Heavy Tank. Source: AFV Technical Situation Report No. 33

Development

The first concept of the Heavy Tank T29 was initiated on 1 August 1944 with a proposal of what was essentially an enlarged T26 heavy tank sporting a 105 mm cannon. The initial specification was laid out with OCM 25117, suggesting a heavy tank weighing 54 tonnes and having an effective frontal armor thickness of 8.9 inches (228 mm), with a front hull armor of 5 inches (127 mm) angled at 46°. It also had a large mantlet covering the entire front turret, with 7.9 inches (203 mm) of armor backed with an internal armored plate. The turret design was to be made as simple as possible, with a 4 inch (102 mm) thick turret wall with nearly vertical inclination and streamlined. It was to have a stepped turret roof identical to that of the T26 turret, although it was noted to be a flaw in the protection due to the potential threat of deflecting projectiles. A large bulge was to be constructed at the rear of the turret to balance the turret assembly and the gun mount likewise.

The original concept of the Heavy Tank T29. Source: Development History of the Heavy Tanks, T29 & T30

The crew arrangement placed the commander on the right side of the turret, provided with a vision cupola. The gunner was in front of him, with the loader on the left side of the turret, provided with a single escape hatch. The driver and the co–driver were in the front hull. The armament consisted of a 105 mm T5 L/48 gun (a derivation of the prototype 105 mm T4 anti-aircraft gun intended for tank use), using stub fixed-type ammunition with just a single loader. A muzzle velocity of 2799 fps (853 m/s) for the armor-piercing round was expected. The main armament would have an elevation ranging from –10° to +20° and a .30 caliber (7.62 mm) Browning M1919A4 machine gun would be mounted coaxially. An anti-aircraft .50 caliber (12.7 mm) Browning M2HB heavy machine gun was also placed on top of the turret to be used by the loader. The tank would be powered by a Ford V12 petrol engine and a new cross–drive transmission developed by General Motors. The suspension used a similar approach to that of the T26, with torsion bars and center guided tracks.

However, the initial specification was revised a month later in favor of increasing firepower and a design overhaul. The front hull armor was switched to 4 inches (102 mm) angled at 54°, while maintaining the same effective armor thickness as previously. The general design of the turret received minor changes. The front plate of the turret remained the same but the rear bulge was increased in depth and reduced in thickness to 3 inches (76 mm). The 105 mm T5 L/48 gun was replaced with a much longer 105 mm T5E1 L/65, using large separated type ammunition. The turret now accommodated two loaders for the new shell loading type. The muzzle velocity was increased to 2,998 fps (914 m/s). A muzzle brake was developed for the new gun as a blast deflector, designed as an enlarged version of the 90 mm gun muzzle brake.

Contracts were awarded to the Pressed Steel Car Company for the construction of the tank and to Buick for the transmission development. The first pilot turret was to be mounted on the M6A2E1 in order to conduct trials in place of the T29. The second pilot turret assembly was being produced in February 1945 and expected to arrive in June. At the same time, a further design had been prepared and a new wooden mockup was built. The design received major alterations, with the turret wall now curved throughout the side to reduce the height of the turret. The roof plate was crested in the center to clear the gun breech and sloped down to either side of the turret walls to prevent shot deflection inside the turret. The actual weight of the turret was unchanged, and any weight savings were used to increase the armor protection. The thickness had been increased; 5.9 inches (158 mm) from the front to sides, tapering to 5 inches (127 mm) on the centerline of the turret, and 102 mm to the rear. The rear bulge of the turret was thickened again to 102 mm. The turret body was cast with the roof and the floor welded in position.

Wooden mockup of the second turret. Source: AFV Technical Situation Report No. 34

The gun mount was redesigned with the 105 mm T5E1 repositioned so that it would balance on its trunnions without the need for an equilibrator (although the installation of a muzzle brake would negate this). The recoil distance of the 105 mm gun was limited to 12 inches (305 mm) and regulated by three hydraulic cylinders located above the barrel. A recoil guard was fitted to the gun mount and extended from the gun cradle to the breech face. The single coaxial M1919A4 was replaced with two M2HB for increased firepower.

The main sight for the gunner was an M10E5 periscope with dual sights, 1x for a wide field of view, and 6x for high magnification, fitted with a reticle graduated for the 105 mm T5E1. An auxiliary telescope M70E2, a special M70 direct telescope lengthened by 15.7 inches (40 cm), occupied the vision port on the right side of the 105 mm gun with 3x magnification. An azimuth indicator was located on the gunner’s right. Elevation was controlled by means of a vertical handwheel and traverse by powered hydraulic control. An emergency hand traverse crank was also available. The gun traverse was equipped with a 5 hp power unit to drive the pump. The turret could be satisfactorily traversed either manually or by power traverse on a 30° slope. The power traverse system was designed to allow turret rotation at a speed of 3 rpm (18°/second). A full 360° turret rotation took 20 seconds. A gun traverse lock was located under the traverse pump and in front of the gunner, which consisted of a toothed segment that could be clamped into the traverse rack.

The primary firing controls consisted of an index finger trigger on the handle of the power traverse gear operating the main gun. A thumb button was provided to fire the coaxial machine guns. Secondary foot firing gear was also arranged beside the main one.

Separate ammunition was issued for the 105 mm T5E1. The shells would be derived from the ones for the 105 mm T4 gun, with the T12 HE and T13 APCBC–HE, weighing 38 pounds (17.2 kg) and 41 pounds (18.6 kg) respectively, with 33 pounds (15 kg) of propellant charge. 63 complete rounds were stowed and 46 of the projectiles were packed in bins inside the racks on either side of the commander. It was intended that the commander should pass these projectiles to the loaders. Nine charges were stowed in ready racks, 7 for the left loader and 2 for the right loader. The remaining ammunition was stored in the hull. Additional stowage for 23 boxes (110 rounds each) of .50 cal machine gun rounds was provided.

The commander’s seat in the turret bulge with the cupola above. Source: AFV Technical Situation Report No. 34.

The turret crew was reshuffled to adapt with the second turret. The commander sat right behind the 105 mm gun, and the cupola was moved to the center rear of the turret. There were now two loaders stationed on both sides of the turret, provided with their respective escape hatches. The right loader had access to a pistol port to his side, and the left loader could use the .50 caliber machine gun mounted outside the tank. The gunner retained his original seat at the front right side of the turret, though now distanced away from the commander.

The gunner’s fire control, including telescopic and periscopic sights inside the second wooden turret mockup. Source: AFV Technical Situation Report No. 34.

Two pilot tanks were being constructed by the Pressed Steel Car Company in March 1945. The T29 was planned for production with as many as 1,200 units, with 2 pilots to become available earlier for preliminary testing. Chevrolet worked on the turret and gun mount. Frankford Arsenal was given a directive for designing and manufacturing the fire control installations. The development of the engine and transmission would be undertaken by the Detroit Transmission Division of General Motors, whilst Buick inspected the final drive. Work on the T5E1 was temporarily suspended pending details of the new rounds and chamber design. In the redesign, provision for the subsequent scavenging device installation was being made.

The pilot turret received some modifications during production. The elevating gear was now anchored to the turret ring, whilst the box which contained the nut and screw elevation gear was mounted on the gun cradle. The main ventilation for the crew consisted of a 28.3 m3/min fan set to draw air from an inlet between the driver and co–driver. In addition, there was a blower fan with an inlet on the right side of the turret bulge, close to the deflector guard, intended to suck gun fumes and blow them out through a hole in the right rear of the turret. The ammunition arrangement was reallocated. 27 shells would be stowed in the right and 13 in the left of the turret bulge. The 9 ready racks were switched in position, with 7 shells on the right and 2 on the left side of the turret. The remaining shells and charges would be stored on the hull floor inside an armored rack. The whole complete ammunition load weighed about 2.2 tons (2.08 tonnes).

Due to the favorable results from variable power sighting telescopes and the request for the standardization of the T122 as the M83 telescope for issue to tanks and tank destroyers armed with high-velocity guns, a project was initiated to develop a bigger telescope designed for the T29. The substitute M70E2 telescope that was carried over from the M6A2E1 was replaced by the new scope, designated as T143E1.

The tank’s weight increased significantly from 59 ½ tons (54 tonnes) to almost 68 tons (62 tonnes). This crippled any common transportation methods, as there was no adequate bridge capable of supporting the T29. The widened Bailey–type triple–double panel bridge would carry the tank over a maximum span of 110 feet (33.5 m) width. However, this bridge was under procurement and none were ready in stock yet. Heavy floatation bridges and dry ferries for up to 79 tons (72 tonnes) of loading were undergoing development, and expected to arrive by the end of 1945 (OCM 26825). A new 30 inch (762 mm) wide steel track, designated T93, was being developed and expected to replace the T80E3 track currently used by the T29. A reason for this change was that T80E3 was an asymmetric type of track, a combination of T80E1 and Duckbill extended end connectors, and therefore, not considered sufficiently robust or reliable.

The new rounds in development for the T5E1 gun were designed to replace the substitute rounds of the T4 gun, including AP, HE, and APCR. The T32 was a solid APCBC projectile weighing 39 pounds (17.7 kg), capable of penetrating heavy armor at high obliquity. The shell design had been completed, and it was anticipated that the performance would surpass the earlier T13 round.

