WW2 without V-1710: options for the Allies?

GregP · Aug 23, 2013

Yes the Brownings were a US design and I wish we'd have used some foreign 20 mm cannons in our planes a LOT sooner than we did in preference to the Brownings. Our own 37 mm cannon was certainly nothing to write home about.

My statements above aren't isolationist of in any way depricating of products made outside the USA. I was, rather, saying that the attituides prevalent at the time were to buy American, especially for critical military items. The reason the Merlin was produced over here by Packard comes down to a British request for it, not the USA seeking engines for itself. You may recall that Ford turned down the request to build the Merlin and Packard was induced to do it.

So while we DID use some Merlins, we didn't use many other than in the P-51, which I maintain would probably NOT have gotten a Merlin had it been a primary US military aircraft from its inception. Most Merlins went to the UK or to Canada.

These are statements about how I think it WAS at the time, not how I personally feel about it.

Shortround6 · Aug 23, 2013

beitou said:
Browning machine guns in the UK fighters were a US design.

So was the Bren gun and the Besa. So was the Hispano gun and so was the Bofors 40mm. So was the Browning High power pistol. British were not above using somebody else's design if it worked.

Shortround6 · Aug 23, 2013

The reason for "buying American" was to insure supply in time of war. The US was not above licencing (or coping) 20mm Hispano guns, 20mm Oerlikon guns, 40mm Bofors guns, 57mm (6pdr) AT guns and agreeing to build 4.5in artillery guns for common ammo supply with the British (although the last was a mistake).

British did request a US production line, The US would NOT agree unless it got some of the production. At the time the agreement was signed (sept 1940) the US had more Merlins on order than it did Allisons. However as some deliveries were several years in the future delivery dates and quantities changed, let alone later contracts.

GregP · Aug 23, 2013

What is your point Shortround? Specifically?

I said if the Allison had not been a viable engine, we would have developed an alternative engine or used radials. You seem to think that means using the Merlin in quantity. I simply disagree. There's no use debating a what-if since it never happened.

If it makes you happy, then by all means imaging scores of Merlin-engined P-38's and P-39's. In real life, it might not have been a bad idea, but it didn't happen. I'd love to see what a P-40 with a 2-stage Merlin would do at altitude. It would no doubt be a step up from the non-turbo Allison setup.

I wonder if anyone ever tried a Merlin supercharger housing on an Allison with an adapter plate. Sir Stanley Hooker was a genius with superchargers and it might have made a real winning combination. If they did, I haven't read about it as yet.

Piper106 · Aug 23, 2013

Back to our regularly scheduled programing... What if there was no Allison V-1710.

The Packard V-2500 (dismissed as a 'PT boat' engine) could have been developed into something comparable to the Daimler Benz and Jumo 211 engines. Seemed to have been reliable enough at 1350 HP in naval service, and was developed to 1500 HP later in the war, again for naval service. Before you jump on weight issues, most references will quote the weight for the naval version, with likely some of the major casting being iron rather than aluminum, and heavy water cooled exhaust manifolds, etc. Don't know what an aviation version would have weighed. Biggest problem would be reliability. What I think I know is that Packard's aviation engines in the 1920s and early 1930s were none too reliable.

Another tact would have been to 'go big' and build something like the Hawker Typhoon with the doubled H-24 version of the Lycoming O-1230. That actually might have been do-able rather that the effort wasted on the proposal R-40C pushers and unconventionals.

Finally, discussions always seem to forget the Hispano Suiza 12Y. Start with the 12Y and then spring off with some American thinking to get rid of that horrible multiple carb induction system, and a general strengthening to run at higher rpm and boost, ala the 12Z. The Klimov gang in the Soviet Union got more out of the 12Y than the French did, no reason the US could not have. For a real "outside the 9 dots" idea, license the Milukan AM-38. Having said all that, I agree 110% with earlier posters that a foreign engine would heve been a no go.

drgondog · Aug 23, 2013

swampyankee said:
With the last sentence, I disagree: the engines from Pratt&Whitney and Wright were quite capable of providing power for world-beating fighters. USAAF preference for liquid-cooled inlines was more due to fashion (they looked more streamlined, more modern) than to aerodynamics (the zero-lift drag coefficient of almost all fighters ranged between 0.02 and 0.025, whether powered by in-lines or radials: the Spitfire and the Corsair had quite similar zero-lift drag coefficients). There were also, of course, development efforts that were not being heavily funded, like the "Hyper" project, that could have been funded more heavily, and there were liquid-cooled engines under development by Wright and P&W.

