Wednesday, August 14, 2013

The Future of the Aircraft Industry Is Quiet and Electric

Remember the first time you sat at a stoplight in your car with the window open near a hybrid or electric vehicle? While you may not have been paying close attention, it was probably the sound — or lack of it — that gave it away. In the near future, this silence may be heard in a new place: on an airplane.
While the idea of electric airplane systems isn’t new, it’s only lately that the aviation industry has been showing some strides that may soon leap out of concept aircraft and into passenger planes. This year’s Paris Air Show showcased several electric technologies that are nearly ready for primetime.
Most of the new innovations involve electric taxiing systems that allow grounded aircraft to taxi without using their engines, saving fuel and emissions and reducing airport noise. One of the most prominent is the Electric Green Taxiing System (EGTS) prototype demonstrated by development partners Honeywell and Safran.
The system uses an aircraft’s auxiliary power unit generator to power motors on its main wheels, allowing the plane to pushback and taxi without starting the main engines. One wheel on each main gear is equipped with an electric motor, reduction gearbox, and clutch assembly. Power electronics and system controllers allow pilots to control the plane’s speed and direction during taxiing.
The system’s developers say the ETGS can save airlines between 2 and 4 percent of total block fuel consumption per flight, which would translate to savings of as much as $200,000 per aircraft each year. Beyond those savings, it can also reduce total flight time and ease airport congestion, Brian Wenig, vice president of the EGTS program for Honeywell Aerospace, told IMT.
“EGTS allows the pilots to autonomously pushback from the gate and taxi to the runway without the use of tugs and other ground-handling equipment, even in tight spaces,” said Wenig. “This allows them to complete the process faster than they can today. Ground crews can also load and perform checks right up until the final moments before push-back without the safety concerns of at least one running engine at the gate. All this could reduce overall taxi time by as much as two minutes.”
While two minutes may not seem like much, multiplied by thousands of flights a day, it could yield a real bump in efficiency. The system also saves wear and tear on aircraft tires: traditional taxiing with the aircraft’s main engines requires pilots to continually brake against the thrust, which is hard on tires.
Honeywell and Safran, together with new development partner Air France, say their testing has evaluated the system in various load configurations and runway conditions, through a series of complex maneuvers, such as pushbacks, tight turns, and U-turns, according to varying specifications of acceleration and speed.
“The next major milestone of the testing program is to conduct these same maneuvers with the aircraft at maximum takeoff weight,” Wenig told IMT. “We expect to begin full scale development in 2014 ahead of market entry in 2016.”
Another entry to watch in this space is Israel Aircraft Industries’ hybrid-electric diesel TaxiBot system, which has two diesel generators that provide power to electric motors on an aircraft’s wheels, allowing the plane to reach normal aircraft taxiing speed of up to around 23 knots. IAI says this normal taxiing speed is what differentiates TaxiBot from slower-moving rival systems.
The TaxiBot system, which is undergoing testing and is expected to be available to the commercial market by 2015, has huge potential in terms of fuel savings, particularly with larger planes. IAI notes that a Boeing 747 taxiing for 17 minutes burns about 1,250 liters (330 gallons) of fuel. With TaxiBot, the same process would require only 30 liters (8 gallons) of fuel and emit far less carbon dioxide.
While electric taxiing systems are interesting, what about an all-electric airplane? While the idea has been around, mostly in concept aircraft, since the 1970s, Cessna is currently engaged in an interesting experiment: a fully electric plane, the Cessna 172, designed by Beyond Aviation and using advanced lithium batteries built by Panacis. In testing, say the companies involved, the plane performed admirably.
All-electric passenger aircraft are still an idea of the future, despite breakthroughs and niche markets such as battery-powered unmanned drones. Designing a safe battery scaled down to reasonable size and weight but still capable of powering a passenger aircraft will be the greatest challenge. Panacis reported that the prototype airplane performed for over a year with no significant battery issues and no degradation in capacity or performance. Still, costs for such batteries will remain prohibitively high for years. Analysts say an all-electric aircraft future is more than 20 years off.
“If developments go according to plan, all-electric commercial aviation could take off by 2035 to 2040,” said Alix Leboulanger, aerospace and defense analyst for consulting firm Frost & Sullivan. “Therefore, it’s the right time to start thinking of new electric infrastructures for airports, electric storage areas, new airplane support in service, and power by the hour bespoke deals.”
For now, said Leboulanger, the commercial market will be primarily focused on not only taxiing systems, but on using electrical innovations to replace aircraft pneumatic and hydraulics systems to make planes lighter and faster, and mechanical problems easier to pinpoint and fix.