Rotary‐Wing Aircraft: The Fourth Article of a Series Summarizing the Current State of Knowledge Available to Purchase

THE direct method of take‐off which has been successfully applied in the last few years to the rotaplane, commonly known as “jump‐off,” is achieved by setting the blade angle at a lower value than that required for flight and driving the blades to a high rotational speed, thereby storing kinetic energy in the rotor. This energy is partly transformed into potential energy whenever the blade angle is suddenly increased and the blades swing upwards about their horizontal hinges. If the excess of rotational speed above normal is sufficient, the aircraft is projected off the ground and rises until the excess kinetic energy has been absorbed.