Tailless aircraft

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Tailless aircraft
DH 108 Swallow tg283.jpg

A tailless aircraft (often tail-less) has no other horizontal surface besides its main wing. All its aerodynamic control and stabilisation functions in pitch and roll are incorporated into the main wing. A 'tailless' type usually still has a vertical stabilising fin (vertical stabilizer) and control surface (rudder). However, NASA has recently adopted the 'tailless' description for the novel X-36 research aircraft which has a canard foreplane but no vertical fin.

The most successful tailless configuration has been the tailless delta, especially for combat aircraft, though the most familiar tailless delta is the Concorde airliner.

Flying wings[edit]

Main article: Flying wing

A flying wing is a tailless design which also lacks a distinct fuselage, having the pilot, engines, etc. located directly in or on the wing.

Aerodynamics[edit]

Drag[edit]

A conventional fixed-wing aircraft has a horizontal stabiliser surface separate from its main wing. This extra surface causes additional drag requiring a more powerful engine, especially at high speeds. If longitudinal (pitch) stability and control can be achieved by some other method (see below), the stabiliser can be removed and the drag reduced.

Longitudinal stability[edit]

A tailless aeroplane has no separate horizontal stabilizer. Because of this the aerodynamic center of an ordinary wing would lie ahead of the aircraft's center of gravity, creating instability in pitch. Some other method must be used to move the aerodynamic center backward and make the aircraft stable. There are two main ways for the designer to achieve this, the first being developed by the pioneer aviator J. W. Dunne.

Sweeping the wing leading edge back, either as a swept wing or delta wing, and reducing the angle of incidence of the outer wing section allows the outer wing to act like a conventional tailplane stabiliser. If this is done progressively along the span of the outer section, it is called tip washout. Dunne achieved it by giving the wing upper surface a conical curvature. In level flight the aircraft should be trimmed so that the tips do not contribute any lift: they may even need to provide a small downthrust. This reduces the overall efficiency of the wing, but for many designs - especially for high speeds - this is outweighed by the reductions in drag, weight and cost over a conventional stabiliser. The long wing span also reduces manoeuvrability, and for this reason Dunne's design was rejected by the British Army.

An alternative is to use of low or null pitching moment airfoils, seen for example in the Horten series of sailplanes and fighters. These use an unusual wing aerofoil section with reflex or reverse camber on the rear or all of the wing. With reflex camber the flatter side of the wing is on top, and the strongly curved side is on the bottom, so the front section presents a high angle of attack while the back section is more horizontal and contributes no lift, so acting like a tailplane or the washed-out tips of a swept wing. Reflex camber can be simulated by fitting large elevators to a conventional airfoil and trimming them noticeably upwards; the center of gravity must also be moved forward of the usual position. Due to the Bernoulli effect, reflex camber tends to create a small downthrust, so the angle of attack of the wing is increased to compensate. This in turn creates additional drag. This method allows a wider choice of wing planform than sweepback and washout, and designs have included straight and even circular (Arup) wings. But the drag inherent in a high angle of attack is generally regarded as making the design inefficient, and only a few production types, such as the Fauvel and Marske Aircraft series of sailplanes, have used it.

A simpler approach is to overcome the instability by locating the main weight of the aircraft a significant distance below the wing, so that gravity will tend to maintain the aircraft in a horizontal attitude and so counteract any aerodynamic instability, as in the paraglider. However in practice this is seldom sufficient to provide stability on its own, and typically is augmented by the aerodynamic techniques described. A classic example is the Rogallo wing hang glider, which uses the same sweepback, washout and conical surface as Dunne.

Stability can also be provided artificially. There is a trade-off between stability and maneuverability. A high level of maneuverability requires a low level of stability. Some modern hi-tech combat aircraft are aerodynamically unstable in pitch and rely on fly-by-wire computer control to provide stability. The Northrop B-2 Spirit flying wing is an example.

Pitch control[edit]

Many early designs failed to provide effective pitch control to compensate for the missing stabiliser. Some examples, such as Dunne's, were stable but their height could only be controlled using engine power. Others could pitch up or down sharply and uncontrollably if they were not carefully handled. These gave tailless designs a reputation for instability. It was not until the later success of the tailless delta configuration in the jet age that this reputation was shown to be undeserved.

