Category: WW2 Australian Prototypes

Commonwealth of Australia (1941)
Amphibious Tank – None Built

In March 1941, Messrs. Wales and Whitehead wrote to the Australian Army Inventions directorate with a memorandum and booklet proposing the construction of an amphibian tank along with an armoring system designed to overcome the problems which existed in Australia at the time with the manufacture of heavy armor plate. An amphibian tank would suit much of the terrain in which Australian forces were fighting in the Far East. The terrain was often swampy or involved transport on and off islands, terrain unsuited to conventional tank designs.

The design

The proposal did include two drawings. One of the proposed vehicle, and a second for the proposed armor plate, but sadly only the armor sketch survives, so it is hard to know exactly what this vehicle might have looked like. The proposal itself was very brief, just a two-page letter, but it was a well thought out and considered proposal, perhaps more than some of the inventions and ideas sent into the directorate during the war.

The overall shape of the vehicle is not known, but it was envisioned to be 18’ x 9’ x 8’6” (5.48m x 2.74m x 2.59m), and to use equalized spring suspension when traveling on land, which was seen as being particularly useful when traversing undulating ground. Displacement in water was stated to be 430 cubic feet (12.17 m3) for a vehicle measuring 18’ x 9’ x 8’6” (5.48m x 2.74m x 2.59m). This 12-ton vehicle was driven and steered by means of a controlled differential from an unspecified pair of V8 or similar engines. The main shafts for this design were positioned under the working floor level of the tank.

For protection this design was to use “2” (50.8 mm) thick armour plate equalling 80 lbs/sq.ft., but using a composite scheme consisting of armour plate and wood rather than simple steel armour plate. The metal layer of the armour was to be formed from rolled sheet and this laminated scheme was seen to provide ample protection and the potential to be reduced to 40 lbs/sq.ft. in the future. Several overlapping layers were used.

Assessment

All invention suggestions submitted during the war were subjected to a technical assessment by a committee of experts, and the Wales/Whitehead Amphibian, being a very thoroughly drafted idea, received an equally thorough appraisal. In terms of vehicle weight, the 12 tons envisaged by the designers was seen as unrealistic when considering the proposed size of the machine with 2” (50.8 mm) of armor plate. The assessment considered that armor at 40 lbs. per square foot (195 kg / m2) was possible for the desired 12 tons weight of the vehicle, but that this would be barely bulletproof. A little confusingly though, under ‘Armour’, the evaluation contends that in terms of the scheme for 2” of armor that:

“I have no reason to suppose that the proposed armour is, in any way superior to a single homogenous plate…. It is not clear how the various laminations are bonded together”

This, then, means that the 2” of armor in the design was not just a single homogenous layer of armour but some type of laminated protection possibly accounting for the thickness and the relative light weight of the machine. The design had mentioned the use of wood, but the exact composition is not known.

Floating

In terms of floatation, the technical assessment looked at the design seeing it would displace less than half of the stated 430 cubic feet (12.17 m3) and were not able to figure out how the designers came up with 430 cubic feet. It was assumed that in order to do so, the track guards were to act as floats for the machine. This design was condemned as it was open at the bottom, allowing any trapped air to escape easily adversely affecting buoyancy. Either way, the floats would be easily pierced by enemy machine-gun fire. The designers had selected a pneumatic gun mounting to resist the gun recoil of “as large a calibre gun as possible”, but did not specify a particular weapon. The only weapons specified were the machine-guns which were to be Bren and Lewis guns positioned on the vehicle in locations to be determined by the military.

The inventors were vague as to exactly how the machine could enter the water at ‘launch’, suggesting some kind of lowering would be needed, but this obviously rendered the machine unsuitable as an easily launched amphibian.

Firepower

For armament there was a complete disagreement between the inventors and the military experts. The inventors contended that it was the recoil length of the main gun which limited the firepower available whereas the experts concluded that this was not a problem and that the stowage of ammunition was a far bigger factor in determining the gun carried.

Termination

Following this assessment, the Army decided it was not worth further consideration, although the technical appraisal section of the department did have a few points of its own to raise which did not agree with those of the Army experts.

The technical appraisal section did not, for example, agree with the overall characteristics of the design, saying it was done to provoke some discussion so that it could be developed further for submission to the inventions board. Further, the low weight of the machine (just 12 tons) was as a result of the 40 lbs/sq.in. protection rather than the original 80 lbs./sq.in. and that the final weight would depend entirely upon the armor protection specified by the military – an entirely fair point.

Having made that fair point about the protection and weight, the section in the proposal did not accept the criticism of the scheme stating that “the writer [of the assessment] has no direct evidence of the efficiency of the proposed armouring” and that simple tests should be done to check out their idea. Here, this section also made clear that the proposed armouring scheme may have used more than just a lamination of steel or steel and wood. The appraisal of the design specifically referred to the armour on some British Cruiser tanks in the desert whose protection consisted of two armour plates with an airspace between them which suggests the armouring scheme involved some novel ideas about spacing between plates.

For floatation, again, the criticism was rejected, saying that the track guards did not play any part in floating the machine and the “the criticism does not apply being misconceived”

End

The Wales/Whitehead Amphibian Tank was considered to be well thought out and used some novel features. It had gained sufficient interest for the Army to consideration and the technical assessment did, in some regards, rate the vehicle as worthy perhaps of some further investigation.

The Army though was not interested, and was dismissive of the whole concept. Their final word on the matter was that it did not justify expenditure to investigate and that “in any case, there is no requirement, from the General Staff, for an amphibious tank”.

The Wales/Whitehead design then, regardless of what merits it may have had, was terminated and the drawings of the tank were sadly lost. All that remains of it are a few pages in a file. It is not even known who the two designers were as there is no information remaining to identify them.

