GB1254175A - Improvements in or relating to jet propulsion nozzles - Google Patents

Abstract

1,254,175. Jet propulsion nozzles. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. Jan. 20, 1969 [Jan. 19, 1968], No.3231/69. Heading F1J. A jet propulsion nozzle arrangement for a gas turbine or ramjet comprises a primary nozzle formed by upstream pivoted flaps 7, 8 and downstream pivoted flaps 9, 10, and a secondary nozzle comprising flaps 4 pivotally mounted to an annular axially movable element so as to be able to create a divergent portion variable in axial position and gradient. The upstream flaps 7, 8 define a convergent zone and are pivotally mounted at 7a, 8a to axially extending beams 29 spaced around the jet pipe 2. Flaps 7 are controlled by jacks 12, each of which is pivoted at 12b to the adjacent beams 29 and connected by its piston rod 12a to a rocker 11 pivoted to the beams 29 at 11a. Each jack 12 and its rocker 11 are in alignment with a flap 8, though not connected thereto, and the rocker is connected to the flaps 7 on either side of the flap 8 by oblique links 13, 14. This arrangement ensures that all the controlled flaps 7 move in unison while the flaps 8, which circumferentially overlap the flaps 7, follow the movement thereof. The downstream primary flaps 9, 10 are pivoted at 9a, 10a, to the ends of the flaps 8, 7 respectively. The flaps 10 are follower flaps whilst the flaps 9 are controlled by jacks 15, each of which is pivoted at 15a to the adjacent beams 29 and connected through a yoke 16 and oblique links 17, 18 to the flaps 9 on either side of the flap 10 with which the jack 15 is aligned. Thus all the flaps 9 move in unison and can be adjusted through a range of configurations from slightly convergent to divergent depending on the operating conditions. In order to prevent jamming of the flaps 9 when subjected to transverse forces, e. g. resulting from aircraft manoeuvres, these forces are transmitted by way of triangular linkage 20, 21 from the flaps 9 to a ring 22 forming part of the axially movable control element of the secondary flaps 4. Each follower flap 10 carries a torsion bar 19 on its outer surface with arms 19c, 19d engaging the adjacent controlled flaps 9 to ensure that the flaps 10 are always urged into engagement with the flaps 9. The secondary flaps 4 can be moved from their subsonic position, Fig. 1, to their supersonic position, Fig. 2, by axial movement of the ring 22 to which the flaps 4 are pivoted at 4a. This movement is effected by jacks 36, each fixed at one end 36a to the beams 29 and at the other end to an axially movable ring 33 which is connected to ring 22 by way of rails 32 and links 34 having a surrounding fairing 35. The rails 32 are guided for axial movement by rollers 32a co-operating with the beams 29. Ring 22 is connected by links 25 to a series of levers 24 each pivoted at one end 24a to the beams 29 and at the other end 23b to a further link 23 connected at 23a to a heel portion 4b of a flap 4. Thus axial movement of ring 22 causes axial and pivoting movement of the flaps 4.