T-tail

A T-tail is an empennage configuration in which the tailplane is mounted to the top of the fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs from the standard configuration in which the tailplane is mounted to the fuselage at the base of the fin.

Advantages

The tailplane is kept well out of the disturbed airflow behind the wing and fuselage, giving smoother and faster airflow over the elevators. This configuration may give more predictable design characteristics and better pitch control; but in the case of an aircraft with a tractor propeller, pitch control is reduced because the T-tail takes the control surfaces outside the propeller slipstream. Responsive pitch control is crucial for aircraft flying at low speed, to allow effective rotation on landing. deHavilland Canada's larger STOL aircraft all use a T-tail for this reason. This configuration also allows high performance aerodynamics and an excellent glide ratio as the empennage is less affected by wing and fuselage slipstream. A T-tail has a better effective aspect ratio (better lift slope), less interaction drag than a cruciform tail, and a more efficient vertical tail (the horizontal tail plate effect increases the effective aspect ratio of the fin). Therefore, the T-tail configuration is especially popular on gliders.