Patent GB-740015-A (GB)
Title: Improvements in or relating to aircraft convertible to and from fixed- and rotary-wing flight
IPC: B64C29/00
Filed: 1953-05-11
Abstract: 740,015. Aircraft adapted for fixed and rotary wing flight. HERRICK, G. P. May 11, 1953, No. 13055/53. Class 4. An aircraft convertible to fixed or rotary wing flight includes wing portions variable in angle of attack, and means for vertical control of said aircraft in rotary wing operation, said means including an inclined surface on each of said wing portions, a laterally movable guide adapted to co-operate with said inclined surface, and a control handle operatively connected with said guide, whereby movement of said control handle laterally moves said guide to vertically move said inclined surface. The aircraft shown in Fig. 1 has stub planes 24 carrying twin booms 22 supporting fins 26, a tailplane 30, rudders 28 and an elevator 32 which with the ailerons 42 are used for fixed wing flight. A fixed wing portion 34a is supported on a mast 38, and wing portions 34b are hinged about axes B, and have ailerons 40 on their rotational trailing edges. Jet propulsion devices 222 are used for rotary flight, and a turbo-prop 20 for fixed wing flight. The control mechanism is shown in Fig. 2 where a duplicated hand wheel 44 is rotatable about its axis 92 and can swing shaft 66 fore-and-aft or laterally. These movements control the fixed wing flight surfaces in any conventional manner, and can be connected by lever 256 to the rotary flight control surfaces. Collective pitch control.-Wing sections 34b, preferably of symmetrical cross-section, are pivoted about their axes B by lever 168, movement of which rotates the internally-toothed arcuate portion 172a which through gear 174, worm 176 and worm-wheel 178 rotates shaft 180 and levers 182 to shift rods 184. The upper end of these rods (Fig. 3) are secured at 186 to the outer race 188 of a bearing whose inner race 190 is secured to a collar 192 rotating with driveshaft 48. Pins 196 on collar 192 engage bellcranks 198 adapted to reciprocate sleeves 202 mounted on a rod 204 extending between sockets 56, in each of which is mounted a stubshaft 58 bearing a shaft 62 supporting, by bearings 63 and a sleeve 65, a spar 61 of the movable portions of the wing. A ball-race 206 on sleeve 202 has a pin adapted to move a lever 210 (Fig. 5) pivoted at 212 to the mast head and carrying at its opposite end two pairs of rollers 214, 216. Rollers 214 embrace a horizontal arcuate track 218 fixed to the mast head, and rollers 216 embrace an inclined track 220 fixed to wing portion 34b. Rotation by hand lever 168 of lever 210, constrained to a horizontal plane by track 218, raises or lowers track 220 by wedge action, rotating wing portion 34b, about spar 61. A portion of track 220 is made horizontal for a purpose later described. Cyclic pitch control.-Translational movement in rotary wing flight is achieved by cyclic pitch change of the ailerons 40. Rotation of hand wheels 44 (Fig. 2), moves levers 94, shaft 96 an lever 98, and rotates shaft 100 and an eccentric portion 100a, to move shaft 104 longitudinally. Fixed to shaft 104 is a block 106 having rollers bearing on the curved member 108 pivoted by the aircraft at one end and to lever 110 at the other, so that longitudinal movement of shaft 104 rotates lever 110 and moves rod 112. The curves of member 108 are preferably chosen so that the movement is irreversible. The upper end of rod 112 (Fig. 3) is connected to lever 114 pivoted to the mast 46, the other end of which lever (Fig. 4) is connected by a strut 124 to the inner race 84 of a ball-bearing 85, so that rotation of hand wheels 44 tilts the ball-bearing about a lateral axis. Fore and aft movement of wheels 44 (Fig. 2) rocks shaft 66 fore and aft, translating rod 64 to move rod 80 by a block, roller, curved member and lever as previously described. The upper end of rod 80 (Fig. 3) is attached by link 82 to the inner race 84 of ballbearing 85, rocking it about a transverse axis. Ball-bearing 85 is pivoted longitudinally to a gimbal ring 86 itself pivoted transversely to the mast 46. Rotation and fore-and-aft movement of hand wheels 44 thus inclines the ball-bearing 85 in any direction. Pivoted at 127 to the outer race 128 of ball-bearing 85 is an arch 126 (Fig. 4) constrained by rollers 130 to move in a vertical plane, and rotating with the wings. As the wings rotate, arch 126 inclines in accordance with the inclination of ball bearing 85 in the plane of the arch, the pivots 127 taking up the inclination measured in a perpendicular plane. Arch 126 thus oscillates sinusoidally, with amplitude and phase determined by the hand controls. Pivoted to the arch at 132 is a walking beam 134 (Figs. 3, 5 and 6) movable longitudinally of the wings by arch 126 and to which are attached, through universal joints and a " pick-up " mechanism 284, described later, rods 1361. These rods control the ailerons by a conventional bell-crank arrangement and are counterbalanced against centrifugal forces by weights 140. Beam 134 can pivot about point 132 in a horizontal plane, so that the ailerons 40 adjust themselves so that the aerodynamic force on each is equal. Directional control and throttle control.