An F-22 Raptor receives synthetic fuel from a KC-135 Stratotanker during an Aug. 28 aerial refueling test using alternative jet engine fuel. The fuel is a 50/50 mix of JP-8 jet fuel and a natural gas-based fuel. The test was done as part of the secretary of the Air Force’s initiative to certify the entire fleet on synthetic fuel, an effort to lessen foreign dependence on oil. (Photo courtesy of Lockheed Martin)