The P-51 CDo was closer to .016 as a specific 'contrary' example - which was due more to the wing than fuselage But the 2nd order compound lines of the nose also helped, and was possible with the In-line Allison, and slightly modified for the Merlin.

swampyankee · Aug 23, 2013

The Allison engine had a rather long history, actually starting as an engine for airship use (http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=804 ; the first V-1710 was bought by the USN: Allison ); the first USAAC use of the V-1710 was in 1932. At the time the engine's development had started, the NACA cowling was probably not yet tested (it was used quite soon, with some notably clean aircraft, such as the 1931 Lockheed Orion, with a zero-lift drag coefficient of about 0.021 [ see http://history.nasa.gov/SP-468/ch4-4.htm ]).

With the notable exception of the P-51, it seems that most WW2 fighters had zero-lift drag coefficients that were grouped between 0.021 and 0.025, regardless of engine type. We have to consider the possibility that Curtiss did not do a great job with the P-36's engine installation.

Shortround6 · Aug 23, 2013

My point is trying not rewrite History.
The US wanted a second liquid cooled engine (or 3rd or 4th, army had not have given up on the Continental I-1430 yet or a few others). The Merlin was available, it was low risk. It was already developed even if the two stage supercharger wasn't ready yet (or even being worked on in the summer of 1940) unlike the rest of the American contenders. It size, weight and configuration made it a relatively easy swap with the Allison.
The US use of the Merlin in the P-40 had absolutely nothing to do with it's use in the Mustang.

I could care less about Merlin powered P-39s. The Merlin was designed with the Front gear case as part of the crankcase, I believe, meaning you would need a new crankcase casting to try to make a remote prop drive like the Allison. Not impossible but a lot more work than the Allison design. And all you are ging to fit in a P-39 is a single stage Merlin at best. Once Allison could fit the 9.60 gears in the engine the need for a Merlin XX diminished a whole lot.
P-38 is iffy, The Merlin XX may or may not have worked any better than the early turbo Allisons in the Es and Fs and that is what we would be talking about here for starters. The Merlin may not have given the range of the turbo Allison.

They did try using a Merlin supercharger on an Allison engine on a ground test rig. I can't remember if it was the single stage or two stage at the moment. For some reason it wiped out the bearing on the supercharger (several times), lack of rigidity in the mounting? poor cooling of the bearing ( mounted several inches away from the engine block?) or something else?

People often forget there were some major differences between the single stage Merlins and the two stage Merlins. A few hundred pounds, the extra length and bulk of the supercharger/s, the need for larger radiators and oil coolers in addition to the inter-cooler radiator, the need for a bigger prop. Just because a particular airframe could fit a single stage Merlin doesn't always mean it could fit a two stage Merlin. The Mustang took a 7in splice in the height of the fuselage. From the bottom of the fuselage to the top, not including air scoop or height of the tail fin.

GregP · Aug 23, 2013

Good points swampyankee. If they had cleaned up the radial installation in the p-36 and upped the installed power, I wonder how the performance might have been improved ...

Shortround6 · Aug 23, 2013

Piper106 said:
Back to our regularly scheduled programing... What if there was no Allison V-1710.

The Packard V-2500 (dismissed as a 'PT boat' engine) could have been developed into something comparable to the Daimler Benz and Jumo 211 engines. Seemed to have been reliable enough at 1350 HP in naval service, and was developed to 1500 HP later in the war, again for naval service. Before you jump on weight issues, most references will quote the weight for the naval version, with likely some of the major casting being iron rather than aluminum, and heavy water cooled exhaust manifolds, etc. Don't know what an aviation version would have weighed. Biggest problem would be reliability. What I think I know is that Packard's aviation engines in the 1920s and early 1930s were none too reliable.

Weight in PT boat form might include the flywheel, clutch, reduction gear and reverse gear box.

There is some evidence that Packard built both a direct drive and Geared drive V-2500 in 1938/39 that offered 1500hp at 2500rpm and 1750hp at 2800 rpm but no altitude figures are given. Weight is listed as 1430lbs.

Piper106 said:
Another tact would have been to 'go big' and build something like the Hawker Typhoon with the doubled H-24 version of the Lycoming O-1230. That actually might have been do-able rather that the effort wasted on the proposal R-40C pushers and unconventionals.

Maybe but for some reason they didn't stack the flat 12s but flipped them on their sides. Engine was about 2400lbs before they tried playing with two speed propeller drives.

