Hello
Butcher... They are new as they can be, using loops of engine sounds found on the internet. The P40 for example is taken from a real in-cockpit youtube video of someone taking off and flying a P40. I took a small cut from this (which didn't vary too much in pitch etc) then altered the speed to try and suit AH (and a few other minor tweaks). I also found the odd sound clips of 109's, fw190, and spitfire etc (the quality varied however). I listened to loads of other clips and basically mixed/blended, (altered tones, speed, echo, reverb, equalised etc) just to get something I quite liked. The spitfire sounds are actually altered P40 internal sounds blended with slightly altered external 109 sounds. I did find a genuine in-cockpit spit sound but it sounded like a half-dozen briggs and stratten lawnmowers going full pelt in a tin shack. So they're a bit made up, but I tried to get them some where near (well for starters)
Coogan... engine sounds should be stereo (unless I missed one or two, done a lot of fiddling so may have left something mono) but the channels are mainly duplicated except on twin+ engine starts and shut-offs.