How does an autogyro perform a jump takeoff?
The process of performing a jump take-off is pretty straight-forward. The prerotator consists basically of a drive shaft and a gearbox, connecting the rotor to the engine through a clutch. Because the system is used only for short periods on the ground, and not continuously in flight, it can be much lighter than the corresponding system on a helicopter. On the ground, where the landing gear can counter the torque driving the rotor, the prerotator is engaged to spin up the rotor. It is spun to an rpm much higher than the rpm the rotor will be operating at in flight (for example, the rotor on the CGD/T will need to spin at about 250 rpm in flight, but will be prerotated to 500 rpm for a jump takeoff). This extra rpm stores quite a bit of energy, and with the tip weights of the Carter rotor, makes for a very good flywheel. During prerotation, the rotor is set to a flat pitch, both to keep it from producing a force to lift the aircraft, and to reduce the induced horsepower, to allow it to
