Military Review

Convair NX2 CAMAL bomber project (USA)


NX2 and equipment for its maintenance. 1 and 2 - carts for transportation of reactor components; 3 - airplane structure cooling system; 4 - secure transport for personnel; 5 - ammunition transporter with a trailer. Photo

In the fifties, the American company Convair, together with other organizations, worked on the topic of strategic bombers with a nuclear power plant. The last project of its kind to go far enough was NX2 CAMAL. It was based on the most daring ideas that deprived the project of any prospects.

"Weapon system 125"

In the first half of the fifties, various US organizations carried out a lot of research and prepared a scientific and technical basis for creating aircraft with nuclear engines. Soon, the Air Force launched the development of such technology, using the accumulated experience. So, at the beginning of 1955, the Weapon System 125A High Performance Nuclear Powered Aircraft theme was launched ("An aircraft with a nuclear power plant and high performance").

The main contractor for the WS-125A was Convair. She was responsible for the overall coordination of the project and for the creation of a glider with general aircraft systems. General Electric was commissioned to develop nuclear engines. Later, Pratt & Whitney was involved in the work on the power plant.

Already in September 1955, Convair began testing the NB-36H flying laboratory, which showed the principal possibility of placing and using the reactor on an aircraft. Early the next year, GE began testing early prototype engines for the WS-125A.

The layout of the latest version of NX2. Schematic from Convair documentation

Despite the good pace of work and the expected outstanding results, the customer quickly became disillusioned with the WS-125A. Already in 1956, the Air Force considered the atomic bomber unpromising. By that time, it became clear that the aircraft was becoming too complex and extremely dangerous - the gain in performance did not justify the costs and risks. However, the program was not stopped. The work continued with the aim of gaining experience and finding new solutions.

CAMAL project

At Convair, the project for a promising aircraft received the working designation NX2. Also used the name CAMAL (Continuous Airborne Missile Air Launcher - "Missile for long missions").

The preliminary research, assessment and search process continued for several years. Only by 1960 was it possible to form the final overall appearance of the future NX2. At this stage, it was proposed to build an airplane with a swept wing and a forward horizontal tail. In connection with the use of a special power plant, it was necessary to provide for a lot of characteristic innovations in the field of layout, biological protection, etc.

The final version of the airframe had a high aspect ratio fuselage, supplemented by side nacelles with air intakes in the central and tail sections. The center section of the swept wing departed from the gondolas. The wing received a "tooth" in the central part of the leading edge. Developed mechanization passed along the trailing edge. The tips were made in the form of large keels with rudders. It also provided for a trapezoidal PGO with rudders.

Convair NX2 CAMAL bomber project (USA)

One of the engines developed by General Electric. Such a product was tested on the HTRE-3 stand. Photo by US Goverment

One of the measures to protect the crew from radiation was the maximum separation of the cabin and the power plant. The reactors were proposed to be placed in the tail of the fuselage. Protection elements were placed directly next to them. Other screens were located next to the cockpit or in other parts of the glider, covering people and sensitive equipment.

Atomic engines

General Electric and Pratt & Whitney offered several powerplant options for use on the NX2 with different designs and capabilities. It is curious that these engines were considered not only in the context of the CAMAL program. Such products or their modifications could find application on other aircraft.

GE's project, X211, proposed an open-cycle engine combining the XMA-1A reactor and a twin-compressor / twin-turbine system. The air from the compressor had to flow directly into the core, heat up to 980 ° C and exit through the turbine and nozzle. Such a design, according to calculations, made it possible to obtain maximum thrust with minimum dimensions.

P&W worked on two projects - X287 and X291. They offered a more complex enclosed engine. In it, the transfer of heat from the reactor to air was provided by an intermediate system with a liquid metal coolant. Such an engine was more complex, but safer for the environment.

Airplane model in a wind tunnel, 1960 Photo by NASA

According to calculations, the X211 engine could provide a thrust of approx. 6,1 t. The presence of a traditional afterburner made it possible to increase the thrust to 7,85 t. The competing "closed" engine had to show similar technical characteristics with greater safety.

When developing nuclear engines, specific problems had to be addressed. The reactor and other units were supposed to be small in size and weight. It was also necessary to protect the reactor from overheating, and the surrounding structures from the negative effects of excessive heat and radiation. It was necessary to provide procedures for the maintenance of engines and the aircraft as a whole.

As the NX2 was developed, the appearance of the power plant changed. Engines on the wing appeared and were removed; the number of nozzles in the tail of the fuselage was changed. In the latest version of the project, they stopped at two nuclear engines, each of which included one reactor and two gas turbine units.

