Patent GB-375931-A (GB)
Title: Control device for aircraft
IPC: B64C23/00
Filed: 1931-04-30
Abstract: 375,931. Controlling aircraft. OEHMICHEN, E., Rue des Graviers, Valentigney, Doubs, France. April 30, 1931, No. 12743. Convention date, June 20, 1930. [Class 4.] A control device for aircraft having propellors of different inclination, in particular aircraft of the type described in Specification 369,248, comprises two distinct control members capable by simultaneous action on the thrusts developed by at least two propellers having different inclinations of varying, by the operation of the first member, the lift component without acting on the horizontal tractive component, and, by the operation of the second member, the tractive component without acting on the lift component. Fig. 1 shows an aerostat having inclined propellers p<1>, p<2> of which the axes pass through the centre of aerostatic thrust C making angles of a, # respectively with the vertical. The thrusts of the two propellers are represented by CF<1>, CF<2> respectively, which combine to give a resultant CR having a lift component CV and a tractive component CH. If the thrust CF<1> of propeller p<1> be increased and the thrust CF<2> of propeller p<2> be reduced in the ratio cos # cos alpha the lift component CV will. be unaffected and the tractive component CH increased. Conversely if the thrusts of propellers p<1>, p<2> are simultaneously increased in the ratio sin #/sin alpha the tractive component CH will be unaffected and the lift component CV increased. The variation in the thrusts of the propellers may be effected by varying their speeds of rotation or by varying their respective pitch angles. A control device acting in the last-named manner is shown in Fig. 4, wherein 1 and 2 are the hubs of two variable pitch propellers of different inclination. Mechanisms for varying the pitch of the blades are housed in casings 4, 5 and are controlled by levers 6, 7 actuated by rods 8, 9. The operating device comprises a cage 10 slidable on guides 11 and connected by a pin 23 to a slot in a lever 25 movable over a rack 26 to shift the cage 10 upwardly and downwardly. Integral with cage 10 is a bracket 14 providing a bearing for a shaft 15 to which are keyed gear wheels 16, 17 of different diameter. Gear wheel 16 meshes with a rack 18 and wheel 17 with a rack 19, both racks being slidably mounted in cage 10 and being connected by levers to the rods 8, 9 respectively. Shaft 15 is rotatable by a hand-lever 31, movable over a fixed segment 32, through a telescopic shaft 28 universally jointed at either end. If lever 31 is held stationary and lever 25 moved, the cage 10 is moved along its guides 11 and, since the wheels 16, 17 are held fixed, carries the racks 18, 19 with it thereby adjusting the incidence of the two propellers. The transmission levers and pitch changing mechanism are so arranged that for equal displacements of racks 18, 19 the variation of the incidence of both propellers is proportional to sin #/sin alpha. If lever 25 is held stationary and lever 31 moved to rotate shaft 15 and the gear wheels 16, 17 the racks 18, 19 will be displaced in reverse directions. In order that the variation effected thereby in the pitch of the propellers should be in the ratio cos #/cos alpha the ratio of the radii of the wheels 18, 19 is arranged equal to sin alpha cos #/sin # cos alpha. Thus lever 25 controls the lift component and lever 31 the tractive component, the latter being arranged so that when the tractive effort is nil the lever is vertical. On account of the low C.G. of the apparatus if lever 31 is rapidly actuated the resulting acceleration will cause a pitching torque to be set up until such time as the thrust is again balanced by the air resistance so that the lever 31 may be employed in a similar manner to the elevator control of a normal aircraft. Where more than two propellers of different inclinations are provided two of them are considered as a single propeller acting in the direction of their resultant and the controls are arranged to act on a single central device controlling at the same time the incidence of both propellers. If movable panels such as 34 are arranged in a propeller slipstream these can be actuated at the same time as the members for controlling the incidence or speed of the propellers, the reaction of the slipstream on the panel combined with the thrust of the associated propeller being arranged to give a resultant which is constant in direction.