Patent GB-202659-A (GB)
Title: Helicopter aircraft
IPC: B64C27/10
Filed: 1923-08-21
Abstract: 202,659. Perry, T. O. Aug. 21, 1922, [Convention date]. Screw propellers. - A helicopter having two propellers rotating in opposite directions about a central hollow column is provided with means for feathering the blades to produce a forward drive, means for altering the pitch of the two propellers in the same or opposite directions for controlling the lift and for steering respectively, means for disconnecting the ordinary control for enabling the pitch of both propellers to be suddenly increased or reversed in an emergency and subsequently controlled to permit of a descent with freely rotating propellers and to check the speed on landing, and with means for permitting free rotation of the engine. The general structure of the machine, and the ordinary means for feathering and varying the pitch of the propellers, are known. The two propellers are carried by tubular hubs 21 of sheet metal having internally toothed rings 26 at their lower ends which gear with pairs of pinions 27, 28 projecting through the central column 20 and mounted on the ends of shafts 105, 103. A rotary engine 106 is connected directly or through a coupling to a central pinion 90 meshing with two gear wheels 98, Fig. 11, connected to the ends of the shafts 103, the shafts 105 being connected to wheels 99 geared to wheels 100 rigid with the wheels 98. The crank shaft of the engine has an arm 115 normally held against rotation by a bolt 116 which can be raised clear of the arm 115 by a bell crank lever 117 and a rod 119 having a flattened end 120 provided with notches for engaging the edge of a slot in the column 20. The bar 115 balances the weight of the crank and piston rods when rotating. The blades 35 of each propeller are mounted on shafts 34 pivoted in the upper bearing-ring of its hub, the outer ends of the shafts being stayed by arms extending to the corners of a square plate 29 mounted on the ring 26 and stayed to the upper bearing-ring. Arms 37 on the shafts 34 are bent into the central longitudinal plane of the machine and connected by rods 39 to the ends of rocking frames 40. These frames have rollers 41 guided between channel members 42 depending from the plates 29 and have rollers 43 running within channelled rings 45 surrounding the central column. The rings 45 are supported by transverse rods 46 passing through vertical slots in the column 20 and connected to pairs of downwardly convergent arms 49, 50. These arms have nuts respectively engaged by right and left hand screws 53, 55, Fig. 4, upon a vertical shaft 54 having a square lower end 128 which engages a hole in the hub of a wheel 130 geared to an internally toothed ring 133 on the outside of the column 20 and provided with a hand-wheel 134. Movement of the hand-wheel causes the shafts 46 to approach or separate and adjust differentially the pitch of the propellers to vary the reactive torque. The lower ends of the arms 50 have a bearing 127 on the shaft 54. The shaft 54 is supported against vertical movement by a collar 59 having trunnions connected to a lever 60 pivoted in horizontally slotted bearings 61 on the central column. The opposite end of the lever has a pin 77<a> engaging notches in two parallel links 62 connected to a nut 63 on a screwed shaft 64 having a square lower end passing through a sleeve 67 of a pinion 66 geared to a toothed ring 70 provided with a hand-wheel 71. Movement of the hand-wheel 71 causes the rods 46 to be raised and lowered simultaneously to control the lift of the propellers. The notches in the links 62 are normally kept in engagemnt with the pin 77<a> by springs 78. One arm of a bell crank lever 73 normally prevents upward movement of the shaft 64, the lever 73 being held by a detent 75. The detent 75 may be raised by hand when required and may also be connected to a cord 126 having a weight, 125 some distance below the machine, which counterbalances a spring 124. When the weight 125 contacts with the ground, the spring 124 raises the detent and the shaft 64 is then free to rise, whereupon a spring 85 acts upon the lever 60 causing the pitch of both propellers to be suddenly increased to check the descent. A lever 80 is provided on the end of the lever 60 and is connected to a rod 82 having a forked end guided in a bracket 83 on the lever 60 so that by depressing the lever 80 the links 62 are pressed by the forked end of the rod 82 out of engagement with the lever 60 which can then be lowered to effect a sudden reversal of pitch should the engines fail. A lever 89 on the lever 80 mav be actuated at the same time to raise a detent 88 which releases a lever 86 and relieves the tension of the springs 85. The tilting of the rocking frames 40 for causing the periodic feathering of the blades during rotation is effected by arms 147 and levers 140, the ends of the levers working in vertical guides on the parallelogram linkage shown in Fig. 4. The guides are displaced by a lever 141 connected by rods 140 to a nut 139 on a screwed shaft 139 which is turned through gearing by a hand-wheel 135 surrounding the column 20.