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"Best engine in a tank of WWII" Topic


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733 hits since 10 Sep 2018
©1994-2018 Bill Armintrout
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Tango0110 Sep 2018 9:25 p.m. PST

Interesting Old thread….

link

Amicalement
Armand

Lion in the Stars10 Sep 2018 10:00 p.m. PST

Poor arguments all around.

From sheer reliability, best American tank engine was the Ford GA(whatever) series.

The Meteor engine was arguably better, but not in any American tanks.

T34 diesel is marginal, due to planned obsolescence. Might be easy to fix, but I'd rather not have to fix it in the first place.

German stuff was way too over-engineered. Too lightly built for the power levels, and horribly hampered by lousy fuel. Germans were running on 67 octane, with their planes getting 87 octane, when the US was running 130 or even 145 octane in the planes and 87 or higher octane in tanks and trucks.

Gaz004511 Sep 2018 1:32 a.m. PST

The diesel Sherman was preferred by most users but not necessarily available…
Some of the Soviet diesels seem to have been very resilient, dragging them off war memorials, oil change and a battery boost to fire them up 70+ years later in the Ukraine. I wonder if the T-34's still in service around the world have been reported or maintained with their original powerplants?

Lion in the Stars11 Sep 2018 2:03 a.m. PST

Yes, the diesel Sherman had a pair of Detroit 6-71s, which are still in service today. Hard to argue with success. If I was given a choice about which Sherman variant I was going to crew, I'd choose the diesel M4A2, second choice going to a wet-stowage M4A3.

Dunno about the T34s engines. Wouldn't surprise me, though, as the T72 tank engine is a development of the T34s engine.

Legion 411 Sep 2018 7:28 a.m. PST

German stuff was way too over-engineered.
Almost everything they made was …

But I'd also think generally the US made engines were the most reliable, etc. And diesel over mogas …

Fred Cartwright11 Sep 2018 8:31 a.m. PST

Almost everything they made was …

I think that is a rather sweeping generalisation that doesn't stand up to much scrutiny. Weapons like the MP40, MG42 and Stg44 made maximum use of stamping and had minimal requirements for machining and yet produced reliable effective weapons. Was the Me109 more over engineered than the Spitfire? I don't think so.

Personal logo Patrick R Supporting Member of TMP11 Sep 2018 10:21 a.m. PST

A good engine is only part of the equation, transmission, suspension, tracks, spare parts and a steady supply of POL is just as important.

Some have claimed that US equipment was not more reliable than others, but that they had more spare parts than everyone else combined and had a bigger logistics train and could therefore keep their tanks going. On the other hand it's clear that US parts at the time were produced to a consistently high standard. Compared to German and British production which still included a lot of hand-fitting and required highly skilled labour.

You can have the best engine in the world if it's in the wrong kind of tank, the transmission won't last more than a few hours and your suspension is more of a hindrance than an advantage, it's probably not going to help much.

Fred Cartwright11 Sep 2018 11:12 a.m. PST

Compared to German and British production which still included a lot of hand-fitting and required highly skilled labour.

Where does that information come from? It is not something I have seen before. I'd be surprised if anything needed hand finishing. All engines, transmissions etc require a lot of machining, but none of it was done by hand.

Tango0111 Sep 2018 11:26 a.m. PST

What about the Italians?….

Amicalement
Armand

Legion 411 Sep 2018 3:16 p.m. PST

A good engine is only part of the equation, transmission, suspension, tracks, spare parts and a steady supply of POL is just as important.
What is that saying ? … "Amateurs talk tactics, Professionals talk logistics." …

I've been at both ends of the that paradigm. wink


What about the Italians?….
Well AFAIK, Fiat has not been known for producing a very reliable vehicle until a couple of decades ago … huh? evil grin

Fred Cartwright11 Sep 2018 3:40 p.m. PST

What has always puzzled me is why the US produced relatively few inline watercooled engines. Much of the production was radial air cooled engines in both tanks and planes. The Ford GAA being the first single block non radial engine for the Sherman. IIRC all US bombers used radials and of the fighters that used the Allison engine only the turbocharged P38 was a real success the others with the single stage supercharger, like the P39 and P40, being poor performers at medium heights and above.

Lion in the Stars11 Sep 2018 5:20 p.m. PST

Where does that information come from? It is not something I have seen before. I'd be surprised if anything needed hand finishing. All engines, transmissions etc require a lot of machining, but none of it was done by hand.

