Hi FAUDOA,
>I am just reading the chart the way it is written. The F6F MAP remains at 51.75 inches from 2K up to 15K. And the climb doesn't change 1 foot all the up.
As you can see from the standard aircraft characteristics, the F6F-5 with R-2800-10W is mostly steady for the interesting altitude range, but it's not entirely constant in its climb at MIL power.
In fact, it's very strange to see a perfectly constant climb rate from 2000 to 15000 ft as in the British chart as not only the engine's power output varies with altitude, but also the aerodynamics of a steady-state climb.
The USN values are derived from flight tests. I don't know if the same is claimed for the British numbers, but they look more like the results of a simplified calculation to me. Extrapolated from flight tests, maybe - but simplified.
>My Question would be this. The F6F chart shows an obvious improvement in SUSTAINED performance.
I don't see any improvment. The British chart shows a 2460 fpm climb rate for the F6F-5 up to 15000 ft. At 7500 ft - right in the middle of the altitude range - the American chart shows about 2450 fpm.
>I say sustained because the F4U-1 had a better initial climb in Mil power in the British test but quickly dropped off as MAP fell off.
The better initial climb resulted solely from the F4U-1 benefitting from the use of "neutral" supercharger at low altitude, which the British test denied the F6F-5. Look at the USN figures for the climb rate for a Hellcat on neutral blower - it beats the Corsair easily with 2980 versus 2550 fpm.
>If it was possible to maintain MAP all the way up and not loose climb rate why wouldn't you. It does no harm to the engine and improves sustained performance.
Maximum power at the propeller shaft is not always reached at maximum MAP as the superchargers necessary to sustain the MAP eat some power as well.
Regards,
Henning (HoHun)
