Lift/Propulsion engines
7. The lift/propulsion engine is capable of providing thrust for both normal wing borne flight and for lift. This is achieved by changing the direction of the thrust either by a deflector system consisting of one, two or four swivelling nozzles or by a device known as a switch-in deflector which redirects the exhaust gases from a rearward facing propulsion nozzle to one or two downward facing lift nozzles (fig, 18-4).
 |
| Fig. 18-4 Thrust deflector systems. |
8. Thrust deflection on a single nozzle is accom- plished by connecting together sections of the jet pipe, the joint faces of which are so angled that, when the sections are counter-rotated, the nozzle moves from the horizontal to the vertical position (fig. 18-5). To avoid either a side component o! thrust or a thrust line offset from the engine axis during the movement of the nozzle it is necessary that the first joint face is perpendicular to the axis of the jet pipe. If it is desired that the nozzle does not rotate, as may be the case if it is a variable area nozzle, a third joint face which is perpendicular to the axis of the nozzleis required.