Desired characteristics

The project of the latest version proposed the construction of an aircraft with a length of 50 m with a wing span of 40 m. According to calculations, the NX2 could fly at speeds up to 950-970 km / h at altitudes up to 12 km. It would also be possible to break through air defense at low altitude. The flight duration could exceed 24 hours, the range - at least 20-22 thousand km. The flight lasting a day required approx. 300 g of nuclear fuel.

The same product from a different angle. Photo by NASA

For the placement of weapons, a large internal cargo compartment and suspension under the wing were provided. The plane could carry modern and advanced bombs and missiles, primarily strategic ones. It was noted that due to a fundamentally new power plant, which does not need a large supply of fuel, it is possible to significantly increase the combat load. On "traditional" aircraft, this parameter was no more than 10% of the takeoff weight, and on the atomic NX2 it was planned to get up to 25%.

Component testing

The final appearance of all the main components of the promising bomber was determined by the beginning of the sixties. So, in 1960, NASA carried out a blowdown of models in a wind tunnel and made proposals for improving the airframe. In particular, the need to use the front horizontal tail was confirmed.

By this time, tests of promising nuclear jet engines had begun. Idaho National Laboratory at EBR-1 has built two stands, HTRE-1 and HTRE-3, for testing GE engines. The Oak Ridge Laboratory worked with the P&W product. Experiments on several stands did not take long, and by the early sixties Convair and related organizations had all the necessary engine data at their disposal.

Project Finale

In 1960-61. the head contractor, Convair, continued to develop and improve the NX2 CAMAL aircraft, while the contractors were engaged in the improvement of power plants and the development of other products. In the near future, it was planned to submit the project materials to the customer for evaluation. There was still a chance that the Air Force would change its mind and decide to continue the project. In this case, over the next few years, an experienced bomber could appear - and after it, adoption into service should be expected.

HTRE engine test benches as memorials to ourselves. Photo Wikimedia Commons

However, the Air Force did not change its mind. The WS-125A / CAMAL atomic bomber project turned out to be too complicated, expensive and dangerous. A large amount of money had already been spent on the work, but the project was not yet ready, and its completion required new expenses and an indefinite time. Safety issues remained unresolved, both during normal operation and during accidents.

In general, the NX2 project had the same problems as all other developments in the field of nuclear aviation... Further development of this direction was considered inexpedient, and in March 1961, by the decision of the president, all work was stopped. 15 years of active research and spending at the level of $ 1 billion did not give any real result. The Air Force decided to abandon the atomic bombers.

At the time of the cessation of work, the Convair NX2 bomber existed only in the form of blueprints and models for purging. Also, layouts of individual units were made. The development of engines progressed further - they had time to be tested at the stand. Later, experimental engines from General Electric were partially disassembled and deactivated. Currently, two HTRE stands are monuments to themselves and are located in the parking lot at EBR-1.

The American program for the development of nuclear aircraft in general and the WS-125A project in particular did not lead to a radical update of the US Air Force fleet. However, they have generated a wealth of data and critical expertise. And also make the right conclusions and close the unpromising direction in time, insuring yourself against unnecessary costs, operational problems and environmental disasters.
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  1. The leader of the Redskins
    The leader of the Redskins 8 August 2020 07: 13
    When the first reactors had a positive effect, there was some kind of nuclear euphoria, or what?
    What assumptions have not been put forward by ordinary people.
    Up to the point that geologists will go into the taiga, carrying a mini-reactor in a separate backpack!
    Nobody thought about technical problems, and most importantly - protection!
    Only the engineers realized that everything was not so simple.
    1. Zaurbek
      Zaurbek 8 August 2020 08: 31
      Well, the rocket flew a cruise missile of unlimited range ...
      1. Firelake
        Firelake 8 August 2020 13: 12
        When did you fly? Where did you fly? What is the test range? What's the payload? What is the exhaust?
        1. Zaurbek
          Zaurbek 8 August 2020 18: 13
          If I knew everything, I would have told you ... I don’t know who I would have given more. GDP said "flew".
          1. Firelake
            Firelake 10 August 2020 18: 29
            With a high degree of probability this missile is not.
    2. Sancho_SP
      Sancho_SP 8 August 2020 08: 56
      AND; actually, what's wrong? These problems have simply not yet been resolved, but this does not mean that compact nuclear installations are unnecessary and, moreover, impossible.
      1. Narak-zempo
        Narak-zempo 10 August 2020 19: 10
        Quote: Sancho_SP
        AND; actually, what's wrong? These problems have simply not yet been resolved, but this does not mean that compact nuclear installations are unnecessary and, moreover, impossible.

