Boeing B-52 Stratofortress

After completion of acceptance and standard B-52 service tests, the last B-52A (S/N 52-003) was modified as a carrier (mothership) for the North American X-15.

A mounting pylon for the X-15 was installed between the fuselage and the right inboard engine nacelle.

The pylon had mount points to attach the X-15 and service lines which kept the fuel cells (liquid oxygen and hydrogen peroxide) topped off while climbing to altitude.

When preparing for a test flight, the X-15 was mated to the NB-52A on the ground.

The X-15 pilot was sealed into the cockpit on the ground as well.

The NB-52A would typically carry the X-15 to about 45,000 feet and release the aircraft at about 500 mph.

The X-15 would then fire its engines for about two minutes of powered flight followed by 10 minutes of unpowered flight while returning to the landing zone at Edwards Air Force Base, Calif.

One RB-52B (S/N 52-008) was similarly modified and designated NB-52B.

This aircraft was used for the X-15 program, but also was used as a carrier during the lifting body research program.