And, looking at the nuclear submarines, going under the polar ice in the middle of 1950-s, could anyone suggest that ships, airplanes and even nuclear-powered cars would be far behind?
As for the aircraft, the study of the possibility of using nuclear energy in aircraft engines began in New York in 1946, later the research was transferred to Oakridge (Tennessee) to the main center for US nuclear research. As part of the use of nuclear energy for the movement of aircraft, the NEPA (Nuclear Energy for Propulsion of Aircraft) project was launched. During its implementation, a large number of studies of open-cycle nuclear power plants were conducted. The heat carrier for such installations was air, which flowed through the air intake into the reactor for heating and subsequent release through the jet nozzle.
However, a funny thing happened on the way to making the dream of using nuclear energy happen: the Americans discovered radiation. So, for example, in 1963, the project of the Orion spacecraft was closed, in which it was supposed to use an atomic pulse jet engine. The main reason for the closure of the project was the entry into force of the Treaty banning the testing of nuclear weapon in the atmosphere, under water and in outer space. A nuclear-engineered bombers that had already begun to conduct test flights did not take off again after 1961 (the Kennedy administration closed the program), although the air force had already begun an advertising campaign among the pilots. The main "target audience" became pilots who came out of childbearing age, which was caused by radioactive radiation from the engine and the concern of the state about the gene pool of Americans. In addition, the congress later learned that in the event of the crash of such an aircraft, the crash area would become unfit for habitation. This also did not play to the benefit of the popularity of such technologies.
So, just ten years after the debut, the Atoms for Peace program of the Eisenhower was not associated with strawberries in size with a soccer ball and cheap electricity, but with Godzilla and giant ants that devour people.
The fact that the Soviet Union launched Sputnik-1 also played a significant role in this situation.
The Americans realized that the Soviet Union is currently the leader in the design and creation of missiles, and the missiles themselves can carry not only a satellite, but also an atomic bomb. At the same time, the US military understood that the Soviets could become a leader in the development of anti-missile systems.
To counter this potential threat, it was decided to create nuclear cruise missiles or unmanned atomic bombers that have a long range and are capable of overcoming enemy defenses at low altitudes.
The Strategic Development Authority in November 1955 asked the Atomic Energy Commission about the appropriateness of the aviation engine concept, which was to use a nuclear power plant in a ramjet engine.
The US Air Force in 1956 year formulated and published requirements for a cruise missile equipped with a nuclear power plant.
The American Air Force, General Electric, and later the Livermore Laboratory of the University of California, conducted a series of studies that confirmed the possibility of creating a nuclear reactor for use in a jet engine.
The result of these studies was the decision to create a supersonic low-altitude cruise missile SLAM (Supersonic Low-Altitude Missile). The new rocket was supposed to use a nuclear ramjet.
The project, the purpose of which was the reactor for this weapon, received the code name "Pluto", which became the designation of the rocket itself.
The project got its name in honor of the ancient Roman ruler of the afterlife world of Pluto. Apparently, this gloomy character inspired the creators of the rocket, which has the size of a locomotive, which was supposed to fly at the level of trees, dropping hydrogen bombs on cities. The creators of "Pluto" believed that only one shock wave arising behind a rocket, capable of killing people on the ground. Another deadly attribute of the new deadly weapon was the radioactive exhaust. As if it was not only that the unprotected reactor was the source of neutron and gamma radiation, the nuclear engine would throw out the remnants of nuclear fuel, polluting the territory in the path of the rocket.
As for the airframe, it was not designed for SLAM. The glider was supposed to provide at sea level the speed of the 3 Max. In this case, the heat of the skin from friction with air could be up to 540 degrees Celsius. At that time, the aerodynamics for such flight regimes were little studied, but a large number of studies were carried out, including 1600 hours of wind tunnels. As the optimal chosen aerodynamic scheme "duck". It was assumed that this very scheme would provide the required characteristics for the given flight modes. According to the results of these blow-outs, the classical air intake with a conical flow device was replaced with a two-dimensional flow input device. It worked better in a wider range of yaw and pitch angles, and also made it possible to reduce pressure losses.
Also conducted an extensive materials science research program. As a result, the fuselage section was made of Rene 41 steel. This steel is a high-temperature alloy with high nickel content. The plating thickness was 25 millimeters. The section was tested in a furnace in order to study the effects of high temperatures caused by kinetic heating on the aircraft.
