The Convair X-6 was an experimental aircraft project to develop and evaluate a nuclear-powered jet aircraft. Experiments were carried out on a testbed aircraft named Convair NB-36H, based on the B-36 bomber. The program was canceled before the actual X-6 and its nuclear reactor engines were completed. The X-6 was part of a larger series of programs that ran from 1946 through 1961, and cost 7 billion

USD The United States dollar (symbol: $; currency code: USD) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it int ...

. The basic idea was that nuclear-powered

strategic bombers A strategic bomber is a medium- to long-range Penetrator (aircraft), penetration bomber aircraft designed to drop large amounts of air-to-ground weaponry onto a distant target for the purposes of debilitating the enemy's capacity to wage war. Unl ...

would be able to stay airborne for weeks at a time, as their range would not be limited by liquid jet fuel.

Development and design

In May 1946, the Nuclear Energy for the Propulsion of Aircraft (NEPA) project was started by the

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. Studies under this program were done until May 1951 when NEPA was replaced by the Aircraft Nuclear Propulsion (ANP) program. The ANP program included plans for Convair to modify two B-36s under the MX-1589 project. One of the B-36s was used to study shielding requirements for an airborne reactor, while the other became the X-6.

Nuclear Test Aircraft

The first modified B-36 was called the Nuclear Test Aircraft (NTA), a B-36H-20-CF (Serial Number 51-5712) that had been damaged in a tornado at Carswell AFB on September 1, 1952. This plane was redesignated the XB-36H, then the NB-36H and was modified to carry a 1

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, air-cooled

nuclear reactor A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...

in its bomb bay. The reactor, named the Aircraft Shield Test Reactor (ASTR), was operational but did not power the plane. Water, acting as both moderator and coolant, was pumped through the reactor core and then to water-to-air heat exchangers to dissipate the heat to the atmosphere. Its sole purpose was to investigate the effect of radiation on aircraft systems. To shield the flight crew, the nose section of the aircraft was modified to include a 12-ton lead and rubber shield. The standard windshield was replaced with one made of acrylic glass. The amount of lead and water shielding was variable. Measurements of the resulting radiation levels were then compared with calculated levels to enhance the ability to design optimal shielding with minimum weight for nuclear-powered bombers. The NTA completed 47 test flights and 215 hours of flight time (during 89 of which the reactor was operated) between September 17, 1955, and March 1957 over

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and

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.. This was the only known airborne reactor experiment by the U.S. with an operational nuclear reactor on board. The NB-36H was scrapped at Fort Worth in 1958 when the Nuclear Aircraft Program was abandoned. Based on the results of the NTA, the X-6 and the entire nuclear aircraft program was abandoned in 1961.

Development plans

Had the program progressed, follow-on aircraft would have been based on the successor to the B-36, Convair's swept-wing B-60.. The X-6 would have been powered by General Electric X-39 engines (J47 engines modified to use nuclear energy as fuel), utilizing a P-1 reactor.. In a nuclear jet engine, the reactor core was used as a heat source for the turbine's air flow, instead of burning

jet fuel Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by Gas turbine, gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for ...

. One disadvantage of the design was that, since the airflow through the engine was used to cool the reactor, this airflow had to be maintained even after the aircraft had landed and parked. GE built two prototype engines, which can be seen outside the

Experimental Breeder Reactor I Experimental Breeder Reactor I (EBR-I) is a decommissioned research reactor and U.S. National Historic Landmark located in the desert about southeast of Arco, Idaho. It was the world's first breeder reactor. At 1:50 p.m. on December 2 ...

in Arco, Idaho. A large, wide hangar was built at Test Area North, part of the National Reactor Testing Station (now part of the Idaho National Laboratory; Monteview) to house the X-6 project, but the project was canceled before the planned runway was built, necessitated by the expected weight of the nuclear-powered aircraft.

Specifications

References

External links