GB479461A - Improvements in or relating to aero-revolving wings or blades - Google Patents

Abstract

479,461. Aircraft with rotary wing systems. KAY, D. Aug. 6,1936, No. 21712. [Class 4] In a rotating blade arrangement for aircraft with a normally autorotative rotor, each of the blades is provided with sliding (or guiding) means adapted to engage with guiding (or sliding) means provided on the rotor hub, said means being so disposed as to provide fulcra permitting the displacement of the blade in the general plane of rotation, such displacement being accompanied by a change from a normal or positive pitch angle to a neutral or negative angle both when the blade experiences a lagging displacement during starting of the rotor and a leading displacement when the rotor is being braked, the said means at all times permitting flapping. The root end of each blade spar 1, Figs. 1 and 2, is formed or provided with a cross member 2 formed with or carrying ball ends 3, 4 engaging in spaced oppositely inclined slots 5, 6 in rotor hub 7, providing curved tracks along which the balls can travel. In the normal radial position the centrifugal force is taken by the ends of slots 5, 6. Flapping takes place about an axis passing through the centres of balls 3, 4. A leading swing causes the blade root to pivot about ball 2, ball 4 moving downwardly in track 6 to effect a reduction in pitch angle, whilst lagging causes the blade root to pivot about ball 4, ball 3 now moving upwardly in track 5 again producing reduction of pitch angle. In a modification, the tracks may be formed in members secured to the blade roots which co-operate with spherical or like members fixed in the hub. Means may be provided for altering the mean pitch angle on the ground or in flight by providing for angular adjustment of the ball-carrying or the slotted element.