Convair NB-36H

Last updated
NB-36H with B-50, 1955 - DF-SC-83-09332.jpeg
The Convair NB-36 in flight, with a B-50 Superfortress
Role Experimental aircraft
Manufacturer Convair
First flight1955
StatusCanceled in 1961
Primary user United States Air Force
Number built1
Developed from Convair B-36
Developed into Convair X-6

The Convair NB-36H was an experimental aircraft that carried a nuclear reactor. It was also known as the "Crusader". [1] It was created for the Aircraft Nuclear Propulsion program, or the ANP, to show the feasibility of a nuclear-powered bomber. Its development ended with the cancellation of the ANP program.

Nuclear reactor device to initiate and control a sustained nuclear chain reaction

A nuclear reactor, formerly known as an atomic pile, is a device used to initiate and control a self-sustained nuclear chain reaction. Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. Heat from nuclear fission is passed to a working fluid, which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for medical and industrial use, or for production of weapons-grade plutonium. Some are run only for research. As of early 2019, the IAEA reports there are 454 nuclear power reactors and 226 nuclear research reactors in operation around the world.

Aircraft Nuclear Propulsion

The Aircraft Nuclear Propulsion (ANP) program and the preceding Nuclear Energy for the Propulsion of Aircraft (NEPA) project worked to develop a nuclear propulsion system for aircraft. The United States Army Air Forces initiated Project NEPA on May 28, 1946. After funding of $10 million in 1947, NEPA operated until May 1951, when the project was transferred to the joint Atomic Energy Commission (AEC)/USAF ANP. The USAF pursued two different systems for nuclear-powered jet engines, the Direct Air Cycle concept, which was developed by General Electric, and Indirect Air Cycle, which was assigned to Pratt & Whitney. The program was intended to develop and test the Convair X-6, but was cancelled in 1961 before that aircraft was built.

Nuclear-powered aircraft aircraft powered by nuclear energy

A nuclear-powered aircraft is a concept for an aircraft intended to be powered by nuclear energy. The intention was to produce a jet engine that would heat compressed air with heat from fission, instead of heat from burning fuel. During the Cold War, the United States and Soviet Union researched nuclear-powered bomber aircraft, the greater endurance of which could enhance nuclear deterrence, but neither country created any such operational aircraft.


Design and development

The Aircraft Nuclear Propulsion (ANP) program, and the preceding Nuclear Energy for the Propulsion of Aircraft (NEPA) project, worked to develop a nuclear propulsion system for aircraft. The United States Army Air Forces initiated Project NEPA on May 28, 1946. [2] After funding of $10 million in 1947, [3] NEPA operated until May 1951, when the project was transferred to the joint Atomic Energy Commission (AEC)/USAF ANP. [4] The USAF pursued two different systems for nuclear-powered jet engines, the Direct Air Cycle concept, which was developed by General Electric, and Indirect Air Cycle, which was assigned to Pratt & Whitney. The program was intended to develop and test the Convair X-6, a planned prototype for a fully functional nuclear-powered plane. [5]

United States Army Air Forces Aerial warfare branch of the United States army from 1941 to 1947

The United States Army Air Forces, informally known as the Air Force,or United States Army Air Force, was the aerial warfare service component of the United States Army during and immediately after World War II (1939/41–1945), successor to the previous United States Army Air Corps and the direct predecessor of the United States Air Force of today, one of the five uniformed military services. The AAF was a component of the United States Army, which in 1942 was divided functionally by executive order into three autonomous forces: the Army Ground Forces, the Services of Supply, and the Army Air Forces. Each of these forces had a commanding general who reported directly to the Army Chief of Staff.

United States Atomic Energy Commission former agency of the United States federal government

The United States Atomic Energy Commission, commonly known as the AEC, was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President Harry S. Truman signed the McMahon/Atomic Energy Act on August 1, 1946, transferring the control of atomic energy from military to civilian hands, effective on January 1, 1947. This shift gave the members of the AEC complete control of the plants, laboratories, equipment, and personnel assembled during the war to produce the atomic bomb.

General Electric American multinational conglomerate corporation

General Electric Company (GE) is an American multinational conglomerate incorporated in New York and headquartered in Boston. As of 2018, the company operates through the following segments: aviation, healthcare, power, renewable energy, digital industry, additive manufacturing, venture capital and finance, lighting, and oil and gas.

In 1952, the Carswell Air Force Base in Texas was hit by a tornado, severely damaging a number of aircraft. [6] One of the damaged planes was a B-36 bomber, and Convair suggested to the Air Force that it should be converted into an early prototype for the X-6, instead of being repaired. [6] The Air Force agreed to this plan, and provided funding for an overhaul of the plane. [6] The intention was to test flying a plane with a functioning nuclear engine on board, but with it not yet powering the plane at this stage. [5]

Carswell Air Force Base

Carswell Air Force Base is a former United States Air Force (USAF) base, located northwest of Fort Worth, Texas. For most of its operational lifetime, the base's mission was to train and support heavy strategic bombing groups and wings.

