A stabilator is a fully movable aircraft horizontal stabilizer. It serves the usual functions of longitudinal stability, control and stick force requirements[1] otherwise performed by the separate parts of a conventional horizontal stabilizer (which is fixed) and elevator (which is adjustable). Apart from reduced drag, particularly at high Mach numbers,[2] it is a useful device for changing the aircraft balance within wide limits, and for reducing stick forces.[3]
Stabilator is a portmanteau of stabilizer and elevator. It is also known as an all-moving tailplane (British English), all-movable tail(plane), all-moving stabilizer, all-flying tail (American English), all-flying horizontal tail, full-flying stabilizer, and slab tailplane.[2]
All-movable tail surfaces became interesting... when high Mach number theory and transonic wind-tunnel tests disclosed poor performance of ordinary flap-type controls.