A stabilator is a fully movable aircraft horizontal stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements otherwise performed by the separate parts of a conventional horizontal stabilizer and elevator. Apart from reduced drag, particularly at high Mach numbers, it is a useful device for changing the aircraft balance within wide limits, and for reducing stick forces. Stabilator is a portmanteau of stabilizer and elevator. It is also known as an all-moving tailplane, all-movable tail(plane), all-moving stabilizer, all-flying tail(plane), all-flying horizontal tail, full-flying stabilizer, and slab tailplane. General aviation Because it involves a moving balanced surface, a stabilator can allow the pilot to generate a given pitching moment with a lower control force. Due to the high forces involved in tail balancing loads, stabilators are designed to pivot about their aerodynamic center (near the tail's mean quarter-chord). This is the point at which the pitching moment is constant regardless of the angle of attack, and thus any movement of the stabilator can be made without added pilot effort. However, to be certified by the appropriate regulatory agency, an airplane must show an increasing resistance to an increasing pilot input (movement). To provide this resistance, stabilators on small aircraft contain an anti-servo tab (usually acting also as a trim tab) that deflects in the same direction as the stabilator, thus providing an aerodynamic force resisting the pilot's input. General aviation aircraft with stabilators include the Piper Cherokee and the Cessna 177. The Glaser-Dirks DG-100 glider initially used a stabilator without an anti-servo tab to increase resistance: as a result, the pitch movement of the glider is very sensitive. Later models used a conventional stabilizer and elevator. Military All-flying tailplanes were used on many pioneer aircraft and the popular Morane-Saulnier G, H and L monoplanes from France as well as the early Fokker Eindecker monoplane and Halberstadt D.II biplane fighters from Germany all flew with them, although at the cost of stability: none of these aircraft, with the possible exception of the biplane Halberstadts, could be flown hands-off. Stabilators were developed to achieve adequate pitch control in supersonic flight, and are almost universal on modern military combat aircraft. All non-delta-winged supersonic aircraft use stabilators because with conventional control surfaces, shock waves can form past the elevator hinge, causing severe mach tuck. The British wartime Miles M.52 supersonic project was designed with stabilators. Though the design only flew