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A T-tail is an empennage configuration in which the tailplane is mounted to the top of the fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs from the standard configuration in which the tailplane is mounted to the fuselage at the base of the fin.
T-tails were common in early jet aircraft. Designers were worried that an engine failure would otherwise damage the horizontal tail.
The T-tail is very common on aircraft with engines mounted in nacelles on a high-winged aircraft or on aircraft with the engines mounted on the rear of the fuselage, as it keeps the tail clear of the jet exhaust. [1] Rear-mounting the engines keeps the wings clean and improves short-field performance. This was necessary in early jet aircraft with less powerful engines. [2]
T-tail aircraft can have better short-field performance, [2] such as on the Avro RJ-85. The disturbed airflow over a lower stabilizer can make control more difficult at lower speeds. [1]
During normal flying conditions, the tailplane of a T-tail is out of the disturbed airflow behind the wing and fuselage, [2] which provides for more consistent elevator response. [3]
The design and structure of a T-tail can be simpler. [2]
For a transsonic aircraft a T-tail configuration may improve pitch control effectiveness, because the elevator is not in disturbed air behind the fuselage, particularly at moderate angles of attack.[ citation needed ]
Depending on wing location, the elevator may remain in undisturbed airflow during a stall. (However, T-tail aircraft may be vulnerable to deep stall, see Disadvantages below.)
An aircraft with a T-tail may be easier to recover from a spin, as the elevator is not in a position to block airflow over the rudder, which would make it ineffective, as can happen if the horizontal tail is directly below the fin and rudder. [4]
The T-tail increases the effectiveness of the vertical tail because of "end plate" effect. The horizontal stabilizer acts like a winglet, reducing induced drag of the rudder. [5] [2] Smaller and lighter T-tails are often used on modern gliders.
When the vertical tail is swept, the horizontal tail can be made smaller because it is further rearwards and therefore has a greater lever arm. Tail sweep may be necessary at high Mach numbers.
A T-tail may have less interference drag, such as on the Tupolev Tu-154.
T-tails may be used to increase clearance at the rear of a cargo aircraft such as the Boeing C-17 Globemaster, to provide extra clearance when loading the aircraft. [1]
The aircraft may be prone to deep stall (or super stall) at high angles of attack, when airflow over the tailplane and elevators is blanked by the wings. [6] [2] The American McDonnell F-101 Voodoo jet fighter suffered from this problem,[ citation needed ] as did the British Gloster Javelin, Hawker Siddeley Trident and BAC One-Eleven. A stick-pusher can be fitted to deal with this problem. [2] [7]
For propeller aircraft, a T-tail configuration may reduce pitch control effectiveness if the elevators are outside the propeller slipstream.[ citation needed ]
The vertical stabilizer must be made stronger (and therefore heavier) to support the weight of the tailplane. [1] (However other factors may make the T-tail smaller and lighter, see Advantages above.)
A T-tail produces a strong nose-down pitching moment in sideslip.
T-tails can cause aeroelastic flutter, as seen on the Lockheed C-141 Starlifter. The fuselage must be made stiffer to counteract this.
Many large aircraft can have the fin and rudder fold to reduce height in hangars, however this generally isn't feasible or useful if there is a T-tail.[ citation needed ]
The T-tail configuration can also cause maintenance problems. The control runs to the elevators are more complex, [1] and the surfaces are more difficult to inspect from the ground. The loss of Alaska Airlines Flight 261 was attributed to improper maintenance of the T-tail.[ citation needed ] T-tails can be harder to inspect or maintain, due to their height. [3]
The T-tail can often be found on military transport aircraft, such as the Airbus A400M and the Boeing C-17 Globemaster III. It was used in the 1950s by combat aircraft such as the Gloster Javelin, McDonnell F-101 Voodoo, and Lockheed F-104 Starfighter interceptors, and on the Blackburn Buccaneer attack aircraft.
T-tails are often used on regional airliners and business jets. In the 1960s, several passenger jets with rear-fuselage-mounted engines featured T-tails, such as the BAC One-Eleven, the Vickers VC10, the McDonnell Douglas DC-9, the Boeing 727, the Fokker F28 Fellowship, and the Russian Ilyushin Il-62 and Tupolev Tu-154. It has been used by the Gulfstream family since the Grumman Gulfstream II. It has been used by the Learjet family since their first aircraft, the Learjet 23.
In the 1970s it was used on the McDonnell Douglas MD-80, and the Russian freighter Ilyushin Il-76, as well as the twin turboprop Beechcraft Super King Air. In the 1980s it was used on the Fokker 100 and the British Aerospace 146.
In the 1990s it was used on the Fokker 70, the McDonnell Douglas MD-90, the Boeing 717, the Embraer ERJ family, and the Bombardier CRJ700 series. The single-engine turboprop Pilatus PC-12 also sports a T-tail.
T-tail is especially popular on modern gliders because of the high performance, the safety it provides from accidental spins, and the safety it provides the stabilizer and elevator from foreign object damage on take-off and landing.
A tailplane, also known as a horizontal stabiliser, is a small lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters and gyroplanes. Not all fixed-wing aircraft have tailplanes. Canards, tailless and flying wing aircraft have no separate tailplane, while in V-tail aircraft the vertical stabiliser, rudder, and the tail-plane and elevator are combined to form two diagonal surfaces in a V layout.
A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ).
Aircraft flight control surfaces are aerodynamic devices allowing a pilot to adjust and control the aircraft's flight attitude.
The V-tail or vee-tail 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 a rudder and elevator.
The Gloster Javelin is a twin-engined all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. It was a T-tailed delta-wing aircraft designed for night and all-weather operations and was the last aircraft design to bear the Gloster name. Introduced in 1956 after a lengthy development period, the aircraft received several upgrades during production to its engines, radar and weapons, including support for the De Havilland Firestreak air-to-air missile.
A stabilator is a fully movable aircraft horizontal stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements otherwise performed by the separate parts of a conventional horizontal stabilizer and elevator. Apart from reduced drag, particularly at high Mach numbers, it is a useful device for changing the aircraft balance within wide limits, and for reducing stick forces.
Atlas Air
An airplane or aeroplane, informally plane, is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for airplanes includes recreation, transportation of goods and people, military, and research. Worldwide, commercial aviation transports more than four billion passengers annually on airliners and transports more than 200 billion tonne-kilometers of cargo annually, which is less than 1% of the world's cargo movement. Most airplanes are flown by a pilot on board the aircraft, but some are designed to be remotely or computer-controlled such as drones.
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A twin tail is a type of vertical stabilizer arrangement found on the empennage of 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. This arrangement is also known as an H-tail, as it resembles a capital "H" when viewed from the rear. The twin tail was used on a wide variety of World War II multi-engine designs that saw mass production, especially on the American B-24 Liberator and B-25 Mitchell bombers, the British Avro Lancaster and Handley Page Halifax heavy bombers, and the Soviet Union's Petlyakov Pe-2 attack bomber.
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