At the same time, work on improving the T13 progressed mainly in heat treatment, in which early batches of T13 shells were considered unsatisfactory. Newly redesigned shells with the improvements were the T13E1, T13E2, and T13E3. The T13E1 was tested and resulted in sufficient performance in both the design and the heat treatment against 102 mm and 127 mm face-hardened armor plates at 20°. The T13E2 had a thinner cap and was made from WD–9465 steel, and reported to be superior to the earlier T13E1 against face-hardened armor. The furthest of the T13 design, the T13E3, differed with a single radius on the projectile body and reduced diameter explosive cavity, was produced from WD–4370 steel. Aberdeen conducted tests with both T13E2 and T13E3 against various homogeneous and face-hardened plates for comparison, and concluded that the T13E2, with its better heat treatment, was still superior to the T13E3.

A new T30 HE shell was being designed to replace the T12 HE that originated from the 105 mm T4 ammunition, designed to work at both high velocity for achieving maximum range of attack and low velocity against hardened structures. High Velocity Armor–Piercing shot (HVAP) was the latest of the 105 mm weapon development, intended to create a more effective anti–armor ammunition than the regular AP shot. The shell designated as T29 consisted of a tungsten core contained in a magnesium body fitted with a steel bourrelet band, magnesium ballistic cap, and a steel base with copper driving band. Up to four designs were made; T29 (7.9 lbs/3.6 kg core), T29E1 (9.9 lbs/4.5 kg core), T29E2, (12 lbs/5.4 kg core), and T29E3 (9.9 lbs/4.5 kg core). The latter round was a redesign of the T29E1 that was 2.8 pounds (1.3 kg) lighter (estimated weight around 24 lbs/11.1 kg).

Procurement of the Heavy Tank T29 was reduced, from 1200 vehicles to 1152 in April, with the approval of production starting next year (OCM 27331). 6 pilots were planned for construction in total (OCM 27245). The first pilots of the T29 heavy tank hull and turret were being constructed in July and expected to be completed in the same month.

The T29 was classified as “B” type heavy tank, indicating heavier type than the preceding “A” type heavy tank of the T26 series. At the time of the writing of this report, 6 pilots were planned for development with two in manufacturing, with subsequent production vehicles following up later. Source: AFV Technical Situation Report No. 36.

With the end of hostilities on the European front in May 1945, the production of T29s under the request from OCM 27331 was suspended as the heavily armored opposition that the T29 was designed to combat in Europe had already been defeated, leaving Japan as the sole threat. Amphibious operations against the Japanese forces were dangerous due to the coastal defense guns located inside heavy bunkers. The firepower of the 75 mm, 76 mm, and 90 mm cannons already available would not be able to damage their reinforced structures significantly. Seeking the advantages of using the 105 mm cannon of the heavy tank for this purpose, T29 resumed production in readiness for Operation Downfall, a planned large-scale invasion of Mainland Japan. Owing to the expectation of difficulty when traversing the mainland terrain with a tank weighing over 66 tons (60 tonnes), the development of the 30 inch (762 mm) wide T93 steel track was prioritized, although it was only on 1 July 1948 that the track would be completed and delivered to the T29 for testing. The track width had been reduced from the initial design to 24 inches (609.6 mm) during the development. It did not provide any substantial improvements over the asymmetric type T80E3 during the trials and the project was terminated in 3 September 1953.

The first T29 was finished in late July 1945 and located at General Motors’ Milford Proving Ground to provide data for the Detroit Transmission Division about its CD–850–1 cross–drive transmission. An equilibrator was installed to offset the added weight of the muzzle brake. The ammunition arrangement was redistributed again. 46 projectiles and 19 propellant charges would be stored in the turret, with the remaining ammunition stored in the hull. At the same time, the shell loadout for the T29 was standardized. Improved versions of the recently developed rounds would be made available for the gun to use; T32E1 APCBC, T29E3 HVAP, T30E1 HE, and a new burst–type white phosphorus smoke shell, designated as T46 WP.

The first T29 pilot finished at Milford Proving Ground in July 1945. Source: AFV Technical Situation Report No. 39.

After the end of the Pacific War, the production contract with Pressed Steel Car Company was terminated, with one pilot tank completed and a partially finished second pilot. All materials for the completion of 10 production tanks, including one partially finished pilot tank, were transferred to Detroit Arsenal for post-WWII development studies authorized by OCM 28848 on 23 August 1945. The first production T29 arrived at Aberdeen Proving Ground in October 1947. By this time, there was no longer any requirement for production of these heavy tanks and the test program was limited to evaluating the various power train components for application to new tank designs. Two additional T29s arrived in April and May 1948 for the endurance and engineering test programs. Ten tanks were built in total, two of which were the pilot vehicles built by Pressed Steel Car Company and eight were production tanks with the development continued by Detroit Arsenal. Some were modified independently to mount various experimental components such as new engine, fire control system, and stereoscopic rangefinder. This resulted in the development of T29E1, T29E2, and T29E3 heavy tanks that would test these new modifications.

The front and rear position of the T29 Pilot, September 1945. Source: Pressed Steel Car Company

The T29 project was discontinued in late 1950 in favor of a new heavy tank development based on the 120 mm cannon of the T34 in a new tank design, designated as T43 heavy tank, and standardized as 120 mm Gun Tank M103 in 1956.

Armor

The T29’s basis armor requirement of up to 228 mm of armor protection from frontal attack direction. Source: AFV Technical Situation Report No. 27.
The T29’s basis armor requirement of up to 228 mm of armor protection from frontal attack direction. Source: AFV Technical Situation Report No. 27.

The T29 was required to gain significant armor protection over the T26E3 Pershing. It was meant to be protected against the threat posed by the German high velocity cannons, notably the 8.8 cm Kw.K.43 high velocity cannon of the Tiger II. Basis armor thickness is the contemporary US term for what is today known as effective armor thickness. Necessary overhauls to both hull and turret protection were required beyond what the previous tank designs could offer, starting with 228 mm of basis armor requirement on the frontal projection.

U.S. Armor Basis Curve.
U.S. Armor Basis Curve.

Hull

The hull armor was a welded assembly of cast and rolled plates. The upper front glacis retained the 102 mm armor thickness from the Pershing, but with increased inclination to 54° to improve the basis armor thickness up to 228 mm, arranged with additional two rows of spare track links as a form of additional armor. A 7.62 mm machine gun port was stationed on the right side of the hull.

The proposed change of the upper front hull from 127 mm at 46° (same inclination as the Pershing’s front hull) to 102 mm at 54°, while maintaining basis armor equivalency of 228 mm.
The proposed change of the upper front hull from 127 mm at 46° (same inclination as the Pershing’s front hull) to 102 mm at 54°, while maintaining basis armor equivalency of 228 mm.

The lower front plate was 2.7 inches (70 mm) thick and angled at 58° at the center of the plate. The sides were split into two sections, 3 inches (76 mm) covering the fighting compartment and 51 mm covering the engine compartment toward the rear hull. The roof armor was .9 inches (25 mm) around the turret and half an inch (13 mm) above the engine deck.

  • Front, upper : 4 inches (102 mm) @ 54°
  • Front, lower : 2.7 inches (70 mm) @ 58°
  • Side, front : 3 inches (76 mm)
  • Side, rear : 2 inches (51 mm)
  • Rear : 2 inches (51 mm)
  • Roof, front : .9 inches (25 mm)
  • Roof, rear : ½ inch (13 mm)
  • Floor, front : .9 inches (25 mm)
  • Floor, rear : ½ inch (13 mm)

Turret

The variable armor thickness of the turret started at 6.2 inches (158 mm) at the front, tapering to 5 inches (127 mm) to the side of the loaders hatches, and 4 inches (102 mm) around the commander’s cupola and the rear of the turret. The turret roof armor consisted of 1.4 inches (38 mm) on the front and .9 inches (25 mm) on the rear.

A massive cast turret was welded on 78 inch (2 meter) wide turret ring and mounted a large gun mantlet at the front, covering a large portion of it. The thickness exceeded 8 inches (203 mm) on overall area, with up to 10 inches (254 mm) around the gun collar and 12 inches (305 mm) on the joints around the corner of the mantlet. An internal armored plate was attached to the gun mount as a secondary protection, forming the estimated 9 inches (228 mm) basis armor requirement on the frontal portion of the turret.

  • Mantlet : 8 – 12 inches (203 – 305 mm)
  • Front : 6.2 inches (158 mm)
  • Side : 4 – 6.2 inches (102 – 158 mm)
  • Rear : 4 inches (102 mm)
  • Roof : .9 – 1.4 inches (25 – 38 mm)
Heavy tank armor specification per August 1945. Source: AFV Technical Situation Report No.37, Appendix C.
Heavy tank armor specification per August 1945. Source: AFV Technical Situation Report No.37, Appendix C.

Weapon

In order to develop a tank with the firepower to assault enemy fortifications and heavily armored combat vehicles, particularly the German heavy tanks, it was important to mount a gun able to fulfill these multiple roles. As such, the 105 mm T5E1 was developed for the current U.S. heavy tank projects, T95 GMC and T29, with M6A2E1 becoming a test subject for feasibility of mounting the gun into a turreted tank design.

The 105 mm T5E1 was a 65 caliber long, high velocity multipurpose cannon based on the 105 mm T4 anti–aircraft gun, with a muzzle velocity of 914 m/s. The gun was made of a monoblock construction with uniform right hand rifling. It had a vertical sliding wedge breech block, with three recoil cylinders located on top of the gun cradle, installed on the T123 gun mount. Loading characteristics of the tank intended for installation demanded that the cartridge case and shell be separated as two–piece ammunition, with an effective rate of fire of 6 rounds/minute with 2 loaders. Another variant of the gun was the 105 mm T5E2, installed on the T123E1 gun mount. The only key difference was the relocation of one recoil cylinder to the bottom of the gun cradle.

