There is a superb aviation museum at the military base at Kbely and across the road from this is a grass airfield where there was a big club with a lot of aircraft to fly. I havent been there for quite a few years, but I understand its all still there. I was even able to get there on the bus from Prague city center for not much.
I seem to remember that Kbley is on the opposite side of the city to the main airfield.