Brussels, 25 Oct 2004
Modern aircraft still suffer from systems that do not consume or distribute power efficiently, a problem that grows more acute with rising on-board operational and passenger demands for electrical energy. The POA (Power Optimised Aircraft) projects aims to achieve a 'more electrical aircraft' that better distributes power and uses it only when needed.
Launched in early 2002, the four-year POA project, whose budget of €99.2 million is jointly provided by the EU and a 45-company consortium, is seeking to improve efficiency in four areas involving aircraft systems: engine, electrical power, actuation and pneumatic. By switching more of these systems or their sub-systems to electrical power, the project aims to save energy and substantially reduce operational costs.
"Simply put, the idea behind POA is to generate, distribute and use power more efficiently," says Lester Faleiro, POA project manager at Liebherr-Aerospace, a Franco-German aerospace company. "An inefficient system is not necessarily one that just wastes energy, but also one that doesn't use energy at the right time."
Smoothing out the power peaks
All the stages of a flight, from take-off to landing, place different power demands on an aircraft's systems: maximum actuator power for manipulating flaps during approach and take-off, or more energy to the air conditioning system when a plane changes altitude. These create peak demands and a distribution of power that is often inefficient.
POA is analysing how to smooth out the peak demands by either reconfiguring the kinds of non-propulsive power systems installed in an aircraft or changing the way electrical energy is used in existing ones. For instance, to function on command, hydraulic and pneumatic systems currently maintain constant pressure levels, which requires constant power. Switching an aircraft's landing gear from hydraulic to electrical power supply would mean limiting energy consumption only to those moments when wheels must be lowered or raised.
Similarly, deploying the flaps on an airplane's wings in a different way could reduce energy peak levels. Instead of lowering all flaps at once, they could be moved into place sequentially: first one set of wing flaps (either those closest to the fuselage or the outlying ones), then the other. This would cut the flaps' peak power demand substantially.
Minimising the trade-off
Switching to a more electrical aircraft is not a win-all solution, however: it does have a price. "Electrical systems are heavier than many of the systems they would replace," explains Faleiro. "But that doesn't mean we can't save fuel."
On the contrary, he says, the constant progress in new electrical component development should allow a future POA aircraft to keep the weight of non-propulsive power systems down at their current levels. "Also, electrical systems tend to be more energy efficient and reliable, and can show potential savings in maintenance. That means energy savings on-board the aircraft and, for the airline, lower operating costs for its fleet in the long-run."
Spreading the technological benefits
With the testing of POA's new equipment scheduled for 2005, Europe's airlines will soon be able to judge for themselves the feasibility of flying a more electrical aircraft. Though the project's reference model is a wide-bodied, 350-passenger, twin-engine aircraft, Faleiro says that some of POA's technologies will be readily transferable to any new aircraft.