GB788787A - Auxiliary power units of the jet reaction type - Google Patents

Abstract

788,787. Jet propulsion plant. NAPIER & SON, Ltd., D. Oct. 13, 1955 [Aug. 17, 1954], No. 23968/54. Class 110 (3). [Also in Group XXXIII] An auxiliary jet propulsion engine for use with a rotary wing system comprising a casing of rectangular cross-section and of streamlined shape except for approximately rectangular inlet and outlet openings has closure members pivoted to two opposite sides of the approximately rectangular inlet and outlet openings so that in the " open " position, the openings are free for the entry of air and the passage of the reaction jet and in the " closed " position they close the openings and form with the casing a substantially closed completely independently streamlined body. A streamlined shape is defined as a shape having low drag at its normal operating speeds. The invention is described with reference to a ram jet unit having a casing 1 of approximately rectangular cross-section disposed with its major axis horizontal in the rotary wing system of a helicopter. The casing has inner and outer walls 2, 3 and, at its inlet end, a substantially rectangular air inlet opening leading through a short approximately parallel or slightly expanding passage 4 formed by the wall 2 into an expanding section 5 constituting the forward end of the combustion chamber 6. The chamber 6 is followed by a contracting outlet passage 7 terminating in an approximately rectangular opening 8. A rectangular flame tube 9 is mounted in the combustion chamber 6. The forward portions of the upper and lower walls of the passage 4 are formed with two part cylindrical recesses 10. Pivoted on a horizontal axis midway between the upper and lower walls of the passage are a pair of closure members 11. When the closure members are in the " closed " position shown, they block the inlet opening and form a substantially cylindrical nose for the casing. When in the " open " position, the flat surfaces of the closure members form part of the inlet opening. Two flap-like closure members 12 are pivoted to the upper and lower edges of the rectangular outlet opening 8. When the members 12 are in the " closed " position shown, the block and the nozzle form part of the faired exterior of the casing 1. The closure members 11, 12 are operated by a servomotor 14. This servomotor is actuated by the supply of fuel to the combustion chamber of the ram jet so that when fuel is supplied to the burners through the conduit 25, the fuel pressure acting through the conduit 24 moves the piston 15 to the right and opens the closure members. The jet propulsion unit may be of the compressor-turbine type.