Sources

Australian Inventions Directorate File G177/701/1264 March – April 1941

Commonwealth of Australia (1944)
Flying Light Tank – None Built

Naming tanks is a complex business. The name is supposed to capture the essence of the vehicle, inspire the crews with confidence and the enemy with fear and, as a result, many such vehicles are named after large raptors, predators, and wild animals. There are also cases in which vehicles receive a less aggressive name, but one which perfectly encompasses the entire vehicle. One of these perfectly named vehicles is the Australian Grasshopper Light Tank designed in March 1944. It is also referred to in Army correspondence as “Grass-hopper”, although in the original 1944 letter to the Adelaide Office of the Inventions Directorate, the designer referred to it as the ‘“Grass Hopper”.

Designed by William (Bill) Hope Murray of Verdun, South Australia, the Grasshopper was quite simply a light tank fitted with twin helicopter rotors “somewhat on the lines of a helicopter” to enable it to fly clear of obstacles. In other words, this was not a flying tank, but a light tank capable of great leaping jumps – at least in theory.

The Design

The aerial aspects of the design were inspired by the Igor Sikorsky YR-4 and VS-300 ‘Helicopter’ designs, although the designer did not have much information to work from based on wartime military security. Murray had, however, pieced together information on the YR-4 as being 35 feet (10.7 m) long with three 19 feet (5.8 m) long rotor blades powered by a single 180 hp engine. Capable of less than 100 mph (160 km/h) and an maximum altitude of 14,000 feet. (4,270 m), Murray had some data, but had no information regarding payload, range, fuel consumption, etc. He did however, estimate the weight of the machine to be 6000 lbs. (2.7 tonnes) gross and capable of carrying a load of ⅓ of that (~0.9 tonnes).

For the VS.300, Murray had the specifications as 27 feet (8.2 m) long with a 90 hp air-cooled engine, capable of 80-100 mph (130 km/h to 160 km/h ). Whilst these specifications for the VS.300 and YR-4 are not completely accurate, it is clear that Mr. Murray had done his research well considering the constraints of wartime secrecy and the newness of helicopter technology.

In outlining his design, however, Murray skipped over significant pieces of information. His design was really more of an outline for what could be done with the helicopter technology to blend it with a light tank than a very specific and detailed design.

What can be discerned from his plans though is that the machine was to have a crew of at least 4 or 5 men. Two men (although there appears to be space for at least a third man) sat at the front behind the unique (for a tank) aircraft style cockpit windows. Presumably one of them was the pilot/driver. Above the position of the driver/pilot was the main gun position in a very unusual elevated semi-rotating position. The gun is not specified, but even a 2-pounder gun and ammunition would have been a big demand on the payload available. Although there is only one crew member shown in this turret, the commander would have also been in the turret, as this was the highest crew position and would likely have had to have a second crew man to man the main gun or else the commander would have to load, aim and fire the gun, all while commanding the tank. At the rear of the tank was another member of the crew in a bubble-shaped turret with excellent visibility from the glass or perspex bubble he was sat in.

Looking side on in the drawings provided, at least two unspecified weapons, likely machine-guns, were at his disposal, positioned unusually on top of each other. This might have meant that, in fact, Murray was picturing a quadruple mounting as a side view, but irrespective whether the turret was to mount 2 or 4 machine-guns, the positioning was very poor. It would be able to provide very little anti-aircraft fire when on the ground, as firing upwards was hindered by the rotors, very little fire backwards due to the position of the tail, and no fire at all to the front of the vehicle. Neither could it provide any fire downwards when flying.

Between the fore and aft turrets lay the engine for the rotor in a small vertical box structure. Below this was a large space in the hull for the engine of the tank which actually ran under both the fore and aft turrets. This was actually one of the better parts of the design as there was no complicated linkage to use a single engine, but it would have added significant weight the machine.

Murray had selected dual rotors for extra lift, giving the impression of a helicopter with counter-rotating rotors, although this is not the case. These would, he felt, provide ample mobility for independent attack surmounting obstacles and hopping past enemy lines. In deployment though, Murray seems to have not done as much research as he did for the flying elements of the design as he envisaged the tank being used in “large numbers [with] a fast fighter support” where it “would be a very dangerous weapon”. Obviously, with a large accompaniment of fighters, the need for the anti-aircraft part of the armament would seem superfluous. He wanted the design to be “as light as possible”, which would clearly mean little or no armour could be used, and he was unclear on what he meant by a ‘belly periscope’, although it is likely to do with trying to see where it was landing.

Flaws

The visibility, despite the huge windows, was very poor. The pilot would effectively be unable to see where he would be landing this large helicopter through the front windows and instead would have to use the large windows in the lower front portion of the hull. All of this glass effectively meant that this vehicle was going to be unarmored. Comparing protection and weight, bulletproof glass was, and still is, substantially worse than steel, therefore, to be even bulletproof, this glass was going to have to be heavier than the weight of bulletproof steel. For a ‘light tank’ this was a significant problem with the concept and one unaddressed by Murray in his letter. Assuming the ‘glass’ to actually be aircraft type perspex at the front and back, this would mean that the tank was not even bulletproof. Although this would mean that the weight would be very low, it was a significant flaw for a ‘tank’ meant for fighting the enemy head on. The rear turret would be useless when attacking forwards and almost useless for anti-aircraft use. The arc of fire was too constrained by the design and the crew member would have been idle the majority of the time on the ground or in flight.

The selection of two engines, one for flight and one for driving, did ensure mechanical simplicity of design, but it also added a huge amount of unnecessary weight. When on the ground, the vehicle had to haul around the aircraft engine which had no use on the ground and when trying to ‘leap’ or fly, the helicopter now had to lift the tank engine as part of the payload rather than as part of the drive for the rotors.

