SH3 Air Layer

Can anyone tell me how to reduce the number of aircraft in GWX 2.1 and GWX 3?

I've made up a single mission involving the Graf Zeppelin carrier, but when ever she meets enemy ships, up to 50 German aircraft turn up. Between the ship and aircraft action it's too much for my pc and the game crashes.

Strangely, even though most of the action is between Scapa and the Shetland Isles, there's hardly a British aircraft ever seen.

50 Stuka's seems a bit excessive in that area, specially in 1942.

How do i edit the number of aircraft that turn up?

I need a lot less German and a few more British.

Or perhaps there's a way of disabling the aircraft layer so i can add an air layer for the mission myself?