GB1076188A - Improved stall-correcting apparatus for aircraft - Google Patents

Abstract

1,076,188. Stall correcting apparatus. BRITISH AIRCRAFT CORPORATION (OPERATING) Ltd. March 2, 1965 [Dec. 3, 1963], No. 47701/63. Headings: B7G and B7W. [Also in Division F1] An aircraft has incidence sensing means arranged, when the incidence exceeds a given value, to actuate a stall warning device such as a stick shaker, and afterwards to actuate elevators to pitch the aircraft nose-down. The elevators may be actuated a predetermined time after the warning, to allow the pilot to correct, or at an incidence higher than the warning incidence. The signal to the elevators may be modified by a generator (20) in accordance with variations, e.g. in flap angle. The pilot's elevator control may comprise mechanical links (15) to spring links (18) and power actuated units (16) coupled to the elevators (Figs. 1 and 2, not shown), and the pitch signal from the incidence sensing means (10) may be applied either through an autopilot (19, Fig. 1) or directly (Fig. 2) to lock the spring links (18) and to operate the units (16). In another embodiment (Fig. 3, not shown), two sensors (30, 31) give warning of the approach of a stall and two further sensors (34, 35), are operative at a higher incidence. The sensors (30, 31) actuate relays (44, 45, 49, 50) so that signals from the sensors (34, 35) cause klaxons (46, 47) to be sounded and valves (55, 56) to be opened, permitting compressed gas to flow to a ram (36) to push the control column. Where the aircraft has turbo-jet engines which are liable to flame out at high incidence, the sensors (30, 31) may also operate igniters in the engines. The signals from the sensors are modified by phase advance networks and altitude switches to compensate for rate of change of incidence and for altitude. The ram (Fig. 4, not shown), has two pistons in series the piston (63) having a hollow rod (66) which abuts, and allows compressed nitrogen to pass to, a second piston (69) carrying the actuating rod (70). Thus initially, fluid pressure is applied to both pistons. The travel of the piston (63) is limited by an abutment (68), and then only the piston (69) produces a load on the rod (70), and this is further reduced by a precompressed spring (74). The force applied to the control column is therefore reduced from its initial value to avoid an excessive negative " g " on the aircraft.