GB663952A - Improvements in and relating to automatic control devices for aircraft power plants - Google Patents

Abstract

663,952. Jet propulsion plant. LEDUC, R. Dec. 13, 1948 [Dec. 12, 1947], No. 32159/48. Class 110(iii) [Also in Group XXIX] Means for automatically controlling the thrust developed by an aircraft power plant so as to maintain constant at a value selectable in flight the mach number corresponding to the aircraft's true air speed comprises a power control device such as a fuel regulating valve, two ele- 'ments such as the aneroid capsules 1, 2. respectively responsive to the static pressure P 0 of the ambient atmosphere and the total ram pressure p 1 , a lever 7 to which mutually opposed forces proportional to the pressure p 0 , p 1 are applied, manually controlled means for varying the leverage of these forces about the lever pivot 8, and a connection 9 between the lever and the power control device operable so as to decrease or increase the thrust developed according as the moment applied to the lever by the ram-pressure responsive element exceeds or is less than that applied by the static pressure responsive element. The invention is especially applicable to high speed aircraft propelled by thermopropulsion ducts including "athodyds'' or " ram-jets " and " impulse ducts ". Thus in Fig. 2, the aneroid capsules 1. 2, are situated in chambers 3, 4 fixed to the aircraft and operate through rods 5, 6 on a lever 7 pivoted at 8. One end of the lever is connected through a link 9 to means for adjusting the fuel valve. The preselected value of the pressure ratio may be adjusted by movement of the pivot 8 so as to vary' the ratio of the lever arms x, y. Fig. 3, shows a modification in which the length of the lever arm x is changed by angular adjustment of the capsule 2. The lever 7 is cranked in this case, and the capsules 1, 2 act on opposite sides of one arm, the rods 5, 6 having a common pivot 10, 11. The chamber 4 and its capsule 2 are mounted in a stirrup 13 manually adjustable about a pivot aligned with the pivot 10, 11 in the equilibrium position of the lever by a link 12. To allow for movement of the pivot 10, 11 the chamber 4 is mounted on a bracket 32 pivoted on the stirrups at 33. The link 9 is connected to the fuel valve as before. Increased sensitivity is provided by a spring 15 which assists any movement of the lever 7 away from the equilibrium position. In each modification, the link 9 controls a fuel valve through a fluid-pressure servomotor, Fig. 4 (not shown) (see Group XXIX).