You need to look in the blueprints and shop manuals. Lots of things from UK and Germany have instructions of "file to fit". Especially suspension components on German tanks.

Hell, that was one of the major changes the US did to the Bofors 40mm, removing every single File to Fit instruction and making the parts fit without any work at the installer's end. Just remove old part and bolt new part into place.

Blutarski11 Sep 2018 6:26 p.m. PST

Some time ago, I read a reference history of British industry in WW2 published under the auspices of the British government. Cannot recall the title, but I believe the author's name was "Pout". The author commented upon the prevalence of hand-fitting on British factory shop floors, attributing it to a refusal of the machinist fraternity to abandon traditional manufacturing methods.

B

Personal logo Patrick R Supporting Member of TMP12 Sep 2018 1:41 a.m. PST

The Bovington tank museum has some videos where they show David Fletcher highlighting British tank designs and also the restoration of a Matilda II, they often mention the "hand built" aspect of British tanks.

4th Cuirassier12 Sep 2018 2:27 a.m. PST

@ Fred

Most navies that operated carriers were not too keen on inline engines. They made the aircraft longer, so you could fit fewer of them on board for a given length of hangar, and also visibility past the nose was poor when on deck. In WW1 the alternative for early aircraft carriers was to embark types with rotary engines. These were much more compact (although the peculiar characteristics of rotaries meant that if you had to abort, go round again and gun the engine, the aeroplane would climb but also turn; most rotaries climbed to the left, so early carriers were built with the island on the right, so as to provide them with an unobstructed path to go back around).

The radial engine eliminated this last problem, and it's noticeable that pretty well every navy that built dedicated naval aircraft built them with radial engines.

Radials were thus highly versatile and this may be a reason why the US built so many of them in preference to inlines, which can normally only be used in land-based aircraft no matter how you try to adapt it. When fitted in tanks they made them taller, unfortunately.

Blutarski12 Sep 2018 4:41 a.m. PST

From the US navy's perspective, a great operational advantage of the radial engine versus the in-line type was that the radial did not require liquid cooling with all its associated vulnerable plumbing.

B

Frontovik13 Sep 2018 7:56 a.m. PST

I wonder if the T-34's still in service around the world have been reported or maintained with their original powerplants?

Model 1946 – This was a production model built in 1946, with the improved V-2-34M engine, new wheels and other minor details.

Model 1960 – A refurbishing program introduced a new V-2-3411 engine and an improved air cleaner, a cooling and lubrication system, a battery generator, new BDSh smoke canisters, an infrared headlight, a driver's sight and a 10-RT radio set instead of the old 9-R.

Model 1969 (also called T-34-85M) – This was a refurbishing program introducing the new R-123 radio set, 'starfish' road wheels similar to those on the T-54/55 tank, night driving equipment, drivetrain improvements, repositioned or removed smoke canisters to make a space for additional 200-litre external fuel tanks and a ditching beam at the rear. An external fuel pump was added to ease refueling.

Fred Cartwright13 Sep 2018 10:50 a.m. PST

Most navies that operated carriers were not too keen on inline engines. They made the aircraft longer, so you could fit fewer of them on board for a given length of hangar, and also visibility past the nose was poor when on deck.

True, although the Corsair wasn't noted for having a short nose. I have seen one comment that it was marginal as a carrier aircraft. Probably why a lot of them went to land based Marine Corps units and the Hellcat favoured for carrier use. The FAA used them on carriers, but they were better than the assorted Seafires and Sea Hurricanes they had before.
But the radial engine has no real advantages for tank use and a lot of disadvantages. High silhouette, difficulty with maintenance etc. I wonder why they never considered using the Allison engine for tanks, in the way that the Merlin was adapted into the Meteor for tank use. A look at the specs suggests it would have made a very good tank engine. It had a low part count and was already designed to have a wide variety of gearing and anc ancillary configurations, suggesting adapting to tank design would have been quite straightforward. I mean if you are going to use an aero engine in your tank, why not use one that has the requirements a tank engine needs.

Tango0113 Sep 2018 12:45 p.m. PST

Good threads… thanks!.


Amicalement
Armand

Mark 114 Sep 2018 11:01 a.m. PST

I wonder why they never considered using the Allison engine for tanks, in the way that the Merlin was adapted into the Meteor for tank use. A look at the specs suggests it would have made a very good tank engine.

I do not claim any particular expertise on the decision-making that led to the engine choices in US tanks.

But I think that there are some factors we have not yet raised in this discussion that were probably important considerations.