The front sections of the fuselage were supposed to be treated with a thin layer of gold, which was supposed to dissipate heat from the structure heated by radioactive radiation.
In addition, they built a model of the nose, air channel of the rocket and the air intake, made on the scale of 1 / 3. This model has also been thoroughly tested in a wind tunnel.
Created a draft design of the location of hardware and equipment, including ammunition, consisting of hydrogen bombs.
Now “Pluto” is an anachronism, a forgotten character from an earlier, but no more innocent era. However, for that time, "Pluto" was the most compellingly attractive among the revolutionary technological innovations. "Pluto", as well as the hydrogen bombs, which he had to carry, in the technological sense was extremely attractive to many engineers and scientists who worked on it.
The US Air Force and the 1 Atomic Energy Commission on January 1957 selected the Livermore National Laboratory (Berkeley Hills, California) as responsible for "Pluto."
Since Congress recently handed over a joint project on a rocket with a nuclear engine at the national laboratory at Los Alamos (pc. New Mexico) to an opponent of the Livermore laboratory, the appointment for the latter was a good news.
The Livermore Laboratory, which had highly skilled engineers and qualified physicists in its staff, was chosen because of the importance of this work - there is no reactor, there is no engine, and without an engine there is no rocket. In addition, this work was not easy: the design and creation of a nuclear ramjet engine posed a large amount of complex technological problems and tasks.
The principle of operation of a ramjet engine of any type is relatively simple: air enters the air inlet of the engine under pressure of the incident flow, after which it heats up, causing it to expand, and high-velocity gases are ejected from the nozzle. This creates jet thrust. However, in “Pluto”, the use of a nuclear reactor to heat the air was fundamentally new. The reactor of this rocket, in contrast to the commercial reactors surrounded by hundreds of tons of concrete, had to have sufficiently compact dimensions and mass in order to lift itself and the rocket into the air. At the same time, the reactor had to be strong in order to “survive” a flight of several thousand miles to targets located in the USSR.
The joint work of the Livermore Laboratory and Chance-Vout Company on determining the required reactor parameters resulted in the following characteristics:
Diameter - 1450 mm.
The diameter of the fissile core - 1200 mm.
Length - 1630 mm.
Core length - 1300 mm.
The critical mass of uranium is 59,90 kg.
Power density - 330 megawatts / m3.
Power - 600 megawatts.
The average fuel cell temperature is 1300 degrees Celsius.
The success of the “Pluto” project largely depended on a whole success in materials science and metallurgy. We had to create pneumatic drives that controlled the reactor, capable of operating in flight, when heated to ultra-high temperatures and when exposed to ionizing radiation. The need to maintain a supersonic speed at low altitudes and under different weather conditions meant that the reactor had to withstand the conditions under which materials used in conventional rocket or jet engines melt or collapse. The designers calculated that the loads assumed during the flight at low altitudes will be five times higher than the similar ones acting on the experimental X-15 aircraft, equipped with rocket engines, which at a considerable height reached the number M = 6,75. Ethan Platt, who worked on Pluto, said that he was "pretty close to the limit in every sense." Blake Myers, the head of the Livermore jet propulsion unit, said: "We constantly pulled at the dragon's tail."
The project "Pluto" should have been used tactics flight at low altitudes. This tactic provided stealth from the radars of the air defense system of the USSR.
In order to achieve the speed at which a ramjet engine would work, the Pluto had to be launched from the ground with a package of conventional rocket boosters. The launch of a nuclear reactor began only after the Pluto reached the height of a cruising flight and was sufficiently removed from populated areas. The nuclear engine, giving a virtually unlimited range, allowed the rocket to fly over the ocean in circles, awaiting orders to go to supersonic speed to a target in the USSR.
SLAM sketch project
Delivery of a significant number of warheads to different targets remote from each other, when flying at low altitudes, in the rounding mode of the terrain, requires the use of a high-precision guidance system. At that time, inertial guidance systems already existed, but they could not be used under the conditions of severe radiation emitted by the “Pluto” reactor. But the SLAM creation program was extremely important, and a solution was found. Continuation of work on the inertial guidance system of “Pluto” became possible after the development of gas-dynamic bearings for gyroscopes and the appearance of structural elements that were resistant to strong radiation. However, the accuracy of the inertial system was still not enough to complete the assigned tasks, since the value of the guidance error increased with increasing route distance. The solution was found in the use of an additional system, which in certain sections of the route would carry out a course correction. The image of the sections of the route was to be stored in the memory of the guidance system. Research funded by Vout has led to the creation of a guidance system that is sufficiently accurate for use in SLAM. This system was patented under the name FINGERPRINT, and then renamed to TERCOM. TERCOM (Terrain Contour Matching, Terrain Tracking) uses a set of reference maps for the route. These maps, presented in the memory of the navigation system, contained data on the height of the relief and sufficiently detailed to be considered unique. The navigation system, using a downward-directed radar, makes a comparison of the terrain and the reference map, and then corrects the course.
