The sole Convair NB-36H, fitted with a nuclear reactor.

Convair NB-36H 51-5712 was referred to as the Nuclear Test Aircraft (NTA) and made its first flight on July 20, 1955, at Carswell Air Force Base in Texas, in the hands of test pilot Beryl Erickson. The comparatively small nuclear reactor fitted within it was used only to test radioactive shielding and powered no part of the aircraft. Here it thunders into the air with the crew capsule hatch in the up-and-locked position.

The NB-36H, with the distinctive radioactive warning symbol on the fin, during one of the 47 test flights it made during its successful test programme. The first of these with a fully functioning ASTR was made on September 17, 1955, and the last was completed in March 1957.

The fully pressurised lead-lined crew capsule for the NB-36H weighed some 11 tons. Note the panels installed on the side of the capsule with connection ports for the various control, electrical and hydraulic systems.

The Aircraft Shield Test Reactor (ASTR) and crew capsule ranged in their approximate prospective positions within the NB-36H on test rigs before installation. Note the extensive security measures at bottom left...

The unique role of the NB-36H called for unique ground support vehicles - the tracked vehicle on the left was a heavily shielded crane for the emergency removal of the reactor and the tug on the right was also shielded.

Кабина летчиков самолета NB-36H
A pair of rare photographs of the interior of the NB-36H’s capsule, including a view of the cockpit on the
left and the flight engineer’s station on the right. The capsule was so heavily insulated that the crew reported that
the combined racket of six R-4360 piston engines plus four J47 jets at full pelt was barely audible during take-off.

Convair constructed a large model of the proposed X-6 to demonstrate the various aspects of ground-handling that would be required. This front view of the model shows the bank of four J53 turbojets that would make up the P-1 powerplant, the reactor being given the designation R-1. Note the flattening of the fuselage as it fairs into the powerplant/reactor bay.

A model of the Aircraft Shield Test Reactor installation for the NB-36H. The unit, to be mounted in the massive bomber’s capacious aft bomb-bay, was built by Convair and weighed some 35,000lb (15,900kg). It was configured to be removed from the bomb-bay after each test flight for further ground testing and examination.

As this photograph of a specially-designed handling robot shows, it was intended that all ground-based activities involving the X-6 would be dealt with remotely, as the potential radiation hazards were deemed to be significant. A proposal to use the jet-powered Convair YB-60 was also mooted, but rejected.

Another view of the model, looking forward from the rear fuselage. Note the staggered arrangement of the four J53s, in which the two inner engines are placed further forward than the outer pair. The X-6 would also have required a special pit to have been built for the installation and removal of the 14-ton P-1 nuclear powerplant.

Nuclear-powered flight: step 1, the NB-36H

Nuclear-powered flight: step 2, the X-6