Letov Š.4 / SHS. 1

Intended as a successor to the Spad 7 and 13 in service with the newly-created Czechoslovak Air Force, and selected in preference to the Š 3 parasol monoplane, the Š 4, initially designated S HS. 1, was a single-bay unstaggered biplane of mixed construction with fabric-covered wooden wings and metal fuselage and tail.

Flown in 1922, the Š 4 was powered by a 220 hp Hispano-Suiza 8Ba engine and carried an armament of two synchronised 7,7-mm Vickers machine guns.

A series of 2054 fighters was ordered, but 20 of these were completed with the 180 hp HS 8Aa engine as Š 4a aerobatic trainers. As a result of low manufacturing standards a number of difficulties were experienced with the S4 which was grounded in 1927, the surviving aircraft being rebuilt in 1928 to Š 4a trainer standard.

A series of S-4 fighters was ordered, but 20 of these were completed with the 180 hp HS 8Aa engine as Š 4a aerobatic trainers. As a result of low manufacturing standards a number of difficulties were experienced with the S4 which was grounded in 1927, the surviving aircraft being rebuilt in 1928 to Š 4a trainer standard.

Š -4a
Engine: 180 hp HS 8Aa