In general, after some improvements, TERCOM would enable the SLAM to destroy many remote targets. An extensive testing program for the TERCOM system was also carried out. Flights during the tests were carried out over various types of the earth's surface, in the absence and presence of snow cover. During the test was confirmed the possibility of obtaining the required accuracy. In addition, all navigation equipment that was supposed to be used in the guidance system was tested for resistance to strong radiation exposure.
This guidance system turned out so successful that the principles of its work still remain unchanged and are used in cruise missiles.
The combination of low altitude and high speed was supposed to give the Pluto the ability to reach and hit targets, while ballistic missiles and bombers could be intercepted while traveling to targets.
Another important quality of “Pluto”, which engineers often mention, was rocket reliability. One of the engineers spoke of "Pluto" as a bucket of stones. The reason for this was a simple design and high reliability of the rocket, for which Ted Merkle, the project manager, gave the nickname “flying scrap”.
Merkle was given the responsibility of creating the 500 megawatt reactor, which was to be the heart of Pluto.
Chance-Vout has already been given a contract to build a glider, and the creation of a ramjet engine, with the exception of the reactor, was the responsibility of the Marquardt corporation.
Obviously, along with the increase in temperature to which air can be heated in the engine channel, the efficiency of the nuclear engine increases. Therefore, when creating a reactor (codename "Tori"), the slogan of Merkle became "hot is better." However, the problem was that the operating temperature was about 1400 degrees Celsius. At this temperature, high-temperature alloys were heated to such an extent that they lost their strength characteristics. This led Merkl to contact Coors Porcelain Company (Colorado) to develop ceramic fuel cells that can withstand such high temperatures and ensure uniform temperature distribution in the reactor.
Now Coors is known as a manufacturer of various products, thanks to the fact that Adolf Kurs once realized that the production of vats with ceramic lining intended for breweries would not be the business that should be engaged. And although the porcelain company continued to produce porcelain products, including the pencil-shaped 500000 fuel cells for Tori, it all started with Adolf Course’s little business.
For the manufacture of fuel elements of the reactor was used high-temperature ceramic beryllium oxide. It was mixed with zirconia (a stabilizing additive) and uranium dioxide. In the ceramic company of the Course, the plastic mass was pressed under high pressure, after which it was sintered. The result is a fuel element. The fuel cell is a hexagonal hollow tube about 100 mm long, the outer diameter is 7,6 mm, and the inner one is 5,8 mm. These tubes were connected in such a way that the length of the air channel was 1300 mm.
In total, 465 thousand fuel elements were used in the reactor, of which 27 thousand air channels were formed. A similar reactor design ensured uniform temperature distribution in the reactor, which, together with the use of ceramic materials, made it possible to achieve the desired characteristics.
However, the extremely high operating temperature "Tori" was just the first problem of a number that needed to be overcome.
Another problem for the reactor was flying at a speed of M = 3 during precipitation or over the ocean and sea (through salt water vapor). During the experiments, Merkle engineers used various materials that were supposed to provide protection against corrosion and high temperatures. These materials were supposed to be used for the manufacture of mounting plates installed in the stern of the rocket and in the rear part of the reactor, where the temperature reached maximum values.
But only the measurement of the temperature of these plates was a difficult task, since the sensors intended to measure the temperature from the effects of radiation and the very high temperature of the Tori reactor ignited and exploded.
When designing fasteners, the temperature tolerances were so close to critical values that only 150 degrees separated the operating temperature of the reactor and the temperature at which the fastening plates self-ignited.
In fact, in the creation of "Pluto" there was a lot of unknown that Merkle decided to conduct a static test of a full-scale reactor, which was intended for a ramjet engine. It was supposed to solve all the issues at once. In order to conduct tests, a laboratory in Livermore decided to build a special facility in the Nevada desert, near the place where the laboratory tested its nuclear weapons. The object, called the “401 Zone”, built on eight square miles of Donkey Plain, surpassed itself by the declared value and ambitions.
