Patent GB-1199595-A (GB)
Title: Trailing Rotor Convertiplane
Inventor: SAMBELL KENNETH WILLIAM
IPC: B64C29/00
Filed: 1967-08-03
Abstract: 1,199,595. Convertiplanes. BELL AERO-SPACE CORP. 3 Aug., 1967, No. 35755/67. Heading B7W. A convertiplane comprises a fuselage 10, wings 12, 14, 250 each carrying a rotor assembly 24, 26 tiltable about a transverse axis 152 between a stored position, Fig. 1, with the rotor axis of rotation lying fore-and-aft and the rotor blades 32, 34 folded parallel thereto, and an operative position as in Figs. 12, 13 for normal helicopter operation. When moving from the stored to the operative position the blades are first unfolded, and then their speed in autorotation is controlled by varying the blade pitch as the rotor assemblies are tilted about the transverse axis. When in the operative position, power from forward flight engines 18, 20, 22 is transferred to mechanically driving the rotor assemblies 24, 26. The blade pitch is controlled both cyclically and collectively not only when power driven in the operational position by the pilot, but also automatically when autorotating during both the unfolding of the blades and the rotation of the rotor assemblies about the transverse axis. The blades 264, Fig. 13, are folded about axes 272 by the extension of jack 302 acting through shaft 298 and links 294 on lever arms 292 integral with the blades. The rotor assemblies are rotated about the transverse axis by motors 334 driving worm gears engaging pinions which rotate with gear-boxes 304, there being gearing 336 and a cross-shaft to ensure that both rotor assemblies move together. Collective blade pitch control, Fig. 12. The pitch of the blade 100 is varied about the pitch axis 128 by the rotation of gear 126 by gear 124 rotating with pinion 122 driven by worm 120 which rotates about the folding axis 150. Unfolding the blade about axis 150 changes the collective pitch from - 90 to - 80 degrees, thereby starting autorotation of the rotor head. Worm 120 is rotated through gearing 118, 116, 114 moved by rack 112 linked to the rotating part of sleeve 110, the axial position of which along the axis 108 of rotor rotation is controlled by link 136 from the arms 160 pivotable about a transverse axis displaced from axis 152. The arms 160 are controlled by linkage 162, 164, 174, 172, 170. When the blades have been unfolded motor 166 acting through gearing 168 increases the collective blade pitch to about - 40 degrees, causing autorotation at about half full speed. Then as the rotor assembly is rotated about axis 152, the displacement of the axis of arms 160 causes the collective blade pitch to further increase with the speed of autorotation, so that full rotational speed occurs when the mast is erect. Then when the rotors become power driven a mechanism 178 connects up the pilot's collective pitch control sticks 176. Cyclic blade pitch control.-The cyclic pitch of blade 100 is varied by moving the worm 120 axially along axis 150, by linkage 148, 146, 144, 142, 140 connected to the rotating part 105 of swashplate mechanism 104, whose tilt about axis 106 is controlled by a link 138 attached to a bell-crank. This engages a cam groove 158 in a cylinder 154 which automatically controls the rotor blade cyclic pitch as the rotor assembly is rotated about axis 152. Cyclic blade pitch is controlled when the rotors are powerdriven by the axial movement of the cylinder 154 along the axis 152 by a linkage 220 connected via mechanisms 216, 218 to the pilot controls 180, 182 which also control the control surfaces by suitable linkages 184, 186, 188.