pumping air over wing?? So if hot/cold air is blown over the top surface of a small sized wing inflight which has a medium angle of attack, will it help in the lift or will it be a disadvantage? I can only think of two things 1) Advantage: It will reenergize the airflow and help in reducing turbulence. Higher speed of wind will decrease pressure and increase lift though temperature of hot air might render the effects of the increased lift negligible. 2) Disadvantage: It might detach the boundary layer and might increase the drag substantially. If the blow speed gets even a little bit uneven, it may destabalize the aircraft considerably. It will result in uneven distribution of lift accross the wingspan unless the air is uniformly blown all over the wing. This will result in increased stress. What do you think? If it turns out to be a disadvantage, would blowing the air under the wing instead of the top result in increased performance/lift? Also a question about winglets. Why are winglets oriented with a positive angle and not a negative one? What if one has two winglets with + and - angles? Would that help in performance especially in small aircraft?