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.
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 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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