T-tail

A T-tail arrangement is used in some kinds of aircraft. The horizontal tail surfaces (tailplane and elevators) are mounted at the top of the fin rather than on the fuselage at the base. There are a number of pros and cons to this arrangement.

Pros

• The tailplane surfaces are kept well out of the airflow behind the wing, giving smoother flow, more predictable design characteristics, and better pitch control.

• The effective distance between wing and tailplane can be increased without a significant increase in the weight of the aircraft. The distance between the two planes gives the "leverage" by which the tailplane can control the aircraft's pitch attitude - with a greater distance, smaller, lighter tailplanes and elevators can be used.

• The tail surfaces are mounted well out of the way of the rear fuselage, permitting this site to be used for the aircraft's engines.

Cons

• The aircraft will tend to be much more prone to a dangerous deep stall condition, where blanking of the airflow over the tailplane and elevators by a stalled wing can lead to total loss of pitch control.

• For similar reasons, T-tailed aircraft can be much more difficult to recover from a fully-developed spin.

• The fin must be made considerably stronger and stiffer to support the forces generated by the tailplane.

• The control runs to the elevators are more complex.

• The elevator surfaces are much more difficult to casually inspect from the ground.

Some aircraft feature a tailplane that is mounted part way up the fin rather than right at the top. This form of design combines some of the pros of both the T-tail and conventional arrangements, while avoiding the most serious cons.