For reference throughout this post I have used the following test report as the basis for my conclusions:
After a rather heated discussion regarding P-47D performance on the warclouds forums ( http://www.war-clouds.com/modules.php?name=Forums&file=...topic&t=1915&start =0 ), I felt moved to conduct some testing, and have concluded that the P-47D's altitude performance with regard to top speed is somewhat excessive. The same may also be said of its low level speed performance.
Most glaring as regards kinematic performance however would appear to be a considerable error in its rate of climb, though I have yet to conduct tests.
In addition, the P-47D does not appear to suffer from any form of overheating at altitude, which would appear to be historically inaccurate based upon the following, taken from the Recommendations section of the report:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">It is recommended that pilots using these higher powers be cautioned concerning the high cylinder head temperatures and carburetor air temperatures which may be encountered in extended climbs or level flight. </div></BLOCKQUOTE>
Irrespective of the accuracy or otherwise of actual overheating, it would appear that overheating is used in general within the sim as a device to prevent players from greatly exceeding various engine limitations (such for example as the 5 minute limitation for +25 psi operations of the Mustang III, or 67"Hg operations of the P-51B-D) despite the fact that test documentation would suggest that overheating would not in fact limit performance at high speed (see http://www.wwiiaircraftperformance.o...51h-64161.html , which cites average radiator openings of 8" corrected to give performance equivalent to a flush radiator [7¼" opening], and http://www.wwiiaircraftperformance.o...ang/tk589.html which cites a radiator adjustment to 8½" opening to provide adequate cooling at +25 psi, thus suggesting that normal engine temperatures should in fact be provided by the AUTOMATIC radiator setting in level flight even at high powers)
As such, the P-47 appears to be something of an anomaly, which it would be nice to see corrected.
IL2 Compare for v4.07 has been used as the source of performance graphs for convenience. However, tracks taken in v4.08 will be supplied to support the IL2C data.
Without further ado, here is the data:
Speed vs manifold pressure and altitude (in game via IL2C with R/L overlaid):
Climb rate vs manifold pressure and altitude (in game via IL2C with R/L overlaid):
Very long track of the P-47D being flown at 110% power with WEP until the water runs out, and then at 110% power without WEP until the fuel runs out at altitude (also demonstrates top speed capability in agreement with IL2C):
Note when viewing the above that water injection should in fact only be available for a total of 11 minutes of continuous use, at least in those blocks of P-47D fitted with 15 U.S. Gallon water tanks. See:
*edit* JtD has updated his work, and has therefore asked me to remove his earlier test data to avoid confusion.