For the last several years the National Aeronautics and Space Administration (NASA) has been challenging the aerospace community to design super efficient next generation commercial airliners that could take to the skies in the coming decades.
The resulting designs – streamlined, bird-like and in some cases ‘space-age’ in appearance – give us a glimpse of what air travel might be like in the future.
In 2008, NASA awarded research contracts to teams led by Boeing, GE Aviation, Northrop Grumman and the Massachusetts Institute of Technology (MIT) to develop subsonic concepts for a generation of aircraft known as N+3 (three generations beyond the current commercial transport fleet), and selected Boeing and Lockheed to develop supersonic concepts for the same 2030-2035 time period.
A key goal of the NASA challenge was for participants to create energy-efficient and environmentally friendly aircraft concepts. “The future of air transportation is all about protecting the environment and responding to increasing energy costs in a balanced way,” said NASA at the time. “We will need airplanes that are quieter and more fuel efficient, and cleaner-burning fuels to power them. We are challenging industry to introduce these new technologies without impairing the convenience, safety and security of commercial air transportation.”
This required designers to focus on exterior design, but considerations such as passenger comfort, cargo space, cost, safety, and compatibility with the Next Generation Air Transportation System (NextGen) could not be ignored, says NASA public affairs officer Beth Dickey.
Accommodating rapid growth in passenger traffic was also a central focus of the challenge. Air traffic has doubled in the past ten years, according to the International Civil Aviation Organization (ICAO), and NASA expects the demand to double again in the next 15 years.
In the subsonic category the team led by Boeing proposed The Subsonic Ultra Green Aircraft Research, or SUGAR, Volt design concept; GE Aviation together with its partners proposed a 20-passenger commercial aircraft design concept; MIT and its teammates offered the “double bubble” D8 design concept (pictured below), which incorporated a roomy passenger cabin; whilst the Northrop Grumman-led group proffered the Silent Efficient Low Emissions Commercial Transport, or SELECT, design concept.
Dr. Marty Bradley, Boeing research and technology principal investigator for the SUGAR project (pictured bottom right), cautions that these types of studies do not represent an offer, commitment or promise on the performance or capabilities of any future Boeing product.
But, he says, the Boeing team came away from the design challenge with insightful takeaways. “One of the key objectives, if not the primary objective, of the SUGAR study is to help NASA determine which technologies have the best potential to improve commercial aviation in the future – in 2030 to 2050. What we have done is give NASA the information on which technologies have high potential and give them a technology plan roadmap that tells them what steps they need to take now to get the technologies ready for applications on future aircraft.”
“Our study has opened up new design space by quantifying potential payoffs of new concepts and aerodynamic structures, systems, propulsion, fuel and operations technologies. In fact, there are more options than we thought when we started. Even though we don’t know for sure which technologies will end up being used in the future, we have greater confidence that we will be able to continue to make significant improvements in each successive generation of commercial aircraft.”
NASA’s Dickey says that phase two of the project – funded research – is underway for the subsonic designs, but that the supersonic designs for 2030-2035 were scrapped due to a lack of resources.
Even so, the industry may see the entrance of supersonic or near supersonic commercial aircraft sooner in the next two decades. In a separate initiative, NASA in 2010 selected teams led by Boeing, Lockheed Martin and Northrop Grumman to study aircraft designs for 2025 (the generation referred to as N+2) and that these could burn 50 per cent less fuel than aircraft that entered service in 1998. Each design had to fly up to 85 per cent of the speed of sound; cover a range of about 7,000 miles and carry between 50,000 and 100,000 pounds of payload, either passengers or cargo. The contracts totalled USD 10.9 million.
Boeing, Lockheed Martin and Northrop Grumman tabled their ideas at the beginning of this year. “In addition to an unconventional flying-wing design from Northrop Grumman, and an innovative Rolls-Royce engine with an extremely large fan powering Lockheed Martin’s box-wing concept, the studies unexpectedly underlined the significant benefits that would accrue from flying advanced airliners within the FAA’s NextGen airspace system…” reported Aviation Week in a January article.
FASTER THAN THE SPEED OF SOUND
Meanwhile, in a May feature displayed on NASA’s web site, Jim Banke of the NASA Aeronautics Research Mission Directorate says NASA’s aeronautical innovators are “one step closer to confidently crafting a viable commercial airliner that can fly faster than the speed of sound, yet produce a sonic boom that is quiet enough not to bother anyone on the ground below”. (See Lockheed Martin’s supersonic concept below).
“The key to this recent advance came when wind tunnel tests of scale model airplanes verified that new approaches to designing such aircraft would work as hoped for when aided by improved computer tools, which were used for the first time together in each step of the design process,” says Banke.
The famous Aerospatiale-BAC Concorde supersonic aircraft, which was retired in 2003, registered a boom noise level that was 105 PLdB (perceived decibel level). “The PLdB that researchers believe will be acceptable for unrestricted supersonic flight over land is 75, but NASA wants to eventually beat that and reach 70 PLdB,” says Banke. Additional studies are under way “to keep whittling away at the supersonic noise challenge” and come up with solutions that will be acceptable to regulatory agencies.
Meanwhile, small supersonic business jets could be launched far sooner. Banke quotes Peter Coen, NASA’s supersonic project manager at Langley Research Center in Virginia, as saying: “The business jet would probably be the first on the market, and that would help introduce some of the technologies that eventually would be used on the supersonic airliner. But such product decisions belong to others outside of NASA.”
Indeed, there have been a variety of mixed reports in recent weeks suggesting that industry players may sketch out details of a supersonic business jet in mid-July at the Farnborough Air Show.