Categories
WW2 Australian Prototypes

Grasshopper Light Tank

Australia Australia (1944)
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).

Sikorsky R-4 helicopter in RAF Service as the ‘Hoverfly I’ in 1945 showing the relative size and scale of this small, light helicopter. Photo: wikimedia. The VS.300 (right) flown by Igor Sikorsky himself wearing his trademark Homburg. Photo: Avistar.org

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.

An artistic interpretation of the Grasshopper Light Tank based from the description and drawings. Drawing: Author’s own.

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.

Composite of views of Murray’s Grasshopper tank design from Australian Army Inventions Directorate file 15430, 1944. Source: Author

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.

Bill Hope Murray. Source: Butler


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

Specifications

Dimensions ~8.2m (27’) long
Crew 4 – 5
Weight 2.7 to 3.6 tons
Armor Bullet Proof

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


4 replies on “Grasshopper Light Tank”

I thought Melvaine’s Pillbox (aka, the Outhouse tank) was a crazy Aussie design. But this one really takes the cake. I thought it was a Cobra chopper when I initially looked at it this morning and wondered why you guys put it here. Until I saw the title. Great work on this one guys. Keep it up. And I hope there’s more Outback Oddities from down under to share.

I think this is a typical case of a design by someone with
a) no idea about military requirements, and
b) too much irrelevant technical knowledge!

BTW, what was Mr. Murray thinking about for the main and secondary armaments on this thing. It looks like this thing has a 6-pdr as it’s main gun and two Browning .30 calliber machine guns. Correct me if i’m wrong.

as an Aussie myself i will admit we have come up with some crazy tank designs but in a time of war everyone would want to help and any design might prove to be the winning thing that turns the tide of war. this reminds me of a pic i have seen on the net showing an Apache helicopter with tank body. it’ll be awesome if something like this was real.

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