1950 Top Secret Propulsión

1950 Top Secret Propulsión Documents Declassified Douglas Aircraft

Serial 009
NUCLEAR PROPULS ICM
Title; A FEW CCMCEHTS ON ROCKETRY
Author: Professor Theodore von Karman, Chairman, Advisory Group for Aeronautical Research and Development, N.A.T.O. , Paris
Source: Interavia, Vol. VIII, №11, 1953, p- 628–629
VERBATIM QUOTATION
Dr. von Karmen mentions unconventional methods of propulsion only in the following words:
p. 628
“The rocket ejects matter (or radiation as visualized in the
imagination of some planners of future rocketry) which is entirely
carried in the vehicle to be propelled. “
P- 629
“Finally there is the problem of the nuclear rocket, at least in
its clearest form, which uses a nuclear process to supply heat to a
fluid with low molecular weight. Even this proposal involves, of course, the still unsolved problem of extracting a controlled amount of heat from the nuclear reactor and transferring it at high temperature to the “working fluid’. Furthermore, the necessary shielding presents a weight problem. However, for large rockets, the weight of shielding may be balanced by the reduction in the weight of the matter which would have to be ejected by an ordinary rocket.”
DAC NOTE : Dr. von Karman makes no reference to anti -gravities, electrical propulsion, etc., although this would have been an obvious opportunity to do so, had he wished to emphasise this subject.
Title: THE USE CSF ATOMIC POWER FOR ROCKETS
Author: Dr. Robert Serber (U. of Calif. )
Source: Research Memorandum #1, Project RAND, July 5, 1946 (UNCLASSIFIED)
Also reprinted as Appendix IV to Second Quarterly Report on Project
RAND, September 1, 1946, RA -15004
DAC COMMENTS
This report which discussed the outlook of propulsion by nuclear power at a relatively early (1946) stage of the development of nuclear power appliances assessed the possible momentum recovery from any conceivable direct exploitat- ion of the energy of fission products of nuclear reactions as extremely inef- ficient and unattractive. Fission fragments have high velocity but short range
and small momentum. Alpha particles fly in all directions, hence half of their energy would have to be absorbed aboard, so something like 1000 times the kinetic energy of rocket flight would have to be transformed into heat and gotten rid of somehow. This leaves the utilization of the nuclear reaction heat for the ejection of an inert working fluid as the only practical solution. Efflux velocity becomes TTgtximum when the total supply of working fluid amounts to about
four times the empty end mass of the vehicle.
These conclusions are in full agreement with similar deductions published in many scientific articles published since then.
ATOMIC POWERED ROCKETS
Cedric Giles
Journal of the American Rochet Society #63, Sept 19⁵
DAC ABSTRACT ASP COMMENT
This is an early speculative assessment of the possibilities of the application of nuclear power to Rocket Propulsion, attempted immediately after the
release of the Smyth Report in August 19⁵* The author thinks of such things as: Fission released energy to heat liquids or gases to he expelled to drive turbines or to be exhausted directly, electron beams to split water into oxygen and hydrogen which would then recombine chemically as steam; atomic jet impelled reaction power plants (?) “electrostatic or magnetic fields produced as a by-product (?) of atomic energy”. The article contains no real technical contribution to knowledge.

Title: A CGNTRIBOTIGN TO THE LEVTEA.TICN PROBLEM
Author: Cedric Giles
Verbatim Quotation:
“A few years ago a suggestion^- was made that a special type of reflector might be used to control the direction of atonic particles for providing a reaction to the rocket. The general idea may be considered similar to the principle of reflecting light rays in straight lines from a parabolic mirror which
has a source of light at its focus point. “As in Fig. 2, atomic particles would emanate from a fixed source of radioactive energy and on meeting a form of electromagnetic parabolic reflector
would be reflected in parallel lines opposite to the direction of travel by the rocket. As discharged particles are now controlled in the cyclotron by magnetic forces the possibility of eventually developing such a source of reflected energy was not considered too remote.

