“It flew like a usual A-10 would without any issues,” said Major Olivia Elliott, an A-10 pilot and an evaluator for the mission.
The A-10 Thunderbolt II is a single-seat, twin-engine, straight-wing aircraft. In combat, they are used as Close Air Support (CAS) platforms and provide support to ground forces by attacking tanks, armored vehicles and other ground targets.
The fuel known as Alcohol-to-Jet (ATJ) is cellulosic ethanol. It can be derived using wood, paper, grass, or anything else that is a cell-based material. The sugars extracted from these materials are fermented into alcohols, which are then hydro-processed into the high grade kerosene used for aviation fuel.
“The A-10 is an excellent platform for testing the new fuel due in part to its segregated fuel system,” said Captain Joseph Rojas, an A-10 test engineer. “The system allows one engine to run off a fuel supply that is completely segregated from the other engine. This allows us to fly with one engine on the new fuel and the other on traditional fuel. If engine operation is normal, as with the ATJ blend, then we progress to flying with both engines on the new fuel.”
An A-10C Thunderbolt II flies over Eglin Air Force Base, Fla., marking the first flight of an aircraft powered solely by Alcohol-to-Jet fuel. Credit: Air Force Photo/Samuel J. King.
ATJ is the third alternative fuel tested by the Air Force for use as a replacement for JP-8 aviation fuel which is derived from petroleum. The Air Force has also explored a synthetic paraffinic kerosene derived from coal and natural gas and a bio-mass fuel derived from plant-oils and animal fats known as Hydroprocessed Renewable Jet.
“Eventually, it is possible that aircraft will see JP-8 consisting of all these alternatives,” said Jeff Braun, Chief for the Air Force Alternative Fuel Certification Division, at Wright-Patterson Air Force Base in Ohio. “You won’t be able to determine the difference and you won’t care because all perform as JP-8.”
Renewable chemicals and advanced biofuels company, Gevo Inc. provided the Air Force Research Laboratories with the ATJ fuel.
“We’re extremely proud to have witnessed and contributed to the USAF’s first and only ATJ test flight,” said Gevo Inc. Chief Operating Office and President Chris Ryan. “Last week’s test flight represented an accumulation of more than 4,000 hours of hard work involving innovative testing, multiple players and years of research on everyone’s part. Together, we have proven that ATJ fuel is a technically viable and promising alternative for both military and commercial applications.
“This is a great accomplishment for the USAF, Gevo and the biofuels industry. We’ve validated that ATJ from isobutanol is a clean burning, homegrown, drop-in jet fuel. The USAF’s flight has taken the industry one step closer to full commercialization. We remain committed to commercialization and believe we have the most economic route to deliver aviation biofuels at scale.”