Six U.S. teams have won contracts to develop concepts and identify technologies for future subsonic and supersonic aircraft to help NASA set its aeronautics research agenda for the next 20 years.

The studies will develop advanced concepts meeting NASA's environmental and performance goals for aircraft that could enter service in 25-30 years - so-called "N+3" designs three generations beyond today's commercial aircraft.

The studies will also support future development of the Next Generation Air Transportation System (NextGen), which will have to evolve to accommodate new classes of aircraft. New designs that fly lower and slower to save fuel, or higher and faster to save time, or operate from short runways to increase airport capacity will all impact air traffic management.

NASA's aeronautics research is aligned with three generations of aircraft: N+1 for entry into service around 2015, N+2 around 2020 and N+3 in 2030-35. Each generation has associated goals for reductions in noise, emissions, fuel burn and field length relative to today's CFM56-powered 737. For N+3, they are an 81-dB. reduction in noise below Stage 3, better than 80% lower NOx emissions, 70% lower fuel burn and the ability to operate from small airports.

These goals were derived from the need to mitigate the environmental impact of a projected 2-3-fold growth in U.S. air traffic by 2030. "We know the N+3 goals are very aggressive, but we can't get there by just evolving incrementally," says Ajay Misra, acting director of NASA's fundamental aeronautics program. "We need to see revolutionary shifts to make it possible."

The six contracts to study advanced concepts are the result of a NASA research announcement designed to elicit industry's ideas for N+3 aircraft able to meet the noise, emissions, fuel burn and field length goals simultaneously. "It will take new concepts, and the integration of new technologies," says Misra. "The idea is for industry to tell NASA to go and invest in these technologies for the future."

Whereas the agency's N+1 research will be completed by 2010-11, ready for industry to begin development of next-generation single-aisle airliners, N+2 and N+3 work is aimed at technologies that are not yet ready for use in product development. N+2 is focused on integrated airframe and propulsion concepts such as hybrid wing-body aircraft offering improved capacity and efficiency. N+3 is looking even further ahead. "If we want to fly in 2030-35, we need to start the pipeline now," says Misra. "That's the reason we needed the N+3 solicitation, to get the ideas on the table."

Of the six Phase 1 study contracts, each worth around $2 million and lasting 18 months, four involve subsonic fixed-wing concepts. Two are for supersonic aircraft, which have their own set of N+3 goals centering on substantial reductions in airport noise and sonic boom. NASA is still drawing up N+2 and N+3 goals for rotorcraft, but similar studies are planned, Misra says.The four subsonic teams are led by Boeing, GE Aviation, the Massachusetts Institute of Technology (MIT) and Northrop Grumman. The supersonic teams are led by Boeing and Lockheed Martin.

In the first phase, each team will develop a future scenario and define advanced concepts, then use these to identify and prioritize enabling technologies. They will assess the risks in these technologies and prepare a road map with tasks and timelines for delivery to NASA to help it set its research agenda.

The teams will focus on different aspects of N+3. GE, with Cessna and the Georgia Institute of Technology (Georgia Tech), will look at small 10-30-passenger aircraft with the short-field performance to operate point-to-point service between small community airports. One of the team's design concepts looks like a Citation Sovereign business jet with open-rotor engines.