https://newatlas.com/sikorsky-s-97-raider-maiden-flight/37716/
Sikorsky S-97 Raider spins up coaxial rotors on maiden flight
May 27, 2015 - Sikorsky's S-97 Raider prototype helicopter has taken to the air for the first time. Based on the design of the X2 Technology Demonstrator, the S-97 Raider...
sikorsky s 97 raidercoaxial rotorsspins