After years of false starts and setbacks, the hybrid of a plane and a helicopter, known as a tiltrotor, is all set for commercial operations. Bell Helicopter Textron and the Boeing Company's helicopter division have come out with Bell-Boeing 609, a nine-passenger commercial tiltrotor. It has two sets of rotors mounted on the wings of the aircraft that allow a horizontal take-off. Once airborne, the rotors tilt forward to act as propellers in planes. The swivelling propellers are quieter than horizontal rotors and can propel the aircraft at twice the speed of a helicopter of a comparable size ( New Scientist , Vol 154, No 2086).