The Convair X-6 was a proposed experimental aircraft project to develop and evaluate a nuclear-powered jet aircraft. The project was to use a Convair B-36 bomber as a testbed aircraft, and though one

NB-36H The Convair NB-36H was an experimental aircraft that carried a nuclear reactor. It was nicknamed "The Crusader". It was created for the Aircraft Nuclear Propulsion program, or the ANP, to show the feasibility of a nuclear-powered bomber. Its d ...

was modified during the early stages of the project, 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, costing US$7 billion in all, that ran from 1946 through 1961. Because such an aircraft's range would not have been limited by liquid jet fuel, it was theorized that nuclear-powered strategic bombers would be able to stay airborne for weeks at a time.

Development and design

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

Air Force An air force – in the broadest sense – is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an ...

. 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

and was modified to carry a 3

megawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James ...

, air-cooled

nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...

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

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...

and

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

.. 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. After the ASTR was removed from the NB-36H, it was moved to the National Aircraft Research Facility. 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 engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...

. 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 20, ...

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 Idaho National Laboratory (INL) is one of the national laboratories of the United States Department of Energy and is managed by the Battelle Energy Alliance. While the laboratory does other research, historically it has been involved with nu ...

; 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.

Soviet program

In the 1960s, the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...

Tupolev Tupolev (russian: Ту́полев, ), officially Joint Stock Company Tupolev, is a Russian aerospace and defence company headquartered in Basmanny District, Moscow. Tupolev is successor to the Soviet Tupolev Design Bureau ( OKB-156, design off ...

design bureau had its own design for an experimental nuclear-powered aircraft, the

Tupolev Tu-119 The Tupolev Tu-95LAL (russian: Летающая Атомная Лаборатория, translit=Letayushchaya Atomnaya Laboratoriya, lit=flying atomic laboratory) was an experimental aircraft that was a modified Tupolev Tu-95 Soviet bomber aircra ...

, which was a

Tu-95 The Tupolev Tu-95 (russian: Туполев Ту-95; NATO reporting name: "Bear") is a large, four-engine turboprop-powered strategic bomber and missile platform. First flown in 1952, the Tu-95 entered service with the Long-Range Aviation of t ...

bomber A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped from an air ...

with two of its conventional turboprops replaced by nuclear-powered turboprops.

Specifications

References

External links

*
Dream of Atomic-Powered Flight
original published on Aviation History, March 1995.

Section devoted to NB-36H {{X-planes X-006 Cancelled military aircraft projects of the United States X-06, Convair Nuclear-powered aircraft Six-engined pusher aircraft Aircraft with auxiliary jet engines High-wing aircraft X-6