THOUGH rockets have aroused a good deal of public interest during the last few years and a great number of very interesting books and articles have been published about the theoretical side of this new science, little is generally known about the experimental progress that has been made, especially in Germany and the U.S.A. In describing this science—the Americans call it “rocketry”—as “new,” it is to be understood that this term applies only to the mathematics of it. The ordinary powder or “sky” rocket is by no means new, but has a long and very involved history, going back to Hassan Alrammah, called “nedshm‐eddin” (The Faithful) in A.D. 1280, who designed the first rocket‐driven torpedo. But though rockets in general (i.e. the powder rocket, which alone existed previous to 1929) have a history of almost a millennium and have even been of historical importance (Sir William Congreve's war‐rockets), the manufacturers of powder rockets knew nothing about their mathematics. When, for example, in 1928 the German Verein für Raumschiffahrt discussed the problem of exhaust velocities and impulses, its president, Johannes Winkler, asked the largest rocket factories about this information and received the answer that they did not know it and had no way of determining it. Winkler was therefore obliged to take the thrust‐diagram of a powder rocket himself (Fig. 1). This diagram revealed that the thrust of a sky‐rocket lasts for only two‐tenths of a second; this result was really amazing and the most amazed were the manufacturers of these rockets.
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