Radial engines favored for powering the tanks & AFVs, 1935-45 (2 Viewers)

[tomo pauk]

It doesn't change - radials aren't the right choice for AFVs.

Was that also the conclusion of the folks that drove and fought in the radial-powered tanks?

 

[Shortround6]

Was that also the conclusion of the folks that drove and fought in the radial-powered tanks?

Hard to say, for the Soviets it was radials vs diesels.
A lot of crewmen blamed the fuel for fires and not the ammunition so perceptions are screwed up.
British in NA were comparing good radials to really, really crappy Liberty V-12 installations. If fact the radials may have been only mediocre but compared to the Crusader tanks the Radials just looked good

It is worth noting that the US was still using radial engine vehicles in 1953 if not later but ALL of those were left over WW II production. Only the M36B2 shows up with the twin diesel engines.

 

[marathag]

The only new build M36 were the 187 M36B1 built Oct-Dec 1944 on M4A3 hulls, to make up the required contract numbers.

Fisher built 300 turretless M10A1 hulls Dec 1943-Jan 1944 which were used to produce the first M36 with the addition of a new turret with the 90mm gun. Attention then turned to reconditioning M10A1 TD retained with training units in the USA and replacing their turrets. And finally as M10A1s began to run out attention turned in May 1945 to reconditioning diesel engined M10s as the M36B2.

So no opportunity to redo the the M36 drivetrain without spending a lot of money.

You missed the point, I think.

The M10 should have just been an interim, for training and limited combat- Substitute Standard, in US Army speak.
Buick had the 76mm armed M18 in production at Flint in July, 1943 for initial Contract for 8986 units

However, only 2513 were built, production ending in October of 1944 from two far smaller production contracts.

This was mostly from McNair and AGF who (foolishly) wanted more towed AT guns than TDs, with the number of planned TD Battalions halved in number in late 1943

With the M18 in full production, Fisher could have retooled to make a proper low hull using M4 components.

The M18 could use the lower torque Radial successfully from the Torqmatic transmission

Let's throw out the diesel as its tough to compare very different fuels...

Had the V2 been set for Gasoline, it would have been a 700HP class engine. At the end of the day, Torque is all about the bore and stroke of its cylinders, and at what RPM they are operating at- not what hydrocarbon is in the combustion chamber

'No replacement for Displacement' is a valid saying.
It's the cheapest way to get torque.

People talk about HP, but they all drive by Torque.

 

[marathag]

And a tea kettle, right?

They weren't Barbarians, though had to live rough till the first 'civilized' Tank had one from the factory- the Centurion.

 

[Shortround6]

I would delete the Hall Scott engine from the list.
It was interesting and the right power but anybody who put it in a tank needed to be taken away to very quiet place with men in white coats to rest for a number of weeks/months.
It was a very good boat engine but a 3650lb engine should not be going in a tank.
Edit, Torque peak was down around 1400-1500rpm.

 

[marathag]

It was a very good boat engine but a 3650lb engine should not be going in a tank.

It's doable.

The Detroit Diesels in the M4A2 was nearly as heavy as the monstrosity from Chrysler- a monster that turned out to be extremely reliable in British service.

The Hall Scott, being a Marine or Industrial engine, was overbuilt to hold that rated HP continuously. Most of the other engine used in tanks couldn't operate wide open throttle for hours. The 3600 was one of the lighter H-S engines, some models of the V-12 were 4600 pounds

Doing a version in aluminum would shed a lot of weight, if that was needed- but since the other existing engines that were used were heavier, no need.

 

[marathag]

Back to the theory for more radial engines
The A-57.
a sorta-radial

 

[Elan Vital]

The R-975 started with not so good durability (mostly owing to lubrication faults and poorly designed parts for tanks), 100-150 hours back when an A-57 might be good for 225 hours. It was sensitive at high rpm. It also tended to consume oil and gasoline at a more significant rate than the other engines.

Circumstances led the Americans to find themselves with radials as their tank engines at the start of the war so they had to make do with them as it took quite some time for the alternatives to replace it - the GAA was rushed into service but early problems were such its production was kept low for a time, the 6-71 was in high demand in quad form for the Navy. Only the A-57 was available in numbers, as the radial also started being demanded by the Air Force. But other countries that already had Vees or developped them during the war did not need to use radials, and more often than not their industry wasn't set up to make a surplus for tanks anyway, so domestic radial production was absorbed by their Air Forces. In comparison, the peculiar situation with US aircraft industry meant that high power Vees were not as obvious of a choice as radials as off-the-shelf tank engines.

Overall, other countries would have fared worse if they had gone with radials, and making them work probably took as much time as finding a suitable Vee, or even developping one almost from scratch*.
*that time argument was given even regarding conversions of aircraft Vees (Harry Ricardo re the British situation).

 

[tomo pauk]

Back to the theory for more radial engines
The A-57.
a sorta-radial

Seeing that, a 14 cyl radial does not look like a bad idea

A table taken from the Russian book about ww2 tanks:



A few details stand up. Like how he tiny the Valentine was, and especially it's turret. Or, that Cromwell didn't get even the 77mm HV, while the Sherman received the 17pdr despite the small turret. Or, that Panther's turret was just 2/3rds of the volume of the Tiger's turret.
The figures for the turret volume should be just for the 'real' part of the turret, ie. for what is above the hull roof.

The prop shaft that went under the turret basket and the transmission were still eating a lot of volume, even when the 'lowering gearbox' was used.

 

[marathag]

Seeing that, a 14 cyl radial does not look like a bad idea

A table taken from the Russian book about ww2 tanks:

View attachment 810310

A few details stand up. Like how he tiny the Valentine was, and especially it's turret. Or, that Cromwell didn't get even the 77mm HV, while the Sherman received the 17pdr despite the small turret. Or, that Panther's turret was just 2/3rds of the volume of the Tiger's turret.
The figures for the turret volume should be just for the 'real' part of the turret, ie. for what is above the hull roof.

The prop shaft that went under the turret basket and the transmission were still eating a lot of volume, even when the 'lowering gearbox' was used.

Type	Armored	Volume	in M3		Volume	of	Components
	Combat Weight	Hull	Turret	Total	Driver	Fighting Area	Engine Bay	Transmission
Valentine	17	5.8	1.1	6.9	1.2	2.6	2.1	1
Mk III	22	9	1.5	10.5	2.2	4.8	3.5	spread
Cromwell	28	9.7	1.9	11.6	2	4.9	3.4	1.3
M4A2 Sherman	31	11	1.8	12.8	3	6.9	2.9	spread
T-34/85	32	10.6	2	12.6	2.2	5.2	3.7	1.5
Panther	45	14.9	2.3	17.2	5	7.3	4.9	spread
Tiger I	56	14.8	3.4	18.2	4	9.6	4.6	spread

Edit: For others to use in the future

Note that you can see the trade off of sloped armor, more interior space is wasted from the angles, vs the 'bunch of boxes' exemplified by the Tiger and British, that tended to go for thicker vertical plates to protect a smaller volume.

You can see, the Panther was physically larger than it needed to be