Published online by Cambridge University Press: 28 July 2016
Some wind tunnel experiments have been made on a variable pitch airscrew which shall change its pitch automatically as V/nD changes. The change in pitch is operated by the resultant effect of centrifugal and aerodynamic forces.
Reduction in air density, e.g., due to increase in height, causes an increase in pitch.
In the event of engine failure the blades assume the position of minimum drag.
A tentative design for a model screw, together with tests thereon, are described, and it appears that if the friction in the bearings about which the change in pitch occurs can be made reasonably small, it should be possible to construct a satisfactory full-scale screw.
This work was carried out at the National Physical Laboratory. Permission to communicate it was kindly given by the Aeronautical Research Committee.
Note on Page 111 † Les helices a pas Variable. G. Leparmentier. Premier Congres International de la Securete Aerienne. Paris, December, 1930.
Note on Page 113 * R. & M. 829. Experiments with a family of airscrews, including the effect of tractor and pusher bodies. Part I.—Fage, Lock, Howard and Bateman.
Note on Page 125 * loc. cit.