Honeywell Safran EGTS electric taxy

The appearance of the Electric Green Taxiing System (EGTS) at Le Bourget, added to mounting sales of the competing WheelTug system, indicates growing interest in fuel-saving electric-powered taxiing systems for commercial aircraft. The concept involves fitting electrically driven motors to the aircraft’s wheels which will be used in place of the main engines to taxi. The system takes power from the aircraft’s auxiliary power unit (APU), and is designed to save fuel and emissions, cut direct operating costs, reduce maintenance time, extend engine life and provide environmental benefits.

Unlike the taxi system in development by WheelTug, which uses electrically driven motors in the nose wheels, the Honeywell-Safran system incorporates motors fitted to the main landing gear. In development by EGTS, a joint venture formed between the two companies in 2012, the system could save up to $200,000 per aircraft per year in fuel costs, says Honeywell Product Marketing Vice President and EGTS business manager Jim Fusaro.

“We’ve looked at the mid- to short-haul market, and we think that’s where there is the greatest value,” Fusaro says. Based on the standard taxiing procedures of a typical A320 making a 500 naut. mi flight, the company predicts EGTS will save up to 4% of block fuel costs. Assumptions include an average taxi time of 20 min. with a single engine operating. “We are looking at total system savings, fuel consumption of the APU versus the main engine, the weight of the system and any of ancillary type of benefits, such as savings associated with tug operations, a 2-min. shave off the push-back time, reduced brake wear and less foreign object damage to the engine,” he adds. The system will also reduce carbon emissions by 75% and nitrogen oxide emissions by up to 50%, reducing carbon tax liability at various European airports.

The decision to opt for a system based on the wing-mounted landing gear rather than the nose leg was “predicated on the majority of the aircraft’s weight being transmitted through the main gear,” says Fusaro. Less than 10% of an aircraft’s weight is on the nose gear, so the EGTS team believes its system is therefore better equipped to handle adverse conditions on ground, slopes, snow, ice, and breakaway torque considerations when aircraft “sink” into soft tarmac on hot days.

Honeywell and Safran have combined expertise in avionics, power and landing gear systems into an integrated EGTS designed to accelerate to around 20 kt. in 90 sec., or 18 kt. at maximum take-off weight (MTOW). The system will also be capable of accelerating to 10 kt. in 20 sec. to cross active runways. It will also have the power to achieve breakaway torque on a 1.5% slope at MTOW.

The system will be built into one of the two wheels on each main landing gear unit, providing a 50 kW electric motor per leg. The installation includes power converters to drive the motors using power from the APU, and a reduction gearbox to drive the wheel through a clutch/reaction torque mechanism which is integrated with the brake control. The installed unit is currently expected to weigh around 150 kg per wheel, though “there will always be further optimization,” says Fusaro.

Admin a écrit:
Pour le moment un système qui vient à côté des système de vols, mais on peut imaginer qu'intégrer à la logique de l'avion on puisse utiliser les moteurs électriques pour d'autres parties du roule, et pourquoi pas sur la piste ?, sachant que la puissance des moteurs électriques est surtout définie par des conditions d'échauffement est-ce qu'on peut envisager un effet additionnel aux moteurs au décollage ? et une participation au freinage à l'atterrissage (plus compliqué ça, sauf à travers des supercondensateurs)

audac a écrit:Lancer la rotation des roues avant l'atterrissage pour limiter l'usure des pneus lors du touché.

J'ai un doute sur le bilan avantage-inconvégnents pour l'assistance de la motorisation électrique des roues au décollage.

Speaking at the More-Electric Aircraft 2015 conference in Toulouse earlier this month, Airbus executive vice president for engineering Charles Champion expressed high expectations for the electric taxiing system (EGTS) under development by Safran and Honeywell, for example. “The fuel burn benefit could be three percent on a typical A320 sector,” he said. The program has progressed into the production phase and Airbus has started offering it to customers. “Maturation takes time and we have to demonstrate customers they can use it every day,” he added.

As an example, an A320 at MTOW (Maximum Take-Off Weight) of 78 tonnes would only reach a maximum speed of 12kts. The performance is, of course, better for a lighter aircraft of 69 tonnes at 13.5kts.

Ce dernier prévoit une mise en service « en 2021-2022 », sur des Airbus de la famille A320. Pour développer ce petit moteur électrique de moins de 400 kilogrammes placé sur le train d'atterrissage principal, Safran a en effet travaillé uniquement avec l'avionneur européen. Boeing ne s'est en effet pas montré intéressé. Et pour cause, en raison d'un train d'atterrissage très condensé sur ses B737, il n'y a pas suffisamment de place pour installer un tel équipement.
Proposé en option au prix de 1 million de dollars, l'"E-Taxiing" (pour Electric Taxiing),  comme l'appelle Safran, engendre des économies de la consommation de carburant de 4% sur des vols d'une heure en moyenne, voire un peu moins pour les transporteurs qui font déjà le roulage avec un seul moteur en marche.