WWII Aircraft Performance
Mustang Mk.III FA.953 with V-1650-3 at 67" boost and 9,200 lbs.=450 mph./28,000 ft. I believe 5-10 mph. more at 72" and 75" is not unreasonable. There is another test showing 455 mph. with a Merlin 100, but I do not know if this engine was ever used in a production /QUOTE]
Must have been a top 1% aircraft as the USAAF tested the P-51B at 67" with a top speed of 442 mph. At 75" the P-51B with -7 engine did 444 mph.
http://www.wwiiaircraftperformance.org/mustang/p-51b-24771-level-blue.jpg
Hi Dave:
I may have missed something in the flow of the thread, however, please note the following - which might hopefully clarify things a bit:
P-51B with V-1650-3 - 450 mph at 28,000 ft. (67" Hg.)
P-51B with V-1650-7 - 442 mph at 24,500 ft. (67" Hg.)
Those P-51Bs equipped with a V-1650-3 had a higher FTH than those P-51Bs equipped with the V-1650-7 and, everything else being equal, were thus faster.
That said, Wright Field tests of
P-51B-5 43-6883 equipped with V-1650-3 obtained 442 mph at 29,400 (67" Hg.) as you noted, however, of interest is that
P-51B 43-12093 obtained 441 mph at 29,800 ft. while only operating at 60.5 in. Hg.. As CORSNING noted, A. .A.E.E. tests of
Mustang III FX.953 with V-1650-3 obtained 450 mph at 28,000 ft. It's probably not a coincidence that the
Mustang III data card and the test results of
FX.953 are in agreement. Please note also the Navy tests of
P-51B No. 37050 equipped with V-1650-3, which obtained 450 mph at 29,000 ft. operating at 67" Hg. which is in close agreement with the A. A.E.E. trials.
Also for purposes of placing these test results in context the following taken from the report on
FX.953 is of interest:
5.2 The following table gives comparison of the performance results with those obtained on a Mustang III by North American Inc. (Report No.NA.5798). The combat climbs and all-out level speeds were made by the firm with the boost control adjusted to give a maximum of 61" of mercury. For comparison, the corresponding results determined at this Establishment are quoted for this value of the manifold pressure.
The actual take-off weights on test were 9200 lb. (A. A.E.E.) and 8460 lb. (NA) but the N.A. results below have been corrected to 9200 lb.
There is fairly good agreement between level speed results, the N.A. Report being 2 to 4% optimistic compared with the present results. On the climb the maximum difference is 8% although on the whole the agreement is quite reasonable.