HAMPTON, Va. – NASA researchers have just completed a series of flights that studied the effects of alternate biofuel on engine performance, emissions and aircraft-generated contrails at altitudes typically flown by commercial airliners.

The Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) experiment involved flying a NASA Dryden Flight Research Center DC-8 airplane as high as 39,000 feet while an instrumented HU-25C Guardian aircraft, based at NASA’s Langley Research Center, trailed behind at distances ranging from 300 feet to more than 10 miles. The team measured exhaust composition and contrail characteristics depending on fuel type, plume duration and atmospheric conditions.

“We spent several weeks during late winter when contrails are most likely to form over NASA Dryden in California,” said Bruce Anderson, ACCESS project scientist. “That way we could take advantage of Dryden’s restricted air-space to fly in close formation without interfering with commercial air traffic. This let us vary aircraft separation to examine the changes that occur in exhaust plume composition as they mix in the air. It also allowed us to study the role aircraft soot emissions and conditions play in the formation and growth of contrail ice particles.”

Reporters are invited to check out the equipped HU-25C jet and talk to Langley researchers Thursday, April 25, at 9:45 a.m. Please RSVP to Kathy Barnstorff by 5 p.m. Wednesday,April 24, at 757-864-9886/344-8511 or by e-mail to kathy.barnstorff@nasa.gov. Video and stills of flight tests are available on request.

During the flights, the DC-8’s four CFM56 engines were powered by conventional JP-8 jet fuel, or a 50-50 blend of JP-8 and an alternative fuel of hydroprocessed esters and fatty acids (HEFA) produced from camelina plant oil. More than adozen instruments mounted on the Guardian jet characterized the soot, gases and ice particles streaming from the DC-8.

ACCESS follows a pair of Alternative Aviation Fuel Experiment studies conducted in2009 and 2011. Ground-based instruments measured the DC-8’s exhaust emissions as the aircraft burned alternative fuels while parked on a ramp in California.

A second phase of ACCESS flights is planned for 2014. It will capitalize on lessons learned from this year’s flights and include a more extensive set of measurements.

The ACCESS study is a joint project involving researchers at Dryden, NASA’s Glenn Research Center in Cleveland and NASA Langley.

The Fixed Wing Project within the Fundamental Aeronautics Program of NASA’s Aeronautics Research Mission Directorate manages ACCESS.

For more information about aeronautics research at NASA, visit: http://www.aeronautics.nasa.gov