The Sikorsky S-5 was an early design by Igor Sikorsky completed in late April 1911 with a 50 hp (37 kW) Argus water-cooled engine. The S-5 was tested in a series of 20 to 30-second straight-line flights over a period of three weeks before the designer was able to make what he called his first real flight of four minutes in a circuit of the field on 17 May 1911. The S-5 had a wing span of 12 m (39 ft) a length of 8.50 m (27.89 ft) and weight of 440 kg (970 lb).