GB814136A - Improvements in or relating to jet nozzles for jet propulsion purposes - Google Patents

Abstract

814,136. Jet propelled aircraft. ROLLS-ROYCE Ltd. March 4, 1957 [March 5, 1956], No. 6925/56. Class 4. [Also in Group XXVI] An aircraft jet propulsion nozzle comprises thrust-reversing means having vanes extending at least partly round the nozzle axis, the vanes being adapted, when operative, to deflect the issuing gas to have radial and forward components and also, for at least some of the gas, tangential components, the resultants of the radial thrusts and tangential thrusts each being zero. In Fig. 1, a divergent conical duct 11 is joined to the jet pipe 10 and contains six equally spaced members 13 each composed of two triangular walls 13a joined together at an acute angle along one side 13c and with sides 13d contacting duct 11. Each member 13 is closed by a sector shaped wall 13b (see also Fig. 3) and contains partitions 15. Apertures 16 equalize the pressures on the sides of each wall 13a. Part of the outlet of duct 11 is blanked off by members 13, which leave intermediate sector shaped openings between walls 13b, and the dimensions are such that the available crosssection of the duct decreases in the downstream direction. The sides 13c at their downstream ends each contact a fixed central tube 14 on which is rotatably mounted a sleeve 17 bearing twelve radial plates 18, alternate pairs of which are bridged at their radially outer-ends by arcuate plates 19 (see also Fig. 3). The ducts 40 so formed are open at each end, and in normal use these ducts are aligned with the spaces between adjacent walls 13b, the gas stream passing straight through as shown by arrows 31. For thrust reversal, sleeve 17 and plates 18 are rotated on tube 14 through thirty degrees, so that the gas issuing from duct 11 passes into the sector shaped spaces between adjacent ducts 40. These spaces contain deflecting vanes 20 and 21. the latter being inclined as shown in Fig. 2, except for the upstream vane, so that the deflected gases have a lateral component of motion. The spaces are blanked off at their downstream ends by walls 22. Fig. 3 shows a pod-mounted engine supported by a strut 24 depending from a wing 23. To avoid deflecting gases onto the wing, the upper sets of vanes 21b are inclined so that the gases follow arrows 41. To balance out non-axial forces, the vanes 21a only deflect the gas forwardly and radially (arrows 42), and the lower vanes 21b deflect the gases as shown by arrows 43. To reduce drag, six members of sector-shaped section normal to the nozzle axis, each formed by radial walls 25, fairing 26, and a wall 28, are secured to tube 14 Fig. 1. Each wall 25 is continued outwardly of the fairing 26 to form an open trough 29. According to the Provisional Specification, each trough 29 may be closed by an outer fairing at the radially outer ends of walls 25 to form a duct. Bridge members 30 extend each wall 25 forwardly and are secured to duct 11. Specification 811,455 is referred to.