Depends on what performance you are looking for. I have a 47 inch superextra and it came in at 16 oz ready to fly. I am using a hacker A20-20L and a 2100 mah 3 cell lipo battery. The flight performance is unbelievable. It will hover at about 1/4 throttle and has ballistic verticle performance. I am using an APC 10x4.7 slow fly prop. I would have to say that this motor combo would work with an airframe up to 25 oz and still have outstanding performance. If you log onto hacker motors website they have recommendations that they can offer for the size and weight of the airframe. I would recommend this set up to anyone. I have had zero concerns and my flighttimes are 18 minutes on one charge. Of course I do not use full throttle very much so that helps. Since your airframe will be larger and most likely heavier you might want to go with a little more powerful set up. You can always throttle back!!!!