In an arrangement for deflecting a propulsive jet forwardly for braking purposes the jet reversal is effected by moving a series of curved blades at the rear end of the jet pipe to intercept the jet stream. As shown in FIG. 1 the jet pipe 10 terminates in an opening in the upper surface 12 of a delta‐wing, the deflecting blades 17 being mounted to form a grille 14 which is normally housed forwardly of the jet discharge opening, but which is movable rearwardly by an electric motor 33 and rack‐and‐pinion gearing 27, 28 into a position where it extends across the discharge opening to reverse the jet. FIG. 2 shows a modification in which the jet is divided into two streams by a wedge shaped vane 109 to discharge through openings 107, 108 in the upper and lower wing surfaces respectively, deflexion of the streams being effected by upper and lower grilles 102, 103. In addition the vane 109 may be rotated about a pivot 140 to deflect the whole of the jet through the upper or lower wing outlet. A similar effect may be obtained without the use of a bifurcated jet pipe by modifying the arrangement according to FIG. 1 to include a downwardly directed branch of the jet pipe 10 opening in the undersurface of the wing and controlling the flow of the jet through this branch by hinged flaps at the junction of the main and branch pipes, and in the undersurface of the wing, respectively. In the case of a circular jet pipe 40, FIG 3, the rear portion of the pipe is cut off along oblique planes 41, 42, and the cut‐away portions occupied by curved vanes 43, 44 hinged about a rear transverse axis 45. The vanes 43, 44 are surrounded by curved blade grills 46, 47 which in turn are enclosed by external plates 51, 52. To effect reversal of the jet the closure plates 51, 52 are first slid forwardly clear of the grilles 46, 47, and jacks 55, 56 are then operated to move the grilles 46, 47 and the tail portion 53 of the jet pipe forwardly, thus causing the vanes 41, 42 to pivot about the axis 45 to obstruct the jet pipe and cause the jet to escape through the grilles 46, 47.
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