Patent GB-554497-A (GB)
Title: Improvements in or relating to aircraft
IPC: B64C27/04
Filed: 1941-05-08
Abstract: 554,497. Helicopters. UNITED AIRCRAFT CORPORATION. May 8, 1941, No. 6008. Convention date, April, 9 1940. [Class 4] A helicopter is supported by a main rotary wing system just forward of the centre of gravity of the aircraft, and two laterally and rearwardly spaced rotary wing systems, all three systems being adjustable in pitch the last two independently of the main system and individually in the same or opposite directions. In addition a third rotating wing adjustable in pitch is mounted to rotate in a vertical plane to steer the aircraft and to counterbalance the driving torque. The aircraft consists of a central framework carrying an engine 12 driving through belts 62 and bevel gear 66, 72 a vertical shaft 32 of a main rotating wing system 16. A forward outrigger supports the pilot's seat 40, the controls and a landing wheel 52. Lateral outriggers support two main landing gear structures 38, and a rear outrigger supports two laterally spaced auxiliary rotor blades 54, 56 on vertical axes and a rear rotor blade 58 on a horizontal transverse axis. The rotor blade 58 is driven by a shaft 74 coaxial with the bevel wheel 66 and the rotor blades 54, 56 are driven from this shaft by belt gear 82, 84, Fig. 5. The main rotor system comprises three arms pivoted about horizontal and vertical axes 142, 140 and the blades are pivoted about these arms. The blades are adjusted to vary the pitch of the rotor by links 134 connected to a sliding sleeve 122 movable by links 118, 120 and the linkage shown from a hand lever 44. The engine throttle is controlled by a hand lever 46 through links 156 arms 158 and 162 on a shaft 160 and link and lever 164, 154. The shaft 160 is carried by arms 106, 166 on a shaft 104 of the rotor control so that each adjustment of pitch is accompanied by a change in the throttle control. Each of the blades 54, 56, 58 is mounted about a coning and a pitch change axis. The pitch of the blades 54, 56 is changed in opposite directions by lateral movements of a lever 42 and in the same direction as one another by for and aft movements of the lever 42. A quadrant 172 pivoted in a member 170 rockable about a transverse axis actuates cables connected to a lever 184 fixed on a shaft 186 having an arm 190 linked to levers 196, 198 pivoted between members 100, 202 which are normally stationary. The levers 196, 198 are connected to the pitch change mechanism of the rotor blades 54, 56 which comprises axially sliding rods 222, 240 connected by links 224, 244 to the leading edges of the blades. A lever 252 is pivoted on the spindle of the lever 198 and its ends are connected by links 250, 254 respectively to an arm 248 on the shaft 104 and to the member 170. Consequently swinging movements of the member 170 cause adjustments of the two rotors in the same sense, and adjustments of the main rotor, by moving the arm 248 also causes adjustment of the two rotors to compensate for the variation in lift of the main rotor. Two pedals 48, 50 actuate the pitch change mechanism of the rotor 58 through cables 256, 258 and one of these cables is acted upon by a pulley 278 carried by the pitch change mechanism of the main rotor to cause adjustment of the rotor 58 to compensate automatically for the vairation in torque of the main rotor. The driving connections to the main and auxiliary rotors and the control of the main rotor and the rotor 58 are described in Specification 551,156.