Area rule

The area of ​​rule describes the optimal course of the cross-sectional area of a supersonic missile along its longitudinal axis. The area rule applies to the transonic region (around Mach 0.8 to 1.2 ). For higher speeds, applies a slightly modified form of the area rule, there must be taken into account in the shaping of the influence of the Mach cone then.

The rule was discovered in 1943-1944 by Otto Frenzl during the development of the jet bomber Ju 287 Junkers and No. 932 410 officially confirmed on 21 March 1944 as a patent. It was also probably independently rediscovered in the U.S. in 1952 by Richard T. Whitcomb from the National Advisory Committee for Aeronautics ( NACA ) and published in 1955 and is often wrongly attributed to him alone. Another discovery is Wallace D. Hayes in his dissertation at Caltech in 1947.

The ideal shape of a supersonic missile is considered the Haacksche ogive, an elongated, spindle-shaped body. For aircraft is the cross-sectional area of the hull in addition to the wings. If the surface is not observed, an additional shock wave by this enlargement of the cross-sectional area at a supersonic speed generated, which increases the drag of the aircraft and prevented drastically reaching the sonic velocity under certain circumstances. According to the area rule fuselage cross-section must theoretically decrease by the value that is added by the wings to cross-sectional area. Thus the emergence of an additional shock wave is avoided.

Wasp waist

In practice, according to the area rule designed aircraft on a fuselage indentation in the wings. For airplanes with elongated hulls such as the Concorde, this " wasp waist " is hard to see at supersonic aircraft with short trunk, however, it is most clearly seen (as with the Convair F -106 or the Je -152 ).