The following posting was made to rec.models.rockets by Peter Alway, a prize-winning expert on scale model rockets.

Just a little background: The Smithsonian Institution published Robert Goddard's "On a Method of Reaching Extreme Altitudes" early in 1920. At the time, he was not yet building liquid-fuelled rockets. One of the rockets he had invented was a "multiple- charge" rocket, in which successive propellant grains were shot into the combustion chamber in flight. The idea was that the heavy combustion chamber would not have to be large enough to hold all the propellant at once. The next year, Goddard would dig into liquid propellants. Only after the British invention of the center-star propellant grain and Jack Parson's invention of composite propellants would the Solid be used for space travel, as Goddard had proposed.

If the multiple charge-rocket sounds a lot like "Project Orion" (in which a starship would be propelled by a series of nuclear explosions), I should point out that this scheme involved rocket grains in a combustion chamber, rather than, if I may risk using the word, detonations. You might think of the multiple-charge rocket as the predecessor to the pulse-jet, which Goddard patented around 1930. However, the good Professor did suggest the idea of setting off explosives behind a reflector or shield in his notes in the 1930's (maybe I should have copied that?). I believe that is the essence of the Orion scheme.

In his Smithsonian monograph, Goddard calculated the size of rocket needed to send a pound to the moon he then extrapolated how much flash powder might be visible on the moon, from tests over a couple miles on earth. He calculated a rocket of tens of tons (I don't have the figures in front of me) could theoretically send it to the moon.

Anyway, all you Goddard fans should enjoy this enlightened bit of writing.

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A Severe Strain on Credulity

But that is a slight inconvenience, at least from the scientific standpoint, though it might be serious enough from that of the always innocent bystander a few hundred or thousand yards away from the firing line. It is when one considers the multiple- charge rocket as a traveler to the moon that one begins to doubt and looks again, to see if the dispatch announcing the professor's purposes and hopes says that he is working under the auspices of the Smithsonian Institution. It does say so, and therefore the impulse to do more than doubt the practicability of such a device for such a purpose must be--well, controlled. Still, to be filled with uneasy wonder and express it will be safe enough, for after the rocket quits our air and and really starts on its longer journey, its flight would be neither accelerated nor maintained by the explosion of the charges it then might have left. To claim that it would be is to deny a fundamental law of dynamics, and only Dr. Einstein and his chosen dozen, so few and fit, are licensed to do that.

His Plan Is Not Original

But there are such things as intentional mistakes or oversights, and, as it happens, Jules Verne, who also knew a thing or two in assorted sciences--and had, besides, a surprising amount of prophetic power--deliberately seems to make the same mistake that Professor Goddard seems to make. For the Frenchman, having got his travelers to or toward the moon into the desperate fix riding a tiny satellite of the satellite, saved them from circling it forever by means of an explosion, rocket fashion, where an explosion would not have had in the slightest degree the effect of releasing them from their dreadful slavery. That was one of Verne's few scientific slips, or else it was a deliberate step aside from scientific accuracy, pardonable enough of him in a romancer, but its like is not so easily explained when made by a savant who isn't writing a novel of adventure.

All the same, if Professor Goddard's rocket attains a sufficient speed before it passes out of our atmosphere--which is a thinkable possibility--and if its aiming takes into account all of the many deflective forces that will affect its flight, it may reach the moon. That the rocket could carry enough explosive to make on impact a flash large and bright enough to be seen from earth by the biggest of our telescope--that will be believed when it is done.

Peter Alway