Whirly birds

[boatman]

What's the difference in how helicopters and autogyros work?

[BarryScott]

In both helicopters and autogyros the lift to enable flight is provided by the rotation of the rotablades forcing air downwards. The difference between helicopters and autogyros is that in helicopters the rotation of the rota is caused by a motor or engine. In autogyros the rotation of the rotablades is caused by the forward motion of the craft and subsequent airflow over each blade. This forward motion is provided by a propeller system, usually mounted at the rear. Infact, if a helicopter loses power it is possible for it to make a controlled descent using the autogyro effect by maintaining enough forward motion to provide the lift from keeping the rotablades rotating.