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Rocket Planes - The Sparey File
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Sparey's Rocket Exploits

The following account of Laurence Sparey's exploits with rocket planes and rocket fuel is extracted from the June 1999 issue of SAM Speaks (pp. 54-55). Information in that article was in turn taken from the 'Model Aircraft' section of the 1944 issues of the Percival Marshall publication Model Engineer.

Thanks to Peter Tolhurst for this contribution.

(An enlarged plan of Sparey's 'Rocket Plane' is available to view or download.)


At last, on July 27th [1944], Sparey has plans for a "new" model, unusually graceful and well-proportioned. This is because it is based on a German rocket model of 1936 [Ed.: This is undoubtedly the Haase Rocket Plane, depicted by Frank Zaic in his Model Aeronautical Yearbook of 1944]. In discussing the model Sparey doesn't make it clear whether he is talking about the German model or his own, or when the flights of the latter happened, if at all. He mentions liability to damage and the erratic behaviour of the rockets but this could be about the German original. It is clear that our author was interested in rocket flights at that time and gathered information on rocket fuel but whether he built and flew such models is doubtful.

Sparey seemed to think the model resembles what he calls the "doodlebugs", which had only just arrived over his head, in spite of the model's power unit being below the wing. The hollow aperture for the rocket is 7/8 in. diam. which Sparey assures will give a good fit for the appropriate size of commercial rocket. He says nothing about whether the latter were available in wartime: surely Bonfire Nights were not permitted. Again, putting a firework into any kind of model was, in law, presumed to be "modifying" it, which at this time was illegal.

The length of the hole is governed by getting the whole of the model balanced on the C.G. which he places at 50% of the chord. As with so many of his designs, he has no means of altering incidences, so sliding the rocket is the only trimming device. Sparey says the machine would have to be propped up for launching but even here it is unclear whether he has gone through the procedure himself.

PLEASE NOTE
We caution against attempting to emulate Sparey's "illegal activities". This item is reprinted solely for historical interest. Please see our Terms of Use.
On September 7th he blithely resumes illegal activities by telling his no doubt astonished readers how to make rockets! His only word on safety is to avoid steel tools because of sparks! An 11/16 in. diam. wooden rod is wrapped in 5 in. long, pasted, cartridge paper to a thickness of 7/8 in. (Fig. 1). A hole 1/4 in. diam. and 2 in. long is drilled in one end of the rod and a wooden "adapter" shaped as in Fig.2 is plugged in. This is to be used to shape the lower end of the paper tube, as in Fig.1 which is done in curious fashion:- "Fix the end of a strong, thin cord to a staple in the wall and tie the other end around the waist of the operator so that, by leaning back, the cord may be tightened." A loop is made in the cord, to go over the still wet paper tube which has been slid down over the adapter. Once in the right place, the cord is tightened and the case and stick are rolled up and down the tightly stretched cord, while the operator leans backwards. When this "choke" area is formed correctly, strong string is tied round it and the adapter withdrawn.

Now the inside of the choke area has to be shaped and smoothed, by means of a mould made from wood parts as in Fig. 3. A rammer has to be made from a round stick, 5/8 in diam., a 5/16 in. hole at one end, to pass over the spike. "F" is a brass tube that fits over the paper case which in turn fits over the mould. Wet string is coiled about the spike and the rammer used to force it down to the choke area, shaping and smoothing the latter. The string and rocket case are removed and when the latter is dry it is reassembled over the mould with the brass tube in place. The rocket powder is poured in to a one inch depth and compressed with the rammer. Ibis is repeated at one inch intervals until the case is filled to the top of the spike, when paper wads are rammed in to within 1/4 in. of the top. A tight-fitting disc of cardboard goes over the paper, and the top edge of the case hammered over, securing with glue. The filled case is withdrawn and the hole made by the spike filled with loose gunpowder(!) made into a paste with very weak gum. A touch paper completes the rocket.

Sparey gives the following mix, emphasising that all ingredients be dry and well sieved:- Saltpetre - 6 parts: Charcoal - 3 parts: Sulphur - 2 parts.

One wonders if any reader was foolish enough to try this during the war. Percival Marshall was [a] big enough firm to afford legal eyes looking over their print: they must have been "down the shelters" when this piece passed through the office!


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