Sikorsky Helicopter No.2 / S-2
 
Sikorsk-Heli2
 
The Sikorsky Helicopter No.2 of 1910 was also known as the S-2; an identification later designated. Powered by the same Anzani 3-cylinder of 25 hp as in the No.1. Developing lift force using contra-rotating three-bladed rotors, reportedly it could almost lift itself.