could the Allison engine have done what the Rolls Royce Merlin did?

[Geoffrey Sinclair]

Great information but what does this have to do with the development of aircraft engines during the late 1930s and the ability to gain a government contract (and hopefully get the customer to pay for R&D costs)?

I think the idea is every so often large companies will try and create a market. Part of the GM thinking was they could move the rail companies from build your own to buy off the shelf. The depression also stopped a number of US diesel makers, opening up the market. GE would have an idea about the performance of the best German versions, plus the USN desire for high performance diesels, the 1931 USN attempt to buy European engines for trials was blocked by congress. Yet the USN BuEng thought diesels suitable for fast locomotives were the ones for submarines, versus switcher engines which could be much heavier, with its own diesels GE could provide the complete submarine propulsion package. The USN started using "modern" GE diesels in the mid 1930's.

Back to aircraft, The CAA reports V-1710 production was 1,141 in 1940, 6,447 in 1941, 14,905 in 1942, 21,063 in 1943, 20,191 on 1944, the War Production Board agrees but notes one 2 stage in 1942, 514 in 1943 and 2,867 in 1944. That gives 43,492 engines 1940 to 1943, while new P-38+P-39+P-40+Allison P-51+A-36 production for the time period required 27,929 engines plus spares, somewhere between 20 and 33% of numbers fitted to new aircraft. Plus stocks ready to be fitted to the early 1944 production.

Now to complete, from sea to air to land. When it comes to tank engines the need was in 1943. The US cut back production in 1944.

Sherman production peaked in July 1943 at 2,401 and was down to 508 in February 1944 before picking up again. The US had 10 Sherman production lines December 1942 until September 1943 then down to 7 in December and 3 in February 1944. This includes the short lived Canadian line (October to December 1943). It means 29,450 out of 49,422 Shermans were built to end 1943, then another 13,179 in 1944, down from 21,433 in 1943.

The M4 ceased production in March 1945, the M4A1 in July 1945, (both Continental R-975) the M4A2 (GM Diesel) in May 1945, the M4A3 in June 1945 (Ford GAA V8) (plus a pause October 1943 to January 1944), the M4A4 (Chrysler Multibank) in September 1943 and the few diesel M4A6 in February 1944.

The 1944 mix was 1,432 M4, 2,171 M4A1, 2,428 M4A2, 7,089 M4A2 and 59 M4A6. When it comes to allocations the US mostly kept the 76 and 105mm gun armed Shermans.
M4 All from February 1944 on were 105mm,
M4A1 all 1944 or later were 76mm gun armed.
M4A2 Fisher built 843 75mm January to May 1944, otherwise all 1944 or later M4A2 were 76mm gun armed.
M4A3 in 1944/45 came in 75mm (3,325), 76mm (4,542) and (3,039) 105mm

HVS appeared in January 1945 for the 75mm gun, August 1944 for the 76mm and September 1944 for the 105mm gun versions.

The big army equipment push in 1942/43 also included the tank destroyers and SP artillery, which used the same engines as the Sherman, and production also tapered off in 1944, production of 7,518 tank destroyers to end 1943, 3,095 in 1944, 2,814 M7 to end 1943, 1,164 in 1944 .

 

[Admiral Beez]

Wasn't this engine based on the Merlin?

There was a V-8 based on the Merlin. The Meteorite. Available in both diesel and gas versions.

 

[Milosh]

No. It was based on an engine Ford offered to mass produce in lieu of the Merlin.

When the deal went south to build Merlins, Ford used the Merlin drawings as a base for the Ford engine.

 

[FLYBOYJ]

I think the idea is every so often large companies will try and create a market.

Well I can tell you that assumption is generally wrong with regards to pre war military aviation.

Part of the GM thinking was they could move the rail companies from build your own to buy off the shelf. The depression also stopped a number of US diesel makers, opening up the market. GE would have an idea about the performance of the best German versions, plus the USN desire for high performance diesels, the 1931 USN attempt to buy European engines for trials was blocked by congress. Yet the USN BuEng thought diesels suitable for fast locomotives were the ones for submarines, versus switcher engines which could be much heavier, with its own diesels GE could provide the complete submarine propulsion package. The USN started using "modern" GE diesels in the mid 1930's.