1 U.S. Naval Institute Proceedings, Jun

Reference
1 U.S. Naval Institute Proceedings, June 1942.”
Astronautics Literature Index Serial 013
ELBCTR(34AG5ETIC PROPULSION
NUCLEAR PROPULSION
Title: ON THE APPLICATION OF A REACTION FORCE RESULTING FRG1 AN INTERACTION CF WAVES IN AN ELLIPTIC REFLECTION SPACE
Author: Hans J. Kaeppeler
Title: ON A THEORY QF POIAR FORCES AS A PRINCIPLE FOR APPLICATION CF ATOMIC ENERGY TO ROCKET PROPULSION
Author: Hans J. Kaeppeler
MC ABSTRACT AND COMMENTS
Kaeppeler develops a theory of the generation of thrust from a highly
hypothetical radiation engine comprising an interior reflector in the shape of a prolate ellipsoid of revolution in the forward focus of which a pulsating source of nuclear energy generates enormously intense radiation and induces an opposite phase pulsation at the rear focus. The reflector shell is open at the rear end. The very involved mathematical calculations are allegedly based on an analogy with the forces generated in a fluid between two sources
pulsating in antisymmetric unison source sink action.
Kaeppeler Hakes light of the technical problems conjured up in the
design of the mirror shell end the containment of the enormous temperatures necessary to yield any sizable thrust effect. He assumes deuterium helium processes and nonchalantly (!) speaks of temperatures of 2 million degrees, envisages a reflector shell 1 m long, exhaust velocity 1000 km/sec, tons of liquid heavy hydrogen and other fantastic or visionary requisites. The author’s Imagination is rather uninhibited.
EIBCTRCMAGRETIC PROPULSION
NUCLEAR PROPULSION

HOTE 1 : The articles vere submitted, to the Journal of the Detroit Rocket Society, Inc. in German and translated by A. J. Zaehringer, editor of the Journal. The translation is in many places non-idiomatic
and therefore even more difficult to understand than (presumably)
the original text.
NOTE 2 : “ About the Author : Although born in 1926 he has already done much in the field of rockets. A member of the BIS, DRS and G?W he has written many articles. He attended the University of Dillingen and Tuebingen where he had studied theoretical physics. His early education was at Dillingen and Weissenhorn. During the war he was a member of the German Air Force. After the last war he worked at
the Power Plant Laboratory at Wright Field, Ohio as an assistant
of Dr. W. C. Noeggerath and later working with the U.S. Military
Government in Germany. He is now Chief Research Specialist for
the USAF Historical Research Division, Ulm/Donau, Germany* M (Dr. Noeggerath, now with Lockheed Missiles Group, in a telephone
conversation stated that he remembers Kaeppeler only vaguely as
a PCW detailed to do draftsman’s duties at Wright Field until sent home. Kaeppeler left the impression of an eager beaver with a flair for scientific grandiloquence. In 1952 Kaeppeler was a very busy member of the Illrd Astronautical Congress in Stuttgart.)

"Types of Atomic Power Plants

"Several basic types of power plants can be adapted to utilize atomic
energy for the propulsion of aircraft. They are all thermal power plants, since
fission energy is released predominantly in the form of heat. Some thought has been given to the direct production of electricity from the fission process,
but there is at present, no known practical way of achieving this."

