LIQUID HYDROGEN AS A PROPULSION FUEL,1945-1959

 

Part I : 1945 - 1950

3. Hydrogen-Oxygen for a Navy Satellite

 

 

The Hall Committee

 

[35] Haviland's August memorandum proposing a manned space station (p.32) was convincing to his supervisor, Comdr. J. A. Chambers, head of a special weapons section, who saw among its advantages the possibility of a worldwide navigation and communication system on high frequencies-free from horizon limitations and sky-wave errors. He endorsed it and passed it up the line. It also received support from Capt. Lloyd V. Berkner, head of the electronics materiel branch. During this time, Hall was arguing his case for the single-stage rocket, and he must have been persuasive because on 3 October 1945, Capt. R. S. Hatcher, deputy director of engineering in the Bureau of Aeronautics, established the Committee for Evaluating the Feasibility of Space Rocketry. Its purpose was "to investigate the presently available materials and techniques and to arrive at some estimate of the possibility of attaining a velocity of liberation from one stage of operation." Hall was made chairman and the first meeting was held five days later.* Both Haviland and Hall explained their ideas, and it was revealed that detailed calculations for an earth satellite were under way in another branch of the Bureau of Aeronautics.7

 

The second meeting took place on 15 October 1945, and the subject was experimental data on some fuels and theoretical estimates on others. Lt. Comdr. F. A. Parker presented experimental data on only two propellant combinations: mixed nitric and sulfuric acid with methyl-ethyl-aniline, and alcohol with liquid oxygen. He gave their exhaust velocities at sea level as 1950 and 2300 meters per second, respectively. He thought that any hydrocarbon-oxygen system would likely have an upper limit near that of the alcohol-oxygen value. Parker estimated that increasing the combustion pressure to practical limits would increase exhaust velocity about 15 percent. A greater increase would be possible by increasing the area ratio of the exhaust nozzle. The upper limit on this appeared to be an increase in velocity of about 40 percent over sea level values. The theoretical performance of hydrogen and oxygen was given as 3000 meters per second at sea level and 4300 at altitude. The performance of diborane and oxygen was unknown, but was estimated (optimistically) to be about the same as for hydrogen and oxygen.

 

The Hall Committee concluded that a single-stage rocket for boosting a satellite to orbit would need an exhaust velocity on the order of 4300 meters per second and recommended that the performance of both hydrogen and diborane be investigated, [36] theoretically and experimentally.8 The same day, Aerojet made their first experimental rocket test with hydrogen and oxygen. The exhaust gas velocity during the run was estimated at 2600 meters per second, which meant that 3600 would be attainable at altitude with proper design. No one had tried cliborane, but Hall was attracted to it as an alternate to hydrogen. At the next meeting, on 22 October 1945, he discussed diborane and estimated that it could produce an exhaust velocity of 5500 meters per second, a value far greater than that for hydrogen-oxygen.9 Diborane therefore appeared to be the dream fuel, but Parker pointed out that boron oxides, formed during combustion of diborane and oxygen, might solidify when expanded to the lower temperatures in the nozzle, and this would lower performance.** L. A. Hansen raised the problem of dissociation, where energy is absorbed in breaking molecules apart, which would further reduce the exhaust velocity. In spite of these cautions, the committee accepted the 5500 meters per second theoretical value for diborane-oxygen and estimated that actual performance would probably be close to the desired 4300. Hall recommended that: (1) an experimental program be initiated leading to a satellite orbiting the earth at an altitude of 1850 kilometers; (2) engineering layouts be made on the basis of an exhaust velocity of 4300 meters per second and a mass ratio of 10, and an empty mass of at least 4500 kilograms; (3) the vacuum performance of the most promising fuels having estimated exhaust velocities of 4300 meters per second be tested; and (4) diborane and similar compounds be studied. With this proposal, Hall-the original proponent of hydrogen-oxygen-was now referring to that combination only indirectly in terms of performance and was urging the study of diborane as a fuel. The committee agreed with Hall's proposal for an engineering design layout with his guidelines, but made no reference to diborane.

 

By the fourth meeting, on 29 October, the committee amended the minutes of the previous meeting to agree with Hall's higher estimate for the performance of cliborane. Both Lancaster and Haviland, however, had analyzed boosters, and they continued to prefer hydrogen and oxygen. The two analysts differed in their mass assumptions. Lancaster found an initial-to-final mass ratio of 10 impractical, but Haviland did not. The committee found both sufficiently close to the desired goal to be promising and recommended that a more detailed study be made.10 This was carried out by Lt. Comdr. Otis E. Lancaster and J. R. Moore.

 

In November 1945, Lancaster and Moore reported their study: "Investigation on the Possibility of Establishing a Space Ship in Orbit above the Surface of the Earth." Using the basic energy relationships and a simplified formula for estimating structural weight, comparisons were made of the minimum mass ratio needed for rockets to orbit at various altitudes with the mass ratios attainable with several propellant combinations. Liquid hydrogen-oxygen was considered the best on the assumptions [37] of a jet velocity of 4300 meters per second in a vacuum, which was realistic. The structural formula, however, made mass ratio results very pessimistic. Lancaster and Moore concluded that an initial-to-final mass ratio of from 10.9 to 12.1 was needed to orbit at a high altitude. Since the structural mass formula indicated that for a ratio of 10, a very large rocket (one with a mass of some 2270 metric tons) would be necessary without considering payload, the authors concluded that a single stage to orbit was not feasible.*** A multiple stage rocket using alcohol and oxygen, however, could orbit a satellite. 11

 

The analysis was a blow to Hall's single-stage-to-orbit concept, and he proposed that JPL conduct an independent analysis.

 


* Other members: Comdr. C. D. Case, Lt. (jg) K. W. Max, Lt. R. P. Haviland, Lt. Comdr. F. A. Parker, Lt. L. A. Hansen, Comdr.O. E. Lancaster, and J. R. Moore.
 
** Parker was right. In 1948, at the NACA Conference on Fuels, Flight Propulsion Research Laboratory, Cleveland, the author, P. M. Ordin, and V.N. Huff reported results from rocket experiments in which boron oxides were deposited on the nozzle, verifying Parker's speculation. In the 1950s the Navy and Air Force mounted a major effort to use boron hydrides in turbojet engines and failed, largely because boron oxides clogged the turbine blades. Hearings on Boron High Energy Fuels before the Committee on Science and Astronautics, U.S. House of' Representatives, 26 27 Aug. and 1 Sept. 1959.
 
*** Lancaster and Moore doubted the accuracy of the structural masses they were using and recommended that a detailed structural design study be made. They also recommended intensifying the research program on rocket fuels and engines to find fuels with higher exhaust velocities and to develop larger engines.
 

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