Taxiing

El Al, WheelTug ink LOI for aircraft drive system

WheelTug and EL AL Israel Airlines (LY) on Monday announced a Letter of Intent (LOI) under which LY will “obtain a substantial part of the initial production of WheelTug Aircraft Drive Systems for Boeing 737NG aircraft for installation on their own aircraft subject to financial and operational feasibility checks and regulatory approvals.” LY is the launch customer for the system.

WheelTug, a ground propulsion system, allows aircraft to have full mobility on the ground without the use of its engines or tugs, for both pushback and taxi operations. The system uses two electric motors, integrated inside the wheels of an aircraft’s nose landing gear, to drive the aircraft forward and reverse, controlled by the pilot. The motors draw electricity from the aircraft’s auxiliary power unit, cutting taxi fuel burn by up to 85%, the Gibraltar-based company said.

The system is being developed initially for the 737NG, but systems for other aircraft models will follow. WheelTug began testing in 2005 with a proof-of-concept demonstration on a 767, and last November conducted a data-gathering test at Prague Airport using test motors mounted on a Travel Service Airlines 737NG. WheelTug expects FAA and EASA certification of its system in the first quarter of 2013.

ElAl launches WheelTug

At the [Vous devez être inscrit et connecté pour voir ce lien] conference in Barcelona today, WheelTug CEO Isaiah Cox announced a launch customer for the WheelTug. (WheelTug is an AirInsight client)

There are two interesting aspects to the Wheeltug story; one is airline operations and the other is the environment aspect.

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ElAl has decided to be the launch customer of the WheelTug system, [Vous devez être inscrit et connecté pour voir ce lien] to equip its fleet of 737NGs.

Airline Operations

• WheelTug’s novel electric motor tackles a critical bottleneck in airport operations. Pushback and taxi requires a ground vehicle to physically push a parked aircraft away from the gate, followed by the crew’s use of main engines to drive the airplane to the runway. After landing, the main engines are used to drive the airplane to an arrival gate.
  
• WheelTug’s system is centered on two powerful electric motors, integrated inside the wheels of an aircraft’s nose landing gear. Controlled by the pilot, the motors drive the aircraft forward and back, from the gate to the runway for takeoff, and back to the gate after landing. The motors draw electricity from the aircraft’s auxiliary power unit (APU), cutting taxi fuel burn by up to 85%.
  
• The WheelTug concept grew out of fundamental research into electric motor efficiency that began in the mid-1990s at Princeton University. “It became clear that our group had developed a methodology that redefined what AC electric motors could deliver,” said CEO Isaiah Cox. “The research team realized that the improved power and reliability of its patented motor technology could bring enormous benefits to aviation.”
  
• Those benefits are dramatic, with WheelTug assessing that a typical Boeing 737NG can directly save over €300,000 ($500,000) annually with the system installed. The company estimates that additional benefits could bring an even larger windfall to cash-strapped airlines.
  
• WheelTug’s began testing with a successful 2005 proof-of-concept demonstration on a Boeing 767 at an airport in Arizona. That led to several years of funding and engineering work to prepare the system for commercialization. Last November, the company conducted a [Vous devez être inscrit et connecté pour voir ce lien] at Prague Airport using specialized test motors mounted on a Boeing 737NG belonging to Czech airline Travel Service
  
• WheelTug’s engineering team is now building its motors into the standard nose wheel for the Boeing 737NG, in preparation for certification tests with regulatory authorities.
  
• WheelTug expects FAA and EASA certification of the system in 1Q13. The company’s first target markets are commercial narrow-bodies operators, but its vision of the future is even larger, encompassing both regional jets and military aircraft.
  

Environmental Impact

• A Boeing 737NG burns an average of 7 kg/minute of fuel during single-engine taxi, “those are the numbers I have to keep in mind,” says WheelTug’s Chief Pilot, Joseph Goldman. “Even if taxi-out is officially expected to take 15 minutes, I may plan for 45 minutes to cover an unplanned slowdown.” That extra 30 minutes of fuel adds over 200 kg of fuel that will usually go unburned. “I hope for a timely departure, and to simply carry that extra fuel to my destination. And usually, that’s what happens.” With WheelTug, however, a pilot’s calculations change. “We can plan around the APU’s fuel burn, instead of the engines’,” says Goldman. “Instead of over 200 kg of taxi contingency fuel, I can load 60 kg, and have the same operational flexibility while taking off more than 140 kilos of dead weight.” This translates into a 70% lower taxi fuel load with consequent on airport improved emissions and lower noise levels. With the European Emissions Trading Scheme coming into force, aircraft operators need a way to keep their engines powered-off when unneeded, and to lower emissions when they’re powered-on. “At current rates, WheelTug will save airlines at least €10 per flight in taxi CO2 fees under ETS.”
  
