Just to approach this from a different angle

I wanted to compare the AH Spitfire IX to the real life Spit IX.
The Spit IX came in three basic variants, the F, LF and HF, and with four different engines, Merlin 51, 63, 66 and 70
The first 350 planes were Fs, fitted with the Merlin 61. Then production switched, initially to Fs with 63 (another 1000 built), then the LF an HF with Merlin 66 and 70 respectiely. Fairly small numbers of the HF were built, but well over 3000 LFs.
The first problem is that AH doesn't state which Spit IX, but we can narrow it down by a process of elimination.
The AH Spit has an engine that delivers 18lb of boost. This rules out the Merlin 61 engined F, as it had a max of 15lb boost. All the others had 18lb boost, however.
Secondly, the AH Spit can carry bombs, tanks and rockets. All the Spit IXs could carry a drop tank, but none of the early F series could carry a bomb. I am almost certain the HF aircraft couldn't carry bombs either.
Thirdly the armament. The AH Spit is equipped with the E wing of 2 20mm and 2 50 cal Brownings. This narrows the aircraft down to a late model aircraft, from 1944 on. None of the aircraft being produce then had Merlin 61s.
The bombs, rockets, boost gauge and armament all show the plane isn't an early F IX. The rockets show it isn't an HF. In short, the options on the AH Spit IX show it can only be an LF IX, from 1944 on.
Now that we hae narrowed it down, we can compare performance of the AH Spit with it's real life counterpart.
Speed (in mph) at alt (in feet)
Alt AH IX RL IX RL HF
0 . 321 . 336 331
4K . 340 . 353 348
10k . 365 . 380 373
18K . 378 . 390 394
20K . 385 . 399 392
Above 20K things are almost correct, with the AH Spit being up to 5 mph too fast at around 25K for an LF, but about 5mph too slow for an HF.
Climb (in feet per min) at Altitude (in feet)
Alt AH IX RL IX RL HF
2K . 3750 4640 4470
6k . 3800 4690 4520
10K . 3850 4280 4570
15K . 3500 3860 4030
20K . 3350 3560 3500
Again above 25K the AH Spit is a bit better than RL LF, but not many combats take place up there. Again the RL HF is better than the AH model.
In summary, the Spit IX in AH is about 15mph too slow, and between 300 - 900 ft/min too slow climbing below 20,000ft. Please fix ASAP