The T29 could store up to 63 rounds, located in an armored rack in the hull and a ready rack in the turret. Ammunition types comprised the T13E2 APCBC–HE, T29E3 HVAP, T30E1 HE, T32E1 APCBC, T37 APBC, and T46 WP. Most of the 105 mm shells were rescaled from 90 mm shells, with the exception for the T13E2, which was based on the 75 mm M61 due to being developed much earlier for the T4 gun. Two separate propellant charges were provided, T8 for AP shot, HE, and WP shells, and T9 specifically for HVAP shot (with finer powder granulation). Both charges were assembled with the same cartridge case and components, namely 105 mm Case T4E1, Primer T48, Supplementary Igniter T9, and M1 Powder. The charges had been established to give a working pressure of 40,000 psi (2812.27 kg/cm²). Each cartridge case was closed by differently shaped plastic plugs, with flat contour for the T8 and convex contour for the T9 (to fit the recessed base of the HVAP projectile) to prevent mistakes in loading the separate projectile and charge.

105 mm T5 L/48 originally intended for tank use. The gun was somewhat 90 kg heavier than the 105 mm T5E1. Source: Watervliet Arsenal.
105 mm T5 L/48 originally intended for tank use. The gun was somewhat 90 kg heavier than the 105 mm T5E1. Source: Watervliet Arsenal.
105 mm T5E1 L/65. Source: Watervliet Arsenal.
105 mm T5E1 L/65. Source: Watervliet Arsenal.

The main cannon was complemented with two coaxial 12.7 mm M2HB machine guns, and a dual power telescope T143E1 in T154 telescope mount, adjustable from 4x to 8x of magnification. It was based on the T122/M83 telescope used for the 90 mm cannon. A secondary M10E5 periscopic sight with dual sights from 1x to 6x was provided for the gunner to give a wide angle of vision and acquire the target. Gun elevation/depression was +20/–10, and the turret was rotatable to 360° with an effective turret rotation of 18°/second.

The T143E1 telescope would have a similar sight to the M83 telescope, adjusted for the 105 mm cannon. Source: TM 9-735 - Medium Tanks M26 & M45.
The T143E1 telescope would have a similar sight to the M83 telescope, adjusted for the 105 mm cannon. Source: TM 9-735 – Medium Tanks M26 & M45.

The T13E2 APCBC–HE was the earliest anti–tank shell in development, carried over from the T4 AA gun. It had a muzzle velocity of 900 m/s, weighing 18.6 kg. It was a rescaled 75 mm M61 APCBC–HE. The fuze was a standard U.S. armor–piercing high explosive B.D. (Base Detonating) M66A1. It could penetrate 208 mm of vertical armor at 500 yd (457 m) and 180 mm at 2,000 yd (1,829 m).

The second armor–piercing shell was the T32E1 APCBC, a solid shot for the T5E1 after the T13E2 was developed. The base shell weighed 15.8 kg with 1.9 kg of hardened penetrating cap and steel ballistic cap, totaling 17.7 kg in overall, coming at a slightly higher velocity of 914 m/s. The third shell was the T37 APBC. It was not much different from the T32E1, as both were based on the same shell, the 90 mm T33 APBC. However, the T37 was a fully rescaled 90 mm, with the whole body and ballistic cap alone weighing 17.6 kg of similar size as the T32E1. Both APCBC and APBC could penetrate up to 235 mm and 216 mm of vertical armor from point blank range respectively.

T30E1 HE consisted of a cast TNT explosive packed inside a forged steel body shell with bursting charge and P.D. (Point Detonating) M51A4 fuze, weighing 15.4 kg in total. It came with two different charges, standard charge T8 for use at maximum range firing at 945 m/s, and reduced charge T20 for increased anti–concrete performance from short range at 762 m/s. It could penetrate 1.3 m of concrete at 1,500 yards (1,372 m).

High Velocity Armor–Piercing T29E3 provided the most effective anti–tank munition for the 105 mm. Weighing 11.2 kg, it consisted of a 4.5 kg tungsten carbide core, an aluminum ballistic cap and body with steel bourrelet band, and a steel base with two rotating bands and a tracer holder. It could achieve a muzzle velocity of 1,128 m/s, and penetrate 360 mm of vertical armor from 500 yd (457 m) and 292 mm from 2,000 yd (1,829 m). This was enough to punch through even the most heavily armored tanks in the war, including the Panzerjäger Tiger Ausf. B, colloquially known as the Jagdtiger heavy tank destroyer.

Armor-piercing performance of the 105 mm T13 APCBC and T29 HVAP. Source: AFV Technical Situation Report No. 34, Appendix D.
Armor-piercing performance of the 105 mm T13 APCBC and T29 HVAP. Source: AFV Technical Situation Report No. 34, Appendix D.

Mobility

The T29 was powered by the Ford GAC, a 12–cylinder petrol engine producing 750 hp at 2,800 rpm, with a maximum torque of 224.6 kgf/m. It had a displacement of 27 liters. Weighing 825 kg dry, it was connected to tanks with a fuel capacity of 300 U.S. gallons (1135 litres), running on 80 octane fuel and equipped with a liquid–cooling system. This gave the 64-ton heavy tank a power-to-weight ratio of 11.68 hp/t. The GAC engine was 35.5 cm longer than the GAA engine that powered the M4A3 medium tank, necessitating a larger engine compartment to fit such a machine.

Ford GAC engine. Source: AFV Technical Situation Report No. 25.

A General Motors Cross–Drive CD–850–1 transmission was connected to the Ford GAC. It combined the functions of a transmission, steering gear, and brakes in a single unit. This unit also incorporated two hydraulically selected gear ranges driving through a single phase torque converter. It had 2 forward and 1 reverse speed steering. The great advantage of the cross drive transmission was its simplicity of operation which eased the task of the driver. The top speed of the T29 was 35 km/h with a maximum cruising range of 160 km. It could climb 30° of sloped terrain, cross a trench up to 2.4 meters wide, ford depths up to 1.2 meters, climb steps up to 1 meter, and was capable of pivot steering by pushing the driver’s wobble stick to the left or right in neutral position, increasing the ability of the tank to exit from difficult terrain.

General Motors Cross–Drive CD–850–1 transmission schematic. Source: AFV Technical Situation Report No. 33.
General Motors Cross–Drive CD–850–1 transmission schematic. Source: AFV Technical Situation Report No. 33.
Assembled Ford GAC and GM CD–850–1 Powerpack. Source: Firepower
Assembled Ford GAC and GM CD–850–1 Powerpack. Source: Firepower

The suspension system was retained from the T26E3 Pershing, with 8 double road wheels with rubber tires connected to torsion bars and 7 return rollers per side. The drive sprockets were placed at the rear, as well as the transmission and the engine powering them, while the idler wheels settled at the front to keep the track tension. The T29 used as many as 102 links of T80E3 tracks on each side, a combination of 584 mm wide T80E1 rubber–backed, steel chevron tracks fitted with 127 mm wide Duckbill extended end connectors, increasing the total width up to 711 mm to reduce the ground pressure of the heavy tank to 0.85 kg/cm². The tank had a ground clearance of 480 mm.

Capt. W. (Bill) Day in front of the T29 Pilot, showing the 8 road wheels and 7 return rollers on the left side of the hull. Note the lack of Duckbill extended end connectors. Source: Pressed Steel Car Company
Capt. W. (Bill) Day in front of the T29 Pilot, showing the 8 road wheels and 7 return rollers on the left side of the hull. Note the lack of Duckbill extended end connectors. Source: Pressed Steel Car Company

Crew

The T29 was operated by a 6–man crew. Inside the turret, the tank commander was seated in the rear bulge immediately behind the 105 mm gun breech. He was provided with an M15 periscope and 6 vision blocks in his cupola. His seat could be adjusted vertically and horizontally for observation and movement. The SCR 508 / 528 radio set was installed in the turret bulge on the left side of the commander for intercom. Two loaders were stationed on each side of the breech, provided with two standard type escape hatches. Both had access to their ready racks located on both left and right side of the turret. When not in loading operation, the right loader could use a single pistol port on his side, while the left loader could use a 12.7 mm machine gun placed outside of the tank. The gunner manned the 105 mm gun and was located to the right of it, sitting on a seat slung from the turret ring, and equipped with a direct sight telescope and a periscopic sight. The driver and co–driver sat in the front hull and used M13 driver periscopes installed on their hatches for driving. Both had access to separate controls, including a mechanical control system to operate the transmission under normal conditions and two manual steering levers for emergency use.

Commander’s seat (left) and driver’s seat (right). Source: Pressed Steel Car Company

Variants

T29E1

The first production T29 completed by Detroit Arsenal was delivered to General Motors for installation of a different engine, the Allison V1710–E32, producing 850 hp at 2,800 rpm, and the CD–850–1 cross drive transmission. The hull length was slightly increased by 5 cm to accommodate the new engine installation. This modification was designated as T29E1 in December 1945.

Allison V–1710–E32 engine with CD–850–1 transmission. Source: Firepower
Allison V–1710–E32 engine with CD–850–1 transmission. Source: Firepower

T29E2

The second production T29 was equipped with a combination of hydraulic power turret traversing and elevating mechanism and computing sight system developed by the Massachusetts Institute of Technology. It was designated as T29E2 in April 1948, and armed with a 105 mm T5E2 cannon in T123E2 gun mount.

