![]() This poses multiple challenges for the wing structure. Supersonic aircraft typically feature airfoils with t/ c around 3%–6%. The best-known aircraft that uses the configuration is the MiG-21 (has HT) and Dassault Mirage III (no HT) and its various derivative aircraft (e.g., Mirage IV, 2000, Rafale).ĭespite this bleak introduction, delta wings are excellent for supersonic aircraft and high-speed fighters. Furthermore, their low AR produces a poor LD max, which is of concern for engine-out emergencies and range. This means the airplane must either land at an excessive deck angle or “come in hot.” This drives their requirements for longer T-O and landing distances. Conventional wings develop this near 10°, give or take. Note that the two deltas being compared produce C L ≈ 1.0 at α ≈ 25–28°. Figure 9-52 shows typical lift curves for delta wings. This is 60%–65% of the capability of a conventional straight wing. This means its 173 ft 2 wing generates a C L max around 0.8–0.9. As an example, the 2000 lb f Dyke JD-2 Delta reportedly stalls at about 61–65 KCAS. Deltas stall at high AOA and low C L max compared to straight wings. While it is possible to use delta wings for that purpose (as evident by the Dyke Delta), the choice is hard to justify for reasons other than fun flying and reduced hangar space. The delta wing is intended for high-subsonic or supersonic aircraft, not low-subsonic airplanes. The unsteady response of the vortex burst is a governing factor when considering delta wings in maneuvering flight since the forces generated on the wing are strongly influenced by the behaviour of the vortices. This is characterised by an abrupt deceleration of the flow in the vortex core, which causes the flow to stagnate and full scale turbulence to develop. An important feature of such vortex dominated flows is the vortex burst. This second flow separation results in secondary and tertiary vortices being formed. This pressure gradient also causes the outboard moving flow to separate from the wing surface, just outboard of the primary vortex core. The leading edge vortices form due to flow separation from the leading edges of the wing (which are generally sharp on delta wings), with the resultant shear layer rolling up due to a span- wise pressure gradient along the surface of the wing. The response of these vortices during maneuvering flight is the dominant aspect of the flow. Menzies, in Parallel Computational Fluid Dynamics 2001, 2002 4.1 Delta Wingĭelta wing aerodynamics are characterised by two leading edge vortices.
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