The dihedral shape of a paper airplane's wings and the angle of its rear elevator flaps affect how it flies. The rear elevator wings, in particular, can be adjusted to make a paper airplane lift, dive or curve to the left or right.
It's recommended that a paper airplane's wings be dihedral. This means that they have a slightly upward tilt. When viewed from the front, the wings should then resemble a slight V shape. Having dihedral wings gives the paper airplane more aerodynamic stability in flight. If the wings are flat, though, the paper airplane can't naturally stabilize itself once it is released from the hand. Because of this, paper airplanes with dihedral wings perform better flights.
Elevator flaps can also be very consequential to the performance of a paper airplane, depending on how they are designed. The elevator flaps are typically installed in the rear edges of the wings by making small parallel cuts that should be about an inch apart. The flaps can then be folded in different configurations to adjust the flight. If the flaps are folded upwards, for instance, the plane will gain altitude. Conversely, if the flaps are folded down, the plane will dive. Also, the elevator flaps can be adjusted to give the paper airplane an inclination towards a certain direction. By adding more elevator to one wing over the other, the plane will turn in its flight.