• Air quality improvements “are very substantial,” according to Aaron Sichel of Wheeltug’s Airports Liaison team, with the company’s analysis projecting major reductions in all taxi emissions. “It starts with taking ground tug emissions out of the mix entirely,” says Sichel. “And then we start with the airplanes themselves. WheelTug will reduce taxi NOx emissions by over 50% compared to single-engine taxi, and over 66% compared to dual-engine taxi.” The same kinds of numbers attend carbon monoxide, the major precursor of ground-level ozone, with an estimated reduction of 65-78%. Unburned hydrocarbons, readily produced by engines at taxi power, will be “reduced by at least 60%.” “Whether it’s CO2, noxious pollutants, noise or jet blast,” says Sichel, “we’re looking at a full-spectrum clearing of the air around airports.”
  

In preparing for the news release, WheelTug demonstrated its technology and numbers to some industry experts who provided this feedback:

• Taxiing without engines “has always been a good idea,” says Tom Ronnell, former Vice President of Sales at Airbus Americas. Now CEO of Ronell Aviation Services, he notes that WheelTug is the first technology capable of turning the idea into a reality. “It’s taken this long for somebody to create an unobtrusive and cost-effective method of accomplishing engine-less taxi.” With such technology finally coming to market, Ronnel predicts strong airline interest in WheelTug adoption. Ronell says those are savings that operators are hungry for. “With the ROI profile projected for this investment, and the reduced fuel burn and carbon emissions, it should be a double-win for the airlines and a break for the environment.”
  
• After designing landing gear for the new Airbus A350 and Boeing 787 Dreamliner, Endeavor Analysis CEO Scott Perkins says his company saw the WheelTug program as an exciting next step. EA joined the WheelTug team in 2010. “It’s an idea whose time has come,” says Perkins, a chief engineer with decades of aerospace design experience. “With WheelTug, we’re using the landing gear itself to enable new levels of aircraft efficiency and safety. That’s new, and it’s quite satisfying to bring that kind of technology to the market.”
  
  
  
  • Other members of the WheelTug team include motor builder Dynetic Systems, gearing designer Gibbs Gears, and aerospace software experts Resource Engineering Projects (REP).
    


• Vice President of Collateral Verifications, an aviation consultancy, Gueric Dechavanne agrees that carriers are ready for the technology. “WheelTug looks to be a great new innovation for today’s challenging airline environment,” says Dechavanne. “The airlines need to focus on becoming more efficient through innovative solutions,” he says, citing growing economic and operational pressures. “WheelTug seems to address that need very well by not only reducing fuel burn, which will always be critical for an airline, but also providing lowered maintenance costs and emissions during taxi.” The result will be “significant savings to any airline utilizing the product.”
  
• Aviation analyst Robert Mann, head of R.W. Mann & Co., agrees that WheelTug should deliver significant revenue benefits to operators. “I expect rapid returns and high ROI” for airlines that adopt WheelTug’s technology, says Mann. “They’ll see improved operational economics and performance, improved reliability and reduced variability.” Mann added that equipping aircraft with WheelTug will “remove a frequent source of delays,” by taking ground tugs out of the pushback equation. Mann foresees “improved departure and arrival punctuality, and reduced block time variance” for operators adopting the technology. Mann sees benefits accruing to everyone with a stake in airline operations. There will be “rapid returns, high ROI, improved operational economics and performance,” for airlines, he says, with “improved reliability and reduced variability” for everyone. “The net result is that WheelTug will be a big win for both airlines and their customers.”
  
• Managing partner at aerospace consultancy G2 Solutions, Michel Merluzeau says “The [WheelTug] system can make a profound impact on aircraft operations worldwide.” He agrees that the operational advantages generated by WheelTug will benefit a wide range of stakeholders. For the majority of carriers, says Merluzeau, “there are near-term tangible benefits that will satisfy airline requirements for more efficient airport ground operations, while also helping airlines reduce their support equipment footprint requirements, thus reducing the environmental impact of aircraft ground operations.” agrees. “With proper procedures in place,” Merluzeau says, “such a system will clearly help airlines and airports reduce fuel and maintenance costs, while also reducing aircraft dependency on support vehicles.” “This system,” Merluzeau says, “is definitely part of a message supporting the use of technology to assist in creating savings for airlines and airports.” WheelTug “is demonstrating that intelligent use of technological solutions will produce far better results than taxation in making air travel more environmentally friendly.”
  

L-3 and Lufthansa get moving with e-taxi demonstrator
Lufthansa and technology company L-3 Communications have conducted taxi trials with an Airbus A320 equipped with electrical motors on both main landing gears (MLG) as part of a feasibility study to gain initial operational experience and data about a MLG-fitted electrical drive system.

The motors and control units were temporarily installed on the aircraft at Frankfurt International airport earlier this week. They are based on existing industrial components manufactured by L-3's Magnet Motor subsidiary in Starnberg, near Munich, and already in use on other applications such as ground vehicles.

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An engineering team comprising staff from Airbus, L-3 and Lufthansa Technik (LHT) replaced the brake assemblies of the inboard MLG wheels with drive units, each one containing a liquid-cooled electrical motor, powered by the aircraft's APU, and planetary gearbox.

