Patent GB-568728-A (GB)
Title: Improvements relating to aircraft propulsion means
IPC: B64C11/00
Filed: 1943-04-27
Abstract: 568,728. Propelling aircraft. MERCIER, P. E. April 27, 1943, No. 6653. [Classes 4 and 114] In order to minimise the loss of efficiency of a tractor or pusher aircraft propeller due to the proximity of a wing or engine nacelle, a turbine or fan coaxial with the propeller and operable upon the air that flows past the central part of the propeller, is provided. The propulsion system may be driven through gearing such as to drive the propeller and the turbine or fan in. opposite directions and such that the torque applied to them is in a predetermined ratio. The air upon which the turbine or fan operates may be air that forms the boundary layer that flows over the nacelle or wing, and it may be air that has served for cooling the engine. The turbine or fan may also supply compressed air to the engine. Fig. 1 shows an engine nacelle 1 provided with a pusher propeller 21 and a turbine 17<1> with rotatable blades 17 and fixed entering vanes 20 disposed within a fairing 16. The turbine and propeller are driven by gearing within a casing 13 supported by a frame 14 and surrounded by a body 19. The boundary air layer flowing over the nacelle enters by slots 11, 12 and in part traverses the engine radiators 9, 10. Fig. 2 shows a slightly modified arrangement and the gearing employed. The turbine blades 17 are carried by a wheel 23 keyed to the tubular shaft of a central pinion 41 rotatably mounted on the shaft 30 of the propeller 25, this shaft being keyed to the carrier 40 of planet pinions 39 that engage the pinion 41 and internal teeth on a member 32a driven from the engine shaft 15 through a coupling 33. The shaft 30 is rotatably mounted in the part 32 of the member 32a. Fixed straightening vanes 24 for the turbine and a fixed casing 35 for the gearing are provided. The ratio of the torque applied to the turbine to that applied to the propeller is thus constant, so that, for instance, the speed of the turbine increases if the speed of the propeller is reduced by increasing the pitch thereof automatically, as the speed of the aircraft increases. The turbine and propeller rotate in opposite directions. A brake or a ratchet-and-pawl device 45 may be provided for preventing rotation of the turbine as during " take-off " and there may be a similar locking device for the propeller. According to Fig. 3, a turbine wheel 69 with blades 70 is carried by a tubular member which is rotatably mounted on the main drive shaft 48 and which is integral with the central pinion 66 of the gearing. The turbine also includes straightening blades 72 secured to the fairing 71 and to the nose-piece 76 mounted on and rotatable with the shaft 48. The blades 72 thus rotate in the opposite direction to that of the blades 70. The internally toothed member 64 is secured to the shaft 48 and the planet carrier 61 secured to the hub 58 of the propeller 57 forms a rotatable casing for the gearing. Lubricant supplied under pressure to pipe 51 flows through passage 52 to the gearing and returns by passage 53 and the interior of the shaft 48. A casing 79 also is secured to the propeller hub. An annular space 78a between outer and inner skins 77, 78 of the nacelle serves for the outflow of cooling air which with boundary layer air from the nacelle flows to the turbine. A turbine or fan may also be provided for tractor propellers, in which case the turbine or fan may also be used in a secondary capacity to supply compressed air to an engine supercharger or to a rear propulsive nozzle.