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Rocket Models
by Howard Boys
Extracted from Aeromodeller, July 1947, p. 467.
The complete article can be read on
another page.
The type of model suitable for rocket drive is one with plenty of space behind the centre of gravity, so that the efflux can be directed away from the model. Tailless, twin boom, or pod and boom types are good, but it is also possible sometimes to fit a rocket in the tail end of a model. I have managed this very successfully in a scale model of the D.H. Swallow. The alteration in the position of the C.G. due to the burning of the charge only results in a higher gliding speed than with the C.G. further aft. To help overcome the difficulty of the charge being well behind the C.G. the unit can be directed downwards a little, so that the thrust helps to counteract the weight.
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Two ways to get the Swallow plan:
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Easy, but smaller
Print this page. At the bottom, and fitting within the page width, is
a copy of the plan.
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More work for you, but larger
Click this link
to a separate copy.
If you want to print it in full, you'll need to save it to disk, then open it in a graphics
program in order to print it.
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The best position for the rocket unit is as close as possible to the C.G. so that there is no change of trim. This means using one of the previously mentioned types. Tails can be kept well out of the way, and quite safe while the model is in the air, but often suffer if the model comes to the ground with the unit burning, through bad launching, or other causes. It is possible to obtain asbestos paper that can be used to protect parts of the model. I have seen various types of models flying, and the most promising have always had the rocket mounted above the wing. These have all been boom types, sometimes single and sometimes twin, sometimes low, sometimes high. Tailplanes have been low or high. Bougeret put his rocket above the wing and his tail low down, and obtained very good flights. A friend of mine has had some very good flights with a model on the style of the American Yogi petrol model. This model has a tall narrow pod, with the boom low down. The wing is on top of the pod, the rocket on top of that, the tailplane low, and twin fins.
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Diagram illustrating rocket positioning
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Aeromodeller, July 1947 (p. 467)
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Plan for Swallow
(A larger copy of the plan is also available to
view or download).
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