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Alternative Fuel Effects on Contrails and Cruise Emissions

NASA researchers conducted a series of flights using the agency's DC-8 flying laboratory to study the effects of alternate biofuel on engine performance, emissions and aircraft-generated contrails at altitude.

The Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) research involved flying the DC-8 as high as 40,000 feet while an instrumented NASA Falcon HU-25 aircraft trailed behind at distances ranging from 300 feet to more than 10 miles.

"We believe this study will improve understanding of contrails formation and quantify potential benefits of renewable alternate fuels in terms of aviation's impact on the environment," said Ruben Del Rosario, manager of NASA's Fixed Wing Project.

ACCESS flight operations were staged from NASA's Dryden Aircraft Operations Facility in Palmdale, Calif., and took place within restricted airspace over Edwards Air Force Base, Calif.

During the flights, the DC-8's four CFM56 engines were either 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 that comes from camelina plants.

More than a dozen instruments mounted on the Falcon jet characterized the soot and gases streaming from the DC-8, monitored the way exhaust plumes change in composition as they mixed with air, and investigated the role emissions play in contrail formation.

ACCESS followed a pair of Alternative Aviation Fuel Experiment studies conducted in 2009 and 2011 in which ground-based instruments measured the DC-8's exhaust emissions as the aircraft burned alternative fuels while parked on the ramp at the Palmdale facility.

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

ACCESS took place in February-April 2013 in Palmdale, California.