What are the four things an airplane needs to fly?

Answer 1

The four "Forces" interacting with an airplane in flight is Lift, Thrust, Weight, and Drag. Weight is gravity pulling the plane down. Drag is the resistance of the air wanting to slow the plane down (two parts, parasitic drag(air resistance) and induced drag(drag created by the wings creation of lift.) Thrust is what makes the plane go forward, either a jet or rocket engine produce thrust, or a propeller produces thrust through an engine producing power (to keep it simple, this is essentially the same thing, just think of a force making the plane go forward). Finally, lift, this is created by the wing, low pressure above it, and a (relative) higher pressure below it.