The whole of the rear compartment of the tank from the back of the aft turret to the rear of the hull was intended to be for fuel for both engines. This fuel tank would have been huge and also very heavy but was at least at the back of the vehicle where it was better protected from enemy fire. Projecting from the back of the tank was a large rotor tail made from hollow tubing with a skin around it and had no need for armouring or protection of any kind as it contained no fuel, mechanicals (other than the tail-rotor drive shaft) or men. It is not clear if this tail could be detached. One further point of note in the design which received no attention from the Army Inventions Directorate was the bomb doors. Positioned directly behind the driver in the bottom of that compartment was a ‘flap’ through which bombs could be dropped, which perhaps accounts for the second crew member in that location, who is possibly supposed to be the ‘bomber’.

Suspension for the vehicle is not mentioned, although given its light nature and contemporary designs could have been either springs or ‘Christie’ type shocks, but relies upon 6 road wheels per side. Some illustrations show the lead and rear road wheel as being larger than the other four but may have simply been an illustration issue. Either way, the central four wheels were relatively uniformly spread from each other but further from the front or rear wheels than they were from each other. It is not clear from the design at which end the transmission for the tank was supposed to go or from which end drive would be applied to the tracks.

The overall outside of the vehicle is extremely heavily curved with what appear to be the two crew access hatches located on either side, although how they would get in and out from their compartments is unknown.

Problems

The design, like so many others, was evaluated dispassionately by the Australian Army for its merits and defects and what it might bring to the Allied war effort. The assessment here was, as with many others, not a positive one. The Grasshopper tank simply had too many flaws to warrant further investigation, flaws like the fact that when in the air the machine had absolutely no means whatever to fire down at any enemy below it. The incredible vulnerability of such a slow moving, rather large and thinly protected vehicle passing slowly and low over enemy positions was a very tempting and vulnerable target for the enemy.

The positioning of the weapons was also criticised. In particular, the two guns in the turret at the back were very poorly located. Intended, as anti-aircraft guns these guns would be completely useless in the air as well as on the ground firing upwards or to the rear as they would be firing through the tail/tail rotor, or the rotors above. Whilst methods for timing machine gun fire through a propeller had been developed during WW2, there was simply no way to time the fire of these weapons through these rotors. Any attempt to use the weapons during flight could, therefore, lead to the crew shooting down their own vehicle.

Although a leaping tank could be very useful tactically and solve many problems, the idea was simply impractical and technically impossible at the time.

This supposed light tank was simply going to be too heavy to be useful as a light tank, too big, and too slow. As a helicopter, it had neither the range nor the altitude and speed to be useful and was not going to be able to be armored sufficiently for ground work nor protected enough for aerial work.

Layout wise, the elevated position for the main gun was desirable, although it was in a limited traverse turret limiting its usefulness and, without a second crew member in it, would be very difficult for the commander to use whilst commanding the tank. The location of the bombs and bomb doors too ensures that, should the tank hit a landmine, the complete destruction of the vehicle and loss of crew was virtually guaranteed.

The road wheel design seems to have been inspired from that of the Valentine, with either 6 uniformly sized road wheels or larger fore and aft wheels with four smaller ones in between, but would have ran on quite thin tracks. Thin tracks increase ground pressure from the vehicle and this design is very wide meaning it would be more vulnerable to becoming grounded out when crossing rough terrain.

Conclusion

The assessment was not completely dismissive however, the general concept was seen as a very desirable one. There would be no need for light bridging equipment to get the tank over trenches or ditches, rocky escarpments or walls. It could leap heavily forested sections, rivers, very soft ground and, most importantly, enemy minefields and wire entanglements. So desirable is the overall concept of a ‘leaping’ vehicle that such ideas continue to be entertained by various military forces, albeit with the same level of success that Murray’s Grasshopper had.

Bill Hope Murray, service number S76738, had already enlisted in the Australian Army (4th Battalion Volunteer Defence Corps) in April 1942, aged 45 (he was born January 1897), which meant that he was 47 when he submitted his design. He concluded his Army service in October 1945 with the rank of Lance Sergeant having served his nation in the war. His design might not have helped to win the war, but his service played its part, and even at home in Australia, he and his wife raised money for the war effort. Post-war, Murray went back to his life in Verdun and eventually retired as the architect for Public Buildings as well as operating a family farm. The patriotism that spawns such ideas should not be discounted though, neither the desire to help which underpins so many of these well intentioned, albeit flawed tank designs.

Illustration of the ‘Grasshopper’ Light Tank produced by Yuvnashva Sharma, funded by our Patreon Campaign.

Sources

Australian Army Inventions Directorate file 15430, 1944
Murray, Bill Hope at rslvirtualwarmemorial.org.au
The Disused Grunthal Gold and Copper Mine, 3rd August 2013 – weekendnotes.com
Reg Butler, Hahndorf Memorial Institute – ‘50 Years On’ – Golden Jubilee of the Hahndorf Institute Extensions 1957-2007

Commonwealth of Australia (1945)
Moving Fortress – None Built

War can stimulate the minds of the young and the old alike to develop weapons. Whilst the majority of would-be tank designers have finished their basic school education, it seems one precocious Australian schoolboy by the name of ‘G.Crowther’ saw his opportunity in 1945 to make his contribution. As such, he drafted up his own design for a ‘Land Fortress’ tank and posted it to the Army Inventions Directorate.

