Abstract: An aircraft propulsion power plant for use in an aircraft includes one or more core engines housed in an airframe of the aircraft, one or more secondary propulsion units, each of the one or more secondary propulsion units being removably attached to the airframe, and one or more power transmission means, each of the one or more power transmission means being configured to transmit mechanical power from the or each core engine to a corresponding one of the or each secondary propulsion unit when the or each secondary propulsion unit is attached to the airframe.

Abstract: A spool for turbo machinery comprises a fluid flow path defined by an axial compressor stage adjacent to a mixed flow compressor stage to thereby provide a compression system which has a relatively high ratio of efficiency to compressor diameter.

Abstract: An aircraft propulsion power plant for use in an aircraft includes one or more core engines housed in an airframe of the aircraft, one or more secondary propulsion units, each of the one or more secondary propulsion units being removably attached to the airframe, and one or more power transmission means, each of the one or more power transmission means being configured to transmit mechanical power from the or each core engine to a corresponding one of the or each secondary propulsion unit when the or each secondary propulsion unit is attached to the airframe.

Abstract: A spool for turbo machinery comprises a fluid flow path defined by an axial compressor stage adjacent to a mixed flow compressor stage to thereby provide a compression system which has a relatively high ratio of efficiency to compressor diameter.

Abstract: A bypass turbofan gas turbine engine is started by means of electric starter motor mounted directly about a downstream end or upstream of the low pressure spool of the engine. This causes air to be driven by a fan through a bypass duct around the engine casing. Closures close to substantially seal an outlet of the bypass duct, and the air is directed into a combustion chamber of the engine and through the turbines, causing the high pressure spool to pick up speed for starting.

Abstract: A bypass turbofan gas turbine engine is started by an electric starter motor that is mounted directly about a downstream end or upstream of the low pressure spool of the engine. This causes air to be driven by a fan through a bypass duct around the engine casing. Closures close to substantially seal an outlet of the bypass duct, and the air is directed into a combustion chamber of the engine and through the turbines causing the high pressure spool to pick up speed for starting.