Delta wing

A delta wing is a type of wing of plane, characterized by a form of Isosceles triangle. This name comes from the capital letter Greek Delta which is of triangular form (Δ).

This shape of wing appeared in the years 1930, initially in France with the prototypes of Nicolas Roland Payen which deposits a patent in 1931, then in Germany with work of Alexander Lippisch. It is however necessary to announce some former projects, as of the end of the 19th century.

Characteristics

Advantages

The delta wing with the same characteristic as a wing in Arrow pronounced, namely that it is well adapted to the flight at speed Supersonique because its form is close to those of the cone of Mach.

Advantages over the sweptback wing:

the long cord with the Root, often higher than the scale, makes it possible to reconcile low relative thickness (3%) and absolute thickness sufficient for the behavior structural (members) and housing of the accessories (train, systems mechanical, tanks).
having generally a larger surface, it can contain a volume of more important fuel,
with a form in plan of Aile in warhead (leading edge with S curve presenting a strong arrow to connection with the fuselage), it can benefit from a lift increasing (swirling bearing pressure) specific of this form (work ONERA, years 1950-1960): the Concorde benefits thus from a supplement of bearing pressure of approximately 20% what makes it possible to reduce minimal speed and the stalling speed of approximately 10%.

Disadvantages

Coefficient of bearing pressure (Cz) maximum limited by the absence of high-lift devices. This disadvantage is partly compensated by the supplements of bearing pressure brought by:

1. swirling bearing pressure described above,

2. the Ground effect important for a low wing in pulled up position, the trailing edge being close to the ground,

3. the vertical component of pushed on takeoff taking into account the high angle of attack. Pulled up to 17°, 30% of pushed engines (increased by post-combustion) carry the plane directly. If one (or it) driving stops…

4. the assembly of plane ducks which allow a light positive steering (downwards) of the shutters great incidence; to see Rafale, Stability in Pitching.

Very strong Trailed induced had with the weak lengthening.
the great possible incidences (weak Slope of bearing pressure) can bring an aerodynamic masking of the vertical stabilizer.
the sweptback wing (with empennage) remains more effective for the very tight turns (at the time of the aerial combats says whirling combat for example).

Use

In the civil field, the delta wing was used only for the Concorde and its twin brother, the Tupolev You-144.

In the military field, the delta wing was used for:

In France: Mirage III, Mirage IV, Mirage 2000 and Rafale;
With the the United States: Convair F-102 Delta Dagger, Convair F-106 Delta Dart, Convair B-58 Hustler;
With the the United Kingdom: Gloster Javelin, Avro Vulcan (wing in warhead);
In Soviet Union: Mig-21 Mikoyan-Gourevitch, Soukhoï Known-11, Soukhoï Known-15;
in Sweden: Saab 35 Draken (wing in double delta), SAAB 37 Viggen, Saab JAS 39 Gripen.

External bonds

Site of the Museum Delta Athis Paray Aviation, devoted to the planes with delta wing

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