Nasa has started a series of flights using a four-engined narrow-body DC-8 airliner 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 involves flying the DC-8 as high as 40,000ft, and a Nasa Falcon HU-25 jetliner trailing behind at distances ranging from 300ft to more than ten miles.
The flight campaign started on 28 February and is expected to take three weeks to complete.
Nasa fixed-wing project manager Ruben Del Rosario said: "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."
Flight operations for ACCESS are being conducted from the agency's Dryden Aircraft Operations facility in Palmdale, California, US and will take place primarily within the airspace over Edwards Air Force Base.
The DC-8's four CFM56 engines will be powered by conventional JP-8 jet fuel, or a 50-50 blend of JP-8 and an alternative fuel of hydro-processed esters and fatty acids that are generated from camelina plants.
Instruments mounted on the Falcon jet will monitor the soot and gases streaming from the DC-8 and the way exhaust plumes change in composition as they mix with air, and study the role emissions play in formation of contrails.
In addition, the falcon jet will trail commercial aircraft flying in the Southern California region, with the assistance from air traffic controllers, to study the exhaust emissions from ten miles away.
ACCESS is a joint project involving researchers at Dryden, Nasa's Glenn Research Center and Langley Research Center; it follows a pair of alternative aviation fuel experiment studies conducted in 2009 and 2011.
A second phase of ACCESS flights is scheduled for 2014, and will build upon on lessons learned from the 2013 flights and include a more extensive set of measurements.
Image: Nasa's flight research campaign on DC-8 airliner is expected to improve understanding of contrails formation and quantify potential benefits of renewable alternate fuels in terms of aviation's impact on the environment. Photo: Carla Thomas / Nasa.