Picture I Kimmo Huosionmaa The problem with the helicopters is that they are not very fast, in the comparison between aircraft, and the second thing is that sometimes helicopters are so noisy. When the SWAT-team would land on the roof of the building, they normally want the operate silent, or that's what normal people think because that allows them to make surprise attack to space, where the target is. If the helicopter would be hit by weapons, it should land safely, and that's why there should be used the autorotation if there would be problems with engines. Autorotation is the thing, what is used in the "Autogyros", and it means that the rotor of the helicopter would let rotate freely, what would be slow the dropping speed. The same system, what makes helicopters safe in the landing situation, makes it silent. The idea of the Autogyro is not new. In the medieval time were created the toys, what were landed slow, when they were thrown in the air. NACA ...