Allison and Merlin in a P-51

GregP said:

This was NOT a question in WWII. If e could make a U.S.-built alternativer, then the decision would have been to do it. At the time, we were nothing if not nationalistic.

I don't think we would have done it simply because we were already making Merlins and there was no desire to spend development dollars to make up an Allison-designed 2-stage when the Merlin was already coming off the lines. I've seen a letter from Allison to the USAAF asking for funds to develop a 2-stage supercharger. It was declined ... the USAAF got exactly what it ordered. About the time the Allison was making really great horsepower, all the development money was going into jets anyway.

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That was actually the point I was making, maybe badly worded. Rolls Royce were working on 2 stage Merlins long before the USA even entered the war, The Mustang Mk I. was arriving in UK before USA entered the war. For the USA to decide on handing Allison a research contract they would need a time traveller to tell them that what we know happened would happen in around 1940-41. Even if it could be done, in terms of US industry every 2 stage Allison engine produced would just replace a 2 stage Packard.

tomo pauk said:

That's very interesting. What date is on the letter?

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Sorry Tomo, I looked at the content of the letter and didn't really notice the date.

It said words to the effect: "Allison Engineering proposes development of a 2-stage, mechanical supercharger to be fitted to the V-1710 series of aircraft engines to materially increase the altitude performance of the engine." It said the supercharger would be a single, self-contained unit suitable to be bolted onto the V-1710 power section.

It took them about a long paragraph to say that. The second paragraph proposed a timeframe of about a year from start of project to working model ready for optimization into a production piece.

The proposal letter was just that, a proposal for a development project. There was not reply with it and there was no indication of any action other than a proposed project.

I have heard people who were around at the time say Allison proposed that development twice during the war and was turned down both times, but have seen no proof of a second proposal letter or a rejection letter of any sort. My proof of rejection (if it WAS communicated to the USAAC/F) is that no such project was ever funded, as far as I know. All I saw was one proposal letter for development of a 2-stage supercharger section.

There is no proof it was ever sent out from Allison ... just a photo of a letter on Allison letterhead that may or may not have been communicated to the USAAC/F. I make no claim except to having seen a pic of a proposal letter, but there is no record of such a development effort at Allison other than the second-stage, external supercharger unit we all know about.

GregP said:

There is no proof it was ever sent out from Allison ... just a photo of a letter on Allison letterhead that may or may not have been communicated to the USAAC/F. I make no claim except to having seen a pic of a proposal letter, but there is no record of such a development effort at Allison other than the second-stage, external supercharger unit we all know about.

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Thanks for the reply.
You will hopefully understand that my suspicion meter is still in the red area.

Suspicion meter for what, Tomo? That I saw such a letter?

Allison never developed a single, 2-stage integral unit and I have no proof the letter I saw was ever sent out to anyone outside Allison. It could have been in internal memo that was intended for the USAAC/F but was never actually approved to send out.

All I saw was a letter.

I never saw acknowledgement of receipt of it, an acceptance or rejection of it, or anything else other than a letter on Allison letterhead stationery. I know someone who says they have a reply to that letter, but have never actually seen it, so I don't know if it is real or not.

When I was in the electronics industry, such a letter was generally an RFP, or a Request for Proposal letter designed to solicit a response from the customer ... it wasn't the actual proposal itself. Since I've never seen the actual proposal or a response to one, it makes me think its possible the RFP letter was composed but may not have ever been sent out.

Can't really say for sure.

GregP said:

Suspicion meter for what, Tomo? That I saw such a letter?

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V-1710 story is even today a matter of misunderstanding. Stipulating about an undated letter that one saw, as well as repercussions (or lack of them) revolving around that letter will not clear the issues, but it will do the contrary.

I really don't get it, Tomo, but ... that's OK. I don't have to get it.

Allison was in the engine business. Everyone in here knows the V-1710 needed a high-altitude boost system and that was either a 2-stage supercharger or a single-stage coupled with a turbocharger. The letter I saw merely shows that, at some point, Allison contemplated development of a 2-stage integrated supercharger unit as well as the auxiliary-stage unit they actually DID develop.

I don't find that hard to believe at all. I DO find it hard to believe the USAAC/F never funded such a development but, left with the fact that it never materialized, I supposed we have to accept it as fact. Stranger things have happened.

If you spend 40 years collecting parts and things about an engine and building the engines, I'd guess you'd find out some things not generally known about said powerplant. I know somebody who DID spend about that long building Allisons and finding parts, tools, and documentation about Allisons. He's about to retire and all this will be just lost. I find that sad in the extreme. Perhaps he will let me have some written items at some point. If so, I'll share them. If not, I didn't see too many mostly-unknown things. I mostly saw real parts and engines. While I worked there, we built 14 Allison V-1710s up from parts. One was left-hand turn. The rest were right hand turn. I wasn't the guy whose name was on the shop, but I DID learn a lot about Allison V-1710s in those 2+ years.

I did see that letter. And, as I stated, I have no proof it was actually sent anywhere; just a paper letter asking about possible development of a supercharger unit that none of us have ever seen or heard of as actually having been developed for the Allison V-1710 series of engines.

None of which alters any history of the Allison V-1710.

Cheers.