The theoretical work herein presented was developed while the writer was at Princeton University in 1912-13, the basis of the calculations being the assumption that, if nitrocellulose smokeless powder were employed as propellant in a rocket, under such conditions as are here explained, an efficiency of 50 per cent might be expected.
Actual experimental investigations were not undertaken until 1915-16, at which time the tests concerning ordinary rockets, steel chambers and nozzles, and trials in vacuo, were performed at Clark University. The original calculations were then repeated, using the data from these experiments, and both the theoretical and experimental results were submitted, in manuscript, to the Smithsonian Institution, in December, 1916. This manuscript is here presented in the original form, save for the notes at the end which are now added.
A grant of $5,000 from the Hodgkins Fund, Smithsonian Institution, under which work is being done at present, was advanced toward the development of a reloading, or multiple-charge rocket, herein explained in principle, and this work was begun at the Worcester Polytechnic Institute in 1917, and was later undertaken as a war proposition. It was continued, from June, 1918, up to very nearly the time of signing of the armistice, at the Mt. Wilson Observatory of the Carnegie Institution of Washington, where most of the experimental results were obtained.
In connection with the present publication, I take pleasure in thanking Dr. A. G. Webster for the facilities of the shop and laboratory at Clark University, used in the preliminary experiments herein described. I also take this opportunity of expressing my gratitude to the Smithsonian Institution, for its support and encouragement in the later work.
ROBERT H. GODDARD.
CLARK COLLEGE,
WORCESTER, MASSACHUSETTS, May 26, 1919.