Couple of things u should know. I can give u the source's for just about 90% of my sounds. Most of my sounds come from live recordings within the cockpit. P38, P51, B17, 109, F4F, FM2, F4U, F6F, Zeke, B25, C47, Spits, Camel, DR1, DVII, B26 and a few others are live recordings. Holding the CD's here in my hand as I type. Other sources are from other games like FSX, WWIIO, etc.. I spent 4-5 months making all the sounds I have. That is alot of work, especially when u have a wife and 2 kids that I took time away from.
2nd thing u should know is you should ask the people u are using their sounds before had. Get there permission. HTC asked me if they could use my camel sound before they made it the default sound. They may have even used the DVII sound to, can't remember. And yes I gave them the permission. I personally wouldn't mind if they asked for more. I always help them out anyway I can.
For future reference, Ask before u take.