A type of two-seat helicopter designed by a man that won the highest award at the 1912 Sud Aviation for the S-6-A airplane. This helicopter was in competition with the Pitcairn XO-61.
The Sikorsky R-4 was a two-seat helicopter designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. 
 His S-6-A received the highest award at the 1912 Moscow Aviation Exhibition. 
 One of the last autogyros produced, in competition with the Kellett YO-60 and the Sikorsky R-4, it fell victim to cooling problems with its rear-mounted engine and the coming of the helicopter with its ability to hover. 