Crowther Land Fortress tank from the right-hand side. Photo: Author

Design and Layout

Generally, tank designs that go by the name ‘land fortress’ or ‘land battleship’ etcetera are huge, impractical, and ill-conceived, even when designed by experienced engineers. Master (not Mister – ‘Master’ here, referring to a youth) Crowther, however, is an exception to this trend. His Land Fortress tank exhibits many interesting features, albeit relatively crudely drawn.
Sporting not two but three caterpillar tracks – the third caterpillar running directly down the middle of the vehicle – this offered the potential for improved off-road performance with a lower ground pressure compared to a design with just the traditional two tracks, although at a significant increase in weight and complexity. The engine and main fuel tanks were positioned at the front, between the driver and the front of the hull. A second emergency fuel tank lay at the rear, along with one on the bottom of the hull. Behind the driver was a small spherical turret for a gunner using machine-guns, and above this, the main turret which housed a 25-pounder gun. Behind that main turret was yet another turret fitted with twin machine-guns. All of the above was set within a highly curved smooth hull providing very clean lines over the body of the tank.
A final machine-gun position was set at the very rear, at the same level as the driver, but operated by a gunner and the final weapon, a flamethrower, was mounted on the front of the hull and was operated by the driver.
In total, Crowther’s design mounted no less than 6 machine guns, 1 flamethrower, and one 25-pounder main gun. With multiple turrets and a very high track design, the vehicle is more emblematic of the inter-war era than the end of World War 2. For a tank of 1945 though, it was unsuitable and brought forth no new ideas about tank design to the Australian Army. Perhaps the most overlooked part of the design though is the choice of a third track. This was not new, the firm of William Foster and Co. of Lincoln had designed ‘belly tracks’ back in WW1 for the same lower ground pressure reason. The addition of tracks under the hull obviously provided more bearing surface on which the weight of the machine was spread out and also reduced the chance of ‘bellying-out’ when crossing obstacles.
It seems extremely improbable that a schoolboy in Australia back in 1945 would have had an in-depth knowledge of experimental tank designs in Great Britain from World War 1, so it is interesting to note that he seems to have developed this idea independently.

Illustration of G. Crowther’s ‘Land Fortress Tank’, produced by Wolfgang ‘Wolf’ Hinze, funded by our patreon Campaign.

The Official View

The June 1945 report into Crowther’s design suggestion was short but was not as dismissive as perhaps a first glance might have suggested. There were some good features to it for crew protection, such as the forward mounted engine and the extremely well-sloped body and turrets, which were obviously well designed to deflect shots too. The era of the multi-turret tank was well over by 1945 and the choice of the powerful but low velocity 25-pounder gun for the main armament was not going to be suitable for a main gun in the post-war era.
The report, perhaps a little gently due to the age of the designer, ended saying:

“whether or not there would be anything of value in this idea is difficult to say. Perhaps one of these days streamlined tanks will be the vogue and the design outlined may then be approached”

Master Crowther was thanked for his idea, the paperwork was filed and quietly forgotten. No examples of this Land Fortress Tank were ever built and the youthful designer likely went back to his studies. It is not known what became of him.

Sources

Australian Army Inventions Directorate file 19886, 1945

Commonwealth of Australia (1884-1944)
Land Battleship – Paper Project

Australia entered the Second World War with very few tanks and an urgent need for armored fighting vehicles. Although the primary opponent for Australian forces was Japan and their its small and thinly armored vehicle in the Far East, Australian forces would also serve throughout North Africa and later in Europe. By 1944, Australia had its own indigenous tank production capability in addition to British and American supplied armour to use. Together, this provided all the armor that Australia needed, and yet, despite this, there were inventors who sought to get their own designs into the hands of the Australian Army. Some of these inventions were reasonable, some not so reasonable, and many – the majority in fact – were totally unsuitable for modern warfare. The Puckeridge Land Battleship assuredly falls into this latter category.

The rough sketch of Puckeridge’s Land Battleship from 1944. Photo: Author’s Collection

The Inventor

The critical weaknesses of current tanks were, according to Puckeridge, the exposed tracks and wheels, which were vulnerable to enemy fire, and Puckeridge had his own ideas for a new, war-winning weapon without these flaws. Mr. Fred B. Puckeridge of Port Lincoln, Australia wrote to the Australian Army in March 1944 submitting his idea and a rough outline for a ‘Land Battleship’ with the intention that these new ‘tanks’ would work in conjunction with existing tanks.
Puckeridge, in his letter to the authrotities, claimed to have recently outlined his idea to the then Minister for the Navy W.M.Hughes on 8th November 1940, and that it was then sent on to technicians who did not approve of the idea as the vehicle was considered too large for Australian production. Puckeridge had hoped in 1940 that this idea would be passed onto Great Britain and the USA, although presumably, this was in hindsight, as the USA did not enter the war until December 1941.

The Design

The Land Battleship was projected to be big. Very big. The whole vehicle was to move on rollers 40 feet (12.192m) in diameter and 20 feet (6.096m) wide. Three rollers arranged two at the front and one at the back. The rear one was used for steering, and all three were attached to the large body of the vehicle completing it at about 190 feet (57.9m) long and 70 feet (21.3m) wide.
The armour was no less grandiose, consisting of 8-inch (203mm) thick plate at the front mounted on “heavy steel girder frame” and 4-inch (101.6mm) thick at the sides. Two gun turrets surmounted this machine with an 8 inch (203mm) and a 6 inch (152mm) gun as the main armament and two 7.5-inch or 8-inch howitzers in the fore turret. The rear turret was to be much less heavily armed, with just a battery of “AA pom-poms” for anti-aircraft use. Additionally, 75mm guns and automatic weapons were to be mounted along the sides of the hull.
The engines were not to be mounted in the body, but were instead to be mounted inside the rollers and fixed permanently to the axles, which in turn were secured to the framework for the body of the vehicle. Using three engines (one for each roller) ensured that the loss of even two engines in combat would not cripple the machine.
Communications and vehicle control traveled through these hollow axles to the engines with the exhausts being vented out of one side.
Puckeridge felt that his design could be very effective in the jungle, for the clearance of jungle, constructing roads, and even as an amphibious fighter when the adequate modifications were carried out.

