Pluto (cruise missile)

from Wikipedia, the free encyclopedia
Pluto SLAM

Pluto-SLAM.png

General Information
Type Cruise missiles
Manufacturer Vought
development 1957
Commissioning Development stopped
Technical specifications
length 26.80 m
diameter 1,500 mm
Combat weight 27,540 kg
Drive
First stage
Second stage
Solid fuel booster
nuclear ramjet engine
speed Do 4.2
Range 182,000 km
Furnishing
Target location INS plus TERCOM
Warhead 16 nuclear warheads
Weapon platforms Bunkered position
Lists on the subject

Pluto was the name of the American research program on a cruise missile with a nuclear ramjet engine and a nuclear warhead . The SLAM (Supersonic Low-Altitude Missile) project began in 1957 and ended in 1964.

The name Pluto refers to the Roman god of the underworld and the realm of the dead.

background

The Pluto cruise missile was at the end of the US Air Force's NEPA (Nuclear Energy for Propulsion of Aircraft) project to build a nuclear-powered bomber that could stay in the air for months with worldwide range. Problems arose primarily from the additional weight of the shield and the reactor , which was supposed to drive the engine through a secondary circuit. An unmanned missile could be built more easily, as it was possible to do without a shield because of the lack of a crew. In addition, a secondary circuit to regulate the thrust was not necessary.

The idea behind Pluto was that a nuclear reactor should provide high amounts of energy over a long period of time to make the cruise missile fly low at a speed of Mach 3 with a range of more than 20,000 km, whereby it would fly under the enemy radar . Defense would have been almost impossible.

concept

In November 1955, the Office of Strategic Development commissioned the Atomic Energy Commission to examine the feasibility of the concept. In October 1956, the strategic situation and the political mood during the Cold War formed the basis for the US Air Force to formulate a formal System Requirement (SR # 149) for such a nuclear-powered missile.

NEPA's earlier research on engines to heat the air flowing through them directly through a nuclear reactor has now proven useful. The concept of a nuclear ramjet appeared promising, as it would not require any moving parts that could wear out. This means that the nuclear reactor could supply large amounts of energy for a long time and ultimately enable an almost unlimited range. A landing or re-use was not intended, rather, after the bomb load had been dropped, Pluto should continue to circle over the targets until it crashed due to material fatigue.

Since a ramjet does not generate any take-off thrust, it should be launched by three conventional booster rockets that would be launched after 30 seconds at sufficient speed and at an altitude of 35,000 feet (10,660 m). Then Pluto should fly to the target area with the atomic ramjet.

Instead of wings , only a three-bladed tail unit was provided at the high speed. Because of the enormous aerodynamic loads, the cell had to be completely redesigned and new materials developed for it.

effect

The pressure wave generated at Mach 3 at low altitude can damage windows and eardrums with a sound pressure level of 162  dB . Furthermore, in flight, Pluto would not only have irradiated its surroundings with strong neutron and gamma radiation due to the lack of shielding of the reactor , but would also have contaminated the air that passed the engine with radioisotopes . However, due to the speed and atmospheric dilution, the level of contamination along the flight path is moderate.

The actual armament was sixteen hydrogen bombs, each with a megaton of TNT explosive force. The designers planned that after the bombs had been dropped on the programmed targets, Pluto would continue to circle over the Soviet Union for days or weeks in order to contaminate other areas at least slightly radioactively by its overflight before the crash .

development

Wind tunnel model of the Pluto cruise missile with launch boosters

Development began in 1957 at the Lawrence Livermore National Laboratory in California . The reactor was also developed and produced here, while the airframe was to be supplied by the Vought aircraft company .

The construction proved to be a tightrope walk in the fields of aerodynamics , thermodynamics and metallurgy and required the development of new technologies in various areas. In addition, the project was equipped with a generous budget, most recently 180 permanent engineers worked on the SLAM.

Because of the lack of shielding, a special test site had to be set up in the Nevada desert. The test flights were later to take place over the Pacific, where atomic bomb tests had already been carried out and the additional contamination thus appeared acceptable.

navigation

One of the first challenges was to develop the electronics necessary for navigation and control that still worked with the high levels of radioactivity; remote control was out of the question because of the susceptibility to failure. In principle , inertial navigation systems seemed to be suitable for navigation over long distances, but for Pluto they had to be "hardened" against radiation and made more precise by gas-dynamic bearings. In addition, a supplementary system was developed in order to achieve the accuracy required for dropping several H-bombs in the target area: the images from a video camera were compared with previously stored terrain contour data in flight. After extensive tests, the system called fingerprint achieved the required reliability. As TERCOM ( Ter rain Co ntour M atching) it is still used in cruise missiles today.

cell

Pneumatic motors had to be constructed for the control, which still worked in an incandescent state. The high speed also placed new demands on the structure and materials of the cell. According to calculations by the engineers, the aerodynamic pressure would have been five to eight times higher than that of the X-15 supersonic experimental aircraft . The speed of Mach 3 was also achieved by an A-12 Oxcart in 1962 ; here too, new materials and techniques such as liquid cooling of the airframe had been developed, although the aircraft only achieved this speed in thin air at an altitude of 20 km - and not at ground level like Pluto.

Engine

Tory IIC engine on the Nevada Test Site prior to the successful 1964 test (technicians in white protective suits on top)

The engine tests alone required an enormous amount of effort, as a fast air flow was required, which for the reasons mentioned could not be tested in flight. For this reason, the company moved from Livermore to the Nevada Test Site , where special systems were built on 21 km²: In addition to 10 km of roads and a manufacturing complex, 40 km of oil pipeline were laid, which were necessary to store 450 t of compressed air. The air was heated to 500 degrees Celsius and fed into the wind tunnel at a pressure of 22  bar - this was the only way to test the ramjet engine on the ground, as a suitable turbine-driven wind tunnel did not exist then (and to this day).

The engine called "Tory" had to withstand 1600 degrees Celsius. The reactor had a length of 163 cm and a diameter of 145 cm, it was equipped with 59.9 kg of enriched uranium . The tightrope walk can be seen in the fact that some substances were operated only 84 K below their ignition temperature . Special ceramic materials were also used; For the reactor alone, 465,000 pencil-sized, tubular fuel elements had to be manufactured with high precision. They were assembled into 27,000 tubes in which the air flowing through was heated.

On May 14, 1961, the world's first nuclear ramjet engine "Tory-IIA", which was mounted on a railway frame, ran for a few seconds. Three years later, the further developed "Tory-IIC" burned for 292 seconds with the full output of 513  MW and a thrust of over 156  kN .

Project termination

Despite this successful test, on July 1, 1964, six and a half years after it began, “Project Pluto” was finally stopped - declared in the declaration of the Department of Defense and the State Department of the United States as “being too provocative”. A Soviet counterpart that could not be intercepted by the USA was also expected. The Ministry of Defense decided to only rely on ICBMs that had been in use for a number of years at the time, could reach their destination more quickly and did not generate any radioactive contamination in flight or during tests.

See also

Web links

Commons : SLAM  - collection of images, videos and audio files

Individual evidence

  1. ↑ SLAM Airframe. Retrieved July 21, 2014 .
  2. ^ SLAM Flight Profile. Retrieved July 21, 2014 .
  3. ^ Muscle in Mothballs. Retrieved July 21, 2014 .