F-35B test aircraft BF-17 was flown over Edwards AFB, California, during several recent aerial refueling missions behind KC-135 Stratotanker and KC-10 Extender tankers. The tests involved a drogue adapter attached to the centerline refueling boom on the KC-135 and the hose-and-drogue refueling system on the KC-10.
This particular series of refueling missions in near-dark conditions, which began in late 2014, was to flight test a new prototype refueling probe light. The white prototype light can be seen immediately to the right of the drogue basket in the head-on photo. The twilight conditions were part of a buildup of tests to certify the aircraft for full night flight clearance. During the tests, the boom operator in the refueling aircraft monitored the F-35’s proximity to the boom, the connection with the F-35’s refueling probe to the drogue, and the transfer of fuel once the connection was made.
During the refueling process on the KC-135, the pilot had to fly the F-35 to within five feet of the rigid boom and maintain a close proximity while dealing with the motion of the tanker relative to the F-35. A ninety-degree bend in the knuckle immediately trailing the basket indicates that the F-35 has connected to the basket and is in the fuel transfer zone.