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Home > Fact Sheets > Convair NB-36H "The Crusader"


Posted 6/26/2009 Printable Fact Sheet
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Convair NB-36H
Convair NB-36H in flight. Note the radiation warning symbol on the tail. (U.S. Air Force photo)
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Note: Information on this page comes from a Convair report detailing the development of the nose section of the aircraft from mock-up to installation.

The NB-36H (originally designated XB-36H) was used in the studies and testing of an airborne nuclear reactor. The reactor to be carried aloft was not to be used for aircraft propulsion but primarily for determining many unknown factors pertaining to the effects of nuclear reaction. The NB-36H, named "The Crusader," flew 47 times during the mid-1950s.

Project MX-1589 was carried under two Air Force contracts -- one pertaining to research and development of an airframe and one for the construction of what became the Nuclear Aircraft Research Facility operated by Convair-Fort Worth for the Air Force.

The project was classified until late 1955 when the Department of Defense revealed the existence of the B-36 testbed for an airborne atomic reactor. The nose section of the aircraft had to be completely redesigned and resulted in one of the first uses of a full-scale working mock-up. The nose section mock-up included a hydraulic design feature providing simulation of aircraft take-off position, and detail design of the crew compartment interior duplicating actual aircraft conditions of ventilation, color scheming and other crew comfort and safety factors never before involved in airframe construction.

The XB-36H carried a crew of five: pilot, copilot, flight engineer, and two nuclear engineers. All crew members were located in the forward section of the aircraft while the atomic reactor was located aft. The greenhouse nose of a production B-36H was replaced by a more conventional cockpit arrangement. The new nose section was slightly shorter than the original and the nose landing gear was moved six inches forward to allow for a crew entrance/escape hatch just behind the nose landing gear.

On Labor Day (Sept. 1) 1952, Carswell Air Force Base was struck by a tornado and several aircraft were damaged. These aircraft were returned to Convair for major repairs. In the group was airplane No. 242 (S/N 51-5712), which had lost the nose section of the fuselage. Convair proposed that this airplane be used for the nuclear program, with the damaged nose section forward of Station 5 to be replaced with the nose section and crew compartment then being designed as a mock-up. The proposal was agreed to by the Air Force.

The size of the crew compartment was determined by the total allowable weight of the nose section of a B-36H airplane. In order to lessen the indoctrination, which would otherwise be necessary, the pilot and co-pilot stations were held as closely as possible to the arrangement of the standard B-36. The nuclear engineer stations were designed to incorporate the necessary instrumentation for the reactor operation. Engine scanning normally performed by crew members from the rear of the conventional B-36, had to be taken over by television cameras in the test aircraft. The placement of the television set presented another problem. The set had to be located where the flight engineer could readily see it. Although space was not available at the flight engineer's station, there was room in the overhead area between the nuclear engineers' stations within easy viewing distance of the flight engineer.

The color treatment and lighting arrangement of the interior surfaces were designed to help eliminate as much eye fatigue as possible. A gray color scheme used in the nuclear and flight engineers' compartments, proved unfavorable for the pilot and co-pilot stations. Exterior light passing through the yellow windshield turned the light gray into an unfavorable color. By using lavender, in the pilot and co-pilot compartment, and illusion of gray is achieved.

Type Number built/
NB-36H 1 (cv) Airborne testbed for a nuclear reactor

Armament: None
Engines: Six Pratt & Whitney R-4360-53 radials of 3,800 hp each (takeoff power) and four General Electric J47-GE-19 turbojets of 5,200 lbs. thrust each
Maximum speed: Approx. 420 mph at 47,000 ft.
Cruising speed: 235 mph
Service ceiling: Approx. 47,000 ft.
Span: 230 ft. 0 in.
Length: 162 ft. 1 in. (as B-36H, the NB-36H was slightly shorter)
Height: 46 ft. 8 in.
Weight: 357,500 lbs. (maximum gross weight)
Crew: Five (pilot, copilot, flight engineer and two nuclear engineers)
Serial number:
51-5712 (originally B-36H-20-CF)

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