"Fig. 13 shows the application of nuclear energy to a rocket. A propellant,
for instance liquid hydrogen, is pumped out of the tank and through the reactor,
where it is vaporized and heated to a high temperature. It then escapes at
high velocity through the exhaust nozzle. The rocket is driven by the recoil
of the escaping propel lant , and is therefore not dependent on atmospheric air for its functioning. It can, therefore, operate outside the earth’s atmosphere .
One may well ask where the advantage lies in using nuclear energy for a rocket, since its endurance is limited, as it can operate only until the propellant is exhausted, regardless of the practically unlimited supply of energy in the reactor. The reason why nuclear energy offers a definite advantage in rockets is that the specific impulse of a rocket propellant , the pounds of thrust that can be obtained from each pound of propellant used per second, is proportional to the square root of the absolute propellant temperature divided by the molecular weight of the propellant . In other words, the highest possible temperature and the lowest possible molecular weight are desired. The high temperature is obtained normally, in a chemical rocket, by the combustion of a fuel and an oxidizer, whose products of combustion are then used as the propellant. Since the weight will obviously be fairly high. For instance, if hydrogen and oxygen are used, the resulting propellant is water vapor, with a molecular weight of 18.
On the other h and, if nuclear energy is used to provide the high h temperature, there is no need for the process of combustion, and very light propellants, hydrogen, for instance, with a molecular weight of 2 can be used. Since the ratio of l£ and 2 is 9, and the square root of 9 is 3, the specific impulse of pure hydrogen at the same temperature is three times that of water vapor."
PHOTONIC PROPULSIÓN
Title: INTERSTELLAR FLIGHT
Author: Leslie R. Shepherd, Ph. D.
Source; Journal of the British Interplanetary Society, Vol. 11, No. k
pp. 149-167 (July 1952)
AUTHOR'S SUMMARY
"The most significant factor in flight to the stars is the vast scale of distances involved. It would be possible, at least in principle, to construct a vehicle, deriving its power from known nuclear reactions, which would be capable of reaching the nearest stars in a period of time measured in centuries. Such a vehicle might achieve a may tmiim velocity of 5,000 to 10,000 km/sec. One difficult problem would be the attainment of reasonable accelerations in conjunction with the necessary high exhaust velocities. An acceleration of 0.3 cm/sec - would be adequate but would involve an almost prohibitive rate of power dissipation.
"Vehicles designed to achieve velocities close to that of light would
need to utilize sources of energy far more potent than any known today.
Nothing less than the complete conversion of matter into utilizable energy
would be sufficient for this purpose. The dynamics of vehicles moving at
such high velocities would have to be based upon the principles of special
relativity. An important consequence of this would be the reduction of
voyage transit times in the traveller’s system of reference. Even if one
assumes the existence of power sources capable of giving vehicles velocities near to the speed of light, the attainment of useful accelerations would be a formidable problem. Accelerations of the order of 1 g would be necessary, to exploit fully the capabilities of the time dilation effect.
A hypothetical vehicle propelled by photons would require to develop a useful power rating of 3 billion watts per tonne of vehicle mass ( 3x10 watts/tonne)
to obtain 1 g acceleration. If the photons were radiated from "black body"
surfaces , the temperatures involved would be of the order of 100,000°C.
"Interstellar matter would not provide a hazard at vehicle velocities
less than 100,000 kra/see., but at near optic velocities, individual nuclei
of the interstellar gas would penetrate through considerable thicknesses
(10 cm) of solid metal and precautions would have to be taken to protect
ary people in the vehicle."
Interstellar Flight
JBIS, Vol. 11, No. 4, Jul 1952
DAC COMMENTS

This is a well -written paper, covering a wide variety of subjects. The
published abstract is quite inclusive. However, a few additional comments on
the portion of the paper covering photonic rocket propulsion are in order.
The author indicates that for a hypothetical vehicle having a mass ratio
of 7*4 and unity efficiency of energy conversion, the true velocity of the vehicle (relative to the system in which it was Initially at rest) would be 59/6l times the speed of light (0.967c). Electrically accelerated photons are not considered and the only emission discussed is black body radiation. As mentioned in the abstract, the emitting surface (l square meter) should have
the tremendous temperature of 100,000°K., and a power of 3X10 1 watts/tonne of ship mass would be required. The paper contains an excellent, elementary discussion of relativity as of importance to space travel.
"More advanced jet -propulsion performance will undoubtedly come about
through the use of nuclear energy in place of chemical energy, but this development has only just begun. In the near future advances in jet propulsion will ccane about through the development of more efficient combustion systems and
the improvement of the means of converting heat into kinetic energy."
From Chapter 8, p. i40-l42
"The investigation of the dynamics of very hot gases not only is beginning
to unravel many mysteries ocf our astronomical cosmos but also offers some
exciting possibilities in the technology of flight. Our present airplanes —
rocket or jet-propelled — are ultimately limited in speed by the gas velocity
that can be attained by chemical reactions. For practical space flight we
shall need much higher velocities. One possible way to attain it is to accelerate gas with magnetic forces instead of merely with chemical combustion.
There is no known theoretical limit to the propulsive Impulse obtainable from
a given mass of gas expelled in this way. Hie electrical energy for acceleration
could be supplied by a nuclear reactor. This propulsion device would be essentially an electric motor with a gas replacing the usual solid armature.
"It say even be possible to find ways to use magneto-hydrodynamic forces
for control and lift, as well as for propulsion, of the ships in which man
eventually will take off into space."
WB Klemperer
14 de diciembre de 1954