First is appropriateness to the task. Yes, the Allison looks like a very good engine. IF you are looking for a 1,000 h.p. engine, that is. But that's not what the US Army was looking for. US Army tanks were powered by 300-400 h.p. engines. If you are looking for 350 h.p., you may well be impressed by an engine that can deliver 375 h.p. in the same weight and space, that does not mean you will give 5 minutes of consideration to a 1,050 h.p. engine. It just isn't the kind of engine you are looking at.

Second, and related to the first, is engineering resource availability. It is certainly true that an Allison engineering team could have done a cut-down version of the engine to make it appropriate. That is, after all, the process that led to the Ford GAA engine -- it was a V8 version of what had originally be designed as a V12 aircraft engine that had been launched as a competitor for the Merlin.

Engineering capacity was not, and never is, unlimited. The Ford V-12 was never taken into production for any aircraft. So the engineering team that had worked on the engine was available for further developmental work. But there were MANY engineering projects needed for the Allison engine for aircraft production contracts -- a continuous flow of variants to the basic design. Diverting engineering resources from the work needed for the P-38F to P-38L update, or the P-39C to P-39D to P-39J to P-39M, or the various P-40s from C through N, was probably just not in the cards.

Third, and probably the dominant issue, was production capacity. The reason that the M4A2, M4A3 and M4A4 variants of the Sherman were developed in the first place was the search for engine availability. They were all projects to make use of available engine production capacity.

The Write Whirlwind engine (the type that went in to the M2 Medium, and from there into the M3 in all production marks, and the M4 and M4A1 Shermans) had been in production for about a decade by the time tank production ramped up. But the Ford Tri-Motor and Lockheed Electra aircraft that used it were no longer exactly in high demand. So there was an existing, mature and well proven engine requiring relatively little re-engineering, AND there was production capacity in excess of demand.

Conversely there was no excess of Allison engine production capacity. Quite the opposite -- it was going in to so many current production planes, and was slated for so many new planes, that the Army probably didn't want so suggest that they should get 90% of the available factory output (actually, at first glance, it looks like the tank production programs would have needed about 120 – 150% of the Allison capacity).

As with so much of the US war effort, we need to think logistics first. Not tactics, not technical features, but logistics.

At least that's how I would look at the question.

-Mark
(aka: Mk 1)

Fred Cartwright14 Sep 2018 11:38 a.m. PST

But that's not what the US Army was looking for. US Army tanks were powered by 300-400 h.p. engines. If you are looking for 350 h.p., you may well be impressed by an engine that can deliver 375 h.p. in the same weight and space, that does not mean you will give 5 minutes of consideration to a 1,050 h.p. engine. It just isn't the kind of engine you are looking at.

Hmmmm! Maybe a bit short sighted. When the Brits were looking for a 5-600hp engine to go into the Cromwell, what did they chose to base it on? The 1,500hp Merlin engine. It is much easier to detune an engine to produce a lower hp than to tune up an engine to increase hp.

So the engineering team that had worked on the engine was available for further developmental work. But there were MANY engineering projects needed for the Allison engine for aircraft production contracts -- a continuous flow of variants to the basic design. Diverting engineering resources from the work needed for the P-38F to P-38L update, or the P-39C to P-39D to P-39J to P-39M, or the various P-40s from C through N, was probably just not in the cards.

Hmmmm! Sounds very similar to the process that lead to the Meteor. Rolls Royce had many demands for the Merlin, from fighters to bombers and had no spare capacity. Rover were looking for a tank engine and wanted to get rid of the development work on the jet engine as they weren't getting on with Frank Whittle. The boss of Rover proposed to the head of Rolls Royce that Rolls give them the Meteor in return for Rover giving Rolls the jet. The Rover engineers then took on Meteor development and production and built the Meteor for the Cromwell.
It is not like the US didn't take on new production contracts that no existing tooling or expertise existed for. Packard took on Merlin production and built thousands. So successfully that if you are in the market for a Merlin now it will almost certainly be a Packard built engine.
I see no reason why Ford couldn't have taken on the Allison engine for tank development and produced a very good engine, quite possibly in a shorter time than they took to get the GAA to maturity. It would have had the advantage of being able to deliver more power for the Pershing rather than saddling it with the GAA and leaving it underpowered. Maybe US companies were more jealous of their designs and not willing to part with them to a potential rival.