Apples and oranges

Back to aircraft, The CAA reports V-1710 production was 1,141 in 1940, 6,447 in 1941, 14,905 in 1942, 21,063 in 1943, 20,191 on 1944, the War Production Board agrees but notes one 2 stage in 1942, 514 in 1943 and 2,867 in 1944. That gives 43,492 engines 1940 to 1943, while new P-38+P-39+P-40+Allison P-51+A-36 production for the time period required 27,929 engines plus spares, somewhere between 20 and 33% of numbers fitted to new aircraft. Plus stocks ready to be fitted to the early 1944 production.

Now to complete, from sea to air to land. When it comes to tank engines the need was in 1943. The US cut back production in 1944.

Sherman production peaked in July 1943 at 2,401 and was down to 508 in February 1944 before picking up again. The US had 10 Sherman production lines December 1942 until September 1943 then down to 7 in December and 3 in February 1944. This includes the short lived Canadian line (October to December 1943). It means 29,450 out of 49,422 Shermans were built to end 1943, then another 13,179 in 1944, down from 21,433 in 1943.

The M4 ceased production in March 1945, the M4A1 in July 1945, (both Continental R-975) the M4A2 (GM Diesel) in May 1945, the M4A3 in June 1945 (Ford GAA V8) (plus a pause October 1943 to January 1944), the M4A4 (Chrysler Multibank) in September 1943 and the few diesel M4A6 in February 1944.

The 1944 mix was 1,432 M4, 2,171 M4A1, 2,428 M4A2, 7,089 M4A2 and 59 M4A6. When it comes to allocations the US mostly kept the 76 and 105mm gun armed Shermans.
M4 All from February 1944 on were 105mm,
M4A1 all 1944 or later were 76mm gun armed.
M4A2 Fisher built 843 75mm January to May 1944, otherwise all 1944 or later M4A2 were 76mm gun armed.
M4A3 in 1944/45 came in 75mm (3,325), 76mm (4,542) and (3,039) 105mm

HVS appeared in January 1945 for the 75mm gun, August 1944 for the 76mm and September 1944 for the 105mm gun versions.

The big army equipment push in 1942/43 also included the tank destroyers and SP artillery, which used the same engines as the Sherman, and production also tapered off in 1944, production of 7,518 tank destroyers to end 1943, 3,095 in 1944, 2,814 M7 to end 1943, 1,164 in 1944 .

All good - a contract was in place to make all this happen. No one works from free.

Again, some aircraft companies will undertake R&D work at their own expense but will expect a return somewhere along the line and if possible have the "customer" help them recover the cost of the R&D work or have it priced into the contract.

 

[Reluctant Poster]

Well I can tell you that assumption is generally wrong with regards to pre war military aviation.

Apples and oranges

All good - a contract was in place to make all this happen. No one works from free.

Again, some aircraft companies will undertake R&D work at their own expense but will expect a return somewhere along the line and if possible have the "customer" help them recover the cost of the R&D work or have it priced into the contract.

I am curious as to how much GM invested in North American pre war. That would be an apples to apples comparison. Perhaps Dragon Dog can tell us.

 

[Shortround6]

Wasn't this engine based on the Merlin?

No. It was based on an engine Ford offered to mass produce in lieu of the Merlin.

Some things are a little murky. Not helped by Ford Fan Boy websites/facebook pages.

It is very close to unbelievable that they only started development in June of 1940 after seeing the Merlin engine and drawings. How long they had been working on the engine in secret is certainly subject to question.
Judging by bore and stroke gets a little tricky. Most aircraft engine designers liked to keep the bore and stroke ratio pretty close because of flame travel and expected rpm. Their goal was fuel burn being done at about 20 degrees after top dead center. Very few engines used variable ignition timing so the ignition timing has to be suitable for both idling and full speed (some engines could use retarded timing for starting).

The Merlin used SOHC valve arrangement, the Ford used DOHC.
The Ford used a pent roof combustion chamber.
The Ford used offset connecting rods and cylinders like a car engine, The Merlin used forked connecting rods and the left and right cylinders were lined up with each other.

