GB745649A - Improvements in or relating to aircraft reaction-propulsion units and installations - Google Patents

Abstract

745,649. Jet-propelled aircraft. ROLLS-ROYCE, Ltd. Jan. 19, 1954 [Jan. 22, 1953; Nov. 20, 1953], Nos. 1943/53 and 32323/53. Class 4. [Also in Group XXVI] An aircraft reaction, propulsion unit or installation comprises a jet pipe terminating in a nozzle, porting in the wall of the pipe upstream of the nozzle leading to auxiliary ducting discharging to atmosphere along a line inclined forward to the direction of flight to produce a braking effect, and at least one valve member swingable about an axis at right-angles to the jet pipe axis and passing therethrough and adapted in a first position to close off the auxiliary ducting and in a second position to block the flow through the pipe to the nozzle. As shown in Fig. 1, a jet engine 21 installed in an aircraft structure 20 terminates in an exhaust cone 24 leading to an upstream portion 23 of a jet pipe and a downstream portion 25 ending in a nozzle 22. A two-part outer casing 26, 27 provides a cooling air flow passage 28. A partspherical portion 30 connects the parts 23, 25 and is provided with two diametrically opposed ports 31 leading to ducting 32 containing guide vanes 34 to assist deflection of the jet when braking is desired. A cylindrical casing 35 partly surrounds spherical portion 30 to join the upstream and downstream portions of passage 28. Two valve members 36 (Fig. 2) consist of part-cylindrical walls stiffened by ribs 37 and occupy similar apertures in the jet pipe wall, portions 23 and 25 being continued as at 43 towards the hinge axis 61 of the valve members. The downstream edges 39 are contained in planes passing through the hinge axis, the upstream edges 38 in planes passing near it. The edges are flanged as at 40, 44 to co-operate with sealing strips 42, 45 in the position shown, and flange 40 co-operates with a sealing strip 47 when the members 36 extend each half-way across pipe 25, the downstream edges 39 then being in contact together, being preferably flexible braided metallic strips. In an alternative embodiment, Figs. 6-9 (not shown), the valve members 36 are part spherical, of such radius as to lie wholly outside the imaginary cylinder geometrically continuing pipe portions 23 and 25 when the valve members block the auxiliary ducts 32. In this case, the upstream portion 23 may be continued within the spherical wall part 30, as in Figs. 10 and 11 (not shown), almost to meet the portion 25, leaving sufficient space for the valve members 36 to swing about their hinge from the position wholly outside the continuation, blocking the auxiliary ducts, to the position blocking pipe 25. Ports must be cut in the continuation to align with those, 31, in the wall part 30. In a further embodiment, the part spherical valve members 121, Fig. 17, have within them part-cylindrical walls 122 secured by ribs to the part-spherical walls 123. Flaps 115 pivoted at 115A may be provided in the aircraft structure, and opened by servomotors 126 when the discharge is directed through the auxiliary ducts. The nozzle may be of variable area and comprise two portions 125 movable about a common hinge axis as shown. One method of mounting the hinge axis of valve members 36 is shown in Fig. 16, each member 36 being secured to a sector 62 having a flange 91 working in a groove in a collar 93 of a cone member 94 secured to wall portion 30 by screws 95. A double cone member 96 also secured by screws 95 forms a bearing for concentric shafts 99, 100 having inner levers 101, 102, and outer levers 56a, 56b, each attached to one member 36 and one of the rods 57 respectively. Nuts 99a, 100a, locate the shafts 99, 100, axially, and a bolt 105 has a blanking plate 106 at one end to prevent outward flow of gas, and is secured by a nut 105a. The two rods 57 (Fig. 1) are operated by a servomotor 58, the rod of which is guided by rollers 59 and guides 60 to ensure equal movement of the two valve members. The strain produced on the valve members by deflection of the gas into the auxiliary ducts 32 may be taken up by rods 107 extending between screws 95 and the aircraft structure. An alternative method of operating the members is shown in Fig. 15, where a bracket 88 on the member is connected by a link 87 to the rod 86b of a ram 86. The servomotors used may be hydraulic or electric.