V-tail
Overview
 
In aircraft, a V-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 elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...

s and rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

.
The V-tail, invented and patented in 1930 by Polish engineer Jerzy Rudlicki
Jerzy Rudlicki
Rudlicki Jerzy was a Polish aerospace engineer who invented and in 1930 patented the V-tail configuration for aircraft combining the ailerons and elevators in one system. He both worked in the World War I and World War II on aircraft...

, has not been a popular choice for aircraft manufacturers.
Encyclopedia
In aircraft, a V-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 elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...

s and rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

.

Design use

The V-tail, invented and patented in 1930 by Polish engineer Jerzy Rudlicki
Jerzy Rudlicki
Rudlicki Jerzy was a Polish aerospace engineer who invented and in 1930 patented the V-tail configuration for aircraft combining the ailerons and elevators in one system. He both worked in the World War I and World War II on aircraft...

, has not been a popular choice for aircraft manufacturers. The most popular V-tailed aircraft in mass production was the Beechcraft Bonanza
Beechcraft Bonanza
The Beechcraft Bonanza is an American general aviation aircraft introduced in 1947 by The Beech Aircraft Corporation of Wichita, Kansas. , it is still being produced by Hawker Beechcraft, and has been in continuous production longer than any other airplane in history...

 Model 35, often known as the V-tail Bonanza or simply V-Tail. Other examples include the F-117 Nighthawk
F-117 Nighthawk
The Lockheed F-117 Nighthawk was a single-seat, twin-engine stealth ground-attack aircraft formerly operated by the United States Air Force . The F-117A's first flight was in 1981, and it achieved initial operating capability status in October 1983...

 stealth fighter, the Fouga Magister
Fouga Magister
The Fouga Magister is a 1950s French two-seat jet trainer. The related CM.175 Zéphyr was a carrier-capable version for the French Navy....

 trainer, and the MQ-1 Predator UAV
Unmanned aerial vehicle
An unmanned aerial vehicle , also known as a unmanned aircraft system , remotely piloted aircraft or unmanned aircraft, is a machine which functions either by the remote control of a navigator or pilot or autonomously, that is, as a self-directing entity...

. The X-shaped tail surfaces of the experimental Lockheed XFV
Lockheed XFV
-See also:-References:NotesCitationsBibliography* Allen, Francis J. "Bolt upright: Convair's and Lockheed's VTOL fighters". Air Enthusiast , Volume 127, January/February 2007, pp. 13–20. ISSN 0143-5450....

 were essentially a V tail that extended both above and below the fuselage. Over 2000 Ultraflight Lazair
Ultraflight Lazair
The Ultraflight Lazair is a family of Canadian designed and built twin-engine ultralight aircraft that were sold in kit form between 1979 and 1984....

 ultralights were produced, all featuring an inverted V-tail.

Advantages

Ideally, with fewer surfaces than a conventional three-aerofoil tail or a T-tail
T-tail
thumb|right|Grob motor gliderA T-tail is an aircraft tail stabilizer configuration in which the horizontal surfaces are mounted to the top of the vertical stabilizer. Traditionally, the horizontal control surfaces are mounted to the fuselage at the base of the vertical stabilizer...

, the V-tail is lighter, has less wetted surface area, and thus produces less drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

. However, NACA
NACA
- Organizations :* National Advisory Committee for Aeronautics, the forerunner of the U.S. federal agency NASA* National Association for Campus Activities, an organization for programmers of university and college activities...

 studies indicated that the V-tail surfaces must be larger than simple projection into the vertical & horizontal planes would suggest, such that total wetted area is roughly constant; reduction of intersection surfaces from three to two, does, however, produce a net reduction in drag through elimination of some interference drag.

In modern day, light jet general aviation aircraft such as the Cirrus Jet, Eclipse 400
Eclipse 400
The Eclipse 400 is a single engine very light jet that was designed by Eclipse Aviation, producer of the Eclipse 500.The Eclipse 400 was cancelled when the company went bankrupt in 2008 and development has not been pursued by Eclipse Aerospace, the company that bought Eclipse Aviation's...

 or the unmanned aerial drone Global Hawk often have the power plant placed outside the aircraft to protect the passengers and make certification easier. In such cases V-tails are used to avoid placing the vertical stabilizer in the exhaust of the engine, which would disrupt the flow of the exhaust reducing thrust, and increasing wear on the stabilizer, possibly leading to damage over time.

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
Federal Aviation Administration
The Federal Aviation Administration is the national aviation authority of the United States. An agency of the United States Department of Transportation, it has authority to regulate and oversee all aspects of civil aviation in the U.S...

 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
Airworthiness Directive
An Airworthiness Directive is a notification to owners and operators of certified aircraft that a known safety deficiency with a particular model of aircraft, engine, avionics or other system exists and must be corrected....

.

Ruddervators

Ruddervators are the control surfaces on an airplane with a V-tail configuration. They are located at the trailing edge of each of the two airfoils making up the tail of the plane. The first use of ruddervators may have been on the Coandă-1910
Coanda-1910
The Coandă-1910, designed by Romanian inventor Henri Coandă, was the first full-size attempt at a jet aircraft. Built as a sesquiplane, it featured an experimental aircraft engine which Coandă called the "turbo-propulseur," a centrifugal compressor propulsion system with a multi-bladed rotary fan...

's X-tail, although there is no proof that the aircraft ever flew. The later Coandă-1911 flew with ruddervators on its X-tail. Later Polish
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

 engineer Jerzy Rudlicki
Jerzy Rudlicki
Rudlicki Jerzy was a Polish aerospace engineer who invented and in 1930 patented the V-tail configuration for aircraft combining the ailerons and elevators in one system. He both worked in the World War I and World War II on aircraft...

 designed the first practical ruddervators in 1930, tested on a modified Hanriot H-28 trainer in 1931.

The name is a portmanteau of the words rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

 and elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...

. In a conventional aircraft tail configuration, the rudder provides yaw (horizontal) control and the elevator provides pitch (vertical) control.

Ruddervators provide the same control effect as conventional control surfaces, but through a more complex control system that actuates the control surfaces in unison. Yaw moving the nose to the left is produced on an upright V tail by moving the pedals left which deflects the left-hand ruddervator down and left and the right-hand ruddervator up and left. The opposite produces yaw to the right. Pitch nose up is produced by moving the control column or stick back which deflects the left-hand ruddervator up and right and the right-hand ruddervator up and left. Pitch nose down is produced by moving the control column or stick forward which induces the opposite ruddervator movements.

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.

External links

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