These are fundamental differences and nobody is even looking at the actual crankshaft in regards to size and bearings (size and length).
Ford claimed they were going to use a cast crankshaft and rods (?) instead of forged. Maybe they got away with it on the tank engines but they ran the tank engines at lower rpm and used no supercharger. A much lighter load on the connecting rods and crankshaft.


"When the deal went south to build Merlins, Ford used the Merlin drawings as a base for the Ford engine."

This is often claimed but the boys at Ford must have been awful fast workers.
Of course we have to define "based on". As noted above they changed the whole cylinder head and valve train and they changed the cylinder bock layout (one cylinder bank offset from the other).
Maybe there were some details Ford used or they used the Merlin drawings to help refine calculations.

 

[FLYBOYJ]

I am curious as to how much GM invested in North American pre war. That would be an apples to apples comparison. Perhaps Dragon Dog can tell us.

Now that would be an interesting to know as it was apparent that war was on the horizon and there would be a need for armaments, be it from the US or a foreign government. The gamble would be "when and how much."

 

[Shortround6]

I am curious as to how much GM invested in North American pre war. That would be an apples to apples comparison. Perhaps Dragon Dog can tell us.

Now that would be an interesting to know as it was apparent that war was on the horizon and there would be a need for armaments, be it from the US or a foreign government. The gamble would be "when and how much."

It is note quite apples to apples.
NA was making the series of trainers starting with the NA-16 which flew in 1935. Both fixed gear and retractable and using several different engines.
They also branched out into bomber design

First flown in Dec 1936. No sales, sort of, evaluation batch was canceled.
The NA-40

was first flown in Jan 1939.
Please note that NA had built or had orders for several hundreds of trainer aircraft at this time and was making a profit, how big a one is subject to question.

In Jan 1939 Allison engine division (as opposed to the bearing division) was not making a profit and was running at loss for quite a while.
The XP-40 had won the Jan 1939 fighter competition and perhaps one could gamble that a production contract for the engines would be soon be coming. But the Army didn't actually make up it's mind until April of 1939. It also ordered 13 YP-39s and 13 YP-38s within a few days with that the future of the Allison engine was certainly more secure.

Please remember that Continental was acting as the assembly shop for the ???-1430 engine (based on engineering from the Army) and Lycoming was dabbling with O-1230 engine and while both were later in timing than the Allison it was by no means assured that Allison had the "lock" on American liquid cooled engines. Both of these programs had been in existence for several years by Jan 1939 and the Continental engine was the Army's fair haired boy.
Progress on the Continental was slow because Continental refused (unlike Allison) to do any new work on the engine until work already done had been paid for. Like two cylinder test rigs and rebuilds of the two cylinder test rigs.

So Allison (GM) was in competition with with these two programs in addition to the two radial engine makers.

Please note that both Continental and Lycoming were successful builders of smaller aircraft engines in addition to making car, truck and bus engines. Their corporation's future did not depend on the big aircraft engine although devoting too much time/effort could affect things.

 

[drgondog]

I am curious as to how much GM invested in North American pre war. That would be an apples to apples comparison. Perhaps Dragon Dog can tell us.

I don't have the precise dollars or the financial mechanism GMC provided NAA but via Ernie Breech, the GMC Board mamber assigned to NAA, GMC provided project funding assistance for XO47 (at Dundalk, MD), BT-9, XB-21 and NA-40. The latter two, while not winning comptition against Douglas B-18 or A-20, firmly established NAA's reputation leading to B-25 contract. The BT-9 led to BC-1 and AT-6 plus several export fighter contracts giving NAA a solid reputation for quality and engineering excellence in Commonwealth contries as well as AAF.

The funding was generally limited to Projects, and was influential at NAA to imbed Production Engineering Projects in middle of advanced design to ensure design to production methodology was incorporated into airframe design. I have seen references suggesting GMC involvement in Q2 1941 in providing funds within NA-83 to design and Propose Allison Low Level Pursuit (A-36) to compete for AAF Dive Bombing Procurement. That said, I do not have any NAA Financial Management records or statements other than the multiple O Contractor Reports which detail all NAA Charge Number projetcs at summary level, but no breakout for total$, nor Direct vs Overhead breakouts or the Project/Contracts.

