Feb 012012
 


The document presented above is a progress report dating from September 15, 1946 for the Martin Orbit Project, an ambitious single-stage-to-orbit satellite launch vehicle designed for the U.S. Navy. The design appears to be a refinement of Martin’s earlier proposal for the High Altitude Test Vehicle (HATV) program, which had its origins in a May 1945 report by Wernher von Braun on advancements in German rocketry, emphasizing the possibility of placing a satellite into orbit. This caught the attention of the US Navy, with the Bureau of Aeronautics (BuAer) issuing a report on the technical feasibility of the concept in November 1945. The ambitious BuAer design used high-energy liquid hydrogen fuel to fly directly from the Earth’s surface into orbit as a single stage vehicle. Contractors were subsequently invited to submit proposals to the program; Douglas, Martin and North American are known to have participated. Some background on these proposals can be found at Project1947.com, though readers are advised to take the UFO speculation presented on the site with a few grains of salt.

The aforementioned report summarizes the status of Martin’s engineering structural study of the possibility of constructing an “Earth Satellite” for a mass ratio (fuel weight to initial launching weight) of .895. Active work started July 15, 1946. The vehicle presented in the document was 115 ft long with a maximum fuselage diameter of 13.5 ft; the gross launch weight was 100,000 lbs. Overall, it resembled a scaled-up German V-2 and was less portly than Martin’s earlier design

According to the introduction, the study showed that it was practical to obtain an effective mass ratio of .882 for the Earth Satellite, providing the basic assumptions given in the body of the report were satisfied. This mass ratio was not far from the .895 value required to place a one-stage vehicle in a circular orbit around the earth with a payload of 1,000 lbs. Much of the desired reduction in weight empty and an estimated mass ratio of .893 could have been obtained by eliminating the tail (weighing 1,394 lbs) if this proved practical by mathematical dynamic stability analyses, flight simulator tests and flight tests of a small-scale model. It was believed that decreases in weight could also be secured by further design refinements, use of new light-density materials, more refined structural analyses, and use of new types of shell construction.

The main body of the report is somewhat technical; those wanting to read it in depth should click through the gallery above. From the analysis presented, Martin concluded that it had been necessary to make a series of assumptions that may or may not have proven correct when reviewed in the light of further research. Thus, there was a very small margin of safety in the mass ratio of .882, which was considered practical (but which was still .013 lower than that required). A thorough investigation was necessary in order to produce a light weight, high-strength construction utilizing materials which were satisfactory at both extremely low and high temperatures. An increase in mass ratio might also have been obtained by elimination of the tail if extensive analyses and tests showed this to be satisfactory.

The Navy sought to develop the vehicle with the Air Force on a joint basis; the latter blocked these efforts and the HATV program was abandoned in 1948. Thus, Martin’s Orbit Project was never built, though the company went on to develop the Viking series of sounding rockets for the Navy. These were launched from 1949 to 1955 and pioneered several technological advances, such as a 5:1 mass ratio by means of an all-aluminum airframe and thrust vector control by gimbaling the rocket motor, among others.

The Martin Orbit Project was funded under contract NOa(s) 8376. The correspondence file for this contract actually survives in the National Archives, and the author recalls having it pulled for examination, only to find the correspondence all related to the Viking program. Thus, it appears that funding for the cancelled Orbit Project was transferred relatively smoothly to Viking under the same contract number, possibly as a budgetary maneuver to avoid conflicts with Congress and/or the Air Force.

All images from NARA Archives II, College Park, MD, RG 18

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