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Best "general purpose" prop fighter also capable of best high altitude performance
- Thread starter BarnOwlLover
- Start date
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Firstly what is "high altitude? In 1940 Spitfires and Hurricanes struggled to intercept at 30,000ft. By 1942 with the Ju 86 being used they had to get up to circa 42,000 . You cannot disregard the laws of physics. Spitfires modified to get to those altitudes were compromised lower down, the extended wing tips lowered rate of roll and made them float on landing, while removing the radio and armour took them back to the bi plane era.
- Thread starter
- #23
BarnOwlLover
Staff Sergeant
This goes back to the P-51H example, since it had basically a "high alt" rated engine (the V-1650-9 was a strengthened -3 with ADI, and the P-51M had the same engine without ADI). It was able to do above 400 mph at sea level but also could hit 470+ (reportedly 485+ clean in interceptor trim on WEP) at 22-25,000 ft, and have a service ceiling of over 43,000 ft. Also, the Merlin 113 powered P-51B hit 454 mph at 30K, but no info that I know of exists for speed figures below 30,000 ft.
But even the Merlin 100 "medium alt." engine was capable of pushing the same aircraft to 455 mph at 17,000 and maintained that speed until about 25K.
But even the Merlin 100 "medium alt." engine was capable of pushing the same aircraft to 455 mph at 17,000 and maintained that speed until about 25K.
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GregP
Major
I'm not too sure a 1949 P-51H would do very well in a 1944 - 1945 fight.
- Thread starter
- #25
BarnOwlLover
Staff Sergeant
Since we're talking a lot about late Mustangs here, perhaps paging drgondog for clarification? Granted, I know that he's busy with work on a YouTube video series on the P-51 and is well underway with work on the sequel to P-51B: NAA's Bastard Stepchild.
GregP
Major
Well, to give the P-51H it's due, a WWII-vintage P-5210H could very likely run with a 1949 P-51H, but I'm not too sure the people in authority would release them for 90" MAP during the war. My entire point was that the chart I posted was the operating limit at one time. As the aircraft was developed, more power was used in the same package, with rather predictable top speed effects.
Here's what happens when you don't use the engine power as you should.
View: https://youtu.be/727Q2fDVXRQ
This was at Biggin Hill in 2001 and the pilot never cracked his Allison throttle above cruise to perform a vertical maneuver. As a result, although he had PLENTY of power available, he didn't use it, fell through the low-altitude maneuver, and didn't have altitude to recover. I don't know for sure, but I'd bet he was not using more than about 43" MAP at the time, even though the P-63 was cleared for a lot more.
In the case of the P-51H, if they actually USED 90" MAP during the war, it would very certainly have been faster than the chart I posted above. It was a bit suspicious anyway since the top speed wasn't anywhere near the P-51H listed speed. But, the "listed" speed usually quoted wasn't established and published during the war. It was post-war.
Here's what happens when you don't use the engine power as you should.
View: https://youtu.be/727Q2fDVXRQ
This was at Biggin Hill in 2001 and the pilot never cracked his Allison throttle above cruise to perform a vertical maneuver. As a result, although he had PLENTY of power available, he didn't use it, fell through the low-altitude maneuver, and didn't have altitude to recover. I don't know for sure, but I'd bet he was not using more than about 43" MAP at the time, even though the P-63 was cleared for a lot more.
In the case of the P-51H, if they actually USED 90" MAP during the war, it would very certainly have been faster than the chart I posted above. It was a bit suspicious anyway since the top speed wasn't anywhere near the P-51H listed speed. But, the "listed" speed usually quoted wasn't established and published during the war. It was post-war.
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wuzak
Captain
They made P-51Hs in 1949, or merely ran tests in 1949?
- Thread starter
- #28
BarnOwlLover
Staff Sergeant
All P-51Hs were built in 1945. It took until 1946 to get the -9 Merlin to make consistent max power at 90" in WEP due to boost control system issues. Manuals cited were published in 1949-1950, when P-51Hs were being used in SAC, just before most got transferred to ANG ADF units.
NeilStirling
Airman
- 24
- Oct 6, 2006
With the end of the war the requirement for fighter aircraft using highly boosted engines came to an end. Cost of operation became more important than having a small advantage in certain situations. For example RAF Mustangs fitted with the V-1650-3 were limited to +15lbs boost and fighters coming in to service post 45 that were intended to operate at high boost didn't. Preserve the engine save money.
GregP
Major
The P-51H made WWII Wayne. I'm sure you know that. Didn't make it into combat, but made the war. Ditto the F8F.
The P-51Hs flying in 1949 were all made in 1945 since all of them were delivered by the end of Nov 1945. But they didn't necessarily approve them for high-MAP power until well after the war. I'm not exactly sure when they were approved for 90" MAP, but I am pretty sure it wasn't before the end of the war.
ThomasP
Senior Master Sergeant
The October 1945 P-51H PFOI manual (Pilot's Flight Operating Instructions for anyone not familiar with the acronym) only allows 80"Hg with ADI, or 70"Hg without. So 90"Hg probably not available before war's end.
