Juzz stated:
"From a standing start on the runway, the Me 109G-10 IS the fastest to 5,000ft with 50% fuel and 1x20mm"
Juzz, I tested the G10 first with 1 30mm plus the 2 mgs and then with 1 20mm and the 2 mgs. I did not carry the gondola. There was no difference in climbrate. Perhaps it's due to the additional 20mm ammo? I dunno.
Anyway, here is the answer. BTW, each time was arrived at by using an inexpensive stop watch. Tests were repeated and I took the mode as the correct answer.
Test parameters: 50% fuel, lightest possible gun loadout. For the p38, that's 800 rounds of 50 cal rather than 2000 rounds.
5k 10k 15k 20k
p38 1:22 2:41 4:07 5:46
g10 1:24 2:29 3:41 4:59
la5 1:25 2:47 4:25 6:13
yak 1:36 3:01 4:33 6:17
All planes were under wep (except the yak).
So, the P38 beats all planes to 5k and the G10 beats everything to 10k, 15k, 20k and 25k.
The N1K while speedy, lags considerably behind the above rockets.

Of interest -- the Spit9 beats all planes (except the g10) from 10k to 15k. As I recall, it took the g10 1:12 seconds to get from 10 to 15k; it takes the spit9 1:19 seconds.
AKcurly