Patent GB-337698-A (GB)
Title: Improvements in helicopters
IPC: B64C27/26
Filed: 1930-02-10
Abstract: 337,698. Trojani, P., (Assignee of Ascanio, C. d'). Feb. 9, 1929, [Convention date]. Helicopters; propelling; controlling. -A helicopter comprises at least two co-axial propellers the blades 12 of which can be tilted about their longitudinal axis of gravity 15 and are also freely movable about an axis which is at rightangles to and passes through the axis of rotation of the propellers and is perpendicular to axes 15. Tail wings 18 secured to the blades 12 are so disposed that the centre of pressure of the combined wing is in proximity to the axis 15 and the tail wings of one or both propellers are fitted with hinged elevators 19, Fig. 3, operable by the pilot to vary the incidence of the blades 12. This movement of the blades about their longitudinal axes may be damped by means of hydraulic shock-absorbers. An engine 2, Fig. 1, drives a vertical shaft 5 at high speed through a clutch 3 and gearing 4. A tubular shaft 8 carried by bearing 9, 10 mounted in a fuselage 1 surrounds shaft 5 and carries the wing arms of the lower propeller on hinge pins 17 and at the upper end a gear wheel 11 which forms the annulus of an epicyclic gear train of which the sun wheel 6 is mounted on shaft 5 and planet wheels 7 on shaft 8. The wing arms of the upper propeller are hingedly connected to the annulus 11. A free wheel device may be interposed between motor and blades. Resilient stays 27 are connected to the blades at points in advance of their axes 15. The blades 12 may be rigidly or resiliently interconnected as shown in Fig. 4. Longitudinal and directional control is effected by two variable pitch propellers driven from the engine 2 through bevel gearing 23, 24, respectively; one propeller 20 mounted aft rotates on an axle parallel to shaft 8, the second is carried by a shaft extending laterally from the fuselage and rotates about a horizontal axis parallel to the longitudinal centre line of the machine. A third propeller may be symmetrically disposed on the other side of the machine. Control of the elevators 19 and of the pitch of the auxiliary propellers is effected by a single handwheel 39, Fig. 5, which is secured to a column 38 rotatablv mounted in a forked lever 37. Lever 37 is pivotally mounted' on a bracket 35 which is adapted to rock about a transverse axis 34 parallel to the pivotal axis 36 of lever 37; the latter is therefore capable of a rocking movement fore and aft and of an upward and downward movement; the first of these movements controls the pitch of the tail propeller and the second, the incidence of the elevators 19. The laterally disposed propeller is controlled by rotation of the hand wheel shaft. Bell-crank levers 60 operating elevators 19 through bell-crank levers and rods mounted in the wing arms and blades, are pivotally mounted on a spindle 59 secured at the upper arm of a bell-crank lever 57, the lower arm of which is linked to a collar 55 co-axial with shaft 8 and controlled by up-anddown movements of the handwheel 39. Vertical arms of bell-crank levers 60 are connected to the elevator-operating mechanism and the horizontal arms are grooved to slide on pins 61 secured to rods 62 slidably mounted in brackets 63 secured to shaft 8 and located by springs 64. The rods are connected to the wing arms by cables 72 arranged so that excessive upward movement of the latter causes the pins 61 which normally serve as fulcra for the bell-crank levers 60 to move upwardly with the rods and rotate levers 60 about the spindle 59 so as to actuate the elevators in such a way as to reduce the incidence and lift of the wing blades and consequently their inclination.