Delta wing

The Avro Vulcan has a delta wing with a double-bent leading edge

As delta wings are wings of an aircraft with a triangular designated form. In addition, aircraft with such wings are also referred to as delta wing aircraft . The name was introduced by Alexander Lippisch , who realized a flying wing with a relatively high aspect ratio , considerable taper and straight trailing edge in his "Delta 1" . The DM-1 test glider was created in order to later test the properties of a delta wing with a considerably lower aspect ratio . This was brought to the USA after the end of the war and extensively tested in the wind tunnel. The Convair XF-92 experimental jet fighter was developed from the knowledge gained . Lippisch is generally regarded as the father of the delta wing, although Boris Iwanowitsch Tscheranowski was researching aircraft with delta wings in the Soviet Union at about the same time and successfully made them fly (e.g. BITsch-7 ).

Delta wings are used in supersonic aircraft, including fighters and horizontally landing spaceships.

The Convair F-106 has a delta wing with a straight leading edge

Schematic representation of the vortex formation on the delta wing at an angle of attack of 15 °. The blue arrow shows the direction of flow.

Delta wings with a low aspect ratio receive additional lift at high angles of attack due to two stable eddies that form along the two leading edges. In the process, the flow is partially detached from the surface. The air in the flow is accelerated by the vortices. The surface is attracted by the resulting negative pressure. Above each wing half, the air flows in a vortex, turning inwards.

particularities

Double delta

In contrast to conventional wing geometries (such as rectangular wings, elliptical wings or trapezoidal wings), delta wings on aircraft have the shape of a triangle and thus the Greek capital letter delta (Δ). In relation to their wingspan and depth, they have a relatively small profile thickness .

The absence of a complete stall represents a special safety aspect. The decrease in airspeed due to a high angle of attack only leads to a steeper sagging and a higher angle of attack in a delta aircraft. As a result, this can be compensated for with sufficient thrust and the aircraft can return to a normal flight position, e.g. B. transfer a straight flight.

Delta wings allow a high level of lift in the short term, but this is at the cost of a high loss of energy. The short-term high buoyancy can be used for quick changes of direction or fallback maneuvers.

In addition to the aileron function , the control flaps on the delta wing can also replace the horizontal stabilizer , the flaps at the end of the wing are then controlled in a correspondingly mixed manner. Alternatively or additionally, duck wings are used. The common complete tail unit can also be combined with delta wings and duck wings.

Application area

Double delta at Saab 35 Draken

Delta wings are particularly suitable for the supersonic area. Their shape allows a large area in the Mach cone . In the subsonic range, however, they have a higher air resistance than conventional wings with a greater aspect ratio with the same lift . In the higher supersonic range (Ma ≥ 2), small, thin, trapezoidal stub wings with a negative V-position like those of the F-104 offer the better ratio of lift to drag, if you can do without the hydraulic, landing gear and integral tank.

In addition to high speed, fighter planes are designed for small curve radii and high roll rates. For small curve radii or high angular speed, a large lift is required, for high speed a low resistance. The delta wing represents a suitable compromise, it can be thin, heavily swept , with a small span and with a large area. The low elongation leads to a lower moment of inertia about the longitudinal axis, which leads to a higher roll acceleration. Its long wing root allows high torsional rigidity.

The high resistance in vortex lift mode was used by the space shuttle to reduce energy in a controlled manner after reentry . Fighter planes have enough thrust to compensate for the losses.

In the field of model aircraft construction, delta wings are widely used due to their simple construction and stall security.

Delta aircraft

Delta wings of different elongation

Well-known aircraft with delta wing are machines of the series:

Origins

Series production aircraft

Trial or prototype examples

The US space shuttle and the Soviet Buran also use this wing shape.

Web links

Commons : Delta wing - collection of images, videos and audio files

literature

Niels Klußmann, Arnim Malik: Aviation Lexicon . 2nd Edition. Springer, 2007, ISBN 978-3-540-49095-1 , pp. 57 ( available online ).
Lugt, Hans J .: Eddy currents in nature and technology . 1st edition. G. Braun, 1979, ISBN 3-7650-2028-1 , pp. 147 .