The SZD-25A Lis (Szybowcowy Zakà Âad Doà Âwiadczalny - Glider Experimental Works) was a single-seat glider aircraft that was designed and built in Poland from 1955, derived from the SZD-16 Gil and SZD-25 Nov.
Although design of the SZD-16 Gil was started in 1955, the prototype was not completed until 1958, when interest in gliders with metal structures increased. The SZD-16 was a simple single-seat training glider originally intended to form part of the LPà » (Soldier's Friends League) aero clubs training regime. The main designer was Zbigniew Badura. The fuselage was of metal and the wings were of wood.
The single-seat training methods were abandoned at around the time of the SZD-16's first flight, but the prototype was used for research into metal structures in gliders as well as new forms of air brakes. The SZD-16 was a cantilever shoulder-winged aircraft with the tail supported on a narrow tubular aluminium alloy boom extending from aft of the wooden wings, which attached to the pod-like welded steel tube fuselage housing the cockpit. Flight trials commenced with Adam Zientek piloting SP-1880 on the first flight on 20 October 1958. After the initial flight trials the fuselage was modified to accept wings from an SZD-22 Mucha Standard, to produce the SZD-16 Gil Z, which was used to test a new form of air brake.
Further testing and the need for single seater aircraft with reasonable performance for club flying, prompted development of the SZD-16Z Gil Z fitted with a wing derived from that of the SZD-22 Mucha Standard. Improved structure, new wing and other improvements resulted in the SZD-25A Lis production aircraft, of which 30 were built.