GB629170A - Air speed and mileage indicator - Google Patents

Abstract

629,170. Aircraft speed and mileage indicators. BENDIX AVIATION CORPORATION. Aug. 22, 1946, No. 25144. Convention date, Aug. 30, 1945. [Classes 106 (ii) and 106 (iii)] [Also in Group XXXVII] A device for indicating speed and mileage of an aircraft comprises centrifugal means, a member responsive to the difference between static and dynamic or impact air pressure, and means actuated jointly by the pressure responsive member and the centrifugal means to control the speed of rotation of said centrifugal means. A bellows 11, Fig. 1, of an air speed indicator 10 causes through a rack 16, pinion 18, shaft 17 and a pinion 24 up and down movement of a rack 25 connected at its foot to one end of a pivoted lever 26 which at its other end has a contact 28 which co-operates with a contact 36 at one end of a pivoted lever 35, the other end of which is connected by a pin 34 to a slidable flange 33 of a centrifugal ball-governor mechanism 32 driven by an electric motor 30. The arrangement is such that when the rack 25 is moved down by expansion of the bellows 11 the contacts 28, 36 are closed and the motor 30 starts to rotate the governor 32. As soon as the motor speed exceeds the indicated air-speed the contact 36 is withdrawn from the contact 28 by movement of the flange 33 whereupon the motor circuit is interrupted. A speedometer attached to the shaft 31 of the motor 30 will thus indicate average air speed and air mileage is indicated by a suitable device counting the revolutions of the shaft 31. If, as in the embodiment shown and described, the air speed indicator 10 is not density-compensated, a density-compensating bellows 41 is connected through levers 43, 44 to the lever 35. In another embodiment, not shown, an air turbine the supply of which is jointly controlled by the pressure-responsive member and the centrifugal governor drives the centrifugal governor.