Longest and smoothes possible. that is either asphalt or concrete. Golf green quality grass is also ideal. The main thing is that the plane can easily roll ont he surface. Obvioulsy the farmer's feild, although harvested, will not be smooth / flat enough. A typical lawn might be / is for the larger planes..

As for yours, you want eh smoothes and flatest as possible, because of eh plane's size. Whell can get hung-up pretty fast in long-ish grass.

And just because we say asphalt or concrete, that dosen't directly mean that the street outside your house is suitable.. far from it! ditto with school yards and shopping centers!!

Head out to the local feild, and see what they are flying from..