Electric technology via Rolls-Royce

The use of electric technologies to help reduce civil aircraft weight and cost is becoming an ever greater reality. Mike Howse, Rolls-Royce's Director of Engineering and Technology, says that new systems will work via a fan shaft generator to produce the bulk of the electrical power. He believes electric starting probably will replace traditional air starter systems. New electrical systems will also improve passenger comfort and significantly reduce complexity and redundancy, claims Howse, who has spoken to Bath University and the Institution of Electrical Engineers in the UK about the "More Electric Engine" and "More Electric Aircraft." He believes developments in the area will be vital in delivering a step-change and substantial growth in the aerospace sector.

Howse maintains that to achieve the expected growth in the aerospace sector, new technologies would be required from the industry. "Only through strategic development of electric technologies will the industry ensure that the products of tomorrow deliver the capability required by the customer," he said. "Without these there is a risk that the 'more electric' vision will remain just that: a vision."

Rolls-Royce is already closely involved in electric technology research programs, including the European Union-funded "Power Optimized Aircraft" program that started earlier this year. This program and other European work will lead to the testing of advanced electrical power systems on an aerospace engine and a "partial iron-bird"—a test facility using a simulated aircraft—in 2004.

Over the next five to ten years there will be many long-term research and development programs that will require funding before the technological improvements in aerospace can be realized and reach the market, according to Rolls-Royce.

- Stuart Birch

Eclipsing aircraft avionics

First flight of the Eclipse 500 was expected around the end of August; FAA certification is expected in December 2003.

In July, Eclipse Aviation Corp. announced its Eclipse 500, a six-person, twin-engine jet, was "close to taking flight." The company is hoping to address the needs of point-to-point travel with the new aircraft, which will have access to 10,000 airports in the U.S. According to the company, 70% of all air travelers pass through just 29 airports.

Available exclusively on the new jet—and developed in conjunction with Avidyne Corp., BAE Systems, and General Dynamics— is the Avio intelligent flight system, a comprehensive avionics and aircraft systems management package. Avio's digital electronics are controlled by redundant central computers that monitor and control the aircraft's systems, with the extensive use of data buses allowing large volumes of data to be shared among the system's components. All components are physically separated and powered by separate power buses and sources.

According to Eclipse, the system will replace dozens of cockpit instruments and gauges through the integration of multiple functions of the major systems on the aircraft, including FADEC (full authority digital engine control), the flight management system, communications, autopilot, autothrottle, flaps, trim, landing gear, and environmental systems. The high level of redundancy of all the subsystems will enable the pilot to maintain situational awareness if one—or all—of the electronic components fails. Avio displays one integrated picture of what the aircraft is doing, instead of pieces of information that must be assimilated and correlated by the pilot. The flight controls and brakes are conventional.

Avio captures health-monitoring data from the Eclipse 500's systems to create a history of each system's performance. This feature allows problems to potentially be identified and fixed before a system actually breaks.

The cockpit features active-matrix color liquid-crystal displays that convey attitude, speed, altitude, navigation data, engine parameters, weather depictions, and more.

The company worked with MTS Systems Corp. and Alcoa to develop a high-volume manufacturing process for the aircraft that includes the use of friction-stir welding for the production of thin-gauge aircraft aluminum. Friction-stir welding replaces many of the rivets that would normally be found in the cabin, aft fuselage, wings, and engine mounts of the aircraft. Thousands of rivets have been eliminated on the Eclipse 500, claims the company, resulting in reduced assembly costs and cycle time, improved quality joining, and stronger, lighter joints.

Electronic circuit breakers are used almost exclusively on Avio, which the company claims deliver higher reliability and tighter tolerances than traditional mechanical circuit breakers. The extensive use of smart actuators and proximity switches instead of microswitches enhances the system's reliability.

The Eclipse 500 will be able to fly 355 kt and travel 1300 nmi, or about the distance between Boston and Miami. It is to be powered by an EJ22 turbofan engine with a mass of about 85 lb, while delivering over 770 lb of thrust. The engine is being manufactured exclusively for Eclipse by Williams International and is a commercial version of the FJX-2 engine Williams developed under a $100 million cost-sharing program with NASA's General Aviation Propulsion program. Eclipse predicts that the engine will easily surpass both Stage 3 and 4 noise requirements.

- Jean L. Broge