Spirit Testbed

This aircraft, 60-0377, started out as a standard C-135A Stratofreighter. It was converted to the NC-135A configuration when it was adapted to be the B-2 avionics testbed, on which the radar and navigation systems were tested and validated, with over 300 sorties, before the B-2 took to the air. (In some sources, it's referred to as an NC-135A and a C-135E, but there's no indication that these are correct). After the B-2 program came to an end, the aircraft was retired and put into storage at Edwards AFB for eventual restoration and inclusion in the Air Force Flight Test Center Museum.

The C-135A started out as a stop-gap logistical transport that the Air Force bought to use until the C-141 Starlifters came on line. After an initial three were converted from KC-135s by having their refueling booms removed, the Air Force bought fifteen production Boeing 717-157s which they designated as C-135A (yes, Boeing has indeed re-cycled the 717 designation). A 1966 view of 60-0377 can be seen here.

In this undated photo, 377 flies over the U.S. Borax Mine that sits just north of Edwards and Rogers Dry Lake. The mine, which opened in 1957, is the largest open-pit mine in California and the largest borax mine in the world.