Patent GB-231482-A (GB)
Title: Aircraft stabilizer
IPC: B64C17/00
Filed: 1925-03-21
Abstract: 231,482. Mazade, M. A. March 26, 1924, [Convention date]. Steering, balancing, and regulating altitude.-A device for stabilizing an aircraft about a transverse or longitudinal axis or for maintaining its altitude or direction comprises a solid movable member adapted to oscillate relative to the aircraft under the influence of accelerations, differences of level, centrifugal effects or tilting movements to control electricallv a servo-motor connected to the control elements of the aircraft, the movable member being also influenced by aerodynamic or aerostatic correcting means. Figs. 1 and 2 show the device as applied to the control of the lateral balance of an aeroplane or other aircraft. A pendulous heavy rim p is suspended from a pin 2 supported by a bracket 3 on the aircraft and may be formed of metal with insulating ends i. Mounted on the same pin 2 is a disc 4 movable by a lever 5 but normally fixed relatively to the aircraft and this disc has two slots 8, 8<1> through which project pins 9, 9<1> mounted on a second disc 10 which can be adjusted relatively to the disc 4 by worm gear 11, 11<a>. Movement of the pendulous rim is damped by dashpots 15, 15' and is further influenced by a lever 1 acted upon by pistons in cylinders 6, 6<1> which communicate with Venturitubes v or Pitot-tubes mounted on the two wing tips of the machine. As the machine tilts one or other of the ends of the metal rim p contacts with one of the pins 9, 9<1> and a circuit is completed which opens the appropriate valve of a pneumatic servo-motor connected to the ailerons. Simultaneously the disc 4 is moved a proportionate amount in the same direction as the displacement of the rim p so that the greater the tilt of the machine the more are the ailerons moved before the circuit is broken. Should the pilot initiate a turn, the device automatically banks the machine, as a result of centrifugal force acting on the rim p, and overbanking is prevented by the differential action of the Venturi-tubes or Pitot-tubes at the wing tips producing a difference of pressure in the cylinders 6, 6'. When used as an incidence stabilizer responsive also to longitudinal and vertical accelerations, the disc 4 is set parallel to the longitudinal axis of the machine and a single cylinder 6<a>, Fig. 11, is employed. The action of the Venturi-tube displaces the rim p as shown, and the pins 9, 9' are adjusted by the worm gear 11, 11<a> until just clear of the rim when the machine is flying horizontally at normal speed. Variations in air speed move the pendulous rim through the Venturi-tube and cylinder 6<a>, whereas pitching movements of the machine and longitudinal and vertical accelerations cause relative displacements of the rim p directly, the elevator being moved appropriately, in each case by the servo motor. When used as an altitude stabilizer an additional cylinder 25, Fig. 15, under initial vacuum is provided with a piston rod butting against an adjustable stop on a part connected to the pendulum. As the external atmospheric pressure falls with increase of altitude a spring in the cylinder 25 forces outthe piston and the pendulum is moved in a direction to effect a reduction in the angle of ascent. The altitude stabilizer may be used independently of the other stabilizers. For maintaining directional stability, the segmental rim is replaced bv a balanced circular rim acted upon by pistons in cylinders connected to Venturi-tubes or Pitot-tubes on the wing tips so that yawing of the aircraft produces a differential pressure and displaces the rim which has contacts for engaging the pins 9, 9<1>. In this case the cylinders can be mounted on a fixed part of the aircraft frame. In all cases the pins 9, 9<1> may be mounted to project across the path of the contacts on the rim instead of being in sliding contact therewith and barometric capsules or bellows may replace the pistons and cylinders. The proportioning or follow up device between the servomotor and the disc 4 comprises a lever on the servo-motor having a block engaging a slot in the lever 5 the position of the block being adjustable by means of a screw in order to adjust the velocity ratio between the parts. The Specification as open to inspection under Sect. 91 (3) (a) comprises an alternative construction of incidence stabilizer in which the Venturi tube is dispensed with, opposed cylinders acting upon the pendulous rim and pressure or vacuum being produced in one of the cylinders which is then closed. This subject-matter does not appear in the Specification as accepted.