Rejection

Puckeridge’s somewhat impractically large roller-tank ‘Land Battleship’ received an assessment from the Australian military and by April 1944 had been quickly rejected for the second time. The specific reasons for rejection were the vulnerability of the driving mechanism by enemy fire, lack of maneuverability on land. Another complaint was the visibility – the design had large blind spots which meant the crew would have been unable to keep an eye on their surroundings. Although not mentioned presumably obvious problems like how to build and transport this enormous machine let alone its combat value (or lack of) were taken into consideration when it was rejected.
The vehicle concept was seen as adding nothing new to the design of armored fighting vehicles from the point of view of the Army and received no more attention.
With his idea rejected it would normally mean the end of the matter, but Puckeridge persevered and wrote back in July 1944. Taking the criticisms point by point, he now further claimed that this idea had been around for a long time, and that he personally had submitted a very similar idea back in 1884 to the then British Prime Minister, W.E. Gladstone. That idea was steam driven and was prompted by the siege of General Gordon at Khartoum in the Sudan. Later, in 1915, Puckeridge had again submitted a similar design to the British Board of Inventions powered by a diesel engine. his latter suggestion was rejected.
Regarding the complaint about it not being as maneuverable as a ship, again Puckeridge argued pointing out that this design could, in fact, turn 90 degrees in a quarter of the time and in a tenth of the space of an ordinary seagoing vessel.

Conclusion

Puckeridge’s design was large and typical of a type of large wheeled ‘tank’ which was seen on the drawing boards and in the fertile writings before the First World War. Despite his assertions that these rollers would be useful for flattening jungle, clearing and making roads, and even airfields, the giant-roller tanks were all seriously flawed in concept. Puckeridge’s grand idea had no effect on the war and got no further than his writings to the Army. The fact that he stuck to an idea from 1884 all the way into 1944 is a testament to his interest in the idea, as well as perhaps also an element of stubbornness to accept that the idea was a poor one.

Sources

Australian Army Inventions Directorate File 15230 April 1944

Illustration of Puckridge’s Land Battleship in a speculative camouflage. An average height man (1.7 meters, 5ft 9in) is standing in front of the vehicle for scale. Modelled by Mr. C. Ryan, funded by our Patreon Campaign.

Commonwealth of Australia (1943)
Landship – None Built

Australia is most famous for a wide range of deadly native creatures, but within the tank community, it is well known for its Cruiser tanks (AC I, II, III and IV Sentinel Cruiser Tanks). Whilst those Cruiser tanks were good designs in their own right, another vehicle, purporting to be a ‘Land Cruiser’, was not. Neither famous nor a sound design, the suggestion by Mr. S. Cossor of Albury, New South Wales, in March 1943 was very poorly considered.
Just like so many other wheeled tank designs, Cossor went for the tricycle setup, with two large front wheels on a roughly triangular body and a third small trailing wheel at the back.
Cossor sent in his idea in March 1943 for consideration and received a particularly quick and blunt appraisal rejecting the idea completely. A review of the specifications makes it very clear why.

The Idea

Cossor’s idea from January 1943 was essentially simple in desire and complex in delivery: “To provide a land offensive unit with more striking power than the largest tanks so far constructed, that could not be destroyed by ordinary mobile artillery, tanks, or landmines”.
Further, perhaps understanding that the design was utterly unsuitable for use on roads, he envisioned that it would roll around without even needing roads, smashing through enemy fortifications and in doing so, roll flat a path for tanks and troops to follow. This is actually a common line of thought for these type of giant wheeled suggestions. In terms of bridges, Cossor, just like other similar inventors, assumed that the vehicle would simply be able, by virtue of its size, to cross even deep rivers.
This outline sketched out in January was sent to the Army in March for consideration, although they were busy enough with conventional tank designs at the time.

The design

The Cossor Land Cruiser was huge, based around wheels about 16 1/2’ feet (5 meters) in diameter. The wheels, when viewed in cross-section, form a ‘C’ shape as they overlap the rolling pin shaped the main body with the axis of the pin forming the axles of the wheels. Although this was a rather neat method to increase the footprint of each wheel, it also served to raise the overall vehicle height to 20’ (6.1 meters). The overall length of the vehicle was at least 50’ (15.24 meters) ensuring that it was completely impractical to move around. The width of the vehicle was not much better, 40’ (12.2 meters) wide from wheel edge to wheel edge. A vehicle of such dimensions was near impossible to move by ship or road, as it was bigger than any bridges could accommodate and wider than a road. When the driving cabin ‘turret’ dome was added to the front, this projected past the front of the wheels and increased the length still further, and as if to make the impractical impossible, Cossor also added detachable sponsons to the wheels.
These sponsons were large domes fitted to extensions of the axle pin for the wheels, so would simply hang and not rotate with the wheel. No easy access seems to have been provided from these sponsons to the main body, although the axle is supposed to be ‘hollow’. Likewise, no consideration seems to have been made of just how these huge and likely very heavy sponsons and driver’s stations were supposed to be fitted.
On top of the ‘pin’ part of the body were two large turrets, and between them, a firing position for anti-aircraft guns. Down the trailing arm part of the body were meant to be ‘living quarters’, giving perhaps an indication of just how big this machine was and how many crew it would have to have. Right at the back was the wheel which controlled the steering that was directed by the driver located right at the front. An access corridor ran the full length of the design from the cabin to the compartment above the rear wheel. The entire body was to be clad in ‘heavy armor plate’ and the trailing arm was to be curved across the top, but other than that there is no indication as to exactly how much armor constitutes ‘heavy armor’, and an accurate weight for the vehicle cannot easily be estimated, although, from the size of it, the machine was to easily exceed 100 tons, if not more.
Some of the design is hard to understand, as only 1 of at least 3 drawings provided by Cossor has survived to this day. The surviving image does, however, give an idea of the size and armament of the vehicle and why it was so quickly rejected.

