February 6, 2012 — Leaner, greener, and quieter. That’s what NASA is hoping for the future of commercial aviation, and three of the aircraft industry’s largest players spent 2011 figuring out how to make it happen.
Teams from The Boeing Company, Lockheed Martin and Northrop Grumman are studying how to meet NASA goals to develop technology that would allow future aircraft to burn 50 percent less fuel than aircraft that entered service in 1998 (the baseline for the study), with 50 percent fewer harmful emissions, and to shrink the size of geographic areas affected by objectionable airport noise by 83 percent.
"The real challenge is we want to accomplish all these things simultaneously," said Fay Collier, who leads the Environmentally Responsible Aviation (ERA) program for NASA. "It's never been done before. We looked at some very difficult metrics and tried to push all those metrics down at the same time."
NASA awarded nearly $11 million to the three teams to assess what kinds of aircraft designs and technologies could help meet the goals. The companies gave NASA their results in January.
Boeing's advanced vehicle concept centers around the company's blended wing body design as seen in the sub-scale remotely piloted X-48, which has been wind tunnel tested at NASA's Langley Research Center and flown at NASA's Dryden Flight Research Center. One thing that makes this concept different from current airplanes is the placement of its Pratt & Whitney geared turbofan engines. The engines are on top of the plane's back end, flanked by two vertical tails to shield people on the ground from engine noise. The aircraft also would feature an advanced lightweight, damage tolerant, composite structure; technologies for reducing airframe noise; advanced flight controls; hybrid laminar flow control, which means surfaces designed to reduce drag; and long-span wings which improve fuel efficiency.
Lockheed Martin’s engineers proposed a box wing design, in which a front wing mounted on the lower belly of the plane is joined at the tips to an aft wing mounted on top of the plane. The company has studied the box wing concept for three decades, but has been waiting for lightweight composite materials, landing gear technologies, hybrid laminar flow and other tools to make it a viable configuration. Lockheed's proposal combines the unique design with a Rolls Royce Liberty Works Ultra Fan Engine. This engine has a bypass ratio that is approximately five times greater than current engines, pushing the limits of turbofan technology.
Northrop Grumman’s design is a flying wing, championed by Northrop founder Jack Northrop, and reminiscent of its B-2 aircraft. Four high-bypass engines, provided by Rolls Royce and embedded in the upper surface of the aerodynamically efficient wing would provide noise shielding. The company's expertise in building planes without the benefit of a stabilizing tail would be transferred to the commercial airline market. The Northrop proposal also incorporates advanced composite materials and engine and swept wing laminar flow control technologies.
"We'll be digesting the three studies and we'll be looking into what to do next," said Collier.
What the studies revealed is that NASA's goals to reduce fuel consumption, emissions and noise are indeed challenging. The preliminary designs all met the pollution goal of reducing landing and takeoff emissions of nitrogen oxides by 50 percent over engines flying today. However, all still have a little way to go to meet the other two challenges. All the designs were very close to a 50-percent fuel burn reduction, but noise reduction capabilities varied.
The Boeing Company's advanced design concept is a variation on the extremely aerodynamic hybrid wing body. Image credit: NASA/Boeing
Lockheed Martin's concept uses a box wing design and other advanced technologies to achieve green aviation goals. Image credit: NASA/Lockheed Martin
Our ability to fly at supersonic speeds over land in civil aircraft depends on our ability to reduce the level of sonic booms. NASA has been exploring a variety of options for quieting the boom, starting with design concepts and moving through wind tunnel tests to flight tests of new technologies. This rendering of a possible future civil supersonic transport shows a vehicle that is shaped to reduce the sonic shockwave signature and also to reduce drag. Image credit: NASA
Northrop Grumman's concept is based on the extremely aerodynamic "flying wing" design. Image credit: NASA/Northrop Grumman