NASA and Centennial Challenge partner organization, the Comparative Aircraft Flight Efficiency, or CAFE, Foundation of Santa Rosa, Calif., are encouraging aerospace enthusiasts to attend the Green Flight Centennial Challenge, set to be held at the Sonoma County Airport in Santa Rosa from Sept. 25 to Oct. 1.

Teams from across the United States will test electric, biofueled and hybrid-powered aircraft, vying to be the most fuel-efficient small aircraft in the world. They're competing for a competition purse of $1.65 million - the largest aviation prize ever offered.

Competitors will tackle a fuel efficiency competition Sept. 27 and a speed competition Sept. 29. To win the fuel competition, an aircraft must fly 200 miles in less than two hours, using less than one gallon of fuel per occupant, or an equivalent amount of electricity. If more than one aircraft meets that criteria, the competitor whose aircraft delivers the best combination of speed and efficiency will take home the prize, according to the competition guidelines.

The Green Flight Challenge's winning aircraft must exceed a fuel efficiency equivalent to 200 passenger miles per gallon (pax mpge). In comparison, typical general aviation aircraft have fuel efficiencies in the range of 5-50 pax mpge. Large passenger aircraft are in the 50-100 pax mpge range.

The winning aircraft also must achieve an average speed of at least 100 mph over a 200-mile race circuit; take off from a distance of less than 2,000 feet to clear a 50-foot obstacle; and deliver a decibel level below 78 dBA at full power takeoff, as measured from a 250-foot sideline.

The Green Flight Challenge also marks the first time in history that full-scale, electric-powered aircraft will fly in competition. This competition will include the first four-seat, electric aircraft ever to fly, as well as the largest battery pack ever developed for a flight vehicle.

Thirteen teams led by America innovators initially took on the challenge. Five successfully completed aircraft and flight qualification requirements and remain in competition for the prize purse.

Ten of the competing aircraft, including many of those still in competition, will be on display Saturday, Oct. 1, at Sonoma County Airport from 9 a.m. to 4 p.m. PDT. The public is invited to visit the competition area during the week of Sept. 26 - Oct. 1 between 10 a.m. to 4 p.m.

The focus of the Green Flight Centennial Challenge is to advance technologies in fuel efficiency and reduced emissions with cleaner renewable fuels and electric aircraft. Such technologies and innovations include,

+ bio-fueled propulsion;

+ breakthroughs in batteries, motors, solar cells, fuel cells and ultra-capacitors that enable electric-powered flight;

+ advanced high lift technologies for very short takeoff and landing distances;

+ ultra-quiet propellers;

+ enhanced structural efficiency built on advances in materials science and nanotechnology;

+ and safety features such as vehicle parachutes and air bags.

The Green Flight Challenge is one of five current NASA Centennial Challenge technology prize competitions. The program, which began in 2005, is named in recognition of the first centennial anniversary of powered flight, and honored the legacy of the Wright Brothers and other American innovators. In the spirit of their endeavors, the Centennial Challenge prizes are offered to independent inventors who work without government support, including small businesses, student groups and individuals.

The prize competitions are targeted at a range of technical challenges that support NASA's missions in aeronautics and space. The goal is to encourage novel solutions from non-traditional sources. In the Centennial Challenge program, NASA provides the prize money and each of the competitions is managed by an independent organization.

NASA's Office of the Chief Technologist in Washington and the Marshall Space Flight Center in Huntsville, Ala. manage the Centennial Challenges program. Additional competition details and travel information may be found at the CAFE website.