The autogiro was for many years the most reasonable alternative to the helicopter as a means of vertical flight. Because the rotor is not powered, the autogiro does not have to contend with torque (the tendency of the aircraft to turn in the opposite direction of the rotor) and thus avoided many of the control problems that impeded the development of the helicopter. It's an epic tale that begins in the 4th Century B.C. and travels to ancient Greek physicists and great thinkers like Da Vinci. With dreams of fantastical flying machines that either soared magnificently or crashed to the ground, designs evolved throughout the centuries until, finally, the helicopter's potential was recognized by the military. In combat, the helicopter's story goes from the early dreams of flight to daring searches and rescue missions...