T29E3

On 31 May 1945, the T29 became the subject of an evaluation for the effectiveness of the integrated fire control system. This followed the development of the T25E1 No. 13 with T31 stereoscopic rangefinder, by incorporating the latest modification, the T31E1, and T93E2 telescope in T136 periscope mount, designated as the T29E3 in mid–1948. Three new panoramic telescopes for indirect fire with the 105 mm gun were also installed: T141 for the T31E1 rangefinder, T144 for the T93E2 telescope, and T145 for the M10E5 periscope. The T141 and T144 were installed in the gunner’s periscopic sight mount and the T145 in the turret roof.

Development for a rangefinder-equipped T29 heavy tank planned in May 1945. Source: AFV Technical Situation Report No. 36 #185

The T31E1 rangefinder was a stereoscopic instrument with the base length of 9 feet (2.74 meters). It was not connected to the other fire control system, as it was operated manually by the tank commander to relay the range information using the control box below the rangefinder. The range and target lead data was transmitted by flexible shafting to the gunner for tracking the target. However, tests at Aberdeen Proving Grounds (APG) showed that backlash, as well as windup and binding of the flexible shifting, resulted in serious errors in the system. Although the rangefinder was particularly useful for spotting purposes. It also displayed the importance of a rangefinder to obtain a first strike capability beyond 1,000 yards (914 m).

The T29E3 heavy tank at Aberdeen Proving Ground on 4 May 1948. The T31E1 rangefinder appeared on each side of the turret. Source: Firepower
The T29E3 heavy tank at Aberdeen Proving Ground on 4 May 1948. The T31E1 rangefinder appeared on each side of the turret. Source: Firepower

Turbine–Powered T29

In 1946, the T29 was planned for a gas turbine engine development program with the associated power train, estimated to produce up to 1,400 hp. The project was separated into three different phases; Researching the development data of the internal combustion turbines and power train suitable for the T29, developing a pilot gas turbine engine based upon the data derived in Phase 1, and installation of the engine into the T29. No further details have been revealed.

Plan to research gas turbine engine for the T29 heavy tank. Source: AFV Technical Situation Report No. 42 #94.
Plan to research gas turbine engine for the T29 heavy tank. Source: AFV Technical Situation Report No. 42 #94.

Conclusion

The T29 was developed too late to enter the war it was designed for, with the first tank finished at the end of hostilities in the Pacific War. The lack of preparation of any practical solutions to transport such massive vehicles overseas also contributed to its delay. However, all the equipment and modules that were developed during World War II would later pave the way for future American tanks. The cross-drive transmission was improved and later used by all subsequent tanks, up to the M60 main battle tank. The 105 mm T5E1 gun and its ammunition were adapted for post-war development and later known as the 105 mm T140 gun, installed on the T54 medium tank. The heavy tank project itself led to the development of the T43, and eventually to the M103 gun tank.

Production T29 at the Pressed Steel Car works, 1947. Source: Pressed Steel Car Company
Production T29 at the Pressed Steel Car works, 1947. Source: Pressed Steel Car Company

There are currently seven surviving tanks, four of which are located at the National Armor and Cavalry Museum, including T29, T29E3, T30, and T34. The remaining 3 are the T30s, located at Fort Jackson, Detroit Arsenal, and Anniston Army Depot.



Illustration of the Heavy Tank T29 showing the large size of the turret and the impressive size of the gun.


Illustration of the Heavy Tank T29E3 showing off the distinctive paraxial rangefinder on the top of the turret. These were used to quickly determine the distance to an enemy tank and improve the first hit chances.

Both illustrations were produced by Tank Encyclopedia’s own David Bocquelet

Specifications

Dimensions (L-W-H) 7.6 (11.6 m with gun forward) x 3.8 x 3.2 meters
Total weight, battle-ready 64.2 tonnes
Crew 6 (commander, driver, gunner, loader, loader, bow gunner)
Propulsion V12 Ford GAC, gasoline, 750 hp
Range 160 km
Speed (road) 35 km/h
Transmission CD–850–1, torque converter, 2–forward/1–reverse
Suspension Torsion bar
Armament 105 mm T5E1 L/65, 63 rounds
3x 12.7 mm M2HB, 2,420 rounds
1x 7.62 mm M1919A4, 2,500 rounds
Armor Hull
Front: 70 – 102 mm
Side: 76 – 51 mm
Rear: 19 – 51 mm
Roof: 13 – 25 mm
Floor: 13 – 25 mm
Turret
Front: 158 mm
Side: 158 – 102 mm
Rear: 102 mm
Roof: 25 – 38 mm
Mantlet: 203 – 305 mm
No. Built 10 (2x Pilot T29, 5x Production T29, 1x T29E1, 1x T29E2, 1x T29E3)

Sources

British Army Staff – AFV Technical Situation Report No. 23, June 1944
British Army Staff – AFV Technical Situation Report No. 25, August 1944
British Army Staff – AFV Technical Situation Report No. 27, October 1944
British Army Staff – AFV Technical Situation Report No. 28, November 1944
British Army Staff – AFV Technical Situation Report No. 29, December 1944
British Army Staff – AFV Technical Situation Report No. 30, January 1945
British Army Staff – AFV Technical Situation Report No. 31, February 1945
British Army Staff – AFV Technical Situation Report No. 32, March 1945
British Army Staff – AFV Technical Situation Report No. 33, April 1945
British Army Staff – AFV Technical Situation Report No. 34, May 1945
British Army Staff – AFV Technical Situation Report No. 35, June 1945
British Army Staff – AFV Technical Situation Report No. 36, July 1945
British Army Staff – AFV Technical Situation Report No. 37, August 1945
British Army Staff – AFV Technical Situation Report No. 38, September 1945
British Army Staff – AFV Technical Situation Report No. 39, October 1945
British Army Staff – AFV Technical Situation Report No. 40, November 1945
British Army Staff – AFV Technical Situation Report No. 41, January 1946
British Army Staff – AFV Technical Situation Report No. 42, March 1946
Armed Services Technical Information Agency – AD301343 – An Analytical Study of Data on Armor Penetration by Tank–Fired, Kinetic Energy Projectiles
Nielsen, K. (2012). Pressed Steel Car Company, Authorhouse
OCM 25117 – Heavy Tanks T29 and T30 – Development and Manufacture of Pilots Recommended, 14th September 1944
OCM 25259 – Tanks, Heavy, T29 and T30 – Development and Manufacture of Pilots Approved, 28th September 1944
OCM 26438 – Gun, 105–mm, T5E1 for Mounting in Tank, Heavy, T29 – Assignment of Model Designation, January 1945
OCM 26439 – Fire Control Equipment for the Heavy Tank T29 – Development and Assignment of Designation
OCM 26825 – Tank, Heavy, T29 – Classification as Limited Procurement Type Recommended; Gun, 105–mm T5E1 and Ammunition Therefor – Initiation of Procurement Recommended, 1st March 1945
OCM 27245 – Tanks, Heavy, T29 and T30 – Procurement of Additional Pilots Authorized, 5th April 1945
OCM 27808 – Gun, 105 mm, T8 and Carriage, Gun, 105 mm, T19, Fire Control Equipment; Accessories, and Associated Equipment, 31st May 1945
Records of the Office of the Chief of Ordnance – Development History of the Heavy Tanks, T29 & T30, 1945
R.P. Hunnicutt (1988). Firepower: A History of the American Heavy Tank


Tanks Encyclopedia Magazine, #3

Tanks Encyclopedia Magazine, #3

The third issue covers WW1 armored vehicles — Hotchkiss Htk46 and Schneider CA and CD in Italian Service. WW2 section contains two splendid stories of the US and German ‘Heavy Armor’ — T29 Heavy Tank and Jagdtiger.

Our Archive section covers the history of early requirements for the Soviet heavy (large) tank. Worth mentioning, that the article is based on documents never published before.

It also contains a modeling article on how to create a terrain for diorama. And the last article from our colleagues and friends from Plane Encyclopedia covers the story of Northrop’s Early LRI Contenders — N-126 Delta Scorpion, N-144 and N-149!

All the articles are well researched by our excellent team of writers and are accompanied by beautiful illustrations and photos. If you love tanks, this is the magazine for you!
Buy this magazine on Payhip!


Categories
WW2 American Prototypes

Heavy Tank T26E5

USA (1945)
Assault Tank – 27 Prototypes

The T26E5 was an assault tank based on the M26 Pershing heavy tank. It was developed from the same premise as the M4A3E2 Assault Tank, that of increasing the armor of the current existing tank with a purpose to break through the enemy defense line. The tank sported the same 90 mm Tank Gun M3 L/53 high-velocity cannon with heavily reinforced frontal armor.

The first T26E5 heavy tank (serial number 10007) at Aberdeen Proving Ground (APG) on 20 July 1945. Source: Hunnicutt’s Pershing

Development

With the rapid increase of enemy high-performance anti-tank firepower on the battlefield during WWII, the American primary tank, the M4 Sherman, found itself in a difficult situation where it could not protect the mobilizing forces anymore. Its existing design could not be pushed further to emphasize armor without hampering the other aspects of the tank, such as mobility. Therefore, a new role was formed to counter this threat, the Assault Tank, a vehicle with the purpose of breaking through highly concentrated enemy defenses and withstand enemy gunfire.

