Aircraft Geared Architecture Reduces Fuel Cost and Noise NASA Technology modern jet engine with its revolutionary J57 Turbojet, J which was the first to achieve 10,000 pounds of thrust. ust 12 years after the Wright brothers became the In keeping with its record of innovation, in the late first to take to the skies in a powered airplane, in 1990s the company started investing considerable time 1915 Congress established the National Advisory and money into finding a solution to a long-known inef- Committee for Aeronautics to advance aviation. In 1958 ficiency in turbofan engines. the agency was dissolved in order to transfer aeronautics Powering virtually all commercial aircraft today, tur- research to NASA, where space exploration would steal bofans generate thrust by drawing in air at the front with much of the limelight, beginning with the space race a fan. While most of the air goes around the engine, some with the Soviet Union throughout the 1960s and ’70s, passes through it, drawn in by a compressor comprising followed by the Space Shuttle Program’s ascendance in many blades attached to a shaft. The compressor pressur- the 1980s. izes the air, greatly increasing its temperature. The hot Yet throughout all those years the agency has never air is then forced into a combustion chamber where it’s wavered in its commitment to also advance air travel. sprayed with fuel and ignited, resulting in hot, high-pres- NASA has worked hand-in-hand with industry to better sure gas that, as it expands, spins a turbine before blasting commercial flight safety and efficiency, from advancing out of the nozzle at the rear of the engine, thrusting the aircraft body components that increase fuel efficiency to aircraft forward. Because all the engine’s components are developing software that helps air traffic controllers better connected through a central shaft, a rotating turbine not monitor and direct airspace. only drives the low-pressure compressor but also spins the In the mid-2000s, as the nation grappled with spik- fan, providing additional thrust. ing gas prices, NASA established the Subsonic Fixed Now for what Pratt & Whitney chief engineer Wing Project, aimed at helping the private sector Michael Winter calls “the paradox” of modern turbofan advance fuel efficiency and noise-reduction technologies. engine design: fans are more efficient the slower they To do so, the agency would partner with an aerospace spin, whereas turbines become more efficient as they spin company to finish its years-long work on a single, game- faster. “And the problem was that the two components changing technology that would accomplish both goals. have always been attached to the same shaft, so they have Collaborating with the agency would provide the extra lift to spin at the same speed,” Winter says. “We wanted to needed to propel the device onto the commercial market. introduce a gearbox that would allow the fan and turbine to spin at their optimum speeds, the effect being greater Technology Transfer fuel efficiency and noise reduction.” Pratt & Whitney, a company within United NASA and Pratt & Whitney had worked together on Technologies Corporation, has long been a leading numerous projects throughout the years, including the aircraft engine manufacturer. Founded by Frederick development of fuel-efficient, low-pressure-ratio fans Rentschler in 1925, the East Hartford, Connecticut-based through the agency’s Advanced Subsonic Technology firm first came to prominence by developing the Wasp program in the 1990s. (NASA was the first to family of piston-powered engines, which were cooled develop such fans under its Quiet, Clean, Short-Haul In collaboration with NASA, Pratt & Whitney developed its PurePower family of turbofan engines, which are more fuel- by air rather than water. The result was a significant Experimental Engine program in the 1970s.) efficient and quieter than other commercial models. Here, the increase in efficiency and reliability during flight. In the The gearbox presented yet another opportunity for PurePower 1217G engine, developed for Mitsubishi Regional Jet 1950s Pratt & Whitney helped to usher in the age of the collaboration. In 2005 the two entered into a Space Act aircraft, undergoes ground testing in West Palm Beach, Florida. 40 Transportation Spinoff 2015 Pratt & Whitney’s PurePower PW1217G engine on its first test flight over Montreal, Canada. Engines in the PurePower family release 3,000 fewer tons of carbon dioxide into the atmosphere each year while saving airlines roughly $1.5 million in annual fuel costs. Agreement, which allowed tip speeds, creating loud tones. The company has slowed the company access to the fan blades in its GTF to where the noise footprint the agency’s aeronautical has been reduced by up to 75 percent. Not only will experts as well as to NASA the decreased noise pollution benefit communities facilities, including the use of Glenn Research Center’s situated near airports and flight routes; air travel could 9-by-15-foot Low-Speed Wind Tunnel, ice tunnels, and become more flexible and efficient. Airports will be able combustion facilities. In 2010 another NASA program, The GTF engine, in one fell swoop, to consider longer operational hours, and flight routes the Environmentally Responsible Aviation (ERA) Project, improves efficiency by over 15 percent.” designed for noise abatement around intercity airports which also has goals of improving fuel efficiency through can be replaced with more direct routes. noise and emissions reduction, provided additional — Michael Winter, Pratt & Whitney In the coming years, other GTF engine models funding and engine testing. will offer even greater fuel-burn efficiency and After several years spent refining and testing the noise reduction, thanks to the ongoing ERA project gearbox’s lubrication system, alignment, and overall The reduction in fuel consumption per aircraft each collaboration between the company and NASA. A third efficiency to withstand more than 30,000 horsepower, year, Winter notes, translates to 3,000 fewer tons of partner, the Federal Aviation Administration, is also in 2010 the full engine was ready for testing. Transport carbon dioxide (CO2) released into the atmosphere, providing funding and guidance through its Continuous Canada certified the engine in February 2013, and Pratt “comparable to the amount of CO2 displaced by Lower Energy, Emissions, and Noise program. “We’re & Whitney brought to market the PurePower Geared 900,000 trees in the same amount of time.” Nitrogen working together to improve all elements of the engine, Turbofan (GTF) family of engines, designed for use in oxide, a major greenhouse gas and air pollutant, is from the fan and compressor to the combustor and regional and single-aisle aircraft, and to date has more also reduced to 50 percent below the most rigorous turbine, and even some of the external flow around the than 5,500 PurePower engine orders and commitments, standard set by the United Nations’ International Civil nacelle,” Winter says, referring to the housing that holds including options, from more than 50 global customers. Aviation Organization. the engine’s components. Decreased fuel consumption benefits not only the Fay Collier, project manager for the ERA program, Benefits environment but also commercial airlines’ pocketbooks. believes the joint effort has been—and will continue to Over the 60 years that jet engines have been used on “Fuel savings with this technology comes to about be—a success. “I’ve been working with the company commercial flights, fuel-burn efficiency has improved at 1 $1.5 million per aircraft every year,” Winter says. “It’s a for 10 years, and it’s been a very reliable and productive to 1.5 percent every year, says Pratt & Whitney’s Winter. key reason for why we’ve already sold over 5,500 GTF partnership,” he says. “I’m looking forward to helping the “The GTF engine, in one fell swoop, improves efficiency engines to major and regional airline companies all over company push the envelope in the aviation sector even by over 15 percent.” The drastic increase is made possible the world.” further.” by the engine’s turbine and fan spinning at more optimal Another main benefit is noise reduction. The Winter says the agency’s role in advancing commer- speeds, and by increasing the bypass ratio. In other words, annoying whine and piercing roar from current engines cial air transport cannot be underestimated. “The first A incoming air is being routed around rather than through during takeoff have been reduced by slowing the velocity in NASA stands for aeronautics, and the agency brings the engine, which adds thrust to the aircraft without of the exhaust gases exiting the engine and reducing the world-class researchers and facilities to the table. It’s a burning extra fuel. fan rotation speed. Fan blades typically run at supersonic tremendous resource for the industry and the nation.” v Spinoff 2015 Transportation 41