F-22 completes synthetic biofuel flight test

Published March 23, 2011
By Kate Blais
95th Air Base Wing Public Affairs

EDWARDS AIR FORCE BASE, Calif. -- An F-22 Raptor completed a test flight March 18, 2011, on a 50/50 fuel blend of conventional petroleum-based JP-8 and a hydrotreated renewable jet fuel, HRJ. This flight test marked the first time this type of biofuel has been used in a fifth-generation fighter like the F-22.

The flight was the capstone in a series of ground and flight test events conducted by the F-22 Combined Test Force using HRJ in the F-22. The Air Force selected the F-22 weapon system to be the biofuel blend flight test pathfinder for all fighter aircraft.

"The F-22 has a complex engine system, it's different than the generation four and prior fighters," said Robert Hogle, 411th Flight Test Squadron project engineer. "The pilot requests a throttle setting, the engine takes that request, processes it and gives the pilot what the engine thinks the pilot wants."

The overall test objective was to evaluate biofuel fuel blend suitability in the F-22 weapon system.

"It's interesting to test this non-100 percent petroleum-based fuel on an F-22 because its engines are pretty advanced with a lot of computer components and software," said Lt. Col. James Bieryla, 411 FLTS director of operations. "We did a large series of test points. We did a ground test that included a series of start-ups and engine shut-downs and then throttle movements all the way from idle up to maximum afterburner."

Air testing consisted of operability and performance points at different speeds and altitude throughout the flight envelope. The Raptor performed nearly an hour and a half of maneuvers that included supersonic and supercruise test points. Supercruise is reaching supersonic flight without using the engine's afterburner.

"Data is still being analyzed," said Mr. Hogle. "We have yet to completely figure out what the difference (in performance) is between the two [JP-8 and HRJ] types of fuels."

Colonel Bieryla went on to explain that a successful test will ultimately be determined by the data review, which will show components like thrust response and changes in suitability of the aircraft.

"So far all of it looks really good," Colonel Bieryla said. "Certainly from a pilot perspective, there's not a lot of [performance] difference, and ultimately this fuel is going out to the warfighter. Hopefully the warfighter can take this fuel and not see a lot of difference in his or her mission."

According to Colonel Bieryla, the Department of Defense has made it clear that testing biofuels on aircraft is especially important for two reasons: reducing dependence on foreign oil and using less fuel to be more efficient. The Air Force has projected a 2016 goal to cost-competitively acquire 50 percent of the domestic aviation fuel requirement via alternative fuel blends in which the component is derived from domestic sources produced in a manner that is 'greener' than fuels produced from conventional petroleum.

HRJ is a hydro-processed blended synthetic biofuel derived from camelina, a weed-like plant not used for food. The HRJ fuel can be derived from a variety of plant oil and animal fat feedstocks.

In February 2011, Air Force officials certified the entire C-17 Globemaster III fleet for unrestricted flight operations using the HRJ biofuel blend.