Successful deployment of the M4A3E2 in late 1944 had garnered interest in the US Army to develop another type of assault tank. While the M4A3E2 was considered satisfactory for its role, it did not provide nearly the same level of protection offered by its contemporaries, such as the German Tiger II. Fortunately, the heavy frontal armor arrangements of the M4A3E2 suggested the possibility of improving the armor for the latest heavy tank under production, the T26E3 Pershing. The earliest draft was recommended by the Ordnance Committee of the Ordnance Corps to increase the effective frontal armor of the Pershing by 203.2 mm. This entailed:

  • A new front hull casting with a maximum thickness of 120.65 mm at 46°.
  • A new turret casting with an effective thickness of 203.2 mm and a counterweight at the rear of the turret.
  • A new gun mantlet casting with an effective thickness of 203.2 mm at 0°.
  • Increased equilibrator capacity to offset the weight of gun mantlet.
The second T26E3 Pershing (serial number 12) heavy tank at APG on 12 December 1944. Source: Pacific Area Materiel

A rough estimation indicated that these changes would increase the vehicle weight to 48 tons (43.9 tonnes), 2.4 tons (2.2 tonnes) heavier than the T26E3. However, by using the T80E1 track with the Duckbill extended end connectors, it was expected that the ground pressure could be kept down to approximately 11 psi (0.80 kg/cm²). The overall width of the tank would be 12.3 feet (3.75 m), but could be reduced to 11.4 feet (3.5 m) for rail transportation. The tank would continue to be powered by the Ford GAF engine with Detroit 900-F torqmatic transmission. The gear reduction had to be lowered to maintain support of the increased tank weight. Dated 18 January 1945, an Ordnance Committee Minute (OCM) action recommended 10 conversions of the T26E3 tanks and designated the modified vehicles as Heavy Tank T26E5 under OCM 26398. This action was approved on 8 February.

A concept of the M4A3(90) HVSS with T26 turret. Source: Sherman

In order to gain information of the new assault tank, along with the performance of the High Volute Spring Suspension (HVSS) for a possible new assault tank using this type of suspension, a trial vehicle entered Utica Proving Ground in early 1945. The vehicle was a modified M4A3 HVSS hull loaded with test weight, and mounting a heavied-up T26 turret with the 90 mm M3 cannon. The overall weight of this trial assault tank was 46.26 tonnes. The M4A3(90) HVSS ran a 2,000 miles (3,218 km) test with this assault tank weight configuration for an endurance test.


The Assault Tank M4A3(90) HVSS, weighing 46.26 tonnes, being used to conduct a 2,000 miles test. Unfortunately, there is no existing photograph of such a tank during the test. Source: AFV Technical Situation Report No. 32

Following the information gathered from the trial assault tank, on 29 March 1945, the specification requirement was updated. OCM 27122 recommended increasing the weight limit of the T26E5 to 51 tons (46.26 tonnes) as well as the effective frontal armor thickness to 11 inches (279.4 mm) to exceed any heaviest known enemy armor. Proposed changes included the use of:

  • A new hull casting with a thickness of 6 inches (152.4 mm) at 46° on the upper slope and 4 inches (101.6 mm) at 54° on the lower slope.
  • A new turret casting with a thickness of 7 ½ inches (190.5 mm) on the front, 3 ½ inches (88.9 mm) on the sides (later changed to 95.25 mm), and 5 inches (127 mm) on the rear in order to balance the turret.
  • A new gun mantlet casting with the actual thickness of 11 inches (279.4 mm) at 0°.
  • A 59 lb (27 kg) counterweight to the recoil guard in addition to the increased equilibrator capacity for complete balance to the gun mount.
  • Increased thickness and weight of the front turret ring splash guard to protect the thin machined surface of the turret adjacent to the ring.
  • Decreased width in the rear portion of the hull escape hatch doors to prevent a weak spot in the turret and to provide clearance between the doors and the turret.
  • Reduced final drive gear ratio from 1:3.95 to 1:4.47.

The Chief of Engineers pointed out that the gross weight and width of the assault tank would place it under the classification of “Exceptional Vehicle”. The only military bridging available which would safely carry it was the Floating Bridge M4. With the bridge width of 12 feet (3.75 m), it could merely afford a clearance for the tank when not equipped with extended end connectors. Regardless, OCM 27122 was approved on 19 April 1945 and the production number for T26E5 had been increased to 27.

As of 10 April, marked prints covering the alterations to the front hull casting, turret, gun mantlet, driver’s door, and the equilibrator spring had been completed. The casting drawings had been delivered to the Scullion Steel Co. and the Continental Foundry and Machine Co. for the production of 27 vehicles, which were to be built by the Chrysler Corp. Production drawings for all other parts related to the vehicle were being made and it was expected that the first tank would be completed by approximately 15 June 1945.

Schematics of T26E5 Heavy Tank. Source: AFV Technical Situation Report No. 35

Meanwhile, a modification unit to the suspension was being worked out in the event that such changes were necessary to carry the unprecedented weight of the tank. These involved increasing the diameter of torsion bars to 23.6 in (60 cm) which would increase their range by 15%, larger inner road wheel bearings to increase the capacity to 80% over the existing bearings on the T26E3. Strengthened shock absorbers and an extra shock absorber, together with a hydraulic bump stop were to be provided on the front suspension member. But none was really installed into the tank, which would bring out the issues of its suspension reliability later in trials.

The first T26E5 (registration number 30150824) arrived at Aberdeen Proving Ground (APG) in July 1945. The final combat weight of the vehicle was measured at 46.40 tonnes, slightly heavier than estimated. All the remaining tanks had finished production by the end of World War II, and no additional unit was ordered.

The T26E5 heavy tank arrived at APG in July 1945. Source: Pacific Area Materiel

Armor

As an assault tank, the T26E5 was heavily armored, far beyond any preceding assault tanks developed by the US. With a maximum effective armor of 279.4 mm, it outclassed even the T29 heavy tank, one of the latest US heavy tanks which was already in production 3 months prior. Unlike the other T26 variants which had lower effective armor on the front hull, the T26E5 was designed to project its maximum armor on the entire front, including the hull and the front turret that was covered by the mantlet. Preliminary study to incorporate the required effective armor into the tank construction was done by measurement using the standards of US Basis Armor Curve. Since most of the changes to protection were allocated to the front, the side and rear of the hull were left without any relevant changes at all.

Final armor specification of the T26 heavy tanks. Source: AFV Technical Situation Report No.33

Hull

The armor structure was relatively similar to the M26 Pershing, with cast and rolled armor forming up the hull. The main aspect of the T26E5 armor came from thicker casting of the front hull, coming up at 6 inches (152.4 mm) at 46° on the upper slope, giving a substantial effective thickness of 11 inches (279.4 mm). The ventilator bulge located above the upper slope was angled at lower obliquity at 25°, and to provide the same protection as the upper slope, the armor plating must be cast thicker than the rest of the upper front hull with an estimation of 9 ½ inches (242.9 mm) at its thickest. The lower plate was also well armored with 4 inches (101.6 mm) at 54° at the center of the lower slope. The side hull was split with 3 inches (76.2 mm) on the front and 2 inches (50.8 mm) on the rear. The rear hull was 2 inches all around the engine compartment.

  • Front, upper: 6 in (152 mm) @ 46° CHA
  • Front, lower: 4 in (102 mm) @ 54° CHA
  • Side, front: 3 in (76 mm) RHA
  • Side, rear: 2 in (51 mm) RHA
  • Rear: 2 in (51 mm) RHA
  • Roof, front: 1.5 in (38 mm) RHA
  • Roof, rear: 0.90 in (23 mm) RHA
  • Floor, front: 1 in (25 mm) RHA
  • Floor, rear: ½ in (13 mm) RHA
A thickness of 6” (152.4 mm) CHA angled at 45° or 4” (101.6 mm) at 51° was required to defeat the German 8.8 cm Kw.K. 43 cannon at point-blank distance. The front hull construction of T26E5 was based upon this information. Source: AFV Technical Situation Report No.34

Turret

The turret was cast all-around, and received a sizable overhaul to its protection, with 7 ½ inches (190.5 mm) at 10° on the front turret giving an effective armor of 8 inches (203.2 mm), and 11 inches of effective armor on the mantlet. The sides had varying degrees of thickness due to casting from 7.8 in (198.12 mm) on the front, which was actually thicker than the front turret face, and tapering down to 3 ½ inches (88.9 mm) on the rear. The rear section of the turret was thickened to 5 inches (127 mm) to balance the weight of the heavily armored mantlet at the front of the turret.

The mantlet shape was improved by trimming a chunk of its lower portion in an attempt to form a straight surface instead of rounded. This offered three advantages: preventing shot trap that was noted to be a serious compromise in the previous design since the T26E1; allowing the drivers hatches to open since the mantlet became thicker externally; and permitting enough space for the gun mount to traverse vertically without bumping into the driver hatches.

  • Mantlet: 7 ½ – 11 in (191 – 279 mm) CHA
  • Front: 7 ½ – 7.7 in (191 – 198 mm) CHA
  • Side: 3 ½ – 7.7 in (89 – 198 mm) CHA
  • Rear: 5 in (127 mm) CHA
  • Roof: 1 in (25 mm) CHA
Cast turret armor of the T26E5 inspected at APG on 16 July 1945. Chalked numbers indicate armor thickness in inches. The front turret face has a thickness of 7.5 inches (190.5 mm). The sides of the turret vary from 7.8” (198.12 mm) on the front to 3.5” (88.9 mm) on the rear. Source: Pershing

Weapon

The T26E5 still used the same weaponry as the M26 Pershing, with no notable differences. The main gun was the 90 mm M3 L/53 cannon, holding 70 rounds of 90 mm ammunition consisting of M71 HE (High Explosive), T33 APBC (Armor-Piercing Ballistic Capped), M82 APCBC-HE (Armor-Piercing Capped, Ballistic Capped, High Explosive), M304 HVAP (High Velocity Armor-Piercing), and M313 WP (White Phosphorus / Smoke). The secondary weapon would be a coaxial .30 caliber (7.62 mm) M1919A4 machine gun on the left side of the cannon. Additional machine guns included a ball-mounted .30 caliber M1919A4 for the bow gunner and .50 caliber (12.7 mm) M2HB heavy machine gun in a flexible anti-air mount on top of the turret.

