peckergnatflyer,
As you already know, the I4C siren has been out of production for a while and hard to find. Not only that, if you DO find one, it will be a bit pricey. My friend, I have an affordable alternative. Check out the accompanying link to J.C. Whitney. This will show you a mini battery-powered siren that is as close to perfect as can be. And it's CHEAP!!!!!!
I got one for my own Stuka and have played with it for a short while. This is what I know:
It will fit inside the bomb slung under the fuselage centerline..............just don't drop the bomb!!!
It is intended to be powered by a 12 volt battery but a standard 9 volt battery works good and it spins the siren at a slightly slower speed........not so high of a pitch.
A variable rheostat from Radio Shack can be added between the battery and the siren to adjust the pitch and the rate that it gathers its pitch. The rheostat could be controlled by a servo or a programable rheostat may be available.
Now, having said that, my Stuka is still under construction and my testing with the siren has only been done on the bench but I think this will work out just great. Good luck, Bud!!
Al
http://www.jcwhitney.com/autoparts/P...Ntt=mini+siren