Piper106 said:
Finally, discussions always seem to forget the Hispano Suiza 12Y. Start with the 12Y and then spring off with some American thinking to get rid of that horrible multiple carb induction system, and a general strengthening to run at higher rpm and boost, ala the 12Z. The Klimov gang in the Soviet Union got more out of the 12Y than the French did, no reason the US could not have. For a real "outside the 9 dots" idea, license the Milukan AM-38. Having said all that, I agree 110% with earlier posters that a foreign engine would heve been a no go.

All you need to fix the Hispano Suiza 12Y is a new intake system, new cylinder heads, a new supercharger, a new crankcase with a new crankshaft, new pistons and some new............How about a new engine? The 170mm stoke limited RPM unless you would settle for a short engine life and it's light weight construction meant that while it was a pretty good engine for 87 octane fuel it was a lousy engine to run high boost levels in without beefing up all kinds of stuff. Russians already had tooling in place to make the engine so they were sort of stuck with it.
Please remember that the Hispano engine came out and was in service in 1932/33 and so was several years ahead of the Merlin and 4-5 years ahead of the DB 601. It is really no surprise it isn't in the same class. For the US to adopt a 6-7 year old engine in 1939 would be an act of desperation.

Balljoint · Aug 23, 2013

If there had been no existing workable V-1710, it would seem that there would have been no P-38, P-39, P-40 or, for that matter, no P-51A (the British wouldn't have signed on to shipping engines to America). Money and talent are fungible, however. With focused development on the radial engines, i.e. both Army and Navy, both the power and aero enhancements probably would have come along a bit sooner.

But then alternative futures are hard to call. Maybe the P-51 would have gone ahead if it was agreed that the Merlins for it were to be made in the US of A. American industry wasn't that prideful as long as the British treasury had the needed wherewithal.

Shortround6 · Aug 23, 2013

We don't have to wonder about the the P-36, I have posted this before.

This plane achieved 389mph at 22,700ft in Sept of 1942. It is a very early P-40 airframe, please note no visible guns and the production batch it was taken from may mean no armor and no self sealing fuel tanks. Please note that that speed at that altitude with an indicated 1100hp form the engine works out to 8% more drag than the XP-40 doing 366mph at 15,000ft with 1090hp. (last modifications)
Please note that this plane used the last version of the two stage supercharged R-1830 and also appears to have a decent exhaust thrust set up for a radial engine. I don't know if the exhaust thrust was figured into the power or not.

Please look at the both the Curtiss XP-42 and the Vultee Vanguard to see the numerous ( 14 different tries for the XP-42?) attempts to get inline streamlining for a radial engine in 1939-41.

GregP · Aug 23, 2013

Not trying to rewrite history? A what-if is ALL abput trying to rewrite history! And if you discount the P-51, which was designed to a British specification and by British request, we used VERY few of the obviously-available Merlins.

We were building them here and hardly used any of them in comparison to the number built ... in the real world. In any case, its OK ... it never happened that the Allison didn't get built.

Would have made things ... interesting at the time.

Shortround6 · Aug 23, 2013

You were trying to claim that the P-40F with Merlin would never have existed without the "demand" for Merlins created by the P-51.

From your post #4 "I don't believe anyone thought of that until both sides wanted to try a Merlin in the P-51. If the P-51 had not come along, I'm not sure anyone would have pursued the license agreement."

from post #12 "Shortround, you and I both know those engines were never slated for front-line USAAF or USN aircraft. They were for the British. If it weren't for the P-51, I doubt the Merlin would have seen the inside of ANY US fighter."

And still from post#12 "There were none before the P-51B/C that first flew in Nov 1942, a few P-40 F's and L's (2,280 of them ... 15 - 16% of the total, didn't come into service until 1943, well after the P-51B/C had proven the merit of the change).

The US and the British signed the agreement with Packard in Sept of 1940 after a number of weeks of talks which started back in July. Packard had been doing a lot of work in the mean time and did not wait for the signing (although getting one of the sample engines and some of the drawings back from Ford Delayed things a bit.) The US was to get 1/3 of the production and the initial order was for 9000 engines. Now this is over two years before the Mustang B prototype flew. You can slice it, dice it even puree it any way you want but the use of the two stage Merlin engine in the P-51 had NOTHING to do with with the original production agreement/licence. Trying to claim it did is re-writing history.

gjs238 · Aug 23, 2013

pinsog · Aug 23, 2013

Shortround6 said:
We don't have to wonder about the the P-36, I have posted this before.