 

[Deleted member 68059]

Copying a 1940 spec merlin gets you just about nothing, no idea why anyone would do that. Also why on earth would RR just leave ford with the drawings if the deal fell through?

 

[Reluctant Poster]

Copying a 1940 spec merlin gets you just about nothing, no idea why anyone would do that. Also why on earth would RR just leave ford with the drawings if the deal fell through?

Maurice Olleys recollection of events with respect to Merlin drawings in this.

The Ford's, the Merlins and Maurice Olley

Origins of Ford Aero and Tank Engines, the American Merlin, and the writings of Maurice Olley. Before the entry of the United States in the Second World War,…

thunderboats.ning.com

I do not agree with the authors conclusion that the Ford engine was superior to the Merlin, particularly with respect to the cast crankshaft. Post war Ford used forged cranks in the very big Super Duty V-8 used in tractor trailers.

Olley certainly had an interesting career. He was a part of the original design team for the original Eagle, but his real claim to fame is as a chassis designer.

https://millikenresearch.com/MauriceOlleybyWFMilliken.pdf

In March 1939 Rolls Royce entered discussions with Ford France to manufacture the Merlin III. From "Hives and the Merlin":
"Before the final details of the agreement had been completed a number of Ford engineers arrived at Derby to gain a general idea of the manufacturing techniques involved in Merlin production. Some of these men were from the parent company in Detroit and had worked on the Liberty project in the First World War. These engineers were given full run of the Derby factory and spent about 6 months there. Most of the informs passed back to Detroit, where the parent company was carrying out production planning of the entire scheme. The special machine tools, none of which were obtainable in France, were all ordered and progressed from the Dearborn headquarters of the Ford Company in Detroit."

"On August 21 there was a completely unexpected development at Dearborn. Henry Ford, who was not impressed by Britain's or France's chances of defeating a sustained German attack, decide to keep his American plants strictly neutral. As a result of this decision all Merlin and other armament work of any description was rapidly cleared out of the Ford factories and organization at Detroit."

 

[tomo pauk]

Maurice Olleys recollection of events with respect to Merlin drawings in this.

The Ford's, the Merlins and Maurice Olley

Origins of Ford Aero and Tank Engines, the American Merlin, and the writings of Maurice Olley. Before the entry of the United States in the Second World War,…

thunderboats.ning.com

I do not agree with the authors conclusion that the Ford engine was superior to the Merlin, particularly with respect to the cast crankshaft. Post war Ford used forged cranks in the very big Super Duty V-8 used in tractor trailers.

Unfortunately, the sentences (my emphasis):
Like Packard, the British Ford factory redrew the RR drawings and tightened the tolerances so the engines could be mass produced.

and:

The Ford GG aircraft V12 showed great potential, producing over 1800 Hp on its initial dyno test!

don't have a connection with what actually happened.

 

[buffnut453]

Unfortunately, the sentences (my emphasis):
Like Packard, the British Ford factory redrew the RR drawings and tightened the tolerances so the engines could be mass produced.

and:

The Ford GG aircraft V12 showed great potential, producing over 1800 Hp on its initial dyno test!

don't have a connection with what actually happened.

The whole "tightened the tolerances" remark smacks of lazily copying assertions made elsewhere that D Deleted member 68059 has, IMHO, effectively debunked. Rolls Royce factories (multiple) produced far more Merlins than the Ford factory in the UK, so it makes little sense that somehow Ford went down its own path with tighter tolerances. To do so would prevent interchangeability of parts between Ford and Rolls Royce produced engines.

Again, Merlin production totals for comparison:

Rolls Royce Factories:

Derby: 32,377
Crewe: 26,065
Glasgow: 23,675

Ford Factory, Manchester: 30,428

Packard Merlin Production: 55,523.

If Ford "tightened tolerances" then those different standards would have had to be replicated at all the Rolls Royce factories...and yet the Ford factory only started production in May 1941 whereas all 3 Rolls Royce factories were in production in 1939 or by mid-1940.