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Power supply cables and coolant hoses were installed along the rear of the MLG, across the landing flap trailing edge, upper wing surface and through opened passenger windows into the aircraft's interior.

System control and ancillary equipment was installed in the twinjet's aft cargo compartment, which had been fitted with a special door with two large openings for cooling.

Operational controls were fitted on the flight deck and coupled with the nose wheel steering system. The two drive units were synchronized so that if, for example, the nose wheel was deflected to its 75-degree maximum, the motor on the respective inside wheel was stopped.

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The pilots reported that the demonstrator system not only handled well, but was more responsive than the main engines normally used for the task, said Christian Mutz, project manager innovation at LHT.

The team trialled a broad range of ground manoeuvres, including sustained taxiing up to a maximum speed of 25kph (13.5kts), a 180-degree turn on a 40m-wide (130ft) taxiway, runs on sloped surfaces, and various self-powered reverse movements.

Approximately 40 test points were covered to assess values such as brake away momentum for taxi start from standstill, acceleration, energy consumption, heat development and tyre deformation in different conditions.

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The team varied tyre pressure, switched off one of the two drive units, and trialled taxiing with a fully fuelled aircraft.

Despite strong winds, with gusts up to 70kt, at Frankfurt airport on 7 December, no adverse handling was encountered with the electric taxiing system, said Mutz.

Acceleration values were a key focus particular in regard to crossing runways, for which aircraft usually must have two engines running in case of redundancy.

The flight crew also operated the system while the engines were running. Mutz said that while the powerplants provided sufficient thrust at ground idle to move the aircraft forward, the drive units were still able to reverse the twinjet. This was not only possible along a linear track, but the pilots were able to do S-turns and tight turns, he said.

Mutz added that the team was surprised about how agile and mobile the aircraft had become, and how easily the pilots adapted to the controls.

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The test data will now be evaluated and flow in the specification of a potential electric drive system in the future.

L-3 and Lufthansa Technik are planning to design a system which could be retrofitted to in-service aircraft.

Installation of the demonstrator system took two days before tests began on 6 December. The equipment is currently being removed again, and the aircraft (reg. D-AIZF) is due to re-enter passenger service on 10 December.

Wheeltug plc announced the successful installation and test of the first in-wheel WheelTug® system in Prague on a Germania 737-700. During testing, pilots were able to push the plane back, and taxi without waiting for a tug or powering up the engines. Pilots were able to move the airplane using motors located in the nose wheel powered solely by the aircraft’s APU. WheelTug anticipates savings to be greater than current average airline per-flight profits.

The four day system test was conducted at Prague Ruzyne Airport. The system performed on all pavement types as well as wet and oil-slicked tarmac. You see a short video of the test [Vous devez être inscrit et connecté pour voir ce lien].

“I’m excited about seeing engineless-taxi come to aviation. It was a great honour to be the first pilot to use WheelTug on a Boeing 737,” said Germania Captain Patrick Hintzen. “In particular, there are many delays on push back and it is where the airline has the least control of aircraft. With WheelTug, we are freed from the ‘chains’ that keep us parked at the gate.”

The WheelTug is designed for rapid retrofit. In under two hours, the test system was uninstalled from the Germania 737-700 and the aircraft returned to service. WheelTug remains on target for Entry-into-Service for the 737NG and A320 families of aircraft. 215 WheelTug delivery slots have already been reserved by European, Middle East, and Asian airlines.

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SEVRIEN a écrit:Bonjour, chers tous. Merci, Jeannot.
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Si ceci réussit, ce sera une excellente chose !

Indépendamment de la diminution potentielle de la consommation, et de l'impact environnemental favorable, ceci pourrait permettre de réduire substantiellement l'usure des freins pendant le "taxiing" !

Sevrien a écrit: Autre point :

Un point spécifique : dans l'état de l'art actuel ("in current state of the art") l'architecture à 3 arbres permet une meilleure gestion "at idle" des moteurs, et, par là, une économie au niveau de l'usure des freins.

Pendant le roulage, moteurs à "idle", dans le 'taxi-ing avant décollage', les avancées par petite distances, lorsqu'on est dans la queue, en attente de décollage, et en train de progresser par a-coups vers le décollage, les moteurs à 3 arbres sont plus faciles à gérer / contrôler. Les petits bonds en avant, par a-coup, sont bien moins saccadés que dans le cas de moteurs à 2 arbres. De ce fait, les multiples petits freinages usent moins les disques sous motorisation RB-211 & Trent (3 arbres ) que sous P&W ou GE (2 arbres). Mesures faites sur des dizaines d'années, déjà ! Economies annuelles considérables, au niveau de la flotte, surtout si la flotte est grande (>GB£1 million par an, par gros porteur ; réfléchir aux flottes de BA, Lufthansa, AA, Qantas,…. ) !

Ceci explique, pour partie, pourquoi on continue les recherches sur des moteurs électriques, fonctionnant sur l'atterrisseur du nez, pour aider à conduire l'avion jusqu'à son lieu de décollage, sans faire marcher les réacteurs. On fait des économies de carburant & sur entretien des freins !