GB895051A - Improvements relating to helicopters and their propulsion means - Google Patents

Abstract

895,051. Driving helicopter rotors. MERCER, A. C. June 8, 1959 [June 6, 1958], No. 18077/58. Class 4. [Also in Group XXVI] A helicopter comprises jet propulsion means located at or near the rotor blade tips, compressed air for the jet propulsion means being supplied from a compressor driven through simple spur gearing by the rotor. In the Figure, framework 11 on the fuselage structure 12 supports a housing 13 from which extend a hollow shaft 14 supporting the rotor head 22, and a coaxial inner shaft 15 driving the impeller of a compressor 21 the casing of which is secured to the rotor head. Shafts 14 and 15 are drivingly connected by spur gearing 18, 17, and a twin belt drive 19, 20 Hollow blades 25 are mounted on the rotor head about pitch change and flapping axes, and the interiors of the blades leading to tip jet combustion chambers, are connected by flexible tubes 26 to the compressor outlets 21a. Fuel is supplied to the combustion chambers by a pipe system 29 including a rotary gland 30 in housing 13, and sparking plugs for starting the tip jets are energized through slip rings 31 in housing 13. On energizing an electric starting motor 16 connected to gear 17, the rotor is rotated through gear 18 and shaft 14, and the compressor impeller is driven in the opposite direction through the belt drive 19, 20, and shaft 15. As the compressor starts to deliver compressed air to the tip jets, the latter can be started up, and maintain the rotor, which then drives the compressor. Motor 16 can then function as a generator. Means may be provided to disconnect the compressor drive from the rotor, for use when autorotation is necessary. It is stated that variations in fuel supply to the tip jets are automatically followed by suitable corresponding variations in the compressed air supply. The rotating impeller also has a stabilizing effect by gyroscopic action.