The first T26E5 heavy tank as seen from above, showing the 90 mm M3 cannon and anti-aircraft .50 cal M2HB machine gun The .30 cal M1919A4 coaxial machine gun was not visible, shrouded by a mantlet canvas cover to prevent dust from entering the gun mount. Source: Hunnicutt

Although using the same M67 Gun Mount type as the Pershing, it was modified with significantly thicker mantlet and increased equilibrator capacity, gathered from experience with the T26E4 Super Pershing to maintain balance of the whole platform with the increased weight at the front of the turret. Despite projecting such a large mantlet, the gun mount was still able to elevate 20° up and depress -10° down. The turret rotation speed was reduced to 18°/second since the turret became heavier.

The 90 mm cannon of the T26E5 was initially planned to use the M71C telescope with fixed 5x (13°) magnification, backed up by the M10F periscope with 1x (42° 10’) infinity sight and 6x (11° 20’) telescopic sight. Although in June 1945, the M83C variable power telescope became available after being standardized and authorized for mass production. Naturally, the T26E5 would immediately adopt it somewhere during production, replacing the M71C in process. This new power telescope was capable of veritable magnification from 4x (14° 27’) to 8x (7° 36’) and had better resolution and optical quality than any previous telescopes. The telescope mount on the mantlet was given a cylindrical cover since the telescope would extend by up to 3.8 cm when magnified to 8x.

The Telescope T122 was a variable telescopic sight developed since March 1944. It was not until June 1945 that the telescope was standardized as Telescope M83. The T26E5 in particular was among the first tanks to adopt the M83C model. This telescope had a magnification ranging from 4x to 8x. Source: AFV Technical Situation Report No.29

Mobility

The heavy tank was still powered by the same power pack as on the M26 Pershing, including the Ford GAF gasoline engine producing 500 hp, which was proven to be underpowered for the tank at just 45 tons (41 tonnes). It should have been expected that the T26E5 that weighed just over 50 tons (46 tonnes) would suffer even more from reduced performance, with abysmal power-to-weight ratio giving an output of only 10.7 hp/ton. The Detroit 900-F Torqmatic transmission was also still used, with a change to the final drive ratio from 1:3.95 to 1:4.47. The top speed had been limited from 30 to 24 mph (48 – 40 km/h). The T26E5 used 23 inch (584 mm) wide T80E1 rubber-backed, steel chevron tracks. There were 82 track links used on both sides, each fitted with Duckbill extended end connectors to reduce the ground pressure from 14.3 to 11.8 psi (1.01 – 0.83 kg/cm²). It could climb up to 30° of sloped terrain, cross a trench up to 7.8 feet (2.4 m) wide, ford depths up to 3.9 feet (1.2 m), climb steps up to 3.9 feet, and turn with a maximum circle of 60 feet (18.2 m) in diameter.


The third T26E5 heavy tank (serial number 10009) during tests at Fort Knox. The Duckbill extended end connectors have been removed from the tracks and standard width sand shields fitted. This was necessary to reduce the overall width for rail transportation. Source: Pershing

Crew

The T26E5 was operated by a 5–man crew, just like the M26 Pershing. The commander, gunner, and loader were stationed inside the turret, while the driver and bow gunner settled down on the front hull.

In the turret compartment, the commander was located on the right side of the turret, and had access to his cupola with 6 vision blocks and a rotating periscope for all-directional observation while inside the tank. Behind him, a radio set was installed inside the turret bustle, either SCR 508 or SCR 528. The gunner was right in front of the commander, armed with the 90 mm cannon and .30 caliber coaxial machine gun at his disposal. Periscope M10F and Telescope M83C were available for him to locate and aim at the target. The loader sat on the left side of the turret, and had a ready rack of 10x 90 mm rounds beside him. The remaining ammunition was stored on the hull floor in an armored rack, which could still be accessed through the turret basket. The loader also had access to a pistol port, an escape hatch, and a rotating periscope.

Both the driver and bow gunner (as assistant driver) steered the tank with a pair of levers to their left and right, respectively. The instrument panel was located in the middle. On top of it, there was a blower to circulate air into the hull compartment. The bow gunner was armed with a ball-mounted .30 cal machine gun with no sighting device, so he had to aim the gun through his periscope and lead the firing direction by watching the tracer bullets. Two CO2 fire extinguishers were provided between their seats. The auxiliary periscopes had been eliminated from the M26 Pershing, leaving only rotatable periscopes on the hatches.

Conclusion

No longer needed for combat in World War II, the T26E5 was utilized for automotive and protection trials by the Service Board to study the effect of increased weight while running the same power pack and suspension as the M26. The consequence of weight increase by up to 5 tonnes would be a clear reduction to the mobility performance as estimated. The vehicle ran for another 2,000 miles (3,218 kilometers) test in the same principle as the M4A3(90) HVSS, to test the endurance of the tank. Unfortunately, due to the absence of the suspension modification unit that was supposed to alleviate the weight carrying capability of the T26E5, the test resulted in numerous malfunctions occurring in each distance recorded:

  • 1,247 km: Left and right hand final drive lock washers failed.
  • 1,879 km: Front right road wheel hub was bent and damaged.
  • 2,199 km: A torsion bar broke at the right front of the hull.
  • 2,354 km: Engine was overheated due to oil and dirt clogging radiator.
  • 2,393 km: Front spring arm shackles were bent and bearings damaged.
  • 2,533 km: Complete power failure occurred, caused by shearing of the torque converter’s rotor blades.
  • 2,623 km: Second torsion bar broke at the left front of the hull.
  • 2,943 km: Speed band in the transmission broke at the point of connection to the link on the adjustment end.

Overloading of the light duty torsion bar originally designed for the M26 caused considerable issues to the suspension, with cases of broken bars occurring twice. The light duty torsion bar was not capable of taking the additional 5 tonnes of weight amassed by the T26E5. The turret operation also suffered from failures, especially during cross-country driving. The problem was traced to be a direct result of the increased turret weight by uparmoring from the entire side, as there was no visible defect to the turret assembly or the material quality.

As the engineering trials proved to be a failure due to the design flaws surrounding its excessive weight and inability of the modified M26 to overcome them, it was decided that the T26E5 would be useful with its heavy armor as a practice target. The target vehicle would be loaded with inert ammunition and wooden crew in each of their positions inside the tank, and a running engine. The vehicle would then be shot by live anti-tank munition to determine the weapon’s performance against the heavy armor of T26E5.

All the 27 tanks were either lost to gunfire tests or scrapped, and none survived.



Heavy Tank T26E5 “Assault Pershing” in the standard US Olive Drab livery in 1945.


Heavy Tank T26E5 No. 1, with registration number “0824” stenciled at the rear side of the turret. The .50 cal machine gun has been mounted on top of the tank for anti-aircraft emplacement. The mantlet is protected by canvas cover to keep the gun mount clean during trials at APG in July 1945.

Both illustrations were produced by Ardhya Anargha, funded by our Patreon campaign

Specifications

Dimesnions (L-W-H) 20 (28, gun forward) x 12.1 x 8.8 feet (6.3 (8.6) x 3.7 x 2.7 meters)
Total weight, battle ready 51 tons (46.6 tonnes) Aprx.
Crew 5 (commander, driver, co-driver, gunner and loader)
Propulsion Ford GAF V8, gasoline, 500 hp
Speed (road) 24 mph (40 km/h)
Transmission Detroit 900-F Torqmatic, torque converter, 2 forward, 1 reverse
Suspension Torsion bar
Armament 90 mm Tank Gun M3 L/53, 70 rounds
1x 12.7 mm M2HB, 550 rounds
2x 7.62 mm M1919A4, 5000 rounds
Armor Hull
Front, upper: 6 in (152 mm) @ 46° CHA
Front, lower: 4 in (102 mm) @ 54° CHA
Side, front: 3 in (76 mm) RHA
Side, rear: 2 in (51 mm) RHA
Rear: 2 in (51 mm) RHA
Roof, front: 1.5 in (38 mm) RHA
Roof, rear: 0.90 in (23 mm) RHA
Floor, front: 1 in (25 mm) RHA
Floor, rear: ½ in (13 mm) RHA
Turret
Mantlet: 7 ½ – 11 in (191 – 279 mm) CHA
Front: 7 ½ – 7.7 in (191 – 198 mm) CHA
Side: 3 ½ – 7.7 in (89 – 198 mm) CHA
Rear: 5 in (127 mm) CHA
Roof: 1 in (25 mm) CHA
No. Built 27