Mark 114 Sep 2018 1:48 p.m. PST

When the Brits were looking for a 5-600hp engine to go into the Cromwell, what did they chose to base it on? The 1,500hp Merlin engine. It is much easier to detune an engine to produce a lower hp than to tune up an engine to increase hp.

No doubt that it is indeed easier to take away power than to put it in.

But that was not the point here. Ford HAD a 1,500 h.p. V-12 already in their hands. So much like the Meteor process, they took a V-12 and lopped off the back 1/3rd of the engine block, and voila! they had a V-8. (Well, not exactly, but kinda…)

However, on this comment:

Hmmmm! Maybe a bit short sighted.

It's a fair question. Short sighted? Better to have an adequate h.p. rating for the Pershing in February 1945, and not enough Shermans in 1944? I think maybe that would have been more short sighted.

The answer you come to is usually determined by the question you ask.

The Brits were not asking the question: "How can we build 20,000 tanks in one year, ship them to the other side of the world, and support them in combat?" The US Army was.

The answer was not "Make it a high-powered 45 ton heavy tank that relies on a single-sourced first-rate aircraft engine."

The answer was much more like "Make it a 30 ton medium tank, using proven mature components as much as possible, and let's find 3 or 4 existing proven in-production engines that we can re-purpose to give us the 300 – 400 h.p. we will need to drive that tank." Only one of those engines (the GAA) was actually a new engine. Not surprisingly, it was the last one to come in to production, even though it was the engine the US Army liked best, wanted to standardize on as much as possible, and the program was launched before the Chrysler multi-bank engine which preceded it into service.

Again, the process was not so much "How can we make the best tank engine in the world, that wargamers will crow about 70 years hence?" It was less about technical features, and more about logistics.

At least that's my reading. But I admit this is not my strong suit, so I am open to other perspectives.

I see no reason why Ford couldn't have taken on the Allison engine for tank development and produced a very good engine, quite possibly in a shorter time than they took to get the GAA to maturity. It would have had the advantage of being able to deliver more power for the Pershing rather than saddling it with the GAA and leaving it underpowered. Maybe US companies were more jealous of their designs and not willing to part with them to a potential rival.

At first Ford approached Rolls for a license for the Merlin engine.

Once it became clear that this would not be forthcoming (on terms that Ford found palatable), they decided instead to design their own engine to compete with the Merlin.

They had this engine in hand, in prototype form, when the Army approached them for a tank engine.

Now, if you have a working V-12 that you think is the best engine in town, and you have the team that designed that engine and that know it from top-to-bottom standing by, and somebody asks you to come up with a V-8 … why would you go off and license somebody else's V-12, that none of your engineers have every worked on, as a starting point?

It may look like it would makes sense to us, here, now. But I can't see how it would make sense to them, there, then.

-Mark
(aka: Mk 1)

Fred Cartwright14 Sep 2018 3:25 p.m. PST

Ford HAD a 1,500 h.p. V-12 already in their hands. So much like the Meteor process, they took a V-12 and lopped off the back 1/3rd of the engine block, and voila! they had a V-8. (Well, not exactly, but kinda…)

Well not quite what Rolls did. They didn't lop 4 cylinders off the Merlin to make the Meteor. Rolls Royce Merlin 27L V12, Meteor 27L V12! Merlin 1,500hp, Meteor 600hp.
Using the Allison in a tank doesn't preclude the use of the Diesel or Chrsyler multibank either.
Also production capacity is production capacity. What takes time is setting up new tooling for a new design. No reason not to use the radial in the M3 while a production line for an Allison tank engine is set up and then switch to the new engine to coincide with the switch from production of the M3 to the M4. To follow your argument to its logical conclusion why switch production from the M3 to the M4 if doing so limits your production so much, or alternatively if they can do it for the M3 to M4 why can't they do it for a switch from radial to Allison inline engine production? Adapting the Allison to tanks from what I can see would have been straightforward. It was already a very flexible engine with provision for different gearing arrangements and the ability to run the ancillaries, magneto, fuel pump, oil pump etc from wherever you wanted. It was also a mature reliable design, something the Ford GAA wasn't. It took Ford 2 years to make it reliable enough design. Another advantage of the Allison is as the war goes on the aircraft designs using it are phased out of production, which would have freed up capacity for tank engines.

Now, if you have a working V-12 that you think is the best engine in town, and you have the team that designed that engine and that know it from top-to-bottom standing by, and somebody asks you to come up with a V-8 … why would you go off and license somebody else's V-12, that none of your engineers have every worked on, as a starting point?