The Cold War and the U-2

In the 1950s, the United States-Soviet Union relations reached their point of maximum tension, with an arms race at the highest level carried out by both countries. The mayor feared the United States government was that, before invading its positions in Berlin and openly revealing its intentions, the Soviet Union carried out a nuclear preemptive strike on American soil, employing intercontinental missiles and new models of long-range strategic bombers. In any conflict, it is vital to know the most accurate way possible of the state and disposition of the total resources with the enemy’s account, which is why the different intelligence agencies of both countries will do their best to collect such data. Of vital importance was the use of reconnaissance aircraft that recognize the possibility of making deep incursions into enemy airspace and obtaining images of airfields, industrial parks and military bases, among others; It was even more important to be able to return to friendly airspace with these data, which is why very high-performance aircraft were used, at a time when there was no link data or, ultimately, real-time transmission of images and data reached during the mission. And just like in the First World War, the Soviet Union could not allow that intelligence to reach its enemy, so it used all possible means to intercept the reconnaissance plane that carried out the corresponding mission, including the recently released early warning radars (EWRs), which detected enemy incursions at low speeds early enough to allow interceptor aircraft to develop their kite.

It was in this decade when the CIA asked Clarence Kelly Johnson, the legendary chief engineer of Lockheed and absolute boss of the Skunkworks, to develop what we now know as U-2, an aircraft equipped with state-of-the-art cameras and sensors ( what is known today as State Of Art), of very high autonomy and capable of flying over very high altitude enemy airspace, at a level greater than the estimated range of Soviet early warning radars, so that it developed his mission undetected.

Placing ourselves a little in the context and importance of this high-performing select division of Lockheed, the Skunkworks, were and continue to be the parents of many State of Art aviation projects: the P-80 Shooting Star has emerged from its facilities , the aforementioned U-2 and the Blackbirds, the F-117 and hypersonic research projects among others http://www.lockheedmartin.com/us/aeronautics/skunkworks.html.

The U-2 certainly deserves a separate entry; However, something must be added at this point that will surprise the reader, and more considering that unlike the SR-71, it is still in service and has received continuous updates; the U-2 was born “old”, that is, the capacity of Soviet early warning radars was much higher than that estimated by the United States, so already on the first mission, to everyone’s surprise, U-2 it was detected and interceptor planes met it. However, none of them approached him, given the plane’s incredible flight ceiling. Unfortunately, in a short time both the first air combat missiles and the SAMs made their appearance, the only way to counter them being the development by the Skunkworks of a black box placed in the rear area of ​​the plane that acted as an electromagnetic frequency emitter. , captured in previous U-2 missions and analyzed, which confused the guidance systems, that is, a primitive electronic warfare system that took its first steps and was not 100% reliable.

Kelly Johnson thought of the U-2’s successor very simply: an even higher ceiling, approximately 90,000 feet, and a speed of Mach 3.0, so that no current and future aircraft and / or missile could approach it at a lethal distance. . The idea was simple, the problem was to make it come true.

As Kelly Johnson already knew, the technical problems they were going to have to solve were enormous, the most critical being the reactor and the construction material of the airplane: the reactor had to be able to operate efficiently at 90,000 feet above sea level and take advantage of the very little, for not to say null, oxygen level existing at that distance. Regarding the structure: how would this behave against the heat generated at such extreme speeds ?; aluminum as a material for the fuselage was completely discarded, as temperatures much higher than those withstood would be reached, and the only viable alternative was the massive use of steel, which meant an unacceptable increase in weight, to which the need was added to have a very efficient equipment cooling system. There was a third factor, which at first passed to a third plane: an airplane had to be made as invisible as possible to Soviet radar.

By 1951, Skunkworks engineer Henry Combas had proposed to Johnson to employ a rare metal, as strong as steel but half as heavy as steel, in the exhaust nozzles of the F-104 Starfighter’s J-79. This metal was titanium, with a single producer in the United States that sold it in sheets of variable quality, so a more reliable supplier capable of providing greater volume was needed, which was sought and found by the CIA: the Union Soviet, one of the largest exporters in the world. Titanium was acquired through shell companies and corporations not officially associated with the CIA. Despite this, although a base material for the aircraft had already been found, it was soon discovered that at Mach 3.0, the metal would expand at least a couple of inches, in addition to the lack of sealants capable of supporting such high temperatures, so the aircraft lost fuel on the ground through panel joints that closed in flight and with the expansion of the metal due to heat. Not only that, but the different mechanical parts of the airplane (actuators, wiring, etc.) had to be designed based on certainly exotic materials, and even precious metals such as gold, capable of maintaining a high conductivity rate at very high temperatures. The cost of the plane was skyrocketing.