Sources

Ballistic Research Laboratories, Aberdeen Proving Ground – Critical Review of Shaped Charge Information, 1954
British Army Staff – AFV Technical Situation Report No. 30, January 1945
British Army Staff – AFV Technical Situation Report No. 31, February 1945
British Army Staff – AFV Technical Situation Report No. 32, March 1945
British Army Staff – AFV Technical Situation Report No. 33, April 1945
British Army Staff – AFV Technical Situation Report No. 34, May 1945
British Army Staff – AFV Technical Situation Report No. 35, June 1945
British Army Staff – AFV Technical Situation Report No. 36, July 1945
British Army Staff – AFV Technical Situation Report No. 37, August 1945
British Army Staff – AFV Technical Situation Report No. 40, November 1945
British Army Staff – AFV Technical Situation Report No. 41, January 1946
British Army Staff – AFV Technical Situation Report No. 42, March 1946
Office of the Chief of Ordnance – Pacific Area Materiel, 1945
Ordnance Corps – Engineering Design Handbook, Ammunition Series. Section 2, Design for Terminal Effects, 1957
Record of Army Ordnance Research and Development – Heavy Tanks and Assault Tanks, 1945
R.P. Hunnicutt (1971) – Pershing: A History of the Medium Tank T20 Series
R.P. Hunnicutt (1978) – Sherman: A History of the American Medium Tank

Categories
WW2 American Prototypes

Armored Utility Vehicle T13 and Cargo Carrier T33

USA (1944-45) Utility Vehicle – Prototypes

The T33 Cargo Carrier and T13 Armored Utility Vehicle were designed in the United States of America during the Second World War. The T13 and T33 occupy a space in development as transition vehicles in the sense that almost everything Armored Personnel Carrier related that comes before the T13 and T33 was adopted from other designs originally intended as artillery tractors, half-tracks, tanks or, mortar carriers. Although neither vehicle was adopted for mass production, much like those that preceded them, they set the standard and bar for future APCs on what was expected and needed of the vehicle.

Initial Development

The T33 Cargo Carrier and T13 Armored Utility Vehicle (the name was changed to this from Armoured Tracked Carrier) were first mentioned in August 1944 in the British Army Staff (AFV) Situation Report Number 25 from August 18th 1944. At the time, the Armored Board and Armored Centre were interested in a design of an Armored Tracked Carrier, eventually called T13, based upon the M24 Light Tank components. The proposal was for the driver and engine room to be at the front, followed by a body which would be capable of carrying a 13,000 lb (5,900 kg) payload. Its dimensions would enable 9 men to be carried in the body with an additional 2 in the driving compartment.
The armor over the hull of the chassis would be 1” (25.4 mm), whilst the body would be ½” (12.7 mm). The total weight of the vehicle was estimated at 40,000 lbs (18,143.69 kg). Such a Carrier was considered to be particularly desirable for acting as a tender for ammunition and fuel for the M24 Light Tank, which only carried 48 rounds, or as a personnel carrier, or command vehicle in theaters such as China, where the absence of roads placed a premium on tracked vehicles. As of August 18th, 1944, “a layout drawing only has been produced and support for the proposal is now being canvased.”
There were no fully tracked armored personnel carriers being produced anywhere in the world since the Mark IX tank of World War One and APCs based upon the Soviet T-26 in the early 1930s. Walking, trains, trucks, and increasingly, half-tracks were the primary ways to move troops. The Tank Policy for 1945, which was published in July 1944, laid out the main focus for the coming year in the European Theater of Operations (ETO), that focus being on Tanks carrying a minimum of 70 rounds of ammunition. Water stowage for these rounds to reduce the chances of fire was acceptable so long as no less than 70 rounds were carried. Ground pressure was not to exceed 10 psi (0.70307 kg/cm2) and tank design was to be split into two types, light armor and high mobility, and heavy armor and infantry support. The end result of the requirements from July 1944 was that the M4A3 Medium Tank and M24 Light Tank fitted the lighter requirements well. At the same time, while the T25E1 Medium Tank was considered, it was thought that it would negatively impact the production of the M4A3 Medium Tank and M24 Light Tank and, if it was introduced alongside the two tanks, it would not arrive in enough quantity to have any impact. The heavy role was to be filled by the T26E1 Heavy Tank, and both the light and heavy tank roles were supposed to be able to mount the 90 mm Gun and the 105 mm Howitzer.
In addition to the Tank Policy, the Army was in need of more tractors to haul towed guns of various calibers due to production of the M4, M5, and M6 Tractors (as well as Tractor Trucks) not being able to keep up with demand and the increasing production of towed gun carriages. The idea to convert M24 chassis into both Cargo Tractors and Armored Utility Vehicles was both sound and nothing new, as the idea had been previously considered and declined.

October 1944

By October of 1944, it had been expressed in overseas theaters of operation, that a definite need existed for a General Purpose Tracked Cargo Carrier with low unit track pressure (PSI) and effective cross-country performance over difficult terrain. To meet this requirement, Ordinance prepared a design for a new carrier with a 7-ton cargo (6.4-tonne) capacity identified as the T33 Cargo Carrier. The vehicle was to be built from standard M24 Light Tank components, be unarmored, have a crew of two, and a .50 cal machine gun for A.A. work manned by the assistant driver. The unit track pressure was to be 6 psi (0.42 kg/cm2). Six pilot vehicles were authorized, but as of October 1944, no manufacturing facility had been located. Also recommended for official investigation was the previously mentioned armored tracked carrier based off the T33, the T13, now called a Personnel Carrier which had been previously reported on back in August of 1944[4].


Images of the Cargo Carrier T33 from October 1944. Source: British Army Staff (AFV) Situation Report Number 27 October 18th 1944

In November of 1944, the T33 Cargo Carrier became better described as 24,000 lbs (10.9-tonnes) (less crew, stowage and fuel) and 39,000 lbs (17.7-tonnes kg) combat laden in a cab over engine design at the front of the chassis.
The T13 also got official recognition as the T13 Armored Utility Vehicle in which the truck cab body of the T33 was replaced with an armored body ½” (12.7 mm) thick on the front, ½” (12.7 mm) thick on the side and 3/8” (9.5 mm) thick on the roof. The roof was lifted by means of mechanical jacks which raised it to any required position up to 6 ft (1.83 m) above the floor. The driver’s compartment accommodated the driver and co-driver with a ring-mounted .50 caliber machine gun over the co-driver. The main body was designed to accommodate 16 men in four rows of four leaving a small central aisle. This vehicle was estimated to weigh 31,000 lbs (14-tonnes) (less crew, stowage and fuel) and 39,000 lbs (17.7-tonnes) combat laden with the ground pressure being 7.3 psi (0.51kg/cm2).
The base carrier design was also intended to be suitable as an a) Armored Personnel or Cargo Carrier, b) Full Track Armored Reconnaissance Vehicle, c) Gun Motor Carriage, d) Litter Carrier and e)Full Track Armored Prime Mover.
The B.A.S. Royal Artillery S.D. and T. (R.A.) Monthly Letter to the War Office(RA) for December 7th, 1944 notes that the T33 had been approved for the production of six pilot vehicles[8]. The Technical Services Armaments Letter (TSAL) for November 29th, 1944 also notes this. Curiously, the British Army Staff (AFV) Situation Report (BASSR) Number 28 for November 18th, 1944 makes no mention of the six pilots for the T13 and both the TSAL and RA reports do and both reports cite BASSR #27 from October 18th, 1944.
By February 1945 and as a result of several user criticisms, the wooden mockup for T13 Armored Utility Vehicle was undergoing modifications and was not yet complete. In addition, six prototype T13 Armored Utility Vehicles were still on order but no delivery dates had yet been established[9].


Armored Utility Vehicle as drawn in the British Army Staff (AFV) Situation Report from November 1944. Illustrated by Yuvnashva Sharma, funded by our Patreon campaign.

Drawings and scale model of the Armored Utility Vehicle T13 from November 1944. Source: British Army Staff (AFV) Situation Report Number 28 November 18th, 1944

March 1945 – All-Change, and the end of the T33

In March of 1945, everything changed for the T33 Cargo Carrier and T13 Armored Utility Vehicle. Cargo Carrier policy, as far as it affected the Armored Force and Tank Destroyer Command, appeared to the British to be focused around the T33 Cargo Carrier. The British at the time called the T33 an Armored Personnel Carrier. The discussion remained open as to if the overhead armored protection, previously mentioned back in November 1944, on the T13 was necessary as it was being contended at the time that its presence would prevent a complement of 30 men from leaving the vehicle speedily. On the other hand, it was also admitted that, with the development of the proximity fuse (VT Fuse), overhead cover was essential.
By the end of the month, the T33 Cargo Carrier was canceled in favor of the T42 Cargo Carrier/Prime Mover/Cargo Tractor. The T42 would be, at first, nearly identical to the T33 Cargo Carrier, but with the adoption of the M18’s 900-T Torquematic gearbox and the R-975-C4 radial engine as its powerplant. The T42 was also cross-adopted as a prime mover as Cargo Tractor T42 to replace the 18-ton High-Speed Tractor M4, a project that originally started in February of 1945.

The end of the T13

In April 1945, the T13 Armored Utility Vehicle, with the new powertrain adopted from the M18, was officially redesignated T16 Armored Utility Vehicle and the T13 Armored Utility Vehicle, based upon the chassis of the M24, canceled.
With the cancelation of the T33 Cargo Carrier and T13 Armored Utility Vehicle, work on another Cargo Carrier and Armored Utility Vehicle would continue on in the development of the T42(M8) Prime Mover/Cargo Tractor/Cargo Carrier and T16(M44) Armored Utility Vehicle both of which would become accepted into Standard and then Limited Standard service by the United States.

