Above 25k ft, the F4U-1 performance drops dramatically. I think that while the Bf-109 may be slightly slower at these altitudes, its superior rate of climb, and probably maneuverability, was sufficient to neutralize any advantage the F4U-1 would have. I am sure some of our German experts could make a more intelligent argument.
A high altitude supercharger was developed, but was not available until mid '44, and was installed in the dash 4. As for a turbo supercharger, the tight cowl and slender fuselage would make an installation dicey (compare with the large fuselage of the P-47).
The F4U was not cleanest of aircraft. It was slightly cleaner than the P-47, however. I have created a variable to compare the aerodynamic efficiency of aircraft at sea level. This is system efficiency since some aircraft generate thrust from their radiators and some from the exhaust. Here are some comparisons. These numbers are mph/hp at SL.
P-51B (-7 engine) .24
P-51D .23
Spitfire Mk XIV .22
Fw-190D-9 .22
Fw-190A-5 .21
Ta-152H-1 .18
F4U-1 .162
P-47D-25 .156
F4U-4 .153
P-38J .13
See above regarding engines for higher altitudes.
A lighter, land based, F4U-1 would have improved climb however speed would probably not have been impacted by more than a couple of miles per hour. If you could give me an estimated weight savings for the land based versions, I could estimate impact to airspeed and climb.
It should be noted that in the Fighter Conference, the P-51 was selected as the second best fighter above 25k, behind the P-47, and second the below 25k, behind the F8F, in both cases ahead of the F4U-1, greatly ahead above 25k, only slightly ahead below 25k (insignificantly so). I believe this is one of the indications of how great the P-51 design was. While not overpowering at all altitudes (it definitely was above 25k until the latter part of '44), it was very formidable from 35k to SL.
In the Soccer War, I believe Soto (?)was a pretty good stick. Also, he was flying an F4U-4 against P-51Ds, not the more equivalent P-51H. However, I agree with your final selection and would hope engine development could get me that -18W engine a lot earlier. And if they could just have squeezed that -57 engine in …….