Rolls-Royce could equip the future Tempest, intended to replace the Eurofighter Typhoon within the RAF, with an embedded electrical starter generator system for turbine engines. Purpose of the operation: save space and provide the large amount of electrical power required by future fighters. Indeed, “existing aircraft engines generate power through a gearbox underneath the engine, which drives a generator. In addition to adding moving parts and complexity, the space required outside the engine for the gearbox and generator makes the airframe larger, which is undesirable in a stealthy platform”, explained Conrad Banks, Chief Engineer for Future Programmes at Rolls-Royce.

In 2014, Rolls-Royce designed an electrical starter generator that was fully embedded in the core of a gas turbine engine, now known as the Embedded Electrical Starter Generator or E2SG demonstrator program. The launch of the second phase of the project in 2017 saw the inclusion of a second electrical generator connected to the other spool of the engine. It also included an energy storage system in the electrical network and the ability to intelligently manage the supply of power between all these systems. The two-spool mounted electrical machines allows, by combination of operation as either a motor or a generator, the production of a series of functional effects on the engine, including the transfer of power electrically between the two spools.

Throughout the Tempest program, Rolls-Royce will be continuing to mature the electrical technologies demonstrated by the E2SG program, with a third phase of testing likely to include a novel thermal management system being integrated with the overall system.