I get 15 - 20 consistantly. It's not that hard to fly with those numbers.
If I look up through my P-51s bubble canopy, I get about 40 FPS (just looking at clear blue sky, no canopy rails, etc.)
In the smoke, I drop to about 9 or 10.
Now I know it is my system. It's time to upgrade. PII 300MHz with 64M RAM. I have a good video board (Radeon 64DDR video)
If your FPS is too low, it's time to look into an upgrade. Can't keep cool games like Aces from improving just because some people don't want to buy a new CPU.