Original rough drawing of the Cossor Land Cruiser. Photo: Author’s Collection

Armament

Cossor did not spare the selection of firepower for his Land Cruiser making it look more like a Land Battleship than anything else. In the front driver’s compartment, ‘control cabin’ were 2 machine-guns positioned to fire at an angle across the front of the machine. Two further machine-guns were located in each of the large domed sponsons angled forwards and back, and three more machine-guns were located in the tail section covering the rear. To this total of 7 machine-guns was added an anti-aircraft position on top. No weapon is specified for this position, but it is flanked by the two large circular turrets, each of which is supposed to be mounting a 6” (152.4mm) gun, presumably of naval origin.

The Assessment

This enormous and adventurous design from Cossor received just a single page assessment. The weight, although not specified, “would be enormous and with only two main points of support the pressure per sq. in. would be very high, causing the wheels to sink into any ground at all soft – a common failing with these types of designs. This huge tank would also have required huge engines to power it, which were neither cheap nor readily available in wartime Australia, and the rest of the vehicle would also have been very expensive to produce. Too expensive to make it worthwhile.
The design was also faulted for not being watertight as well as for being extremely vulnerable to enemy fire. It might have had thick armor after-all, but it was such a huge target that it would not have been able to hide and would easily have been targeted by enemy fire. The idea was duly rejected in total on 2nd April 1943 although perhaps the day before might have been more resonant.

Source

Australian Army Inventions Directorate File 7934, 1943

A left side profile and head on view on the Cossor land Cruiser with an average size man (1.7 meters/5 feet 9 inches) for scale. Both illustrations were modelled by Mr. C. Ryan, funded by our Patreon Campaign.

Commonwealth of Australia (1943)
Light Tank – None Built

Of the many designs for tanks submitted to the Australian Army Inventions Directorate during World War 2, there were some very sound schemes, some very outlandish schemes, and then a few very peculiar schemes. The Modra Revolving Light Tank is one of the latter. It was neither enormous nor technically impossible (unlike so many of the ideas submitted to the Directorate) but it was not based on sound military thought either. It found no place in development or use for the Allies in the Second World War, but it is nonetheless still an interesting concept to record as it has several unusual features. It was sketched by the pen of William Frederick Modra, a gardener by profession from Underdale, although it should be noted that since 1935 he had also been on the Port Lincoln Town Council.
Modra’s design was submitted on 15th October 1943, followed in December by several other ideas for war weapons, including an ‘Anti-Personnel Bomb’ and a ‘Multiple Projectile Bomb/Shell’. The anti-personnel bomb was rejected on the basis of the casing being too heavy, which resulted in a smaller charge and reduced destructive effect of the bomb, whilst the Multiple Projection Bomb was rejected on the basis than one larger shell is more effective than many smaller ones, as the weight of the multiple casings detracted from the explosive charge which could be carried. The Revolving Light Tank received slightly more attention before being rejected though. However, the review of the submission does delve into those component parts of the design briefly.

side-view schematic of Modra’s light tank. Image: Author’s collection

The Design

The design of the revolving light tank was based upon a very simple principle: deflection. A curved body is more likely to deflect an incoming projectile than a flat-sided or vertical-plated body, and therefore, Modra extended this idea to cover the entire vehicle. On top of this, he also chose to forego the usual hull and turret layout to have what is effectively a huge turret overlapping all the sides of the small hull inside the vehicle and extending almost all of the way to the ground. In this way, the design is very unusual whilst at the same time still being quite a simple idea providing uniform armor for the vehicle from all directions. The driver, sat in a rather comfortable looking armchair as drawn, steers the vehicle normally with the engine, transmission and fuel tanks in the small hull under the body. The gun is attached to the revolving floor plate which is also attached to the revolving body so that as the vehicle rotates, the gun is also slewed with the body. The suspension for the vehicle was drawn but not described, and shows a large diameter lead and trailing wheel with 4 smaller rollers, but no return rollers for the track. The ground clearance is also extremely small with this suspension system, leaving very little space between the ground and the hull, but also between the ground and the overhanging armor.
This low ground clearance combined with the shape meant that this design would basically have been unable to traverse broken ground, as even a small bump or tree stump would foul either the bottom of the hull or the edge of the armored body. It was on this basis that the design was rejected in total. Not mentioned in the rejection were the other problems with the design, such as how the driver was meant to drive when the turret was rotated as he would still have been facing the direction of the gun, although the position of the springs at the back would indicate that this design could not rotate fully. Neither was there any consideration of how the crew would get in or out of the vehicle, nor any mention of the primary armament and no consideration was given to a secondary armament, such as a machine-gun.
Modra did not discuss how many crewmen he foresaw his design needed, nor did he mention problems such as manufacturing such a large armored dome or how to transport a vehicle this wide. It seems from his drawing though, that some of this might have appeared in additional pages submitted with the design, as parts of his drawing are actually numbered. Sadly, the rest of the file is missing or lost giving perhaps a slightly unfair review of this design being ill-conceived.

Recreation of the part list from the original patent papers by the Author

A rendition of the Modra Revolving Tank in a speculative livery modeled by Mr. C. Ryan, funded by our Patreon Campaign.

