Best tank engines of WWII

[GrauGeist]

The main takeaway for the M2/M3 designs (and early Shermans) was that the Radial engine produced good horsepower for it's weight and was not dependant on a cooling system.

 

[GrauGeist]

Well, presumably, had they decided to use the Allison as a tank engine they would have produced a non-aviation-rated variant, just like the radial engines used, or the Meteor etc.

In the early years of the war (and just prior), V-1710 production was hard pressed to keep up with demand.

Also bear in mind that the M2 and M3 were designed for radial engines before WWII started.

We also have to take into consideration that V-8 engines were used (Ford, Cadillac, etc.) and their weight and dimensions were such, that modifications were easily made to fit them into an M4 chassis.

But to try and stuff an Allison into a Sherman was going to required considerable redesign. Which in turn would mean delays getting the much needed tank to Europe or the Pacific.

 

[Shortround6]

Well, presumably, had they decided to use the Allison as a tank engine they would have produced a non-aviation-rated variant, just like the radial engines used, or the Meteor etc.

Assuming they could come up with a new, suitable factory for the tank engine, it still doesn't solve the problem of the new larger, heavier, more expensive drive line components.

British sort of cheated. Their early cruisers used the old Liberty engine which was a V-1650 engine and while low rpm kept the horsepower down the engine made a huge amount of torque and allowed the British to use 4 speed transmissions instead of US 5 speed or the German 6 speed transmission. They were used to designing transmissions and steering gear for high torque engines.
you also have to figure out how the cool the bigger engine unless you really put a small carb on it and choke it down to around 400hp.
And extra power does you no good even if you can design a transmission and steering gear to handle the power. You need a suspension that will allow for high speeds without rattling the tank apart or throwing the crew around inside the tank breaking arms and legs.
Early Cromwells could do an easy 40mph. They regeared them to limit speed to 32mph in an effort to save suspension and track parts and to safe on crew injuries.

There were a number of good reasons why Ford turned thier V-12 into a V-8 for tank use.

 

[z42]

In the early years of the war (and just prior), V-1710 production was hard pressed to keep up with demand.

Also bear in mind that the M2 and M3 were designed for radial engines before WWII started.

We also have to take into consideration that V-8 engines were used (Ford, Cadillac, etc.) and their weight and dimensions were such, that modifications were easily made to fit them into an M4 chassis.

But to try and stuff an Allison into a Sherman was going to required considerable redesign. Which in turn would mean delays getting the much needed tank to Europe or the Pacific.

Not disagreeing with any of that. Just pointing out that had they, for whatever reasons, decided to use the Allison engine in a tank, they could and most likely would have produced a non-aviation-rated variant.

 

[z42]

Assuming they could come up with a new, suitable factory for the tank engine, it still doesn't solve the problem of the new larger, heavier, more expensive drive line components.

British sort of cheated. Their early cruisers used the old Liberty engine which was a V-1650 engine and while low rpm kept the horsepower down the engine made a huge amount of torque and allowed the British to use 4 speed transmissions instead of US 5 speed or the German 6 speed transmission. They were used to designing transmissions and steering gear for high torque engines.
you also have to figure out how the cool the bigger engine unless you really put a small carb on it and choke it down to around 400hp.
And extra power does you no good even if you can design a transmission and steering gear to handle the power. You need a suspension that will allow for high speeds without rattling the tank apart or throwing the crew around inside the tank breaking arms and legs.
Early Cromwells could do an easy 40mph. They regeared them to limit speed to 32mph in an effort to save suspension and track parts and to safe on crew injuries.

There were a number of good reasons why Ford turned thier V-12 into a V-8 for tank use.

Not saying there weren't good reasons to not use the Allison in a tank. Just pointing out that had they, for whatever reasons, decided to use the Allison engine in a tank, they could and most likely would have produced a non-aviation-rated variant.

 

[z42]

The main takeaway for the M2/M3 designs (and early Shermans) was that the Radial engine produced good horsepower for it's weight and was not dependant on a cooling system.

Someone posted earlier in this forum, might even have been in this thread, some US Army documents describing desirable features of a tank engine, in particular it seems they really wanted air cooling. This eventually resulted in the AV1790 air cooled V-12 and later a diesel version AVDS1790 which powered many US cold war tanks and other heavy tracked vehicles.

Continental AV1790 - Wikipedia

en.wikipedia.org

 

[GrauGeist]

Not saying there weren't good reasons to not use the Allison in a tank. Just pointing out that had they, for whatever reasons, decided to use the Allison engine in a tank, they could and most likely would have produced a non-aviation-rated variant.

But to produce a non-aviation variant means detracting from the aircraft engine production line.

Let's look at the V-1710's physical specs:
Weight (dry): 1,395 lbs
Length: 7.1 feet
Width: 2.4 feet
Height: 3.1 feet

So now let's compare the Allison's dimensions to the Continental radial:
Weight (dry): 675 lbs
Length: 3.5 feet
Width: 3.75 feet

So it becomes aparent that to consider the Allison as a tank engine, serious modification to the tank (and not just the M4, but nearly a dozen other types) would have to be made before production.