Heat also affected rubber elements such as rubbers and tires: BF Goodrich developed tires with nitrogen-inflated aluminum microparticles, which gave them a characteristic silver color and made them more resistant to temperature. It also affected the fuel, requiring Shell to develop a special one, with an enormous range of operating temperatures and a very high flash point that would not vaporize at flight temperatures; also, in the pressurization of the tanks nitrogen was used; All this made it possible to use the fuel as a secondary cooling system, specifically that it served avionics systems and the vicinity of the landing gear, connecting these areas by means of a network of pipes interconnected with heat exchangers; Thus, the fuel at a higher temperature was transferred to the engines, and the fuel at a lower temperature was used as a “coolant”, a process controlled thanks to an intelligent valve that allowed the passage of fuel at a higher temperature to the combustion chambers.

But the biggest headache for Skunkworks engineers, especially for the future successor to Kelly Johnson and father of the F-117, Ben Rich, was the design of the engines and intake nozzles, while the reactors, submitted at operating conditions with characteristics of 90,000 feet, by themselves cannot function, since the sufficient oxygen density is not available (1/16 of that found at sea level), so it was necessary to develop a highly efficient intake system, capable of enormous compression thanks to the speed developed by the aircraft (remember that the intake nozzle decreases the speed of the air by transforming it into pressure, which helps the compressor to effectively carry out its work). Initially, it was thought to develop its own reactor, but the exponential increase in development costs as well as the need to meet delivery deadlines already exceeded, led to the use of Pratt & Whitney J-58, however, conveniently modified to operate in Afterburning regime continuously, each providing an equivalent of 160,000 CV, requiring for it 2,831.68 cubic meters of air per second (approximately, the equivalent of two million people inhaling in unison). No less impressive was the original starting system, consisting of two engines from a Buick Wildcat V8 that raised the speed of the J-58s to 4500 RPM, which was necessary to start. Subsequently, a pneumatic system was used.

The intake nozzle, on the other hand, would be conical with a variable position, advancing or delaying its position according to the flight conditions, eliminating the shock wave generated at its tip and maximizing the increase in air pressure entering the compressor, minimizing losses by friction; in fact, approximately 80–84% of the total thrust of the aircraft at Mach 3.0 was produced thanks to the intake nozzle, the thrust provided by the engines at that speed being 16–20%. This intake nozzle operated through an electronic control unit, which communicated with the air data computer, which provided it with the data that the control unit needed to effectively operate the intake nozzles: speed and angle of attack. The air entered at -54 ºC and thanks to the intake nozzle, it compressed reaching 427 ºC and 5.80 bars. After passing through the compressor, the temperature increased to 760 ºC, reaching 1260 ºC and 1870 ºC in the combustion chamber during post-combustion.

Finally, the shape of the plane, whose name for both the A-12 (single-seat version of the CIA and shorter, this being the original aircraft) and the SR-71 (version for the two-seat USAF) is “blackbird” due to His black paint, chosen by Kelly Johnson after advice received from Ben Rich about the heat absorption-emission capabilities of black bodies, is very special: it was the first aircraft with a cross-section of radar ( RCS) so low, that compared to its contemporaries, its detection rate was 1/100. This is also helped by being the first aircraft painted with paint based on ferritic compounds capable of absorbing and spreading radar waves through the structure of the aircraft, very similar to that currently used by the most modern combat reactors, which apply them in specific areas. of the fuselage.

With the plane fully conceived, another added problem arose: poor quality controls on titanium, detected after a mere accident; One of the operators dropped a small piece onto the ground, breaking into a thousand pieces like glass. This led to rejecting approximately 95% of the purchased titanium. And not only that, but to define high resistance tooling, given the tremendous hardness of titanium, which made conventional tools useless in a short time.