Sources

British Army Staff (AFV) Situation Report Number 25 August 18th 1944
British Army Staff (AFV) Situation Report Number 24 July 18th 1944
British Army Staff Royal Artillery Monthly Letters September 1944 Para 13 (012)
British Army Staff (AFV) Situation Report Number 27 October 18th 1944
British Army Staff (AFV) Situation Report Number 28 November 18th 1944
British Army Staff Royal Artillery Monthly Letters December 7th 1944
British Army Staff (AFV) Situation Report Number 31 February 18th 1945
British Army Staff (AFV) Situation Report Number 32 March 18th 1945
Technical Services Armaments Number 16 February 25th 1945
Technical Services Armaments Number 18 April 30th 1945
British Army Staff (AFV) Situation Report Number 33 April 18th 1945

Vehicle AUV proposal Cargo Carrier T33 AUV T13
Date August 1944 August 29th 1944 (reported on in October 1944) September 30th 1944 (reported on in November 1944)
Total weight 40,000 lbs (18,000 kg) 39,000 lbs (17,600 kg)
Empty eight 24,000 lbs (10,800 kg) 31,000 lbs (14,000 kg)
Crew 2 2 2 (likely)
Troops 9 0 16 (likely)
Total 11 2 18
Propulsion 2 Cadillac V8, 230 hp at 1400 rpms 2 Cadillac V8, 220 hp at 1400 rpms
Speed 34 mph (55 km/h) (Unsure) 35 mph (56 km/h) (Unsure)
Range 250 mi (400 km) 250 mi (400 km)
Armament M2 .50 cal machine-gun M2 .50 cal machine-gun
Elevation/depression +86 to -10 degrees +86 to -10 degrees
Fording ability 40 in (1 m) 40 in (1 m)
For information about abbreviations check the Lexical Index
Categories
WW2 American Prototypes

Pelican Project and Half-Track Amphibian Cargo Carrier T32

USA (1942-44) Amphibious Utility Vehicle – Scale model only

By July 1942, the US National Defense Research Committee (NDRC), while working on developing the DUKW amphibious transport, concluded that a larger amphibious vehicle would be needed. They presumably expected that the DUKW’s limited capacity of 2.3 tonnes would be inadequate during large scale landings. Testing was done on a number of converted trucks, however, it was found that wheeled vehicles with payloads over 6 tonnes faced severe problems due to the increased ground pressure and unsatisfactory traction on beaches, their most likely landing point. It was therefore decided that a new project would be started, looking at developing amphibious half-tracks. These were meant to provide forces with larger supply payloads during landings in Europe and the Pacific without the inherent problems that wheeled vehicles faced.

The GMC DUKW (“D” – year 1942, “U” – utility, “K” – all-wheel drive, “W” – twin rear axles), designed in 1941, started production at the end of 1942 and was to be the US Army’s backbone during naval landings. Source: warhistoryonline

The Pelican Project

As a result of converted trucks failing evaluation, a number of half-track designs were drawn up for the newly started Pelican Project. These ranged from payloads as little as 2 tonnes, all the way up to an ambitious 25 tonnes. Some designs, in an effort to lower ground pressure and increase traction even further, featured an extra set of front wheels. These extra wheels, if powered, could have increased off-road performance, but none of the designs with them were given any further consideration.
It is not known exactly how all these designs were judged, but the final design that came out of the project did at least see significant evaluation. As well as being the last design in the project, it was also one of the largest. Weighing an estimated 9 tonnes empty, with a 9-tonne maximum payload, the vehicle was to be 15.3 m long and 4.4 m wide, larger than any other amphibious vehicle at the time. The design was to use a Ford 400 hp V8 petrol engine powering a pair of either Kirsten-Boeing or Voith-Schneider vertical propellers, giving the vehicle a water speed of 13km/h.

Blueprint of the final design of the Pelican Project Source: Half-Track: A History of American Semi-Tracked Vehicles, by R. P. Hunnicutt
To take advantage of the large number of new M4 Sherman tanks being produced and to potentially ease the logistical burden of developing a brand new tracked vehicle, the Pelican half-track was to share its VVSS (Vertical Volute Spring Suspension) bogie design. It was to have two bogies per side, totaling four road wheels per side with a central separate return roller, as well as the same track link design as on M4.

VVSS suspension was the standard suspension design of most US armored vehicles until it was replaced on the M4 Sherman by HVSS (Horizontal Volute Spring Suspension). This surviving M4A4 can be found at the Portland D-Day Center, UK. Photo: Mark Nash
A full-width ramp at the rear of the vehicle provided access to the cargo hold which was large enough to accommodate a 6-ton 6×6 truck of any model. Unlike regular half-tracks, the 2.7m wide driver’s cab was placed at the very front of the vehicle in front of the engine. The driver was on the left and on his right would be seated the rest of the vehicle’s crew.
A number of scale models of the Pelican half-track were built and used in water tests, but the project was soon canceled and no working prototypes were built.

Half-Track Amphibian Cargo Carrier T32

In May 1944, the NDRC was requested by the Ordnance Department to once again design an amphibious half-track to assist during landing operations. One main difference with this new program, however, was that the vehicle was required to have a three quarter length track. This was similar to that of German half-tracks, instead of the much shorter two-bogie design of the earlier Pelican half-track and other US half-tracks. This design would reduce ground pressure by having significantly more track in contact with the ground and more road wheels to support to vehicle.
Sparkman & Steven, Inc., contracted by the OSRD (Office of Scientific Research and Development), drew up an initial half-track design with an empty weight of 17 tonnes, and a payload of 13.6 tonnes. At a maximum weight of 30.6 tonnes, this design greatly outweighed the earlier Pelican’s 18 total tonnes. This could be credited to the three quarter length track, but at 12.7 m in length and 3 m in width, the vehicle managed to stay significantly smaller in size.

Blueprint of the initial vehicle design. Note the sloped top edge of the hull, and the matching sloped waterline, suggesting the vehicle would be tilted back slightly when in the water. Source: Half-Track: A History of American Semi-Tracked Vehicles, by R. P. Hunnicutt
The vehicle was to be powered by the Continental R975-C4 petrol engine, coupled with the General Motors 900T Torqmatic Transmission. This combination, the same as on the M18 Hellcat, would have given the vehicle 400 hp with an estimated top speed of 48 km/h on land, and 13 km/h in water. The front two wheels were powered, and propulsion in water was provided by a pair of 711 mm (28 inch) diameter propellers underneath the rear of the cargo bed.


Scale model of the initial vehicle design. It is unclear why the model lacks the sloped top edge of the hull, the rounded bow, and the cover plate over the wheels that are present in the blueprint. It is possible these modifications were done in the time between the initial blueprint and the model being made. Source: Half-Track: A History of American Semi-Tracked Vehicles, by R. P. Hunnicutt
The tracks, being longer than those of the Pelican half-track, allowed the design to have 5 dual road wheels which were also substantially larger. The wheels were on independent torsion bars instead of VVSS bogies, giving them more vertical travel and providing a smoother ride. The tracks also differed from the earlier Pelican in that they were without return rollers, an unusual feature on US vehicles. The design of the links was the same as on the T87 105mm Howitzer Motor Carriage, an ongoing project to have an amphibious vehicle using M18 Hellcat components armed with a 105 mm howitzer, a project that ended soon after the war did.
The design was later modified to include an additional road wheel by moving the drive sprocket forward. The rear ramp was also reshaped to provide clearance when entering an LST (Landing Ship Tank), reducing its overall length to 11 m and its overall height to 3.05 m. On the 29th June 1944, the improved design was designated Half-Track Amphibian Cargo Carrier T32. It was requested that three prototypes be built for testing, but Army Service Forces denied the request and the entire project was canceled, just over one month after the project was started.

The revised design that was submitted for prototype testing designated T32. Source: Half-Track: A History of American Semi-Tracked Vehicles, by R. P. Hunnicutt


The ‘Pelican Project’ amphibious Half-Track.


Early version of the Half-Track Amphibian Cargo Carrier T32.


Later version of the T32.

These illustrations were produced by this article’s author, Mr. C. Ryan, and were funded by our Patreon Campaign.


Conclusion

While the Pelican design, had it been built, might have suffered to a degree because of its small ground contact area for its weight, both the Pelican and the T32 seem to have been reasonable designs for their requirements. Ultimately, the sheer number of DUKWs being produced from late-1942 onwards outmatched any potential production numbers of the two vehicles, making them largely redundant apart from their valuable ability to bring regular trucks and other large vehicles to shore.
The failure of both projects did not end the US’ interest in large amphibious cargo vehicles however, as they would go on to attempt others after the war. One such vehicle was the capable 7.3-tonne, 8-wheeled XM157 Drake in 1956, which did succeed at reaching the prototype stage. It failed to reach production, however, as the army’s interest became focused entirely on the far larger LARC-LX for its amphibious heavy cargo needs. A 4-wheeled vehicle with a 54-tonne payload, it would go on to serve in the Vietnam War and stay in service until 2001.
Dimensions (L-W-H)15.3 x 4.4 x 3.94 meters

Specifications (Pelican)

Total weight, battle-ready 9 tonnes approx.
Propulsion Ford 400 hp V8
Speed (water) 13 km/h

Dimensions (L-W-H)11 m – 12.7 x 3 x 3.05 – 3.34 meters

Specifications (T32)

Total weight, battle-ready 17 tonnes approx.
Propulsion Continental 400 hp R975-C4
Speed Est. 48km/h (land), 13km/h (water)
Payload 13.6 tonnes, several dozen passengers, or a single 6-ton 6×6 truck

Sources

R. P Hunnicutt, Half-Track: A History of American Semi-Tracked Vehicles, Presidio Press