My response to that is why do you need to lop 4 cylinders off a perfectly good (although still untried) V12 engine just to make it produce 500hp? Yes I know it would be a longer engine, but they already had to lengthen the M4 design to take the Chrysler multibank anyway!

The Brits were not asking the question: "How can we build 20,000 tanks in one year, ship them to the other side of the world, and support them in combat?" The US Army was.

Yes I am well aware of the paucity of UK wartime tank production (hangs head in shame). Although part of that might have been due to cutting back on UK tank production to keep US tank factories working at the request of the US. Can't see how dropping the Continental radial needs to prevent the US from reaching that. There was time to get a new engine into production, before the M4 was ready for production, if you went down the simple route and not try to turn a V12 into a V8. Grab an existing engine, adapt it for tank use (you know like they did with the twin diesel and Chrysler multibank), ramp up production by building a new factory to make it and Robert's your fathers brother! :-). And of course that is exactly what they did with the Ford GAA except they went the long way round to do it and got it a year later than they could have done.
2 other interesting facts. The British considered 2 choices for a tank engine. The Kestrel which was rated in the 700hp range and the Merlin which was producing 1,500hp by then, but chose the more powerful design despite the fact that the aircraft the Kestrel was used in were going out of service and not using it closed the production line (sound familiar?). Also Ford Britain produced the Merlin under licence in the UK while presumably still part of the Ford group, so I am wondering why Ford US couldn't negotiate to build it too.

Gunfreak Supporting Member of TMP14 Sep 2018 3:50 p.m. PST

Corporal Thomas was the best tank engine.

Lion in the Stars15 Sep 2018 5:07 p.m. PST

Most navies that operated carriers were not too keen on inline engines. They made the aircraft longer, so you could fit fewer of them on board for a given length of hangar, and also visibility past the nose was poor when on deck. In WW1 the alternative for early aircraft carriers was to embark types with rotary engines. These were much more compact (although the peculiar characteristics of rotaries meant that if you had to abort, go round again and gun the engine, the aeroplane would climb but also turn; most rotaries climbed to the left, so early carriers were built with the island on the right, so as to provide them with an unobstructed path to go back around).

The radial engine eliminated this last problem, and it's noticeable that pretty well every navy that built dedicated naval aircraft built them with radial engines.


The biggest reason that the Navy preferred air-cooled radials over liquid-cooled inlines was that you can still make it back to the carrier if a couple cylinders overheat and burn out on a radial, but you're going swimming if your inline loses coolant.

Same reason the radial-powered P47 was preferred as a ground-attack plane over the P38 and P51.

Mark 117 Sep 2018 11:16 a.m. PST

Same reason the radial-powered P47 was preferred as a ground-attack plane over the P38 and P51.

I believe that the P-38 was preferred by the USAAF in the Pacific. This was for all roles, fighter and ground attack.

The cost of the P-38 was substantially higher. A P-47 cost about 2/3rds as much, and a P-51 was about half as much. But in the Pacific the USAAF wanted as many P-38s as could be provided.

The reasoning was similar -- survivability and the likelihood of a pilot successfully returning to base after receiving combat damage. An inline engine was indeed more likely to be incapacitated by damage than a radial. Maybe you were 20 or 30% more likely to make it home with damage (just a WAG, but for the sake of discussion). But having a "spare" engine for the trip home made all the difference in the world -- effectively doubling your chances of getting home.

It didn't work that way in ETO. There, you had to fly back across enemy territory, and a P-38 limping home on one engine was easy prey. Better to go with the lesser odds of being hit (ANY other fighter was a smaller target than a P-38) or losing an engine (the radial vs. inline bit), than bet on the success of a return trip of hundreds of miles flying low and slow.

But in the Pacific, the flight home was almost always over open, empty ocean. Interception was not a big concern -- keeping the plane in the air was. Low and slow worked just fine.

Or so I've read.

-Mark
(aka: Mk 1)

Fred Cartwright18 Sep 2018 5:53 a.m. PST

The advantages of radial engines in aircraft are well documented, although inline engines have advantages too as even with air scoops for radiator/oil cooler they have a smaller frontal area and thus less drag. That would explain why the F6F-5 Hellcat with a 2,000hp Double Wasp had a top speed of 390mph, whereas the Spitfire VIII with a 1,250hp Merlin 70 had a top speed of 418mph and why in the West a number of top fighters had inline engines.
None of the radials advantages apply to tank use though!

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