TheV-tail orvee-tail (sometimes called abutterfly tail[1] orRudlicki's V-tail[2][citation needed]) of an aircraft is an unconventional arrangement of the tail control surfaces that replaces the traditional vertical and horizontal surfaces with two surfaces set in a V-shaped configuration. It is not widely used in aircraft design. The aft edge of each twin surface is a hinged control surface called a ruddervator, which combines the functions of both arudder andelevator.
The V-tail was invented in 1930 by Polish engineerJerzy Rudlicki[2] and was tested for the first time on aHanriot HD.28 trainer, modified byPolishaerospace manufacturerPlage and Laśkiewicz in the summer of 1931.[citation needed]
The X-shaped tail surfaces of the experimentalLockheed XFV were essentially a V tail that extended both above and below the fuselage.
The most popular conventionally V-tailed aircraft that has been mass-produced is theBeechcraft Bonanza Model 35, often known as theV-tail Bonanza or simplyV-Tail. Other examples include theLockheed F-117 Nighthawk stealth attack aircraft and theFouga CM.170 Magister trainer. TheCirrus Vision SF50 jet is a recent example of a civilian aircraft adopting the V-tail. Some gliders, like theLehtovaara PIK-16 Vasama, were designed with a V-tail, but the production Vasamas had acruciform tail.[3]
TheBlohm & Voss P 213Miniaturjäger was one of the first aircraft to have an inverted V-tail.Unmanned aerial vehicles such as theLSI Amber,General Atomics Gnat andGeneral Atomics MQ-1 Predator would later feature this type of tail. TheUltraflight Lazair ultralights, of which over 2,000 were produced, featured an inverted V-tail, which also carried the rear landing gear.[4]
Ideally, with fewer surfaces than a conventional three-aerofoil tail or aT-tail, the V-tail is lighter and has lesswetted surface area, so thus produces lessinduced andparasitic drag. However,NACA studies indicated that the V-tail surfaces must be larger than simple projection into the vertical and 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 someinterference drag.[5]
Light jet aircraft such as theCirrus Vision SF50, theEclipse 400, theSonex SubSonex or larger jet aircraft, such as theNorthrop Grumman RQ-4 Global Hawk unmanned aerial drone often have the power plant placed outside the aircraft. 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.[6]
In military aircraft, V-tails reduce the number of right angles on an aircraft, improving itsstealth characteristics.[7]
In the mid-1980s, theFederal Aviation Administration re-assessed 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 anAirworthiness Directive.[8]
V-tailed aircraft require longer rear fuselages than aircraft with conventional empennages to preventyawing.[citation needed] This tendency, called "snaking", was apparent on taking off and landing on theFouga CM.170 Magister, which has a relatively short fuselage.[citation needed]
Ruddervators are the control surfaces on an airplane with a V-tail configuration. They are located at the trailing edge of each of the twoairfoils making up the tail of the plane. The first use of ruddervators may have been on theCoandă-1910's X-tail, although there is no proof that the aircraft ever flew.[9] The laterCoandă-1911 flew with ruddervators on its X-tail.[10] LaterPolish engineerJerzy Rudlicki designed the first practical ruddervators in 1930, tested on a modifiedHanriot HD.28 trainer in 1931.
The name is aportmanteau of "rudder" and "elevator." In a conventional aircraft tail configuration, the rudder providesyaw (horizontal) control and the elevator providespitch (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.[11]
