Trapezoidal wing
A trapezoidal wing is a straight-edged and tapered wing planform. It may have any aspect ratio and may or may not be swept.
The thin, unswept, short-span, low-aspect-ratio trapezoidal configuration offers some advantages for high-speed flight and has been used on a small number of aircraft types. In this wing configuration the leading edge sweeps back and the trailing edge sweeps forward. It can provide low aerodynamic drag at high speeds, while maintaining high strength and stiffness, and was used successfully during the early days of supersonic aircraft.
Any wing with straight leading and trailing edges and with differing root and tip chords is a trapezoid, whether or not it is swept.
The area A of such a trapezoidal wing may be calculated from the span s, root chord cr and tip chord ct:
The wing loading w is then given by the lift L divided by the area:
In level flight, the amount of lift is equal to the gross weight.
In a straight trapezoidal wing, such as on the Bell X-1, the thickest part of the wing along its span, the line of maximum chord, runs straight out sideways from root to tip. The leading edge then sweeps backwards and the trailing edge sweeps forward. In a swept trapezoidal wing, the line of maximum chord is swept at an angle, usually forward. This increases the sweep of the leading edge and decreases the sweep of the trailing edge, and in the extreme case both edges sweep backwards by different amounts. The transition form, where the trailing edge is straight, is equivalent to a cropped delta planform.
At supersonic speeds a thin, small and highly loaded wing offers substantially lower drag than other configurations. Low span and an unswept, tapered planform reduce structural stresses, allowing the wing to be made thin. For minimum drag, wing loading can be in excess of 400 kilograms per square metre (82 lb/sq ft).
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