Since, after launch, the Pluton reactor became extremely radioactive, its delivery to the test site was carried out via a specially constructed fully automated railway line. Along this line, the reactor should be moved approximately two miles apart, which separated the static test stand and the massive “demolition” building. In the building, the “hot” reactor was dismantled for inspection using remote-controlled equipment. Scientists from Livermore watched the testing process using a television system that was located in a tin hangar far from the test bed. In any case, the hangar was equipped with an anti-radiation shelter with a two-week supply of food and water.
Only to ensure the supply of concrete needed for the construction of the walls of the demolition building (the thickness ranged from six to eight feet), the United States government acquired the whole mine.
Millions of pounds of compressed air were stored in pipes used in oil production for a total length of 25 miles. This compressed air was supposed to be used to simulate the conditions in which a ramjet engine turns out to be at cruising speed during a flight.
To ensure high air pressure in the system, the laboratory borrowed giant compressors from submarine bases (Groton, Conn.).
For the test, during which the unit operated at full power for five minutes, it was necessary to drive a ton of air through steel tanks that were filled with more than 14 million steel balls with a diameter of 4, see. These tanks were heated to 730 degrees using heating elements, in which they burned oil.
Gradually, the Merkle team, during the first four years of work, was able to overcome all the obstacles standing in the way of the creation of "Pluto". After a lot of exotic materials were tested, for use as a coating for the core of an electric motor, engineers found out that paint for the exhaust manifold copes well with this role. She was ordered through an ad found in the Hot Rod autojournal. One of the original rationalization proposals was the use of naphthalene balls for fixing the springs, while assembling the reactor naphthalene balls, which, after performing their task, evaporated safely. This offer was made by laboratory magicians. Richard Werner, another enterprising engineer from the Merkle group, invented a method for determining the temperature of mounting plates. His technique was based on comparing the color of the plates with a specific color scale. The color of the scale corresponds to a certain temperature.
Installed on a railway platform, Tory-2C is ready for successful testing. May 1964 of the year
14 May 1961. Engineers and scientists located in the hangar, where the experiment was controlled, held their breath - the world's first direct-flow nuclear jet engine mounted on a bright red railway platform announced its birth with a loud roar. Tory-2A launched just a few seconds, during which he did not develop his nominal power. However, it was believed that the test was successful. The most important was the fact that the reactor did not ignite, which some representatives of the atomic energy committee were extremely afraid of. Almost immediately after testing, Merkle began work on the creation of a second Tori reactor, which was supposed to have more power with less mass.
The work on Tori-2B on the drawing board has not progressed. Instead, the Livermore immediately built Tori-2C, which broke the silence of the desert three years after testing the first reactor. A week later, the reactor was restarted and operated at full capacity (513 megawatts) for five minutes. It turned out that the radioactivity of the exhaust is much less than expected. Air Force generals and officials from the atomic energy committee also attended these tests.
Merkle and his staff very noisy celebrated the success of the tests. That there is only a piano immersed on a transport platform, which was “borrowed” from a female hostel located nearby. The whole crowd celebrating, led by Merkle sitting at the piano, singing bawdy songs, rushed to the town of Mercury, where they occupied the nearest bar. The next morning, they all lined up at the medical tent, where they were given vitamin B12, which was considered an effective remedy for a hangover at that time.
Returning to the lab, Merkle concentrated on creating a lighter and more powerful reactor that would be compact enough to carry out test flights. There were even discussions of a hypothetical Tori-3 capable of accelerating a rocket up to the speed of Mach 4.
At this time, customers from the Pentagon, who funded the project "Pluto", began to overcome doubts. Since the rocket was launched from the territory of the United States and flew over the territory of the American allies at low altitude to avoid detection by Soviet air defense systems, some military strategists wondered if the rocket would pose a threat to the allies? Even before the Pluto rocket drops bombs on the enemy, it will first stun, crush and even irradiate the allies. (It was expected that from Pluto flying overhead, the noise level on earth would be about 150 decibels. For comparison, the noise level of a rocket that sent Americans to the Moon (Saturn-5) was 200 decibels at full throttle). Of course, broken eardrums would be the least problem if you were under a naked reactor flying over your head that would fry you like chicken with gamma and neutron radiation.
All this forced officials from the Ministry of Defense to call the project “too provocative”. In their opinion, the presence of a similar missile in the United States, which is almost impossible to stop and which can inflict damage to the state, somewhere between unacceptable and insane, could force the USSR to create a similar weapon.
