NASA wants to build a new series of X aircraft to increase fuel efficiency and reduce noise and pollution from commercial jets.
NASA
NASA wants to build a new series of X aircraft to increase fuel efficiency and reduce noise and pollution from commercial jets. After years of flat or declining aerospace research budgets, NASA will aim for a substantial increase for the coming fiscal year and beyond. Agency administrator Charles Bolden will speak more about this request later today at Washington DC’s Reagan National Airport, but Ars has learned the details of the plan.
The proposed $3.7bn (£2.7bn) budget increase over the next decade would allow NASA to work to dramatically improve both subsonic and supersonic flight. In an interview, Jaiwon Shin, the associate administrator of NASA’s Aeronautics Research Mission Directorate, told Ars that the agency is working with industry and academic partners to explore various “revolutionary” technologies. However, to take the next step and actually fly these concepts, NASA needs to build a new generation of X aircraft. And that costs money.
Shin said the design and build phase will take about four to five years, after which the planes will be tested at the Armstrong Flight Research Center in California and the Langley Research Center in Virginia. If successful, these concepts could be incorporated into commercial fleets in about a decade, and through fuel savings, noise and emissions reductions, could save the aviation industry as much as $255 billion (£183 billion) over 25 years, NASA estimates.
Here are some of the concepts we discussed with Shin.
Subsonic flight
One of the most intriguing concepts NASA has worked on is a version of a hybrid-wing aircraft with rear-mounted turbofan engines flanked by two vertical tails. This unconventional-looking aircraft can fly at the same speed as commercial jets, but it has other important advantages.
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This version of a wing-body hybrid aircraft concept has turbofan engines mounted on top of the rear.
NASA/Boeing
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This is a concept for an aircraft design that could produce a low-impact sonic boom.
NASA
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This is another configuration of the hybrid airplane with square engine intakes.
NASA
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A hybrid electric concept that would use electric motors and generators working in tandem with turbine engines.
NASA
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Another form of electric propulsion that NASA wants to test.
NASA
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NASA has already done some work on this Sceptor concept, short for the Scalable Convergent Electric Propulsion Technology and Operations Research.
NASA
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For example, engineers collected aerodynamic data on the integrated experimental test bed without the electric motor’s propellers.
NASA
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In another tech demo, tests were conducted on flaps that can be changed to different angles in flight, reducing drag and noise.
NASA
On the more familiar modern tube-and-wing aircraft, the nacelles, which are mounted under the wings, have grown so large that they generate a lot of drag, Shin said. These nacelles also reach their physical limitations in size, as they almost touch the ground in some aircraft. The new design solves this problem by mounting the engines on top of the fuselage. In addition to reducing drag and enabling larger, high-efficiency engines, this hybrid wing design also incorporates tail shields that muffle aircraft noise.
NASA has seen a reduction in fuel consumption of up to 50 percent, nitrogen oxide emissions reduced by 75 percent and noise levels dropped by 42 decibels when testing high-efficiency engines with this configuration, Shin said. “This aircraft, when actually produced and taking off and landing, will generate noise well within the airport boundary,” Shin said.
NASA also has other concepts, such as electric propulsion, long but narrow wings and double-wide fuselages. They all show promise in computer simulations, but to prove the concepts they need to be built and tested under real flight conditions.
“We’ve been working with the industry all along, but as you know, the industry isn’t really good at taking on high-risk projects,” Shin said. “They are more evolutionary than revolutionary. Government-funded research focuses on high-risk, high-return technologies, and all of these flight ideas are quite risky. We believe it is an appropriate government role to invest in X-plane research to validate the technologies that can benefit the country as a whole.”
Supersonic flight
The X-plane program began in 1945 when NASA’s predecessor, the National Advisory Committee for Aeronautics, designed and built the Bell X-1 in conjunction with the United States Air Force. In 1947, Chuck Yeager would make the first manned supersonic flight in an X-1 over California, reaching Mach 1.06 after a drop launch from a modified B-29 bomber.
However, supersonic flight has remained on the brink of commercial viability. From 1976 through 2003 Concorde flew transatlantic flights for Air France and British Airways, but the program was discontinued due to lack of customers and other problems.
One of the biggest barriers to viability, Shin said, is a complete ban by the Federal Aviation Administration and other international flight agencies on supersonic overland flights due to sonic boom issues. “That’s a big reason why companies don’t enter this market, and until now we didn’t know how to alleviate this sound wave intensity,” he said.
Now, however, Shin said NASA has developed designs that split a large shock wave into several smaller shocks. An example of such a concept is an aircraft with a long, spiky nose that reduces the intensity of the sonic boom reaching the ground. The idea, Shin said, is that people in this “tree carpet” area might hear a little rumble in the background, but not a disturbing thump.
After NASA develops the concept vehicle, the plan is to fly it over developed areas and then poll the general public about the flight. Did they notice the sonic boom? Did it bother them? Survey and scientific data would allow NASA and aerospace companies to approach regulatory authorities about potentially allowing supersonic overland flight under certain decibel limits.
Shin said he’s excited about the opportunity to show these unconventional aircraft designs to the public and fly them over populated areas — once their safety is established. “We can imagine these planes will create a lot of excitement,” he said.
However, the first Congress must act. For fiscal year 2017, the president’s request seeks an increase in the aviation budget from $640 million to $790 million. Congress has prioritized other areas of the NASA budget, such as the large Space Launch System rocket, so it’s not clear it will support this 23 percent increase in aviation funding.