Tailless aircraft

From Wikipedia, the free encyclopedia

The DH108 Swallow
The DH108 Swallow

A tailless aircraft (often tail-less) traditionally has all its horizontal control surfaces on its main wing surface. It has no horizontal stabilizer - either tailplane or canard foreplane (nor does it have a second wing in tandem arrangement). 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.

Contents

[edit] Longitudinal stability

A tailless aeroplane has no horizontal stabiliser at the rear of the fuselage or canard wing at the front. It is still possible for it to be stable in pitch. There are two ways for the designer to achieve this:

  • Use a wing aerofoil section with reflex camber; also known as reverse camber. (With reflex camber, the flatter side of the wing is on top, and the strongly cambered side is on the bottom. Alternatively, reflex camber can be simulated by trimming the elevators noticeably upwards.)
  • Sweep the wings back, and reduce the angle of incidence of the outer wing section so that it acts rather like a conventional tailplane stabiliser. If this is done progressively along the span of the outer section, it is called tip washout.

Without adequate reflex camber, or wing sweep-back, a tailless aircraft is longitudinally unstable, regardless of how far forward the center of gravity is located.

Many early designs failed to provide effective pitch control to compensate for the missing stabiliser. As a result, these aircraft could pitch up or down sharply and uncontrollably if they were not carefully handled. These gave tailless designs a reputation for instability. The original Dunne biplanes and the later success of the tailless delta configuration show that the problem was due to inadequate design, rather than any problem inherent to the tailless configuration.

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 longitudinally unstable and rely on fly-by-wire computer control to provide the pilot with adequate stability. The Northrop B-2 Spirit tailless aircraft is an example.

[edit] Flying wings

Main article: Flying wing

Flying wings are tailless designs which also lack a distinct fuselage, having the pilot, engines, etc. located directly in or on the wing.

[edit] Notable examples

The examples given here are in historical order.

[edit] J. W. Dunne

A Dunne type biplane in the US Army of 1917.
A Dunne type biplane in the US Army of 1917.

During and shortly after the First World War, the English engineer J. W. Dunne developed a series of tailless aircraft characterised by having swept wings. In his book An Experiment with Time he claims that one of these was the first aeroplane ever to achieve natural stability in flight. Certainly, Dunne designed the first practical tailless aeroplanes. Few records of these aircraft remain.

Most of Dunne's designs were biplanes, typically featuring a fuselage nacelle between the planes, with rear-mounted 'pusher' propeller, and twin rudders between each pair of wing tips.

The D.6 monoplane of 1910 was a pusher type high-wing monoplane which featured turned-down wingtips with pronounced wash-out.

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 B-2 spirit stealth bomber).

[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 after the Second World War went to America to continue his work.

[edit] 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 a rocket-powered interceptor, and was the fastest aircraft to reach operational service during the war. Its rocket propulsion system was highly unsafe, especially the early versions. Landing was hazardous not only because the Komet had no wheels, 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.

[edit] De Havilland DH 108 Swallow

In the 1940s, the English designer Geoffrey de Havilland made a few examples of a tailless jet-powered research aircraft called the DH108 Swallow, based on the forward fuselage of the de Havilland Vampire jet fighter. One of these was 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.

[edit] 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.

[edit] 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.

[edit] Supersonic airliners

The Anglo-French Concorde SST 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.

[edit] Lockheed SR-71 Blackbird

The American Lockheed SR-71 Blackbird reconnaissance aircraft was the fastest known operational aircraft, achieving speeds above Mach 3.

[edit] Northrop B-2 Spirit

The most recent tailless type to see operational service is the Northrop B-2 Spirit flying wing. It is unstable in flight and has artificial stability provided by a fly-by-wire system.

[edit] Other tailless aircraft

[edit] See also

[edit] External links