        You believe in people too much.
        Here, many are not like a reactor - they are scared to give matches, so that the drunken neighbors are not burned.
        And think how many idiots behind the wheel ...
        Around the stationary reactor, you can still put three security rings, so that some dummy does not get there (and that does not always help, because such a Dyatlov may be among the staff). And the mobile will definitely fall into the hands of an idiot sooner or later.
        1. Sancho_SP
          Sancho_SP 10 August 2020 22: 46
          2-3 tons of metal moving at a speed above 200 km / h are given to almost everyone. And nothing, within acceptable limits.

          So here, a balance will be needed between the security of the system and the availability for ordinary citizens. But this does not negate the fact that such technology can be created.
          1. Narak-zempo
            Narak-zempo 10 August 2020 23: 12
            Quote: Sancho_SP
            2-3 tons of metal moving at a speed above 200 km / h are given to almost everyone. And nothing is within acceptable limits

            An idiot driving a car can collect a maximum of ten frags with a lot of luck. But this will not lead to the contamination of the territory or the fall of radioactive materials into the hands of terrorists.
  2. Operator
    Operator 8 August 2020 11: 56
    -10 qualifying.
    The X211 open-circuit nuclear turbojet engine, where air passed through the reactor, was rejected due to a sharp fluctuation in the rate of nuclear reaction when air with varying degrees of humidity and dust passed through the core (the reactor went out of the way).

    Closed-circuit nuclear turbojet engines X287 and X291 with a metal coolant and a metal / air heat exchanger in the turbojet engine heating chamber did not fit in terms of specific thrust (engine weight).

    Now in aviation, a nuclear ramjet engine (without unnecessary turbine and compressor) is driven by the Burevestnik KR with a metal coolant and a heat exchanger in the ramjet heating chamber.

    In other words, Russian engine builders beat American ones in all respects.
    1. dauria
      dauria 8 August 2020 13: 21
      In other words, Russian engine builders beat American ones in all respects.

      The Americans also experienced direct flow. The ramjet "Pluto". The rocket will do - we dispersed it with a kick and let it cut in the same mode. The problem is with an airplane. From zero to subsonic modes, it is extremely ineffective - the working fluid must be carried with you for acceleration. Whether it's air or pure nitrogen. You cannot get the required mass through the intake.
      Nobody beat anyone. The world just crossed another moral line. After Ypres and Hiroshima. What's next ? To take the asteroid out of orbit and direct it to the Earth - so don't get to anyone ...
      1. Operator
        Operator 8 August 2020 13: 56
        The Pluto ramjet engine operated according to an open scheme - air (passing through the core) was used as the coolant of the nuclear reactor, which is also the ramjet working fluid. Water vapor of air of variable humidity led to the acceleration of the reactor to the stage of thermal explosion. Radioactivated airborne dust was released into the atmosphere.

        The Burevestnik ramjet engine operates according to a closed circuit - liquid metal is used as a coolant, which heats the air in the ramjet engine (as a result of which air does not pass through the reactor core).

        "Burevestnik", unlike "Pluto", not only flies without the risk of a reactor explosion, but during a threatened period it can hover in the air over its air defense zones (in the Arctic zone) for almost unlimited time without radioactive contamination of the atmosphere and surface. Something like the Yars PGRK, only at a speed of 2000 km / h.
        1. dauria
          dauria 8 August 2020 15: 01
          practically unlimited time without radioactive contamination of the atmosphere

          Don't give a damn about that "during the threatened period." Disposable single mode is not applicable to aircraft. The Americans can certainly do that. A question of expediency. The idea was to bypass missile defense from an unprotected direction.
          The Americans don't need this. They surrounded both us and China from all directions with bases. Flight range and unlimited time? I don't care, chemical (even solid-fuel) rockets solve this issue in 30 minutes from mainland to mainland. There was still the possibility of maneuvering - aeroballistic blocks also know how to do this. And withdrawal from the START treaty in general nullifies all missile defense.
          Why should they sculpt such nuclear ramjet?
          Yes, we created .. yes, the Americans are thinking. But they will not mold their own. They don't need it. At least like that.
          1. Operator
            Operator 8 August 2020 15: 15
            A threatened period, by definition, can end not only with war, therefore, no one cares about the radioactive contamination of their air, water and soil.

