"AIP" is an interesting term, as it does not appear to include electric batteries nor nuclear power - both clearly also "air-independent" systems - but seems instead to be getting at combustion-engine systems in which both fuel and the oxidizer for it are (more or less) efficiently carried onboard. To that extent, I read about (at least) one very early sub - perhaps by Simon Lake (IIRC), or one of his ilk - which aspirated a gasoline engine with straight, compressed air. The endurance, of course, was pathetic. Seems also like today, liquid-fuel rocket engines - burning hydrazine and liquid oxygen - should work equally well underwater, but are no doubt much more dangerous for any sustained operations.
Again, Gus, my ISP problem is fixed, so send any more pics (and gimme some more writeup to go with 'em) anytime, buddy.
And that's great news indeed, about Orlando in 2012 - two years: just about enough time, with any luck, for Matt Stein Models to get back on track with some new releases!