Paper airplanes don't generate lift in the same way as full-sized aircraft. In a full-size airplane, the wings are curved and shaped in order or deflect air downward and to create a low pressure zone above the wing. In a paper airplane, the airfoil is flat or mostly flat, and the lift is created because the air is deflected downwards. Newton's law: the action of deflecting air downwards pushes the wing upwards. However, this creates a lot of induced drag, which is why paper airplane wings are so inefficient compared to full-scale airplane wings.