Part I : 1945 - 1950

3. Hydrogen-Oxygen for a Navy Satellite



World Circling Spaceships


[39] In their first quick look, the RAND group faced the same problems as the earlier investigators at the Bureau of Aeronautics and JPL. Simple physics gave the required orbital velocity and the Tsiolkovskiy equation gave the vehicle velocity without drag or pull of gravity. The major unknowns, other than those velocity losses, were the structural weights and the performance of propellant combinations. The velocity losses were not difficult to assess. The V-2 data furnished a guide for structural mass estimates as well as the actual performance of the alcohol-oxygen propellant combination. RAND considered 39 different fuel-oxidizer combinations and found that hydrogen-oxygen ranked highest (the same result as the Lemmon report, p.4). [40] Hydrogen's low density, low temperature, and wide explosive range would cause problems, but RAND decided to accept it for design studies anyway. A parallel design study used alcohol and oxygen. A satellite with a mass of 227 kilograms was selected as the payload to orbit at 556 kilometers.20


The RAND study gave the V-2 structural mass as 18 percent of its initial mass, estimated that 16 percent was as good as could be obtained, and used the latter for propellants not involving hydrogen. The larger tank needed for low-density hydrogen would probably increase the structural mass proportion to 25 percent.* This, of course, greatly offsets the advantages of the high exhaust velocity of the hydrogen-oxygen combination. Not surprisingly, RAND concluded that a vehicle using either hydrogen-oxygen or alcohol-oxygen could not reach orbital velocity with a single stage-a repudiation of the Navy proposal.


The RAND study found that with multistage rockets, however, orbital velocities could be reached with either hydrogen-oxygen or alcohol-oxygen, but the designs would differ considerably. The alcohol-oxygen vehicle required 4 stages with an initial mass of about 100 metric tons. A 2-stage vehicle using hydrogen-oxygen, but having a third more mass, could do the same job. A 3-stage hydrogen-oxygen rocket would reduce the initial mass to below that of the alcohol-oxygen vehicle. RAND concluded that hydrogen-oxygen should be given serious consideration in any future study. The cost of constructing and launching a satellite was estimated at $150 million over a 5-year development period.


The RAND study gave the AAF a strong position in discussing satellite proposals with the Bureau of Aeronautics. The War Department had a mechanism for coordinating similar programs between the air services-the Aeronautical Board, created during World War II. In June 1946, the board considered the satellite studies of the two services and took the neutral position that both should continue their studies independently.21 Both the Bureau of Aeronautics and the Air Force moved to strengthen their positions.


The Air Force instructed RAND to start a 6-month study to provide a design sufficiently complete that development contracts could be negotiated for a vehicle capable of launching a satellite. For their part, the Bureau of Aeronautics contracted with North American Aviation for a 90-day study of the feasibility of their proposal using the GALCIT structural limits as a guide. For a more detailed study of the structural aspects, the Navy also contracted with the Glenn L. Martin Company for a 12-month study, using the same guidelines as the North American contract. To supply data on rocket power plants, the Navy contracted with Aerojet for the detailed design study of a 1.33 meganewton (300 000 lb thrust) engine suitable for a vehicle of 45 400 kilograms initial mass. The Navy called its vehicle the High Altitude Test Vehicle, or HATV.


* Structural mass is generally assumed to be the final mass less payload and engine; the RAND structural figures are not convertible directly into initial-to-final mass ratios.