V-tail

From Wikipedia, the free encyclopedia

This article does not cite any references or sources. (December 2007)
Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed.

1950 B35 still operated by the National Test Pilot School at the Mojave Airport

The V-tail of a Belgian Air Force Fouga Magister.

An Ultraflight Lazair showing its inverted V-tail covered with translucent Tedlar

In aircraft, a V-tail (sometimes called a "butterfly tail") is an unconventional arrangement of the tail control surfaces that replaces the traditional fin and horizontal surfaces with two surfaces set in a V-shaped configuration when viewed from the front or rear of the aircraft. The rear of each surface is hinged, and these movable sections, sometimes called ruddervators, combine the tasks of the elevators and rudder. The arrangement was invented by Polish engineer Jerzy Rudlicki in 1930, and first tested on a modified Hanriot H-28 trainer in 1931.

The V-tail has not been a popular choice for aircraft manufacturers. The most popular V-tailed aircraft in mass production was the Beechcraft Bonanza Model 35, often known as the V-tail Bonanza or simply V-Tail. Other examples include the F-117 Nighthawk stealth fighter, the Fouga Magister trainer, and the RQ-1 Predator UAV. The X-shaped tail surfaces of the experimental Lockheed XFV were essentially a V tail that extended both above and below the fuselage. Over 2000 Ultraflight Lazair ultralights were produced, all featuring an inverted V-tail.

Ruddervators have also been used on some airships, such as the US Navy's N class blimps. Accurate pitch trimming of airships can be difficult and this configuration improves clearance beneath the tail.

[edit] Advantages

With fewer surfaces than a conventional tail or a T-tail, the V-tail is lighter and produces less drag. The air flowing over the tail surfaces is also likely to be less turbulent. A V-tail tends to reflect radar at an angle that reduces the return signal, making the aircraft harder to detect. This is an advantage for military aircraft.

[edit] Disadvantages

Combining the pitch and yaw controls is difficult and requires a more complex control system. The V-tail arrangement also places greater stress on the rear fuselage when pitching and yawing.

In the mid-1980s, the Federal Aviation Administration grounded the Beechcraft Bonanza due to safety concerns. While the Bonanza met the initial certification requirements, it had a history of fatal mid-air breakups during extreme stress, at a rate exceeding the accepted norm. The type was deemed airworthy and restrictions removed after Beechcraft issued a structural modification as an Airworthiness Directive.