I really do wish this myth about Rolls Royce's sloppy tolerances would die.

 

[buffnut453]

One other note, this from Wikipedia which isn't the best of sources. However, if it's true then it provides further evidence that Rolls Royce tolerances can't possibly have been sloppy:

With 16,000 employees, the Glasgow factory was one of the largest industrial operations in Scotland. Unlike the Derby and Crewe plants which relied significantly on external subcontractors, it produced almost all the Merlin's components itself.

Now, if the Crewe and Derby factories relied on subcontractors to produce Merlin components, surely sloppy tolerances would have hindered the ability to mass-produce the engines? Yet Derby produced more Merlins than any other UK factory.

 

[Shortround6]

I do not agree with the authors conclusion that the Ford engine was superior to the Merlin, particularly with respect to the cast crankshaft. Post war Ford used forged cranks in the very big Super Duty V-8 used in tractor trailers.

The Ford GG aircraft V12 showed great potential, producing over 1800 Hp on its initial dyno test!

There are several possible things going on with the cast crankshaft/s.
I am saying possible

1 thing is how long were the crankshafts good for? 100 hours or 150 or 300 hours?

2, when you are comparing truck engines you run into a similar problem. Heavy duty truck engines spend a higher percentage of their lives at a higher power level than car or light duty trucks. Commercial trucks also spend a lot more hours per month (or per year) running than cars or light duty trucks. They have to have higher durability or the truck isn't making money.

3, You may be able to design a suitable cast Iron crankshaft but it may not be interchange with with a forged crankshaft. The cast iron part may be bigger though the bearing journals and rod bearings? Some car engines came with cast cranks on light duty engines and forged cranks on heavy duty engines but they were interchangeable.
In 1940 Allison was a lot of trouble with their crankshafts. Solved in part by shot peening the crankshafts and by the end of 1941/ start of 1942 by nitriding and shot peening the crankshafts.
We have no idea if Ford would have been forced to change crankshaft construction.

I would note that RR had gotten over 1800hp out of Merlin on the test stand in 1938 when working on the Speed Spitfire.

What we don't know about the 1800hp Ford is for how long they made 1800hp and what the conditions were.
Was the Ford using a two stage supercharger (mechanical supercharger plus turbo) or a single stage supercharger (turbo only) ?

Were they getting 1800hp at sea level ? or at altitude (many engine test houses could adjust the air pressure of the intake air).

One might also wonder if the turbo was going to standup to those power levels. Every other production turbo spaced the turbo a number of feet further away from the engine to allow for a bit of cooling before the exhaust gases hit the turbo.

 

[Shortround6]

One other note, this from Wikipedia which isn't the best of sources. However, if it's true then it provides further evidence that Rolls Royce tolerances can't possibly have been sloppy:

With 16,000 employees, the Glasgow factory was one of the largest industrial operations in Scotland. Unlike the Derby and Crewe plants which relied significantly on external subcontractors, it produced almost all the Merlin's components itself.

Now, if the Crewe and Derby factories relied on subcontractors to produce Merlin components, surely sloppy tolerances would have hindered the ability to mass-produce the engines? Yet Derby produced more Merlins than any other UK factory.

The thing is that "story" about the loose tolerances comes from Hooker in his autobiography.
What may be missing is when guys for Ford were talking in the office the Hooker was sharing. Hooker, without giving dates, says that it took a year or so to redo the drawings.

It may also assume that RR did not tighten things up at the RR factories.

I would also note that you can have two different fit standards.
One fit standard can have every piston fit into any cylinder. This is what Ford was looking for.
Another fit standard is that a Piston has to fit in a cylinder with a only a certain amount of clearance. If you have a cylinder that is a few thousands of in wider then you need to find a piston that fits that cylinder,
Not filing to fit.

 

[buffnut453]

The thing is that "story" about the loose tolerances comes from Hooker in his autobiography.
What may be missing is when guys for Ford were talking in the office the Hooker was sharing. Hooker, without giving dates, says that it took a year or so to redo the drawings.

It may also assume that RR did not tighten things up at the RR factories.