The truth is that although the difficulties solved were enormous, with absolutely excessive costs, the plane was ahead of its time in several generations; only the time of its conception and period of service is betrayed by a cabin full of analog instrumentation. And in fact, although it was the offspring of a time when the world’s most powerful computer was as fast and capable as a handheld calculator from the 1990s, it had only one catch: a phenomenon Ben Rich and the Skunkworks engineers called unstart, an issue that test pilot Bill Park encountered when flying over New Mexico at 65,000 feet and Mach 2.7. The unstart was produced when the air that entered one of the engines did it with difficulty due to the angle carried in the pitch or in the yaw, which decreased the efficiency of the intake nozzles from 80–84% to approximately 20% (insufficient intake and air compression), turning off the afterburner for it and causing a huge BANG that could be heard by the pilot himself, despite the speed and his position ahead of the engines, followed by shaking of the plane. The original analog engine control system of the aircraft could fix the problem in 10 seconds, but in those 10 seconds, the pilot suffered the consequences, often without being aware of which engine the afterburner had been turned off due to extreme difficulty in reading the instruments and erroneously decreasing the thrust on the contrary, or even turning off both engines. The solution was to adopt an electronic control system that turns off the afterburner in the unaffected engine — through the control of the intake nozzle, simulating an unstart in the engine that did work correctly and that automatically, restored the control of the airplane, the return to its correct operating conditions.

Very few know that this legendary aircraft, which avoided the impact of enemy missiles simply by accelerating, despite having a complete electronic warfare system, and which had unbeaten speed records to this day, could have been the most effective interceptor the United States would have had even today. Indeed, during a visit by General Curtis LeMay to the Skunkworks facilities — and not exactly friendly, but looking for direct explanations from Kelly Johnson about why his XB-70 bomber was seeing his order reduced, holding Johnson and his SR responsible- 71 Blackbird of this fact — he was so impressed that he placed a huge order for SR-71, both in the form of interceptors and reconnaissance aircraft. The Skunkworks went to work immediately, designing one of the world’s first radars with a down-shoot down look from a Westinghouse ASG-18, conveniently modifying it. The results, once again, speak for themselves: They hitched targets over 100 miles and flew at 1,500 feet, all at Mach 3.0 and an average flight level of 85,000 feet. Twelve of thirteen tests were successful, being globally the most successful weapons testing program in the world. Unfortunately, the interceptor version met Robert McNamara head-on, his budget cuts (one of his nicknames was Mac The Knife), and the TFX program, which had his full support.

By: Javier Sánchez Horneros

About Javier Sánchez-Horneros Pérez

Javier Sánchez-Horneros Pérez is a Mechanical Engineer, aerospace technical writer with works published by the Ministry of Defense and specialized media, assiduous collaborator in the Aeronautics and Astronautics Magazine, and pilot of ULM.

He currently performs his daily work at the Flight Test Center in San Pablo (Seville), as a Flight Test Engineer in the FTI branch (Flight Test Instrumentation) in the so-called “Own Products” (C295) and collaborating when he is necessary in the A400M Program. Previously, he has worked as a Systems Engineer in the A330 MRTT Program (Getafe), as well as a Manufacturing and Process Engineer of aerospace components, in a Madrid-based company that supplies aeronautical components for Airbus and Boeing, among other international clients.

He combines this task with the aerospace technical writer, having published two works under the seal of the Ministry of Defense (Defense Publications): “Guided Air Combat Missiles in the Air Force (Systems and Technology)” (ISBN 978–84–9781–764–6. NIPO 083–12–151–4), where the different methods of guiding air combat missiles and the search and tracking systems for targets intended for this purpose are reviewed in an informative manner and “From the T -33 to Eurofighter. Reaction Combat Aircraft in the Air Force ”(ISBN 978–84–9091–040–5. NIPO 083–15–046–5) where an exhaustive analysis of the creation, history, aerodynamics, engines, avionics and search and target tracking systems for combat jets that have served in the Air Force. He combines this literary work with collaborations in the Aeronautical and Astronautical Magazine where he carries out technical-informative analysis of various weapons systems.

In addition, he was a technical advisor to military aerospace systems (aerodynamics, powerplants, avionics and search and target tracking systems) until February 2015, at the Madrid Air Museum as a member of the Association of Friends of the Air Museum, where He made multiple posts on his blog about combat aircraft, technology, and associated systems.

José A. Galán

@galanvazquez