The solution usually adopted is to provide large elevator and/or elevon surfaces on the wing trailing edge. These must generate large control forces, as their distance from the aerodynamic center is small and the moments less. Thus a tailless type may experience higher drag during manoeuvres than its conventional equivalent. The problem is less where sweepback is sharp and the distance between trailing edge and aerodynamic centre larger, as with the delta wing. The Dassault Mirage tailless delta series and its derivatives were among the most widely used combat jets. However even in the Mirage, pitch control at the high angles of attack experienced during takeoff and landing could be problematic and some later derivatives featured additional canard surfaces.

History[edit]

See also History of the flying wing

J. W. Dunne[edit]

A Burgess-Dunne biplane in the US Army of 1917.
Main article: John William Dunne

Between 1905 and 1913, the British Army Officer and engineer J. W. Dunne developed a series of tailless aircraft characterised by swept wings with a conical upper surface.

Although originally conceived as a monoplane design, most of Dunne's designs were required by his superior officer Col. Capper to be biplanes, typically featuring a fuselage nacelle between the planes with rear-mounted 'pusher' propeller and twin fins between each pair of wing tips. His D.6 monoplane of 1910 was a pusher type high-wing monoplane which featured turned-down wingtips with pronounced wash-out. Control surfaces on the trailing edge of each wing tip acted together as combined ailerons and elevators.

In his book An Experiment with Time Dunne claims that one of these, the D.5, was the first aeroplane ever to achieve natural stability in flight. Certainly, Dunne designed the first practical tailless aeroplanes. The British Army eventually rejected Dunne's design for a bomber because its high stability meant that it lacked the required manoeuvrability.

Dunne gave some help initially to Geoffrey T. R. Hill who produced the Pterodactyl series of tailless aircraft from 1920s onwards which were specifically designed to reduce the likelihood of stalling and spinning.

Many of Dunne's ideas on stability remain valid, and he is known to have influenced later designers such as John K. Northrop (father of the Northrop Grumman B-2 Spirit stealth bomber).

Inter-war and WWII[edit]

Lippisch deltas

The German designer Alexander Lippisch produced the first tailless delta design, the Delta I, in 1931. He went on to build a series of ever-more sophisticated designs, and at the end of the Second World War was taken to America to continue his work.

Messerschmitt Me 163 Komet

During the Second World War, Lippisch worked for the German designer Willy Messerschmitt on the first tailless aircraft to go into production, the Me 163 Komet. It was the only rocket-powered interceptor ever to be placed in front-line service, and was the fastest aircraft to reach operational service during the war. Its rocket propulsion system was highly unsafe, especially the early versions, due to the hypergolic nature of the fuel and oxidizer combination used for its powerplant. Landing was hazardous not only because the Komet had no main wheel units following its normal rocket-powered "sharp start" take off, jettisoning its twin-wheeled "dolly" during the takeoff run, but because sparks from the metal landing skid often flew up and ignited fuel vapours escaping from the propulsion system. More pilots were killed in takeoff and landing incidents than in combat.

Northrop

In the USA, jack Northrop was developing his own ideas on tailless designs. The N-1M flew in 1941 and a succession of tailless types followed, some of them true flying wings.

Postwar[edit]

de Havilland DH 108 Swallow

In the 1940s, the British aircraft designer John Carver Meadows Frost developed the tailless jet-powered research aircraft called the de Havilland DH.108 Swallow. Built using the forward fuselage of the de Havilland Vampire jet fighter. One of these was possibly one of the first aircraft ever to break the sound barrier - it did so during a shallow dive, and the sonic boom was heard by several witnesses. All three built were lost in fatal crashes.

Northrop X-4 Bantam

Similar to the D.H. 108, the twin-jet powered 1948-vintage Northrop X-4 was one of the series of postwar X-planes experimental aircraft developed in the United States after World War II to fly in research programs exploring the challenges of high-speed transonic flight and beyond. It had aerodynamic problems similar to those of the D.H.108, but both X-4 examples built survived their flight test programs without serious incidents through some 80 total research flights from 1950-1953, only reaching top speeds of 640 mph (1,035 km/h).

Dassault Mirage

The French Mirage series of supersonic jet fighters were an example of the tailless delta configuration, and became one of the most widely produced of all Western jet aircraft. By contrast the Soviet Union's equivalent widely produced delta-winged fighter, the Mikoyan-Gurevich MiG-21, does have a tail stabiliser.

Convair F2Y Sea Dart

In the 1950s, the Convair F2Y Sea Dart prototype became the only seaplane ever to exceed the speed of sound. Convair built several other successful tailless delta types.

