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A T-tail is an empennage configuration in which the tailplane of an aircraft 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.[ citation needed ] Rear-mounting the engines keeps the wings clean and improves short-field performance. This was necessary in early jet aircraft with less powerful engines. [1]
T-tail aircraft can have better short-field performance, [1] such as on the Avro RJ-85. The disturbed airflow over a lower stabilizer can make control more difficult at lower speeds.[ citation needed ]
During normal flying conditions, the tailplane of a T-tail is out of the disturbed airflow behind the wing and fuselage, [1] which provides for more consistent elevator response.[ citation needed ]
The design and structure of a T-tail can be simpler. [1]
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. [2]
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. [3] [1] 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.[ citation needed ]
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. [4] [1] 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. [1] [5]
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.[ citation needed ] (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,[ citation needed ] 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.[ citation needed ]
The T-tail can often be found on military transport aircraft, such as the Airbus A400M, the Boeing C-17 Globemaster III and the Embraer C-390 Millenium. 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. It has also been used by the Embraer's Phenom 100, Phenom 300 and Legacy/Praetor business jets families.
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 stabilizer, 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 stabilizer, rudder, and the tail-plane and elevator are combined to form two diagonal surfaces in a V layout.
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 Cessna Citation X is an American mid-size business jet produced by Cessna and part of the Citation family. Announced at the October 1990 NBAA convention, the Model 750 made its maiden flight on December 21, 1993, received its type certification on June 3, 1996, and was first delivered in July 1996. The updated Citation X+ was offered from 2012 with a 14 in (360 mm) cabin stretch and upgraded systems. Keeping the Citation III fuselage cross section, it has a new 37° swept wing with an area of 527 ft² for a fast Mach 0.935 MMO and a 36,600 lb MTOW for a 3,460 nmi (6,408 km) range, a T-tail and two 7,034 lbf (31.29 kN) AE3007 turbofans. After 338 deliveries, production ended in 2018.
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.
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's pitch, and therefore the angle of attack and the lift of the wing. The elevators are usually hinged to the tailplane or horizontal stabilizer. They may be the only pitch control surface present, and are sometimes located at the front of the aircraft or integrated into a rear "all-moving tailplane", also called a slab elevator or stabilator.
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.
The empennage, also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow. The term derives from the French language verb empenner which means "to feather an arrow". Most aircraft feature an empennage incorporating vertical and horizontal stabilising surfaces which stabilise the flight dynamics of yaw and pitch, as well as housing control surfaces.
Aircraft flight mechanics are relevant to fixed wing and rotary wing (helicopters) aircraft. An aeroplane, is defined in ICAO Document 9110 as, "a power-driven heavier than air aircraft, deriving its lift chiefly from aerodynamic reactions on surface which remain fixed under given conditions of flight".
A vertical stabilizer or tail fin is the static part of the vertical tail of an aircraft. The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it. Their role is to provide control, stability and trim in yaw. It is part of the aircraft empennage, specifically of its stabilizers.
Mach tuck is an aerodynamic effect whereby the nose of an aircraft tends to pitch downward as the airflow around the wing reaches supersonic speeds. This diving tendency is also known as tuck under. The aircraft will first experience this effect at significantly below Mach 1.
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.
The cruciform tail is an aircraft empennage configuration which, when viewed from the aircraft's front or rear, looks much like a cross. The usual arrangement is to have the horizontal stabilizer intersect the vertical tail somewhere near the middle, and above the top of the fuselage. The design is often used to locate the horizontal stabilizer away from jet exhaust, propeller and wing wake, as well as to provide undisturbed airflow to the rudder.
An aircraft stabilizer is an aerodynamic surface, typically including one or more movable control surfaces, that provides longitudinal (pitch) and/or directional (yaw) stability and control. A stabilizer can feature a fixed or adjustable structure on which any movable control surfaces are hinged, or it can itself be a fully movable surface such as a stabilator. Depending on the context, "stabilizer" may sometimes describe only the front part of the overall surface.
A twin-boom aircraft has two longitudinal auxiliary booms. These may contain ancillary items such as fuel tanks and/or provide a supporting structure for other items. Typically, twin tailbooms support the tail surfaces, although on some types such as the Rutan Model 72 Grizzly the booms run forward of the wing. The twin-boom configuration is distinct from twin-fuselage designs in that it retains a central fuselage.
In aeronautics, a tailless aircraft is an aircraft with no other horizontal aerodynamic surface besides its main wing. It may still have a fuselage, vertical tail fin, and/or vertical rudder.
The Parnall Puffin was an experimental amphibious fighter-reconnaissance biplane produced in the United Kingdom just after World War I. It had several unusual features, principally a single central float and an inverted vertical stabilizer and rudder, and showed promise, but at that time no new aircraft were being ordered in numbers for the RAF and only the three Puffins of the initial order were built.
Throughout a normal flight, a pilot controls an aircraft through the use of flight controls including maintaining straight and level flight, as well as turns, climbing, and descending. Some controls, such as a "yoke" or "stick" move and adjust the control surfaces which affects the aircraft's attitude in the three axes of pitch, roll, and yaw. Other controls include those for adjusting wing characteristics and those that control the power or thrust of the propulsion systems. The loss of primary control systems in any phase of flight is an emergency. Aircraft are not designed to be flown under such circumstances; however, some pilots faced with such an emergency have had limited success flying and landing aircraft with disabled controls.
In aviation, a strake is an aerodynamic surface generally mounted on the fuselage of an aircraft to improve the flight characteristics either by controlling the airflow or by a simple stabilising effect.
A three-surface aircraft or sometimes three-lifting-surface aircraft has a foreplane, a central wing and a tailplane. The central wing surface always provides lift and is usually the largest, while the functions of the fore and aft planes may vary between types and may include lift, control and/or stability.