In February, a team of engineers at Arnold Engineering Development Center (AEDC) in Arnold Air Force Base, TN, successfully conducted back-to-back comparative tests between JP-8 conventional jet fuel and a 50:50 blend of JP-8 and Fischer-Tropsch (FT) derived synthetic fuel (synfuel) on a General Electric F110 engine.
The engine was set up with instrumentation to look for any differences in performance and operability between the fuels. Data from the test will be sent to the U.S. Air Force, helping it to certify the engine for future flight using the FT and conventional fuel blend.
Aerospace Testing Alliance (ATA) Project Engineer Andrew Jackson said the synfuel evaluation and certification test is the first on an F110 engine, which powers the F-16 Fighting Falcon.
“We’re building on the experience of the earlier F101 tests and the F100 tests,” he said. “So, we had a pretty good sense of what to expect with this fuel blend. We did a control run with the JP-8 first and then the 50:50 mix of JP-8 and FT fuel. We established a baseline with conventional JP-8, ran through the series of test points, checking the engine performance and particularly the augmenter operability, how well the augmenter lights, we did some screech profiles and looked at the engine response with the JP-8 baseline. Then we switched to the FT fuel blend and repeated the same testing sequence.”
The GE F101 engine powers the B-1 Lancer strategic bomber, and the Pratt & Whitney F100 powers the F-15 Eagle and the F-16.
Based on early indications from the testing, Tom Holland, Systems Engineer managing the project for GE, believes that the USAF can certify the F110 engine for flight testing with the 50:50 fuel blend.
“We still have to analyze all the data and compile a final report, but at this point everything looks good,” he said.
Since 2006, AEDC has taken an active role in supporting the USAF’s Alternative Fuels Certification Office in evaluating and certifying the use of the synfuel, which is derived from natural gas or coal using the FT process, in all USAF aircraft.
The USAF aims to certify its entire fleet of aircraft to use a 50:50 blend of synfuel and traditional petroleum-based jet fuel by 2011.
“This test gets the Air Force closer to its goal of reducing the country’s dependence on foreign oil and developing viable alternative fuel sources,” Holland said. “This type of testing also helps to support the development work on biofuels, like those derived from algae, in terms of where the characteristics of those fuels have similarities to JP-8 or, in this case, the 50:50 blend of SPK [Synthetic Paraffinic Kerosene],” he said. “This will help add to the research database for working toward the evaluation and certification of other alternatives fuels.”
He also said there is a reciprocal vision that military aviation will benefit from research done by commercial industry on biofuels for use in the future.
“The hope is that with advances in the use of other biofuels in commercial aviation we will have a great deal of leverage for similar applications on the military side,” he said.
Holland acknowledged the complexity of jet engine testing in general, saying that high-performance military jet engines present unique challenges.
“Just like with any jet engine testing, this project was no exception,” he said. “The testing required was complex and involved a large amount of support and preparation to be successful. We’re dealing with a lot of sensitive equipment and instrumentation.”
To date, the USAF has evaluated and certified the engines powering the B-52H, C-17, B-1, F-15 Eagle, and F-16 to operate on the 50:50 blend of JP-8 and synfuel.