Nuclear aircraft

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A nuclear aircraft is an aircraft powered by nuclear energy. Research into them was pursued during the Cold War by the United States and the Soviet Union as they would allow a country to hypothetically keep nuclear bombers in the air for extremely long periods of time, a useful tactic for nuclear deterrence. Neither country created any nuclear aircraft in production numbers. One design problem, never adequately solved, was the need for heavy shielding to protect the crew from radiation poisoning.

Unmanned missiles have been designed to use nuclear thermal rockets, but such designs were considered too dangerous for crews or to actually fly.

[edit] U.S. programs

[edit] NEPA and ANP

Main article: Aircraft Nuclear Propulsion

A US nuclear bomber design by Convair. The nuclear reactor powers the two engines at the rear, used for cruising flight. The two engines at the front are conventional engines, used only for extra power during takeoff and a "dash" to the target.

In May, 1946, the Nuclear Energy for the Propulsion of Aircraft (NEPA) project was started by the Air Force. Studies under this program were done until May, 1951 when NEPA was replaced by the Aircraft Nuclear Propulsion (ANP) program. The ANP program included provisions for studying two different types of nuclear-powered jet engines, General Electric's Direct Air Cycle and Pratt & Whitney's Indirect Air Cycle. ANP also contained plans for two B-36s to be modified by Convair under the MX-1589 project, one of the B-36s was to be used to study shielding requirements for an airborne reactor while the other was to be the X-6. The program was cancelled before the X-6 was completed, however.

The Idaho National Laboratory conducted research to produce a nuclear powered aircraft. Two General Electric turbofan engines were successfully powered to nearly full thrust using two shielded reactors. The two engines complete with reactor system are currently located at the EBR-1 facility south of INL.

The U.S. designed these engines to be used in a new specially designed nuclear bomber, the WS-125. The WS-125 was eventually terminated by Eisenhower who cut NEPA and told Congress that there was no urgency for the program. Eisenhower did back a small scale program developing high temperature materials and high performance reactors. That program was terminated early in the Kennedy administration.

[edit] Project Pluto

Main article: Project Pluto

In 1957, the Air Force and the U.S. Atomic Energy Commission contracted with the Lawrence Radiation Laboratory to study the feasibility of applying heat from nuclear reactors to ramjet engines. This research became known as Project Pluto. The engines being developed under this program were intended to power an unmanned cruise missile, called SLAM, for Supersonic Low Altitude Missile. The program succeeded in producing two test engines which were operated on the ground. On May 14, 1961, the world's first nuclear ramjet engine, "Tory-IIA," mounted on a railroad car, roared to life for just a few seconds. On July 1, 1964, seven years and six months after it was born, "Project Pluto" was cancelled.

[edit] Soviet programs

[edit] Russian Nuclear Bomber hoax

The 1 December 1958 issue of Aviation Week included an article, Soviets Flight Testing Nuclear Bomber, that claimed that the Soviets had made great progress in their own nuclear aircraft program.^[1] This was accompanied by an editorial on the topic as well. The magazine claimed that the aircraft was real beyond a doubt, stating that "A nuclear-powered bomber is being flight tested in the Soviet Union. Completed about six months ago, this aircraft has been flying in the Moscow area for at least two months. It has been observed both in flight and on the ground by a wide variety of foreign observers from Communist and non-Communist countries." Unlike the US designs of the same era, which were purely experimental, the article noted that "The Soviet aircraft is a prototype of a design to perform a military mission as a continuous airborne alert warning system and missile launching platform."

Photographs illustrated the article, along with technical diagrams on the proposed layout. They were so widely seen that one company produced a plastic model aircraft,^[2] a surprisingly faithful rendition of the diagrams in the article.

Concerns were soon expressed in Washington that the "the Russians were from three to five years ahead of the US in the field of atomic aircraft engines and that they would move even further ahead unless the US pressed forward with its own program".^[3] This led to continued funding of the US's own program, for a time.

In reality the entire article was a hoax. The aircraft in the photographs was later revealed to be the entirely conventional Myasishchev M-50 Bounder, a medium-range strategic bomber with performance similar to the USAFs B-58 Hustler. The design was considered a failure and never entered service. The design was revealed to the public on Soviet Aviation Day in 1963 at Monino, putting the issue to rest.^[4]

[edit] Tupolev Tu-95 LAL

It was later learned that the Soviets did have a nuclear aircraft program, but like its US counterpart, it was entirely experimental. On 12 August 1955 the Council of Ministers of the USSR issued a directive ordering bomber-related companies to join forces in researching nuclear aircraft. The design bureaus of Andrei Tupolev and Vladimir Myasishchev became the chief design teams, while N.D. Kuznetsov and A.M. Lyulka, were assigned to develop the engines. They chose to focus on the direct cycle system from the start, testing ramjets, jet engines and even turboprops.

The Tupolev bureau, knowing the complexity of the task assigned to them, estimated that it would be two decades before the program could produce a working prototype. They assumed that the first operational nuclear-assisted airplane could take to the air in the late 1970s or early 1980s. In order to gain experience with the operational problems, they proposed building a flying testbed as soon as possible, mounting a small reactor in a Tupolev Tu-95M to create the Tu-95LAL.^[5]

The reactor was fit in the bomb bay of the aircraft, although it did not fit cleanly and a "bump" was put on top as well. It had 2 conventional turboprop engines and 2 experimental 'dirty' direct cycle jet engines powered by a minimally shielded nuclear reactor in the main fuselage. Between May and August 1961, the Tu-95LAL completed 34 research flights. Most of these were made with the reactor shut down. The main purpose of the flight phase was examining the effectiveness of the radiation shielding which was one of the main concerns for the engineers. Massive amounts of liquid sodium, beryllium oxide, cadmium, paraffin wax as well as steel plates were used for protection. The results were promising; radiation levels were low enough to consider continuing development.

But, as in the US, development never continued past this point. The obvious potential of the ICBM made the expensive program superfluous, and it was scaled back. Several proposed designs have since surfaced, although whether or not these are any more real that the original AvWeek story is questionable. Examples include a Tupolev design that looks like an enlarged F-104 Starfighter with two engines in the rear, and a Myasishchev design, the M-60, that looked much like the M-50Bounder.^[5]

[edit] In Fiction

In science fiction, the concept of nuclear powered vehicles was readily adopted, but after the feasibility studies in the USA during the 1960s, imaginative concepts took on a very tangible form.

Perhaps the most 'practical' imaginary vehicles to embody the principles of NEAP, were the Thunderbirds vehicles of Gerry Anderson. Thunderbird 1 is perhaps the best example, where it is a hypersonic, variable geometry rescue interceptor. In a cutaway drawing prepared for an accompanying comic book, Thunderbird 1's propulsion is by a hybrid gas-turbine/ramjet not unlike the engine system of the SR-71 Blackbird. The heat exchangers of a Thorium Sodium dual-circuit reactor serve as the thermodynamic element of the system - and water injection serves to produce the vehicle's spectacular on-screen pyrotechnics.

There are innumerable other examples in science fiction of NEAP systems.

[edit] See also

• Georgia Nuclear Aircraft Laboratory
• Huemul Project

[edit] References

[edit] External links

• Short overview of the NB-36 programme
• Molten salt reactor experiment (initially intended for aircraft propulsion)
• Descriptions of the Tu-95 experiment: [1] [2] (in Russian)

• [3] (Quantum nucleonic reactor for propulsion)