Conclusion

The design was certainly novel and incorporated a good line of thinking trying to combine good protection from the angles of the armor for a minimum of weight. It was, however, fundamentally flawed in concept as the body was simply sticking out so far and so low that it would foul on the ground. The problems of having the driver in the turret were not addressed either and would later befoul other attempts to have a similar arrangement – most famously in the MBT/KPz-70 program, but also in the Chrysler ‘K’ and the Soviet Object 416.
As it was, Mr. Modra’s designs for this tank and other weapons were rejected. Modra himself was later to become an overseer for the Corporation of Port Lincoln and a member of the town council until his death, aged 59 in June 1953. His obituary noted his “extremely powerful physique” and his “ingenuity”. His ingenuity with regards weapons and tanks did not lead anywhere in WW2, but he was successful in other areas.

Top view of the layout of the Modra design. Image: Author’s Collection

Sources

Australian Army Inventions Directorate File 13834, 1944
Port Lincoln Times, 11th June 1953
The Mail, Adelaide, 10th August 1935

Commonwealth of Australia (1944)
Mobile Pillbox – None Built

The ‘Mobile Pill Box’ was the brainchild of W. W. Melvaine. He lived in Brighton Boulevard, Bondi, Australia. It was one of many inventions submitted to the Army Inventions Directorate of the Australian Army in the Second World War. Many designs were submitted for all manner, shape, and size of weaponry including tanks. Although the inventors of such vehicles often had a preference for huge landships or ‘big-wheel’ designs there were also a number of smaller designs and Melvaine’s Mobile Pill Box’ is perhaps one of the more unusual Australian tank designs of the War.

On 19th January 1944, Melvaine wrote a surprisingly short letter to the Army with this suggestion. It was notable for the total lack of detail and explanation. It did not contain any ideas about why he thought his idea might be good, or better than methods or vehicles currently in use. The entirety of his letter comprised just four handwritten lines:

“Dear Sir, May I suggest the possibility of such a thing as a bulletproof mobile machine gun and grenade pill box for close up attacks on foxholes and dugouts – Yours Faithfully W.W. Melvaine”

The sentence was followed by three crudely drawn sketches of his idea which more resembled the traditional Australian thunderbox (outside toilet) than any kind of useful tank.

The Design

The design was relatively simple, consisting of a small tracked platform with at least two wheels on each side powered by a small motor in the crew space. This small motor was open to the occupant. There was just enough room for a single soldier. This soldier would have to man the single forward facing machine gun from a standing position.

As well as the machine gun the soldier inside would have a box of grenades. From within this armoured-outhouse, he would most likely have had to exit through the open rear to lob a grenade. This would have meant being exposed to enemy fire from the flanks.
The height of the machine would mean it would be visible to the enemy before the soldier could see them and there is no clear indication of how it was to be steered or even how the soldier would be able to see where he was going.

There is no indication provided by Melvaine as to the prospective size of the machine which can only be estimated by the size of the soldier and no idea as to the performance he wanted or expected. Likewise other than saying ‘bulletproof’, there was no thought given to the amount of armour this design should carry.

The Official Review

This idea by Melvaine received perhaps one of the shortest assessments for an invention, and it was as blunt as it was negative, saying:

“Tanks are in use for this purpose. The proposal is crude and retrograde”.

And with that, the idea was dead.

Conclusion

Being disparaging about some of these invention ideas could be considered churlish. This design had, after all, the advantage of simplicity on its side, and perhaps under other circumstances might have found some kind of use. The idea though, that in 1944, this invention might somehow be suited to attacking enemy positions when tanks were available was simply incorrect and betrays a fundamental misunderstanding on the part of the author. The rather short letter, more of a note about it, perhaps indicates that this was more of a whim than any properly considered design. Nonetheless, the idea was recorded and preserved even though the concept was completely disregarded.

Illustration of Melvaine’s Mobile Pill Box by Mr. C. Ryan, funded by our Patreon Campaign.

Sources

Australian Army Inventions File 154142, 1944

Commonwealth of Australia (1942-1943)
Cruiser Tank – 1 Prototype Built

The one with the big gun

Another offspring of the AC I Sentinel was the AC IV, which was to be equipped with the new British Ordnance QF 17-pounder anti-tank gun. After the July 1942 decision to proceed with increased armament for the Australian Cruisers, a plan for expedited local production of 17 pounders was initiated to replace the previously planned 6 pounder production.

Artists rendition of the AC IV. Source: National Australian Archives MP730 10
A new prototype turret was fabricated to facilitate mounting the 17 pounder gun, and fitted to the E1 prototype hull. The new turret had increased dimensions over the previous AC I and AC III turrets, notably featuring a slightly taller roof and an extended rear bustle with an angled rear facing as opposed to the vertical rear face of the previous types. The turret ring diameter was also increased from 54 inches to 64 inches, with the E1 hull being suitably modified.
Testing began in October of 1942. The first test was a simulation of the recoil force of a 17 Pounder, and its effect on the tank. This was done by mounting two 25 Pounder howitzers side-by-side in the turret and firing them simultaneously, this gave an estimated recoil force 20% greater than that of the 17 pounder. The dual 25 pounder mount took up the majority of the turret space and had to be fired remotely via lanyard. In the same month, the first Australian produced 17 pounder guns were completed at the Maribyrnong Ordnance Factory.
The tank was fitted with a locally produced 17 pounder (allegedly one of the first guns produced) equipped with a modified recoil system based off of that developed for the 25 pounder tank mounting. The tank and gun mounting were first test fired on the 11th of November at Fort Gellibrand in Williamstown, Victoria, with tests continuing on until early 1943. These tests proved quite successful and made the AC IV one of the first Allied tanks to mount the 17 Pounder gun.