Outside the laboratory, various questions as to whether Pluto is capable of performing the task for which it was designed, and most importantly, whether this task was still relevant, were also raised. Although the creators of the rocket claimed that “Pluto” was also intangible from the very beginning, military analysts expressed bewilderment - as something so noisy, hot, large and radioactive can go unnoticed for the time necessary to complete the task. At the same time, the United States Air Force had already begun to deploy Atlas and Titan ballistic missiles, which were able to reach targets a few hours before the flying reactor, and the USSR antimissile system, the fear of which had become the main impetus for the creation of Pluto. , did not become a hindrance for ballistic missiles, despite successful test interceptions. Critics of the project came up with their own interpretation of the abbreviation SLAM - slow, low, and messy - slowly, lowly and dirty. After successful trials of the Polaris missile, the fleet, which initially showed interest in using missiles for launching submarines or ships, also began to leave the project. And finally, the terrible cost of each rocket: it was 50 million dollars. Suddenly, Pluto has become a technology that cannot be used for applications, a weapon that did not have suitable targets.
However, the last nail in the coffin of "Pluto" was just one question. He is so deceptively simple that you can excuse Livermores for not consciously paying attention to him. “Where to conduct flight tests of the reactor? How to convince people that during the flight the rocket will not lose control and will not fly over Los Angeles or Las Vegas at low altitude? ”Asked Liver Sea Laboratory physicist Jim Hadley, who worked on the Pluto project to the very end. He is currently engaged in detecting nuclear tests that are being conducted in other countries for the Z unit. According to Hadley himself, there was no guarantee that the rocket would not be out of control and would not turn into a flying Chernobyl.
It was suggested several solutions to this problem. One of them was testing Pluto in the state of Nevada. It was suggested to tie him to a long cable. Another, more realistic solution, is the launch of Pluto near Wake Island, where the rocket would fly, slicing eights over the part of the ocean belonging to the United States. “Hot” rockets were supposed to be flooded at a depth of 7 kilometers in the ocean. However, even when the atomic energy commission inclined people to think about radiation as an unlimited source of energy, the proposal to drop a lot of radiation-polluted rockets into the ocean was enough to stop work.
1 July 1964 g, after seven years and six months from the start of work, the project "Pluto" was closed by the Atomic Energy Commission and the air force. In the country club, located next to Livermore, Merklom organized a "Last Supper" for those who worked on the project. There were handed out souvenirs - bottles of mineral water "Pluto" and clips for tie SLAM. The total cost of the project was 260 million dollars (in prices of that time). In the peak of the heyday of the Pluto project, about 350 people worked on it in the laboratory, and about 100 worked on the 401 object in Nevada.
Even in spite of the fact that “Pluto” has never been lifted into the air, exotic materials developed for a nuclear ramjet engine are currently used in ceramic elements of turbines, as well as in reactors used in space vehicles.
Physicist Harry Reynolds, who also participated in the Tori-2C project, is currently working at Rockwell Corporation on a strategic defense initiative.
Some of the Seamen continue to experience nostalgia for "Pluto." According to William Moran, who oversaw the production of fuel cells for the Tori reactor, these six years were the best time in his life. Chuck Barnett, who led the tests, summing up the atmosphere that prevailed in the laboratory, said: “I was young. We had a lot of money. It was very exciting. ”
According to Hadley, every few years, some new lieutenant colonel of the air force discovers “Pluto”. After that, he calls the laboratory to find out the further fate of the nuclear ramjet. The enthusiasm of the lieutenant colonels disappears immediately after Hadley talks about problems with radiation and flight tests. Nobody called Hadley more than once.
If someone wants to bring the Pluto back to life, then maybe he can find some recruits in Livermore. However, they will not be many. The idea of what could have become a hellish insane weapon is better left in the past.
Specifications rocket SLAM:
Diameter - 1500 mm.
Length - 20000 mm.
Weight - 20 tons.
The range is not limited (theoretically).
Speed at sea level - Mach 3.
Armament - 16 thermonuclear bombs (power of each 1 megaton).
Engine - nuclear reactor (power 600 megawatts).
The guidance system is inertial + TERCOM.
The maximum plating temperature is 540 degrees Celsius.
The material of the airframe - high-temperature, stainless steel Rene 41.
Plating thickness - 4 - 10 mm.