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Good to see this is developing beyond our original discussion. Firstly Nincompoop; I think you are taking my "happy with the fighter" quote out of context; the reason I said it was to counter Drgondog's assertion that the Allison engine performance was a dog. Considering the Mustang was faster and had a greater range than any British or American fighter then in service at that time,
Good to see this is developing beyond our original discussion. Firstly Nincompoop; I think you are taking my "happy with the fighter" quote out of context; the reason I said it was to counter Drgondog's assertion that the Allison engine performance was a dog. Considering the Mustang was faster and had a greater range than any British or American fighter then in service at that time, NAA were happy with it as a fighter and of course they would look at continuing development; goes without saying. Of course the Americans were investigating higher altitude performance in their fighters, XP-60 and P-38 development and also we all know that Allison were working on improving the altitude performance of the V-1710 to reinforce this, but it was the RAF evaluation team that examined the first production examples in the States (the first AG345 flew for the first time on 1 May 1941) that realised its altitude performance was below what was required over Europe, but this still did not seem to deter from the USAAF putting the order in in July '41. And no, I can't tell you have experience with project development and improvement in industry, not that it's relevant or anything.
Nuuumaann - I did indeed state that the Allison V-1710 was a dog but the comment was in context of future great role as escort fighter. The P-51A was very fast on the deck to 10,000 feet but as stated in various comments in this thread was not deemed 'quite enough' in ETO by RAF. Taken into further context, these RAF evaluations culminated in their suggestion of a mating between P-51 airframe and Merlin 61.
As to NAA being 'Happy", yes to a degree but the P-38 and P-47 got the orders. The first USAAF P-47 Production cntract was September, 1940 and August for first USAAF P38...and it was not 'lost' on the NAA execs that a.) P-40's and P-39's were getting USAAF production orders, and b.) NAA was not, despite superior performance. The Mustang funding was sourced solely from Lend Lease and that program was to terminate in September 1942.
The first XP-51 was delivered to USAAF in August 1941 but the first RAF Mustang I production model (AG345) rolled off the line in April 1941 and first flown by Lewis Walt on April 23, 1941. AG346 flown in trials from early July and was accepted by RAF in August, 1941...and first to be shipped to UK.
The reason I wander through the history is that a.) USAAF didn't fly the XP-51 and did not include it in the evaluations of the P-38, PP-39, P-40, P-43, P-47, XP-60, P-66 etc. The most interesting part was the issuance of Board of Officers, October 27, 1941in which 8 production plus 18 experimental fighters were evaluated - but not the P-51. The Board issued an opionion that the prime mission was "to destroy enemy bombers. It must be able to overcome or evade such hostile pursuit as it may encounter". This report was a Major alert to NAA and according to Horkley, was the initiative for NAA to actively campaign with USAAF. It should also be notedthat the Board deemed that the P-40 and P-39 by overweight (proportional to total) and underpowered/restricted to low/medium altitude of the Allison. The decision to experiment with the Packard Merlin 1650-1 in te the P-40F and the 1650-3 in the XP-60 arose from this Paper's recommendations.
So, NAA was in an R&D funding starvation situation until ASAAF let the A-36 contract in April 1942, followed by P-51A contract in June 1942. By that time NAA already knew that most of the P-51A production would shift to P-51B, if successful.
Drgondog, sounds like you've had some fascinating discussions with people about these things, would have been real interesting to sit in and listen.
I grew up as an Air Force brat living at places like Eglin AFB and Edwards AFB, and fighter pilots and test pilots were an integral part of my life until my father passed away in 1979. I also co-op'ed at Lockheed before I graduated with my Aero degree. I have had an enduring fascination with Airpower and aircraft - which was the driving force to study both aviation and airframe technologies including aerodynamics and structures.
You're in an enviable position to be able to get access to these guys and the resources you can. I live in the middle of nowhere in a small country on the other side of the world from you! If I was in your position I'd be divorced for neglecting my family, by now! As for conversations between RAF and American personnel about better altitude, you can guarantee they happened; yep, chit-chat makes the world go round, but when you get to something as important and as urgent - remember, at that time (late '41 early 42) the British were struggling to cope with the Fw 190 - and as pertinent as a fighter with exceptional performance it was bound to get tongues wagging and pens writing. These RAF guys with 26 Sqn that received the Mustang in January '42 had encountered the Fw 190, so discussions regarding offering better performance than their foe led to quite a bit of discussion and evidence shows they were real pleased with the performance of the Mustang - altitude performance aside. As it was, the Mustang I could match the Fw 190 on even terms. Regarding Atwood and Schmued, it seems that Legarra and Bouchelle of NAA did much of the leg work from the British side of things; these two guys seemed to have spent some time in the UK, with visits to Hucknall to view progress on the Mustangs being converted there.
True but Schmeud and Horkey were visitors in 1940 and early 1942 as well as Atwood.
Aozora, interesting information and although I hadn't seen that book and it would be interesting to see the rest of that chapter, I was aware that two Mustangs from the original USAAF order were to be kept aside for evaluation, because this was a condition of the approval that a US company was to build aircraft for the British who were at war, since the USA was not at that stage.