A constant improvement

This, however, was not the finalized design and work would be ongoing for the AC IV until the cancellation of the tank program in mid-1943. Concerns had been raised about the design which would further complicate the matter. The 54 inch turret ring had been considered cramped but workable with the 25 pounder, but there were doubts about the efficiency of loading a 17 pounder in a 64 inch turret ring. It was therefore decided to increase the turret ring diameter to 72 inches for production vehicles.
Additionally, the Army was not satisfied with the proposed quantity of 54 rounds of ammunition carried in the prototype, and insisted that a minimum of 74 rounds be met. It was also considered desirable to mount the 25 pounder in the new turret to take advantage of the potential benefits of the 25 pounder gun alongside the 17 pounder.
The DAFVP responded to these requests with a proposal for an AC IVA design. Documents, however, are unclear as to what the AC IVA design actually entailed. Some documents claim the AC IVA was to be a variation of the AC IV fitted with the 25 pounder and produced at a rate of one 25 pounder armed tank for every three 17 pounder armed tanks. Other sources list the AC IVA as a design with enlarged hull dimensions to allow for an increased turret diameter and increased ammunition stowage for either the 17 or 25 pounder gun.

New powerpacks

16 cylinder 510 horsepower Gipsy Major engine mock-up. Source: National Australian Archives MP730 10
To cope with the added weight, two new engine designs were proposed. The first consisted of four Holden Gipsy Major engines, providing an estimated 510 horsepower, to be mounted together in a two layer opposed piston setup and utilizing air cooling as opposed to the water cooled engines used previously.A non-functional mock-up of the engine, utilizing as many genuine parts as were available was produced. However, funding to continue development was denied due to termination of the tank project.
The second design was a 600 horsepower Michell type crankless engine, the design of which had been extensively developed by respected Australian Inventor A.G Michell in the 1920s. Director of Armoured Fighting Vehicle Production, Alfred Reginald Code, had been the chief draughtsman for Michell’s Crankless Engine Company from 1925 until the company’s closure in Australia in 1928. The crankless tank engine would have had several advantages, such as a smaller size to horsepower output ratio as well as a higher fuel efficiency. The design did not proceed beyond the drawing board.

This cutaway drawing of the proposed 600 horsepower crankless tank engine. Source: National Australian Archives B6118 7

The AC IV prototype, based on the AC E1 – Illustrator: David Bocquelet

The AC E1 – Fitted with the new turret and 17 pdr gun, Fort Gellibrand Victoria,  summer of 1943. Source:- Australian War Memorial PO3498.010

The AC E1 with the turret traversed to the right showing the elongated rear of the turret and higher turret roof, Fort Gellibrand Victoria,  summer of 1943. Source:- Australian War Memorial PO3498.009

Always changing requests

In the quest for a modern tank design the army added a veritable laundry list of new requirements from late 1942 through to 1943, largely focused on standardising with the latest developments in US tank design. By early 1943, it was not clear to Australian authorities if the M4 Sherman would continue to be the standard tank of the US forces or be superseded by the T20 series of medium tanks.
Based on information received from US sources and the assessment of Col G.A Green on behalf of the US Army, desired upgrades included: US style all round vision cupola with additional crew vision blocs to be added around the turret. Ford GAA 525 horsepower tank engine to replace locally designed engines. Oilgear hydraulic turret traverse mechanism and Westinghouse 24 volt gyroscopic gun stabiliser. Removal of the turret basket in favor of crew seats suspended from the turret ring. Torsion bar suspension, or, if not possible, the implementation of US M4 type road wheels and revision to US rubber tracks. Replacement of the Methyl bromide fire suppression system with a Carbon Dioxide system. Arguably the most ambitious and outlandish proposal was the suggestion of a mechanical ammunition rack to better facilitate loading the 17 pounder gun.
‘Accordingly, a magazine containing 18 shells has been designed and this is located across the rear of the turret. The noses of the shells point towards the gun and the magazine has been equipped with gear to traverse each shell in turn to the centre for loading’ – tank production programme Report, on behalf of Director AFVP A.R Code to Mr Pryke, July 21st 1943

Not in vain

The termination of the entire Australian Cruiser program in mid-1943 was dictated by a mixture of practical and budgetary reasons as well as an ongoing political rivalry between the Ministry of Munitions and the Army.
Despite the Australian tanks never seeing combat use, one notable benefit to the development of Allied tanks did occur as a result. In 1943, Colonel Watson returned to the UK after his secondment to the Australian tank program ended. Watson brought with him documents related to the Australian tank program, including photographs and drawings of the 17 pounder mounting on the AC IV prototype.

The experimental 17 pounder mounting complete with  mantlet dismounted from the E1 tank. The modified recuperator system can be seen extending out into the mantlet bulge above the gun barrel. Source: Ed Francis
Watson received a great amount of interest regarding the Australian work with the 17 pounder, notably from Sir Claude Gibb who was adamant that the 17 pounder could be mounted in an M4 Sherman turret, but faced severe opposition from the parties arguing otherwise. Subsequently, a series of meetings was convened where Watson was invited to provide detailed information about the Australian 17 pounder tank mounting, information which significantly expedited the decision to mount the 17 pounder gun on what would later become the Sherman Firefly.

Surviving vehicle

The Australian Armour and Artillery Museum displays a mock-up of the AC IV prototype, assembled from a 17 pounder gun barrel fitted to a fabricated replica of the AC IV mantlet and a salvaged AC III turret, mounted to a salvaged AC I hull. The remains of the AC I E1 prototype hull were held in the collection of the Melbourne tank museum until its closure in 2006. The E1 hull was not listed as an item in the auction of the Museum’s collection and its eventual fate is not known.
An article by Thomas Anderson

Links and Resources

Australian War Memorial Archives
The AC Sentinel on Wikipedia
Tank Hunter

Mock-up of the AC IV prototype on display at the Australian Armour and Artillery Museum