I would also note that you can have two different fit standards.
One fit standard can have every piston fit into any cylinder. This is what Ford was looking for.
Another fit standard is that a Piston has to fit in a cylinder with a only a certain amount of clearance. If you have a cylinder that is a few thousands of in wider then you need to find a piston that fits that cylinder,
Not filing to fit.

I'm familiar with the origin of the story. For all his many talents, Hooker was not a production engineer. I also find it interesting that people just accept the Hooker comment without actually doing the leg-work to determine what tolerances were permitted and whether those tolerances changed over time. If Hooker's comment is to be taken at face value, then at some point in the period May 1940 thru May 1941, there MUST have been a change in tolerances at the RR factories to align with Ford's better production standards. Either that or Ford was producing engines at different tolerances to the rest of RR which would massively complicate second-line servicing at operational units. What evidence is there of ANY change to RR production tolerances?

As noted above, the 3 RR factories were already pumping out thousands of Merlins per year before the Ford factory got up and running. As we all know, implementing changes mid--stream in any production line is challenging to say the least. To suggest that, in late-1940 or early-1941, RR suddenly changed their tolerance standards without any impact on production seems laughable in the extreme.

Yes, there are different fit standards. However, I find it equally laughable that a factory producing circa 30,000 engines wasted time searching for the one piston that fits a particular cylinder. That approach is ridiculous, IMHO. To do the same thing when the Glasgow factory got into its swing, and where there wasn't an experienced engineering workforce, is equally laughable.

 

[Reluctant Poster]

Unfortunately, the sentences (my emphasis):
Like Packard, the British Ford factory redrew the RR drawings and tightened the tolerances so the engines could be mass produced.

and:

The Ford GG aircraft V12 showed great potential, producing over 1800 Hp on its initial dyno test!

don't have a connection with what actually happened.

I didn't make that post to start the tolerance war again. I fully agree that RR tolerances were the same as Packard's . The point I was trying illustart was Olley's recollections regarding Fords involvement with the Merlin which the article quotes. In no way shape or form would I agree that the Ford engine was the equal of the Merlin. And in no way shape or form would I agree that a Packard built Merlin was a marvel of mass production while the Rolls Royce was a hand job.

 

[Deleted member 68059]

I didn't make that post to start the tolerance war again. I fully agree that RR tolerances were the same as Packard's . The point I was trying illustart was Olley's recollections regarding Fords involvement with the Merlin which the article quotes. In no way shape or form would I agree that the Ford engine was the equal of the Merlin. And in no way shape or form would I agree that a Packard built Merlin was a marvel of mass production while the Rolls Royce was a hand job.

 

[Shortround6]

Without detailed histories of each factory there can be quite a bit of cross over. It could between 1 and 2 years to get a factory from start of production to reaching full production.

And in some cases it took a fair amount of time to even get to a few hundred engines a month.

I looked up the S.S. City of Flint and she sank in a storm on Great Lakes on Nov 11th 1940. She was only 500ft from shore and was salvaged and put back in service. NO idea what happened to the machine tools that were aboard.

Now from wiki we have on GLasgow...........................
"Engines began to leave the production line in November 1940, and by June 1941 monthly output had reached 200, increasing to more than 400 per month by March 1942."

But apparently Glasgow was starting production with parts shipped in from other factories to provide training. A good idea, to get the workers up to speed.
There was a whole lot of stuff going on at the same time, and while Ford only started construction of the factory buildings in April of 1940 modern factory construction is not a matter of throwing up buildings and seeing where you can stuff the machinery. You figure out how you want the flow of parts from the different depts to go and join together on the assembly lines lines. Once you have the factory floor plan laid out they you build the building. Ford may have been working on the plans for the factory for weeks or months before they broke ground.

Packard built 4 engines in their first month of production, Sept 1941, they only built 26 in Dec 1941 but in April of 1942 they built 505. Packard had a few advantages, they weren't being bombed for one thing.

I am not trying to say the US was better, I am saying that there was a lot of overlap between some of the factories and the way they were building engines in 1943/45 might not have been they way there were building them in 1940/41. Off course that goes for quite a few engines.