The Chrysler, Ford and Cadillac V engines were close to the 970 radial's dimensions, btw.

 

[z42]

But to produce a non-aviation variant means detracting from the aircraft engine production line.

Let's look at the V-1710's physical specs:
Weight (dry): 1,395 lbs
Length: 7.1 feet
Width: 2.4 feet
Height: 3.1 feet

So now let's compare the Allison's dimensions to the Continental radial:
Weight (dry): 675 lbs
Length: 3.5 feet
Width: 3.75 feet

So it becomes aparent that to consider the Allison as a tank engine, serious modification to the tank (and not just the M4, but nearly a dozen other types) would have to be made before production.

The Chrysler, Ford and Cadillac V engines were close to the 970 radial's dimensions, btw.

Indeed, good reasons to not use the Allison in a M4-sized tank. Or to reiterate what I wrote in the post you quoted

Not saying there weren't good reasons to not use the Allison in a tank.

 

[Engineman]

Hi,
I consider that there are sound reasons for the aircooled tank engine having a limited application. IMO, air cooling has some advantages in respect to lower systems complexity, possibly better adaptability in climate extremes and possibly lower weight. The disadvantages of air-cooling include, possibly less flexible packaging, greater volume and/or restrictive dimensional requirements and lower power/system volume.
Overall, the liquid cooled engine can have much more adventurous power output in a limited system volume, with the complication of a vulnerable cooling system as a downside, although I do suspect that actually proving the real balance of vulnerability in the actual world of combat is difficult.
IMO, in the real world of Tanks, the low system volume for power and flexible packaging possibilities make the liquid-cooled (and probably V-12) powerplant the preferred option, although I can see that this advantageous position could be lost due to poor design.

Eng

 

[Shortround6]

A lot of requirements are based on experience of the officers involved.
British never went for air-cooled after the early 30s and with their experience with Liberty powered tanks that is rather surprising.
I do wonder about the US. They had gone from air cooled in in both the light tanks and mediums (and the M6 heavy) and perhaps they were not happy with the liquid cooled substitute engines.
Twin Cadilac V-8s in the M-5 and M24 light tanks.
Twin GMC diesels in the M3A3 medium, some of the M-10 TDs, the M4A2 medium, the 5 engine star set up in the M3A4 and M4A4. There seems to be pattern hear. Only the M4A3 medium had a single liquid cooled engine. One wonders about the leaks and problems of trying to use two (or 5) engines with a common cooling system or did they try to use separate cooling systems for each engine (I don't think so).
The experience with the Ford V-8 may have been mixed. M4A3 seems to have been OK or good. Experience with the M-26 was not so good. Engine may have been OK but the installation in the M-26 tended to eat the fan belts for the radiator/s. You still need fans for an air cooled engine though.

 

[tomo pauk]

A lot depends on other things, like :
- what engines is your industry more likely to make
- what kind of power is needed
- is the tank likely to be used in the dry/arid/desert conditions;
- how good the liquid cooling is designed and executed
- is there an additional gearing that lowers the driveshaft so the tank/AFV can be lower (does not require a rocket scientist in da hause, but it does require some forethought)
- is the tank/AFV with the 'all rear' powerplant configuration (British, French, Soviet), or 'distributed' (US, German, Czech, Italian)
- do you have light alloys to 'burn', or the engine must be from iron

A V12 might be too fancy engine in your 20 ton tank, let alone in a 12 to tank. If 300-400 HP is all you need (good in a 18-25 ton tank), a radial engine will be a cheaper, lighter and shorter option than a V12. Many times the 12 cyl engines didn't panned out as good as people hoped, many timed the cooling system was badly designed and/or 'executed'.
An inline six engine might be awkward to install, driving the tank length to be to big, and thus making the tank bigger and heavier for no gain.
Is there a debugged V8 ready for mass production?
Cast iron engine, like the HL 230, was at 1200 kg; the Chrysler Multibank was double as heavy - if one can save 500-1500 kg by choosing a lighter engine, that weight of armor can be added to the tank making it survive better.

 

[Admiral Beez]

The Allison was in great demand and couldn't be diverted to power AFVs.

I suppose, but having a single customer for your firm's only mass produced product makes little sense for the company's longevity. Indeed, Rolls Royce would eventually acquire the scraps of the Allison engine company.

Well, presumably, had they decided to use the Allison as a tank engine they would have produced a non-aviation-rated variant, just like the radial engines used, or the Meteor etc.

That was what I was thinking too. I'm not suggesting that Allisons be taken off the aircraft line, but that the firm license out production of the non-aviation version.

 

[WARSPITER]

Allison did quite well after the second world war as they were contracted to make GE turbojet engines. They then developed turboprop units (C130 Hercules)
and turboshaft engines for helicopters.

GM owned Allison and the sale to Rolls Royce came about as GM wanted to get back market share in automobiles.

Aircraft engines being the basis for tank engines is an interesting subject. Engines used on the allied side of things included
the Ford GAA - a cut down of the original V12 aircraft engine developed by Ford which was not taken up, the other being
the Meteor V12. Both were solid designs and gave good service.

