Members of the J-2 test team at the Arnold Engineering Development Center on the grounds of Arnold AFB, Tenn., have set a record by running a Pratt & Whitney F135 engine continuously for 52.5 hours, the longest period that this engine type has run uninterrupted. The team accomplished this feat while conducting altitude-performance and qualification tests of the F135, which is one of the two powerplants currently under development for the F-35 strike fighter. The qualification testing had to do with the initial service release of the F135 engines that will be used in the Air Force’s F-35A aircraft and the Navy’s F-35C carrier variant. (Arnold report by Janae’ Daniels)
PHOTOS: Air Force Shows B-21 Refueling Tests with KC-135
April 15, 2026
The Air Force released new photos of the B-21 Raider conducting aerial refueling tests with a KC-135 Stratotanker—confirming a key milestone in the new long-range strike bomber’s development and offering a rare glimpse of the secretive aircraft’s features.