and reduced for high speed. Charles Rocheville and others flew some experimental aircraft.Flight, August 15, 1929 Polymorphism A polymorphic wing is able to change the number of planes in flight. The Nikitin-Shevchenko IS "folding fighter" prototypes were able to morph between biplane and monoplane configurations after takeoff by folding the lower wing into a cavity in the upper wing. The slip wing is a variation on the polymorphic idea, whereby a low-wing monoplane was fitted with a second detachable "slip" wing above it to assist takeoff, which was then jettisoned once aloft. The idea was first flown on the experimental Hillson Bi-mono. Minor independent surfaces Aircraft may have additional minor aerodynamic surfaces. Some of these are treated as part of the overall wing configuration: Winglet: a small fin at the wingtip, usually turned upwards. Reduces the size of vortices shed by the wingtip, and hence also tip drag. Strake: a small surface, typically longer than it is wide and mounted on the fuselage. Strakes may be located at various positions in order to improve aerodynamic behaviour. Leading edge root extensions (LERX) are also sometimes referred to as wing strakes. Chine: sharp-edged profile running along the fuselage. When used aerodynamically it is extended outwards to form a lifting surface, typically blending into the main wing. As well as improving low speed (high angle of attack) handling, provides extra lift at high supersonic speeds for minimal increase in drag. Seen on the Lockheed SR-71 Blackbird. Moustache: small high-aspect-ratio canard surface having no movable control surface. Typically is retractable for high speed flight. Deflects air downward onto the wing root, to delay the stall. Seen on the Dassault Milan. Additional minor features Additional minor features may be applied to an existing aerodynamic surface such as the main wing: High lift High-lift devices maintain lift at low speeds and delay the stall to allow slower takeoff and landing speeds: Slat and slot: a Leading edge slat is a small aerofoil extending in front of the main leading edge. The spanwise gap behind it forms a leading-edge slot. Air flowing up through the slot is deflected backwards by the slat to flow over the wing, allowing the aircraft to fly at lower air speeds without flow separation or stalling. A slat may be fixed or retractable. Flap: a hinged aerodynamic surface, usually on the trailing edge, which is rotated downwards to generate extra lift and