Patent GB-739105-A (GB)
Title: Variable area jet propulsive nozzle
IPC: F02K1/10
Filed: 1953-05-29
Abstract: 739,105. Jet propulsion nozzles. NATIONAL RESEARCH COUNCIL. May 29, 1953 [June 3, 1952], No. 15044/53. Class 110 (3). A jet propulsion nozzle formed of deformable metal has an outwardly-extending flange around its inlet end and means for bending opposite portions of the flange in the axial direction about not more than two transverse axes within the nozzle to vary the area of the nozzle and flexible connecting means for attaching the nozzle to the jet pipe. The jet pipe 10 is connected to the propulsion nozzle 13 by means of flexible bellows 14. A flange 16 attached to the inlet end of the nozzle 13 is supported from the flange 12 on the jet pipe by means of flexible spacing bolts 17. The bolts 17 are thinned along one dimension and attached to the flange 16 by supports 18 so as to allow them to flex in a direction tangential to the periphery. A portion 10a of the jet pipe slides in the inlet of the nozzle 13 and protects the bellows 14 from the effect of the hot gases. Four stiffening members 19a, 19b are equally and symmetrically spaced around the propulsion nozzle and equally spaced from the spacing bolts 17. The stiffening members are attached to the propulsion nozzle by connecting pieces 20 which embrace the arms 22 of rails 23 fixed to the nozzle so as to allow relative longitudinal movement between them. Levers 24a, 24b are attached to the members 19a, 19b so as to grip the flange 16 between them. Hydraulic cylinders 26a, 26b are attached to the levers 24a, 24b and to stiffening ribs 11 attached to the jet pipe 10. The arrangement is such that when it is desired to deform the outlet of the propulsion nozzle 13 and thus alter its outlet area, hydraulic fluid is supplied to the cylinders 26a so as to force the levers 24a outwardly and at the same time hydraulic fluid is supplied to the cylinder 26b so as to force the levers 24b inwardly. This also causes the portions of the flange 16 between the spacing member 17 to be alternately bent backwards and forwards about axes passing through the members 17. The outlet of the propulsion nozzle is returned to its original form by supplying hydraulic fluid to the cylinders 26a, 26b so that the levers 24a, 24b are moved in the opposite directions. In this arrangement the original form of the propulsion nozzle 13 is a circle and may be deformed into an ellipse. In a modification, the original form is an ellipse which may be deformed into a circle. In a further modification, only two sets of levers and stiffening members are used. In another modification, the propelling nozzle is formed of flexible metal in the shape of a truncated cone having a flange at one end which is encircled by two further truncated cones forming bracing members between the flange and the surface of the propelling nozzle. If desired, cooling air may be supplied to the spaces between the propelling nozzle and bracing members. A convergent-divergent propelling nozzle for supersonic flow is also described. In this arrangement two conical members made of flexible material are arranged to overlap at the throat, and are maintained in axial relationship by diametrically-opposed spring-loaded tierods. The throat of the nozzle is an ellipse which may be deformed into a circle by means of hydraulic cylinders and stiffeners as described above. The stiffeners on the two conical members are connected together at the throat by .a V-shaped linkwork.