III
The existing autogiro, although it may not resemble the more developed types which will eventually appear, is the most successful moving-wing flying-machine yet produced. Señor de la Cierva’s work was described by an aeronautical engineer as being of secondary importance only to that of the Wright brothers. That first flush of enthusiasm may be over, but there seems little doubt that future generations will regard Señor de la Cierva as the inventor of moving-wing flight. And I believe that there will be a fierce battle, more prolonged and more vigorous than has ever been fought between two machines, the battle between moving-wing flight and fixed-wing flight. The struggle between reciprocating engine and turbine, broad gauge and narrow gauge, lighter-than-air and heavier-than-air, water-cooling and air-cooling will be as nothing compared with the imminent struggle between fixed-wing and moving-wing.
The autogiro obtains lift from a free, four-bladed windmill. Each blade of the windmill is a wing and is articulated at the root so that its tip can rise and fall. The autogiro is drawn forward by an ordinary aero-engine and airscrew which are entirely separated from the windmill. As the machine is drawn through the air the relative wind, blowing on the blades or wings, rotates the windmill and it lifts the machine. The wings rise and fall, and this beating motion gives the machine a measure of stability.
To exert lift a wing must move through the air.
The moving-wing aircraft derives lift from wings which can move through the air even though the body of the machine be stationary or nearly stationary. In the fixed-wing aeroplane both body and wings must move if the wings are to exert lift.