Posted by John McHale
PARIS, 23 June 2011. An all electric propulsion system called VoltAir from EADS Innovation Works was displayed at the Paris Air Show this week. VoltAir technology follows the philosophy of the zero-emission air vehicle which could come to fruition over the next couple decades, EADS officials say.
VoltAir technology follows the philosophy of the zero-emission air vehicle which could come to fruition over the next couple decades, EADS officials say. It is a project grouped with others under the name of eCO2avia by EADS Innovation Works as part of the EADS Group’s research towards meetign aviation industry’s climate protection goals.
The next-generation electric energy storage system or batteries will power superconducting electric motors that drive counter-rotating, shrouded propellers.
EADS officials say they believe the concept could lead the way towards ultra-quiet and emission-free flying.
"VoltAir is an upstream research concept, not a near-term commercial approach," says Jean Botti, chief technical officer of EADS. "Our research is very forward-looking and could be beneficial in different applications. As a systems architect for aircraft, we are pushing the envelope in this research to stimulate new ideas. The objective here is to push the envelope to move towards more electric, emission free propulsion."
The VoltAir's batteries are integrated in replaceable, containerized units in the fuselage hold to enable an easy replacement of depleted batteries at the airport, similar to the loading and unloading of cargo or luggage containers. Keeping the recharging and maintenance process for the batteries on the ground reduces the system's weight and complexity onboard the aircraft and enables conventional airport operations. Turnaround times are not affected since repowering can be considered to be at least as fast as conventional refuelling.
Conventional electric engines are known to be very efficient -- as much as to 98 percent propulsive efficiency -- but generally do not offer the power densities (energy output per unit weight/kilowatt per kilogram) required for large airborne missions, according to the EADS release. The discovery of High-Temperature Superconducting (HTS) materials provides the key solution for this problem. These materials are the basis for high-energy density superconducting motors that are already becoming available today and which are expected to exceed the weight efficiency of gas turbines as their development progresses. The necessary cooling of these engines to reach superconducting temperature can be realized with low-cost and environmentally friendly liquid nitrogen. In the VoltAir Technology Platform, HTS motors are expected to reach power densities of 7-8 kilowatt per kilogram with almost no electrical losses, according to the company release.