- Lateral movement of control wheels 44 (Fig. 2) rocks shaft 66 laterally, to move levers 146, 148 and 150, connected through a " pick-up " mechanism, described later, to rod 150<SP>1</SP> adapted to rock lever 154 pivoted at 154a to the aircraft. Rocking in one direction moves link 156 to tighten a band brake on the rotor shaft to turn the helicopter by reaction. Rocking in the other direction releases the band brake and actuates a rheostat 162 to energize a small motor to supply additional power to the rotor and cause rotation of the aircraft in the opposite direction. These controls are preferably arranged so that in neutral position the band brake is slightly tensioned, and the motor is slightly energized. Throttle control is by foot pedals 226 rocking shaft 232 to translate rod 238, pivoted at its other end to lever 240. One end of lever 240 has a pin slidable in a groove 242a in a lever 242 pivoted at one end to the aircraft and at the other to a link 252 attached by lever 248 to one rod 184 of the collective pitch control. The arrangement is such that operation of the throttle pedals 226 moves bell-crank 244 to operate the throttle-rod 246 regardless of the position of the pin of lever 240 in groove 242a, and operation of the collective pitch rod lifts lever 240 bodily to operate the bell-crank 244 without disturbing the position of the throttle pedals, to compensate for change of lift with wing incidence. Lever 224 controls the fuel supply in fixed wing flight. Conversion from fixed to rotary wing flight and vice versa.- This is effected by hand lever 256 moving in a gate 260a (Fig. 11) and involves " pick-up " mechanisms. Fig. 16a shows that in the aileron controls, 284 (Fig. 6). When the control is dropped, lever 288 is in the position shown, where 286a is a fixed pivot for lever 286 in a groove in which a pin in lever 288 slides. Rod 136<SP>1</SP> is thus held in a predetermined position independent of rod 136. When lever 288 is moved by rod 300 and ring 294 to a position collinear with rods 136 and 136<SP>1</SP>, the control acts as a rigid rod, lever 286 swinging about its pivot. With the lever 256 in position G (Fig. 11) the aircraft is a helicopter, with controls as described above, and with fuel and ignition fed to the wing tip jets 222. For gyroplane flight, the lever is moved to position C through the intermediate positions. In position F, shafts 264 and 2641 (Figs. 2 and 12) are translated so as to move armature 266a of switch 266 from making contact 266c only to making contact 266b as well to supply ignition to the turbine for driving propeller 20, and a little later to supply fuel and compressed air through valves 268 and 270. Movement of lever 256 to position E, cuts off fuel and air to the wing tip jets, and then cuts off the ignition. The rotor will continue to auto-rotate. Movement of lever 256 to position D raises levers 272 and 274 to engage the underside of the collective pitch control lever 168 to fix it in the position which gives optimum pitch for autorotation. The aircraft now flies as a gyroplane with cyclic and directional controls. Movement of control lever to position C drops these controls by the " pick-up " mechanisms described to give conventional gyroplane flight. To convert to aeroplane flight, lever 256 is first put into position B (Fig. 11). Lever 272 (Fig. 2) clears the undersurface of lever 256, and lever 274 moves it to a position to align portions 34b of the wing with portion 34a. Lever 210 then moves over the horizontal portion of track 220 previously mentioned without misadjusting the alignment, but does engage a lever 340 releasing high drag flaps 326 and 328 (Fig. 6) to slow the rotor. A lug on portion 34a also engages a crank-arm 306 to centralize the ailerons by the " pick-up " mechanism 284. The lessening of the centrifugal force allows springs 314 to urge a pin 312 to engage and lock the ailerons in neutral position. The flaps 326, 328, as shown in Fig. 9, are biased by springs 332 and actuated by a lever 330. The flaps are placed unsymmetrically so that the resultant drag causes ultimately a slow reversal of rotation. This causes a lever 366 to catch in a socket 374a in the rotor wing (Fig. 10) and the force on this lever moves lever 368 to a position where it engages socket 374b. The wing is then locked against rotation. Movement of the control handle to position A moves pins 386 (Figs. 4 and 5) to double lock the wings. Pin 386 also operates a lever 406 and rod 334 to release flaps 326 and 328, rod 334 being locked by engagement of a groove 334a with a lever 342. The wings being rotatable on stub shafts 58 (Fig. 3), means are provided to render the wings horizontal. A lever 360 (Fig. 5) is pivoted by an elbow joint 360a to an arm 358 of lever 354. A rigid arm 356 is adapted to meet a lug 362 fixed to the aircraft. As the r