Patent GB-1300589-A (GB)
Title: Method and means for opposing the rotation of a windmilling turbojet rotor during flight
Inventor: ROUDIL MAURICE JEAN CLEMENT
IPC: F02K1/60
Filed: 1970-07-08
Abstract: 1300589 Jet deflecting apparatus SOC NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION 8 July 1970 [10 July 1969] 33252/70 Heading B7G [Also in Division F1] A method of preventing windmilling of an inoperative turbo-jet engine during flight of a multi-engined aircraft comprises operating the thrust reversing mechanism to deflect the airflow passing through the inoperative engine and simultaneously throttling the deflected airflow. Each engine includes a pair of members 10 pivotally mounted in the propulsion nozzle 1 so as to be movable by jacks 12 into a position, e.g. shown in Fig. 1a, in which the nozzle 1 is closed-off and the flows F 1 , F 2  through the engine are deflected through channels 7 in a fairing 5. The members 10 are geared together at 11 and are normally operated to provide thrust reversal. To prevent windmilling of an inoperative engine the members 10 are moved into their thrust reversing position and valve 15 is opened to supply compressed air from an operating engine to a container 13 and thence through injection slot 16 to form an air curtain 17 which prevents the deflected airflow from issuing through channel 7. Thus the pressure downstream of turbine 2 increases to such an extent that the turbinecompressor rotor assembly can no longer rotate. In a modification (Figs. 2, 2a, not shown), the air curtain 17 is replaced by a flap (18) slidably mounted adjacent channel 7 in a guideway (19) in fairing 5. For normal thrust reversal a control circuit (100) may link the movement of flaps (18) with members 10 so that when channels 7 are open nozzle 1 is obstructed and vice versa. However this link can be broken by operating a lever (103) so that channels 7 and nozzle 1 are obstructed simultaneously. The flaps (18) may be replaced by inflatable members. In a further modification, Figs. 3, 3a, the vanes 9 in each deflecting channel 7 are supported on a structure 23 pivotally mounted at 24. When windmilling is to be prevented a locking system 27 is released so that structure 23 pivots outwardly under the action of the deflected airflow from the position shown in Fig. 3 to that in Fig. 3a in which the pressures P 1  and P 2  on opposite sides of the structure 23 are equal and the deflected airflow is throttled. A panel 25 is provided to prevent escape of the deflected airflow through gap 26, the panel having at one end a stud 25a slidably engaging a guideway 5a on fairing 5 and at its other end a spindle 25b constrained to move between projections 23a, 23b on the end of structure 23. Panel 25 may be replaced by an inflatable body or by a curtain of compressed air blown out of a container similar to 13 shown in Fig. 1a. The structure 23 can be retracted by rotating a motor driven drum 29 anticlockwise so as to rewind a cable 30 which draws the structure back to the Fig. 3 position. Simultaneously a gear-wheel 28a engages a tooth 27g on rod 27e so as to move bolt 27a into locking engagement with structure 23. In a modification (Figs. 4, 4a, not shown), structure 23 is pivotally moved by an hydraulic jack (33) acting through a bell crank (34a, 34b). The control valves of the jack may be adjusted for the jack to act merely as a damper for the pivotal movement. During normal operation of the engine structure 23 when in its extended position can act as an aerodynamic brake for the aircraft, members 10 in this case being set in the position in which they do not close-off nozzle 1.