Supersonic airliners

The Anglo-French Concorde Supersonic transport and its Soviet counterpart the Tupolev Tu-144 were tailless supersonic jet airliners, with gracefully curved ogival delta wings. The grace and beauty of these aircraft in flight were often remarked upon.[1]

Lockheed SR-71 Blackbird

The American Lockheed SR-71 Blackbird reconnaissance aircraft was the fastest jet powered aircraft at the time it was retired, achieving speeds above Mach 3.

List of tailless aircraft[edit]

Type Country Date Role Status Description
Aériane Swift Glider Foot-launched
Aerospatiale-BAC Concorde SST
AeroVironment Wasp III unmanned aircraft
Akaflieg SB13 1988
Arup S-1 1932 Rounded "heel wing"
Arup S-2 1933 Rounded "heel wing"
Arup S-3 1934 Rounded "heel wing"
Arup S-4 1935 Rounded "heel wing"
Avro 707 1949 Experimental research for Avro Vulcan thick delta wing, 1/3 scale of Vulcan
Avro CF-105 Arrow Canada 1958 Interceptor Prototypes Supersonic jet. Five completed.
Avro Vulcan United Kingdom 1952 Bomber Production Subsonic jet.
BAC 221 United Kingdom 1964 Experimental Prototype Ogee wing. Modified version of the Fairey Delta 2.
Baynes Bat 1943
Boulton Paul P.111 Experimental delta wing
Brochocki BKB-1
Convair XF-92A USA 1948 Interceptor Prototype
Convair F2Y Sea Dart
Convair F-102 Delta Dagger USA 1953 Interceptor Production Supersonic jet.
Convair F-106 Delta Dart USA 1956 Fighter Production Supersonic jet.
Convair B-58 Hustler USA 1956 Bomber Production Supersonic jet.
Dassault MD 550 Mystère-Delta France 1955 Interceptor Prototype In modified form renamed the Mirage I.
Dassault Mirage III France 1956 Interceptor Production Supersonic jet. Many derivatives.
de Havilland DH.108 Swallow
DINFIA IA 38 Argentina 1960 Transport Prototype Designed by Reimar Horten.
Douglas F4D Skyray USA 1951
Dunne 1907-1913 Several types
Fairey Delta 2 United Kingdom 1954 Experimental Prototype 2 built. First aircraft to exceed 1,000 miles per hour. Later modified as the BAC 221.
Fauvel AV.36 and others by Charles Fauvel [2]
General Aircraft GAL.56 1944 Glider Prototype
General Dynamics F-16XL Experimental Prototype delta wing
Granger Archaeopteryx
Haig Minibat
HAL Tejas India
Handley Page HP.75 Manx 1943 pusher design
Handley Page HP.115 1961 Experimental Prototype sharply swept delta wing
Hoffman tailless Arup-type "heel wing"
I.Ae. 34 Clen Antú Argentina 1949 Glider Designed by Reimar Horten and manufactured by the FMA.
I.Ae. 41 Urubú Argentina Glider Designed by Reimar Horten in Argentina.
Interstate XBDR
Kalinin K-12 USSR 1936 [3]
Kasper Bekas
Kollman Composites Raptor [4]
Lippisch delta Experimental Prototype Several types
Lockheed A-12 USA 1962 Reconnaissance Production Mach 3 capability. Long forward-fuselage chines. Several derivatives, especially the SR-71 Blackbird.
Marske Monarch
Marske Pioneer
Marske XM-1
Messerschmitt Me 163 Komet Germany Interceptor Production Rocket powered, swept wing.
Mitchell U-2 Superwing 1977
John K. Moody/Larry Mauro Easy Riser [5][6]
Northrop X-4 Bantam 1948 Fighter Prototype
University of Pretoria Exulans Glider Prototype Stromburg wing.[7][8]
Saab 35 Draken Sweden 1955 Fighter Production Supersonic jet. Double-delta planform.
Short SB.1 Glider Prototype aero-isoclinic wing test vehicle.
Short SB.4 Sherpa Glider Prototype aero-isoclinic wing test vehicle.
Tupolev Tu-144 SST
Vought F7U Cutlass USA 1948
Westland-Hill Pterodactyl 1920s-1930s Series of types
Weltensegler 1921 Glider
X-44 MANTA

See also[edit]

References[edit]

Inline citations[edit]

General references[edit]

External links[edit]