Rolls-Royce has outlined a strategy to vastly increase electrical output on a new generation of aircraft engines with an "insatiable" demand for onboard power supply.

Even as the UK-based company and other engine manufacturers are continuing to focus on reducing specific fuel consumption, noise and emissions of future engines, the power and thermal management of next-generation propulsion systems are also the subject of intense development work.

Rolls-Royce has completed a demonstration programme for a small electric engine that yielded insights into electric power generation and low-cost manufacturing techniques, said Alex Zino, deputy director for the company's defence strategy and business planning.

Speaking at the Unmanned Systems East Asia seminar in Seoul on 21 October, Zino said electric engines will lack the energy density to power large commercial and military aircraft for the foreseeable future - but the technology can be developed to serve onboard power systems.

Electric power needs to become more efficient, as military aircraft add more advanced sensors and solid state radars and come to depend on electro-hydrostatic actuators for better agility, he added.

Part of the firm's strategy involves reaching out to sensor manufacturers. The goal, he said, is to match the aircraft's power supply closer to required loads: "If we can work with the sensor and mission system providers and understand their power needs and power signal requirements, we could provide a more integrated and optimised solution."

Power storage is another long-term need for new aircraft. In aircraft powered mainly by hydraulics, accumulators are able to store energy and distribute extra power at peak loads. That capability is lost with an aircraft power system driven by electricity.

But Rolls-Royce is considering new approaches to the issue of electrical power storage. By mixing fuel cells with gas turbines energy storage will be possible, but the technology is still at the laboratory stage, Zino added.

In the last decade, airframe and propulsion companies have introduced the concept of "more electric architecture" with the Airbus A380, Boeing 787 and Lockheed Martin F-35.

These aircraft use electricity to power engine starters, generators, flight control actuators and an increasing number of onboard applications.

But the efficiency gained from unburdening the power load on the aircraft engine comes with the cost of generating excess heat. Demand for even more onboard electric power is still growing, stressing the limits of the power and thermal management systems of current aircraft.

In the last two years, the Air Force Research Laboratory has launched the integrated vehicle energy technology programme, while European research agencies have funded a power-optimised aircraft concept.

Source: Flight International