View attachment 241259

This plane achieved 389mph at 22,700ft in Sept of 1942. It is a very early P-40 airframe, please note no visible guns and the production batch it was taken from may mean no armor and no self sealing fuel tanks. Please note that that speed at that altitude with an indicated 1100hp form the engine works out to 8% more drag than the XP-40 doing 366mph at 15,000ft with 1090hp. (last modifications)
Please note that this plane used the last version of the two stage supercharged R-1830 and also appears to have a decent exhaust thrust set up for a radial engine. I don't know if the exhaust thrust was figured into the power or not.

Please look at the both the Curtiss XP-42 and the Vultee Vanguard to see the numerous ( 14 different tries for the XP-42?) attempts to get inline streamlining for a radial engine in 1939-41.

Can you give more information about this aircraft? Maybe even a new thread. Looks very interesting and competitive

GregP · Aug 23, 2013

Shortround, for a what-if, you are taking this to ridiculous lengths. I don't really care one way or the other since it never happened, so this time, I'll just let it go.

Rewrite history on your own in good health. Nice pic above.

drgondog · Aug 25, 2013

Greg - Shortround keep dealing in facts to base his conclusions that a.) building the Packard Merlin in the US had zero to do with the P-51B, and b.) that the AAF had placed a reserve 'hold' on the Packard Merlin Production before the P-51 was flying.

You, on the other hand had an opinion (No Way AAF would buy from Brits) supported in part by referencing your Mom and Dad, which even to those used to some of your emotional arguments was pretty strange.

In summary, SR inundated you with facts, overwhelmed you with opinions based on facts and you made your look pretty silly - at least from my perspective. I could be wrong because it is my Opinion that Shortround was entirely correct in his foundation of fact and logic following the foundation.

Namely, if the Allison 1710 had never been built, that other substitutes would have been produced and that the Packard Merlin is the most likely substitute - and the AAF would have agreed to extend the contract for the Packard Merlin 1650.

wheelsup_cavu · Aug 25, 2013

Have to agree with Greg that without the expediency of using the Merlin to solve a war time problem it would have never been used in very large numbers. There were still prejudices against the British going back to the war of 1812 which were not pushed aside until we finally entered WWII. We were still not ready to *save Europe again from itself, hence the isolationist movement. Nothing from the time suggests we were ready, during peace time, to embark upon a massive utilization of a foreign powers defense equipment. Even using it as a backup during peace time would be highly suspect considering the collective mind set of the people in the US during that time period.

Wheels

*please note the italics before you decide to blast me about the "save" part of the comment.

GregP · Aug 25, 2013

Drgondog, let's say that you and I will not usually agree except only once in awhile in passing and go from there.

I don't feel in the slightest overwhelmed. I still don't see, 70 years after the fact, many Merlins used in US fighters of WWII other than the P-51, unless you're hiding them somehwere in an unpublished book. So my thoughts on it are based on what what really happened and people who were there when it went down, not some contrived what-if.

Out of the 50,000+ fighters we built other than the P-51 and the derivative P/F-82, only about 2,200 Merlin-engined P-40's were powered by Merlins plus a handful of others, and that is enough to be obvious to most who take the time to look at it. I don't need any sources for it in this case either. Leave the P-51 out and find all the Merlin-engined fighters produced for US service. They are rather conspicuous by their low numbers.

It has already happened. The results are out there for all to see. I would certainly have left this alone going forward if not for the wording.

Oh, one more thing.

I see you said the drag coefficient for the P-51 was .016.

I am interested and I wonder where you found that. When I check NACA report NA-46-130, dated 2/6/46, NACA reports ACR5D04, L5A30, ACR dated 10/40, ACR 3130, Air Corps Technical report 4677, and Boeing in-house drag data I see they mostly agree on a Cdo of 0.0176.

I want to be accurate in my data files and am NOT arguing with you. I just wonder where you found 0.016, no other agenda. Maybe that value was for a specific model? If so, I have a new "lowest Cdo" candidate for the file.

I have Cdo for a few WWII fighters in a file and, to date, the lowest is the P-51D at 0.0176 and the highest is the Brewster Buffalo F2A at 0.030 (with the Bf 109E-3 next at 0.0290). Interestingly I have the Fw 190A-3 and the Spitfire IX both at the same value of 0.0220. The lowest radial-powered entry I have to date is for the P-47 at 0.0213.

The highest single-engine flat-plate drag area I have is for the F4U Corsair at 8.38 square feet and the lowest is for the P-51D at 4.10 square feet.

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