Helicopter with twin intermeshing rotor machine takes off and four in the air together.
United States of America U.S.A.
Commentary states the Navy releases first films of its new HOK-1 helicopter, powered by an unusual twin intermeshing rotor machine. The long blades and the twin motors give the plane amazing manoeuvrability. This is its first public demonstration flight, built by the Kaman Aircraft Corporation it can be equipped with pontoons and land on water as well as on deck, or be converted as an aerial ambulance.
GV. The New Helicopter HOK - 1. LS. Gyro starting up. LS. Four HOK-1 helicopters flying.