The original crew and avionics cabin was replaced by a massive lead- and rubber-lined 11 ton crew section for a pilot, copilot, flight engineer and two nuclear engineers. Even the small windows had 25–30 centimetres (10–12 in) thick lead glass. [1] [7] [8] [9] The aircraft was fitted with a 1-megawatt air-cooled reactor, with a weight of 35,000 pounds (16,000 kg). [10] This was hung on a hook in the middle bomb bay to allow for easy loading and unloading, so that the radioactive source could be kept safely underground between the test flights. [6] A monitoring system dubbed "Project Halitosis" measured radioactive gases from the reactor. [11]

Lead glass variety of glass in which lead replaces the calcium content of a typical potash glass

Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40% lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. Lead glass is desirable owing to its decorative properties.

Project Halitosis was a 1965 undertaking by the United States Air Force to study the amount of radioactive gases released from their experimental nuclear-powered bomber program. The heavily modified NB-36H bomber contained a small, open-circuit nuclear reactor to test the physical and radiological stresses it placed on the airframe and was not used for power. The radioactive gases released from the air-cooled reactor gave the program its "bad breath" reference. The project was part of the U.S. Air Force's Aircraft Nuclear Propulsion project which operated between 1950 and 1967.

Operational history

An underside view of the aircraft Convair NB-36H airplane, the first aircraft to fly with an operating atomic reactor aboard.jpg
An underside view of the aircraft

The NB-36H 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 [12] over New Mexico and Texas. The test flights revealed, that with the shielding used, the crew would not be endangered by radiation from the reactor, including with low-altitude flights, but that there was a risk of radioactive contamination in the event of an accident. [10]

New Mexico State of the United States of America

New Mexico is a state in the Southwestern region of the United States of America; its capital and cultural center is Santa Fe, which was founded in 1610 as capital of Nuevo México, while its largest city is Albuquerque with its accompanying metropolitan area. It is one of the Mountain States and shares the Four Corners region with Utah, Colorado, and Arizona; its other neighboring states are Oklahoma to the northeast, Texas to the east-southeast, and the Mexican states of Chihuahua to the south and Sonora to the southwest. With a population around two million, New Mexico is the 36th state by population. With a total area of 121,590 sq mi (314,900 km2), it is the fifth-largest and sixth-least densely populated of the 50 states. Due to their geographic locations, northern and eastern New Mexico exhibit a colder, alpine climate, while western and southern New Mexico exhibit a warmer, arid climate.

Texas State of the United States of America

Texas is the second largest state in the United States by both area and population. Geographically located in the South Central region of the country, Texas shares borders with the U.S. states of Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the southwest, while the Gulf of Mexico is to the southeast.

In 1957, at the end of its run of flight tests, the NB-36H was decommissioned and scrapped at Carswell. [5] The nuclear reactor was removed. [5] With Cold War tensions increasing in the late 1950s, the US government pushed for development of a heavy bomber with jet engines. [5] Parallel programs of nuclear and conventional aircraft development sought to achieve this goal, but progress on the nuclear plane was slow. [10] President Dwight Eisenhower was not convinced of the need for the program, and he did not assign any urgency to it, although he did maintain funding. [13] By the late 1950s the concept of nuclear-powered planes was increasingly seen by Congress as redundant, given the ongoing advances in supersonic aviation and ballistic missile development. [14]

Cold War State of geopolitical tension after World War II between powers in the Eastern Bloc and the Western Bloc

The Cold War was a period of geopolitical tension between the Soviet Union with its satellite states, and the United States with its allies after World War II. A common historiography of the conflict begins between 1946, the year U.S. diplomat George F. Kennan's "Long Telegram" from Moscow cemented a U.S. foreign policy of containment of Soviet expansionism threatening strategically vital regions, and the Truman Doctrine of 1947, and ending between the Revolutions of 1989 and the 1991 collapse of the USSR, which ended communism in Eastern Europe. The term "cold" is used because there was no large-scale fighting directly between the two sides, but they each supported major regional conflicts known as proxy wars.

Ballistic missile missile that follows a sub-orbital ballistic flightpath

A ballistic missile follows a ballistic trajectory to deliver one or more warheads on a predetermined target. These weapons are only guided during relatively brief periods of flight—most of their trajectory is unpowered, being governed by gravity and air resistance if in the atmosphere. Shorter range ballistic missiles stay within the Earth's atmosphere, while longer-ranged intercontinental ballistic missiles (ICBMs), are launched on a sub-orbital flight trajectory and spend most of their flight out of the atmosphere.

In March 1961, shortly after he took office, President John F. Kennedy canceled the program. [15] In his statement, Kennedy commented that the prospect of nuclear-powered planes was still very remote, despite 15 years of development and expenditure of around $1 billion. [10] The Convair X-6 was never built, [16] and the NB-36H is to date the only American aircraft to carry an operational nuclear reactor. [17] The scientific work carried out for the project did have some lasting value however, including methods for handling liquid metals and fused salts, which aided the development of nuclear generators and reactors used by NASA. [14]


The NB-36H in flight. Note the 2 pods; each was mounted near the wingtips of the aircraft and both carried two GE J47 jet engines each. NB36H-1.jpg
The NB-36H in flight. Note the 2 pods; each was mounted near the wingtips of the aircraft and both carried two GE J47 jet engines each.

General characteristics


See also

Related development

Aircraft of comparable role, configuration and era

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