GB452407A - Improvements in and relating to aircraft with autorotative wings - Google Patents

Abstract

452,407. Aircraft with rotary-wing systems. LA CIERVA, J. DE, Bush House, Aldwych, London. Jan. 16, 1935, No. 18394/36. Divided out of 452,365. [Class 4] In aircraft having an auto rotative sustaining rotor, means, including a clutch, for initiating rotation of the rotor and automatic means for varying the mean rotor-blade pitch-angle responsive to any or all of the forces acting on the blades, the rotor-blades are articulated to the hub and the rotor includes means automatically responsive to blade displacement relative to the hub in the plane of rotation in the leading direction for decreasing the pitch angle, and means operative while the blades are being positively driven to maintain the pitch angle at a predetermined value less than that utilized in flight. As shown, each blade can flap about an axis 35 whilst rocking about axes # # and alpha alpha results, respectively, when the blades lead in a decrease and increase in blade pitch and conversely when the blades lag. In the construction shown, pronounced lagging displacements of the blades as occur, e.g. when a driving torque is applied are associated with progressive decrease and leading displacements which occur, e.g. when a brake is applied to the rotor hub also result in a progressive decrease in pitch. This result is obtained by the disposition of stops 47, 48b, 49, and two further stops which are not shown in Fig. 1, which limit movement about the axes # #, alpha alpha, and a suitable choice of the aerodynamic and mass characteristics of the rotor blades. If the blades are constructed so that their aerodynamic centres of pressure are in advance of their mass centres then when the rotor is rotating leading displacements will take place about the alpha axis only and lagging displacements about the # axis only. Specification 420,322 is referred to, and Specification 452,364 also is referred to in the Provisional Specification.