quality:correction
Empennage and foreplane

The classic airfoil section wing is unstable in flight. Flexible-wing planes often rely on an anchor line or the weight of a pilot hanging beneath to maintain the correct attitude. Some free-flying types use an adapted airfoil that is stable, or other mechanisms including electronic artificial stability.

In order to achieve trim, stability, and control, most fixed-wing types have an empennage comprising a fin and rudder that act horizontally, and a tailplane and elevator that act vertically. This is so common that it is known as the conventional layout. Sometimes two or more fins are spaced out along the tailplane.

Some types have a horizontal " canard " foreplane ahead of the main wing, instead of behind it. This foreplane may contribute to the trim, stability or control of the aircraft, or to several of these.