            You never know what ideas (not supported by technology) the Americans had, the main thing is that our idea of ​​an air PGRK (supported by Burevestnik) is being successfully implemented.

            The threatened period has one drawback - no one can accurately determine its beginning. Therefore, you can start loitering "Petrels" immediately from the moment they are put into service - let them fly, and let the African Americans bite their elbows with their strategic bombers on duty on the ground.
            1. bk0010
              bk0010 8 August 2020 22: 56
              Quote: Operator
              Therefore, you can start loitering "Petrels" immediately from the moment of putting into service - let them fly
              If it were possible to "let fly", then they would not have made a cruise missile with an atomic engine, but a carrier-UAV with conventional cruise missiles. The reactor is low-resource (for a week of work, it seems).
              1. Operator
                Operator 9 August 2020 13: 11
                Why make a spacer - a carrier (destruction of which leads to damage in the n-th number of missiles), when you can make many, many autonomous missiles of unlimited range.

                And from a technical point of view: the dimensions, weight and power of the Burevestnik nuclear reactor (the same as the Poseidon nuclear reactor) allow making not a carrier, but only a missile with a supersonic flight speed - for the purpose of operability of the ramjet.

                The resource of the Petrel / Poseidon reactor is clearly several years. It is quite possible to splash down the Burevestnik after the peaceful end of the threatened period with the replacement of the aluminum airframe and the new deployment of the rocket on alert.
                1. bk0010
                  bk0010 9 August 2020 13: 17
                  Quote: Operator
                  Why make a spacer - a carrier (destruction of which leads to damage in the n-th number of missiles), when you can make many, many autonomous missiles of unlimited range.
                  So she can sit down for maintenance. "Many, many" - the rubber band will burst: nuclear reactors are not cheap.
                  Quote: Operator
                  The resource of the Petrel / Poseidon reactor is clearly several years.
                  Can I get a link? If this is true, then we are on the verge of a technical revolution. Ships and diesel locomotives will operate only on such reactors.
                  1. Operator
                    Operator 9 August 2020 13: 35
                    The entire tsimes of "Petrel" - unlimited range in military conditions, plus unlimited loitering time during the threatened period (in order to prevent a counterforce strike from the enemy).

                    How do you imagine a low-resource nuclear reactor? laughing

                    The "Burevestnik" / "Poseidon" nuclear reactor requires radiation protection - in the case of KR / NPA onboard equipment and warhead. The "Petrel" / "Poseidon" has the protection of the so-called. shadow - a bulkhead blocking the neutron flux towards the forward end of the hull. Therefore, a reactor with such protection can only be installed on a submarine, where water blocks radiation from other directions. An attempt to install such a reactor on a surface ship or a diesel locomotive will require the installation of protection from all sides, which will multiply the mass-dimensional characteristics.

                    The next installation site for this nuclear power plant with shadow protection, with a high degree of probability, is a small-tonnage nuclear submarine with a displacement of 1000 tons, dimensions of 50x5 meters, an underwater speed of 30 knots and weapons of 20 torpedoes and cruise missiles - of the mini Lyra type in modern design.
                    1. bk0010
                      bk0010 9 August 2020 13: 47
                      Quote: Operator
                      How do you imagine a low-resource nuclear reactor?
                      What's so funny? Poseidon's reactor is designed for a week of work, then it breaks. Why else would he need a carrier?
                      Quote: Operator
                      which will multiply the weight and dimensions.
                      This thing fits on a cruise missile. Even if the mass and dimensions grow at least five times, it will still fit everywhere.
                      1. Operator
                        Operator 9 August 2020 14: 05
                        The service life of the reactor is measured by the resistance of the cladding of the fuel elements; modern materials carbon and silicon carbide provide resistance against neutrons for about 5 years.

                        The actual Burevestnik / Poseidon reactor with an electric power of 10 MW has dimensions of less than a meter due to fast neutrons and 40% uranium enrichment. The problem of its installation (even with all-round protection) on a diesel locomotive or on a surface watercraft in another - a terrorist threat.
    2. Narak-zempo
      Narak-zempo 10 August 2020 19: 07
      Quote: Operator
      In other words, Russian engine builders beat American ones in all respects.

      Rosatom is not Roskosmos for you, and Kiriyenko is not Rogozin, he doesn’t drive empty people.
  3. Mikhail Zakharov
    Mikhail Zakharov 9 August 2020 01: 46
    all these flying Chernobyls do not make sense only money down the drain