GB346496A - Stall warning device for aircraft - Google Patents

Abstract

346,496. Aircraft instruments. BARROS, J., 66, Craven Park, Harlesden, London. Jan. 31, 1930, No. 3336. [Class 97 (ii).] A device for conveying to the pilot of an aircraft an audible warning of the imminence of stalling conditions comprises an electric bell &c. movement operating on a diaphragm which is arranged to be audible in the pilot's acoustic telephones, the unit becoming operative when a predetermined angle of incidence in relation to the air flow is attained. The bell movement 6, Fig. 1, arranged to operate on the diaphragm 5 of a drum 4, is mounted in a casing 1, tubes 3 to which the drum 4 is fixed being let into the inter-cockpit communication tube 2. The means for controlling the operation of the bell movement in accordance with the combined effects of angle of incidence and air speed comprises a vane 7 carried by a spring metal rod 8 secured to a boss 9 in a tubular member 10 attached to a strut &c. of the machine. The member 10 also carries a rod 13 which is insulated therefrom and carries a wedge-shaped contact-member 12 passing through insulation 11. Under normal conditions of flight the rod 8 is kept out of contact with the member 12 by the pressure of air on the vane 7 but when dangerous conditions obtain, contact is established to operate the movement 6. To prevent contact when the machine is stationary a pivoted member 18 is provided to bear downwardly on the rod 8. This member carries vanes 19 so as to be moved to inoperative position when the machine is in motion. The angular position of the tube 10 &c. can be adjusted by a turnbuckle 16, which can be quickly released at either of the points 17 to enable the tube 10 to be folded.