Twin tail

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A twin tail is a specific type of vertical stabilizer arrangement found on some aircraft. Two vertical stabilizers — often smaller on their own than a single conventional tail would be — are mounted at the outside of the aircraft's horizontal stabilizer. Separating the control surfaces allows for additional rudder area or vertical surface without requiring a massive single tail. On multi-engine propeller designs twin fin and rudders operating in the propeller slipstream give greater rudder authority and improved control at low airspeeds, and when taxiing. A twin tail can also simplify hangar requirements, give dorsal gunners enhanced firing area, and in some cases reduce the aircraft's weight. It also affords a degree of redundancy - if one tail is damaged, the other may remain functional.

Many canard aircraft designs incorporate twin tails on the tips of the main wing. Very occasionally, three or more tails are used, as on the Lockheed Constellation and Boeing 314 Clipper. A very unusual design can be seen on the E-2 Hawkeye, which has two additional vertical tails fixed to the horizontal stabilizer between the normal vertical twin-tail surfaces. This arrangement was chosen for the stringent size limitations of carrier-based aircraft.

Significant aircraft with twin tails include the B-24 Liberator, Avro Lancaster, and P-38 Lightning. The arrangement is not limited to World War II-vintage aircraft, however. Many fighter aircraft, like the F-15 Eagle and Sukhoi Su-27, make use of twin tail configurations, as do civilian designs like the Antonov An-225 and Burt Rutan’s Long-EZ and SpaceShipOne.