Hi F4UDOA,
>How would you calculate that?
If you've got performance curves for a given data point, you just have to assume a reasonable propeller efficiency and then can extrapolate the data for another point in the envelope.
>That is exactly what I thought except I can't figure out why the top speed is the same when you have such a huge increase(200HP) in available HP.
The two capped pylons seem to eat up 200 HP of shaft power at top speed. If the Aces High F4U-4 is faster at the same climb than the NAVAIR F4U-4, one might guess it doesn't have the pylons.
However, the inconsistency between Aces High and NAVAIR is bigger than that. The shape of the climb graph indeed looks more like 2400 HP graph, so the lower climb rate would suggest a heavier aircraft. With 2400 HP and no pylons, you'd get the same top speed as with 2600 HP and the pylons in place. Still, you'd need a 14000 lbs Corsair to get the climb rate at 2400 HP down to Aces High level is you're using the NAVAIR document as a basis, and this seems a bit much.
>I have two other F4U charts showing climb at 60" MAP with climbs of 4,000FPM to 4,400FPM at sea level. But they all show the same top speed as the NAVAIR chart.
60" Hg should be equivalent to the 2400 HP I mentioned, so these planes probably didn't have the pylons either.
Another consideration would be that the Aces High F4U-4 could have a different propeller than the NAVAIR F4U-4 that gives less climb power, but more top-speed power. (That would imply the Aces High F4U-4 has the pylons, too.) The difference might be a bit too large to explained this way, though.
The NAVAIR document gives the propeller as 6501A-0 - do you know of any other propeller types used with the F4U-4?
Regards,
Henning (HoHun)
