Jet Helicopter Makes Its Debut -- The Cierva W.9. jet-helicopter hovering over the landing ground at the Southampton Air Pageant to-day (Saturday). The Cierva W.9. an experimental helicopter, the only single rotor British helicopter flying at the present time, made its public debut at the Southampton Air Pageant today (Saturday). The main feature of this new aircraft is what the torque is compensated for by the introduction of an air jet at the rear of the aircraft, taking the place of the conventional airscrew. June 22, 1946.