The Meteor was a problem solver for British tanks as it gave more power and torque without too much weight (835 kg). As
noted in other posts the extra grunt meant it was not a problem to add more armour and larger guns as the speed of the
tank could be kept up (Cromwell and Comet).

 

[GrauGeist]

I suppose, but having a single customer for your firm's only mass produced product makes little sense for the company's longevity.

Bell, Curtiss, NAA and Lockheed all relied on a steady flow of V-1710s.

 

[Admiral Beez]

Bell, Curtiss, NAA and Lockheed all relied on a steady flow of V-1710s.

I meant the Air Force, as the sole customer. Why not look for some Army business for a de-rated Allison V12?

 

[EwenS]

I meant the Air Force, as the sole customer. Why not look for some Army business for a de-rated Allison V12?

But the "Air Force" was the "Army" until 1947.

It was the US Army Air Corps until 20th June 1941 when it became the US Army Air Force. It was in March 1942 that the US Army was split into three autonomous elements each with its own commanding general reporting to the Army Chief of Staff. One of those elements was the USAAF. Then in 1947 it became a separate service.

 

[Shortround6]

Indeed, Rolls Royce would eventually acquire the scraps of the Allison engine company.

In 1995 which is rather late to blame decisions made in 1940-45.

From Wiki so..................
" For this reason, in 1947, the Army decided to take General Electric's versions of Frank Whittle's jet engines and give them to Allison to produce instead. The main production model was GE's 4,000 lbf (18 kN) I-40, produced as the Allison J33. By the time production ended in 1955, Allison had produced over 7,000 J33s."

"Allison also took over GE's axial flow engine design, becoming the Allison J35. The J35 was the primary powerplant for the F-84 Thunderjet and F-89 Scorpion, as well as appearing on numerous prototype designs. The J35 also finished production in 1955, by which point over 14,000 had been delivered."

Allison T-56 turbo prop and derivatives, about 18,000 produced.

Allison model 250 turbo shaft engine, over 30,000 built since 1962-65. Powered about 27 different helicopters in either single or twin engine installations.

Whatever Allison did or did not do in 1940-48 trying to sell V-1710s to army for tanks had nothing to do with the sale of the company to RR 50 years later.

 

[Elan Vital]

The V-1710 ended up being installed in one variant of the T29 Heavy Tank.
The Ford V12 was contemplated for testing/installation in a M4A4, aside from the T2X series of medium and heavy tanks.
So was the 650 hp Chrysler A-65, a custom V12 meant to supersede Chrysler's A-57 with a considerably more compact, lighter, simpler and more powerful engine.
At least by that time, the Sherman's transmission was rated for 550hp input power, so considering power losses before the gearbox, even a 600+ gross HP V12 would have been acceptable if the cooling was adequate, which it could be in a M4A4 hull with a more compact engine than the A-57.

But all of these options were late for the war.

As Shortround said, the problem was the timeframe. The decision to use the Wright radial engines was made in 1933-34, at a time when the V-1710 was not mature enough and would be inefficient (heavily derated). Few non-radial alternatives would have existed in the US and in the required power band, while civilian aviation demand meant there was a decent peacetime production base for R-670 and R-975 radials.

Most of the pre-1941 period was spent looking at the Guiberson radial diesel, commercial diesels for light tanks and the 6V-184 V6 450hp diesel engine, not at a Vee gasoline engine. Then 1941 and 1942 saw a frantic rush to find any suitable powerplant that would fit a M3/M4 Medium at the 400hp+ powerband.
The V-1710 could theoretically have been turned into a tank V8 to fit the Sherman just like the Ford, but Allison had a lot of other work on its plate. Meanwhile, Ford had developed an aircraft V12 that had no demand in the wartime US air forces (focus being on the V-1710 which was already in production), so it had time and ressources to spare and an orphaned engine which could be put to good use in another field.

 

[ThomasP]

re the V-1710 for tanks being derated (if I understand you correctly)

Even the un-supercharged float-carburetter type V-1710-4 (as used in the Akron & Macon airships) was rated at 690 BHP at 2400 rpm on 1930's 83 grade fuel. Weight was around 1160 lbs with reduction gear. The CR was 7:1 for the -4 engine, but even if you decreased the CR for use with lower grade 'pool' fuel (say 6:1 for 75-80 grade) you would still get about 590 BHP. The Meteor with a CR of 5.5:1 put out about 550 BHP at 2500 rpm on 70-80 grade 'pool' fuel.

 

[Admiral Beez]

Had they, for whatever reasons, decided to use the Allison engine in a tank, they could and most likely would have produced a non-aviation-rated variant.

The Merlin's non-aviation siblings went into more than just tanks, including powering Royal Navy torpedo boats. Interestingly, the USN's PT Boats were powered by Packard V-12 engines, which presumably is another lost opportunity for Allison. Rolls Royce also developed the V-8 Meteorite in both diesel and petrol versions for transporter trucks. It seems to me that Allison's V-12 could have found more applications beyond aircraft.