New technology tested to find if electric power can propel taxiing aircraft to a greener future
In the Lufthansa/L-3 test, electric motors were installed on an Airbus A320 (photo: Lufthansa Technik)
Fri 16 Dec 2011 – The amount of fuel burnt by aircraft as they taxi to and from the runway, and the resulting emissions and impact on air quality at and around airports, are not inconsiderable and various technologies and operational measures have been applied to avoid engine use as much as possible. New tests have just been carried out on systems that allow aircraft to taxi without requiring the use of aircraft engines. The first system, developed by a partnership involving L-3, Lufthansa and airport operator Fraport, with support from Airbus, integrates electric wheel drives into the main landing gear to propel the aircraft during ground operations. The other, an initiative of Honeywell and Safran, uses the aircraft’s Auxiliary Power Unit (APU) generator to power motors in the main wheels. Both systems also eliminate the need for aircraft pushback and repositioning by tugs and have the added attraction of less noise in the airport environment.
L-3’s Vice President and Executive Program Manager, Joe Hoffman, cites studies that demonstrate single aisle aircraft can burn greater than 3% of total mission fuel during ground operations. The Safran/Honeywell team say short-haul aircraft can burn as much as five million tons of fuel per year and their electric green taxiing system could result in savings of up to 4% of total block fuel consumption.
In the Lufthansa test, high-performance electric motors were installed by Lufthansa Technik engineers on an Airbus A320 and subject to close scrutiny over a one-week period. The wheel-drive technology leverages the motors’ continuous torque and power density to propel the aircraft. Other modifications included the installation of an interface in the cockpit, changes to the power supply system through the APU and integration of a cooling system.
The ‘e-taxi’ demonstrator was then tested under standard conditions involving typical duty cycles that included aircraft pushback as well as taxiing. The partners say they will evaluate the data in order to make a decision on further development of a prototype.
“We are convinced that L-3’s Green Taxi system will provide materially significantly economic and environmental benefits to airplane operators and airport service providers,” said Hoffman.
The first rolling tests have started on the Safran/Honeywell electric green taxiing system, with initial tests taking place in Montpellier, France, on a recently acquired A320. This will serve to evaluate runway conditions and calculate the necessary loads needed for moving the aircraft on the ground. The team is currently focused on prototyping and component level testing prior to targeted system installation and ground testing in 2013.
Each of the aircraft’s powered wheels is equipped with an electromechanical actuator, while power electronics and system controllers give pilots total control of the aircraft’s speed, direction and braking during taxi operations.
Safran is bringing its landing gear expertise to the venture while Honeywell has considerable experience in avionics and APUs. The two partners say that not only does the technology offer fuel and environmental benefits but also improved on-time performance as aircraft equipped with the system will be able to “pushback and go” more quickly, thus reducing both gate and tarmac congestion.
The system, says Safran and Honeywell, will be particularly attractive for airlines that operate high-cycle single aisle aircraft and they are targeting to offer it either on new aircraft or as a retrofit solution to in-service aircraft as early as 2016.
“The start of electric green taxi testing takes us one step closer to bringing this technology to market, and ultimately to helping to save our customers several hundred thousand dollars per aircraft per year,” said John Bolton, President of Honeywell’s Air Transport and regional business.