Once the Roton has been slowed sufficiently by atmospheric drag, however, the pilot will change the blade-angles so that the blades are set spinning by the airflow, slowing the craft still further. (This technique, called auto-rotation, is used by helicopter pilots in emergency landings.) Small thrusters on the side of the Roton will stabilise it, so that it can be steered towards its landing site.

ECONOMIST: On a rotor-blade and a prayer | The