During my short stay in Beijing the China Aviation Museum in Datangshan was a must see. After leaving the airport and arriving at my hotel where I left my luggage I headed north. Getting to the museum is quiet easy although time consuming. By public transport take the subway line 5 all the way to Tiantongyuan North station then change to bus nr 643 where people will surely help you get out at the right stop (easier to achieve if you have a paper with the museums name written down in Chinese) . From my hotel it took me around 1,5 hour and cost 3 yuan one way. Additionally you have to walk around 10 minutes from the bus stop to the museum itself.
The first thing that grasp your sight is a collection of planes flown by Mao Zedong. Four of them. You can even enter the Ilyushin 18 for 10 yuans. From that spot you can see numerous fighters both soviet and Chinese ones. Basically wherever you look you'll see a plane and it won't be all. There is a cave part to which the entrance fee is around 20 yuans. Unluckily I was out of funds so I didn't enter. From video and photo footage I saw, it is worth going in.