Two P-51A aircraft were pulled for the XP-51B conversion. 41-37352 and 41-37421. The Packard Merlin 1650-3 (allegedly from XP-60D cancellation) failed bench tests and delayed the first flight from late October plan to November 1942 -actual.
The Merlin XX/28/Packard Merlin 1650-1 was never installed
The decision to evaluate them fitted with Merlins didn't come until later, not when the contract to build was signed. At Wright field there was discussion of fitting these aircraft with the V-1650-1 (Merlin 28 ) supplied by Packard for trials, (this is the crux of the matter) and conventional wisdom states this was in conjunction with the suggestion by Rolls Royce of fitting such an engine, as an interim to allay fears by the Air Staff that there wouldn't be enough Merlin 61s for the Spitfire and the Mustang, in May 1942. British reps from A&AAE Boscombe Down had been to the States (when - sometime earlier than mid May 42?) to discuss the fitting of a Merlin 28 to the Mustang, but their response was not encouraging, correspondence states that "...it did not get any further". By June the Americans had promised that by July they would have a Merlin 28 Mustang in the air, which affirms initial consideration and investigation, but the conversion didn't happen. By August 1942, Kindleberger had contacted the USAAF about the unfeasibility of the Merlin 28 and preference for the 61 instead.
The entire conversations regarding the installation of the 1650-1 after May 1942 was contingency based on the 'newness' of the 1650-3 and the issues that NAA were concerned about regarding the multiple challenges encountered with the 1650-1. An added complication is that the Merlin 61 had catastrophic failures at 12 pounds boost at Wright Pat in July, 1942 (due to connecting rod and carburetor issues) if the 4 September 1942 letter from General Lyons to Hives is referenced. This failure kept NAA from planned first flight and re-directed the engine test bed to 1650-3
If anyone can supply it, I'd like to see further reference to Wright Field's investigation of the V-1650-1 for the two XP-51s they had; it'll make interesting reading. Would the USAF Museum be a good source for this?
Yes the P51A really came into its own post Normandy as a superb low level photo Rec /tac air plane though it, of course, did tremendous good work in that field before then. It's low level performance was superb.
The 2nd TAF used them right up until they had none left.
True but Schmeud and Horkey were visitors in 1940 and early 1942 as well as Atwood.
the first RAF Mustang I production model (AG345) rolled off the line in April 1941 and first flown by Lewis Walt on April 23, 1941.
When NAA were investigating the Merlin 20-series/V-1650-1 for the P-51/Mustang I, was it intended for the USAAC/F or the RAF?
Can't find any figures showing how the Spitfire's slipper tanks affected performance.
COMBAT PERFORMANCE WITH 90 GALLON LONG-RANGE TANKS
50. As the Spitfire XIV has a very short range it has been assumed that when a long-range tank is to be carried, it is most likely to be the 90 gallon tank rather than the 30 gallon or 45 gallon. Pending further instructions, no drops or trials have been carried out with the 30 gallon or 45 gallon tanks. The aircraft's performance with either can be estimated from the results given below of trials with the 90 gallon long-range tank.
Drops
51. The aircraft was fitted with assistor springs as for the Spitfire IX. Two drops were made with empty tanks at 50 ft and 25,000 ft, A.S.I. 250 mph, with no trouble. Cine photographs were taken and show the tank dropping quite clear of the aircraft. Further trials would be necessary to check these results thoroughly.
Speeds
52. About 20 m.p.h. is knocked off the maximum speed and correspondingly off the speed at intermediate throttle settings. The aircraft is still faster than the FW.190 (BMW.801D) and the Me.109G above 20,000 ft.
Climb
53. Climb is most affected. With a half-full tank its maximum climb becomes identical with the Spitfire IX without the tank. Even with a full tank it can therefore climb as fast as the FW.190 or Me.109G. Its zoom climb is hardly affected.
Dive
54. So long as the tank is more than 1/3 full, the dive acceleration is similar.
Turning Circle
55. The Spitfire XIV now has a definitely wider turning circle than before, but is still within those of the FW.190 (BMW.801D) and Me.109G.
Rate of Roll
56. Similar.
Conclusions
57. Even with the 90 gallon tank, the Spitfire XIV can equal or outclass the FW.190 (BMW.801D) and the Me.109G in every respect. Its main advantages remain the tight turn and maximum climb.
Yes, just read that in The Spitfire Story; looks like Camm's low drag tanks and faired mountings worked quite well - wonder how much benefit they would have conferred on the P-51?
How much did the P-51's tanks cost in speed?
Cruise, for the Tempest Typhoon was set at 3150 rpm, and for maximum range, the best speed was 210mph IAS, and it was recommended that boost higher than +3psi should not be used, and rpm could go as low as 2000, though it might be found that the minimum needed (to keep the engine smooth) might be 2150.
I'm skeptical of such statement.
The Chief of Staff of the RAF, Marshall Portal, did not believe a single engine fighter with that sort of range could be built, thus no resources were allocated for this purpose.
If he does say that, it's rather worrying, since increasing the Spitfire's range was nothing, whatsoever, to do with the RAF; it would have involved (and did involve) the manufacturers, the Air Ministry, Local Technical Committees, and the companies' Resident Technical Officers.'A Blind Spot? The RAF and Long-Range Fighters 1936-1944' explains how he came to these conclusions and why the RAF did very little to extend the range of the Spitfire.