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PATENT SPECIFICATION 645,897
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Date of filing Complete Specification: Jan.28, 1949.
Application Date: Mar. 3, 1948. No. 6636/48.
Complete Specification Published: Nov. 8, 1950.
COMPLETE SPECIFICATION
Improvements in or relating to
Gas-Escape Reaction Propulsion Devices
We, ALEXANDER CANTLAY HUTCHISON of 36, Caledonia Road, Saltcoats, Ayrshire, and MATTHEW WILSON, of 56, Sharphill Road, Saltcoats, Ayrshire, both British Subjects, and IMPERIAL CHEMICAL INDUSTRIES LIMITED, of Imperial Chemical House, Millbank, London. S.W.1, a British Company, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement:—
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The present invention relates to the provision of an improved gas-escape reaction propulsion device.
The invention has for an object to provide a simple, safe and efficient self-contained gas-escape reaction propulsion device containing a solid charge of a thermally actuable hot gas-generating composition within a casing having a perforated wall element providing a gas vent to the exterior that will maintain an internal pressure and retain its predetermined dimensions until the charge is consumed, by means of which there may be propelled a toy or model to which it is attached.
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[…] a simple, safe and efficient self-contained gas-escape reaction propulsion device […] by means of which there may be propelled a toy or model
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It is well known that rockets can be used for propulsion
purposes. For the propulsion of toys and models, however, the conventional
firework rockets are less efficient than is desirable owing to their high
yield of solid combustion products from blackpowder and like compositions
tending to clog narrow orifices, and because of the high rate of combustion
index and consequent liability of such compositions to explode when the
gases are allowed to rise appreciably in pressure before they escape. Consequently,
the thrust it is possible to maintain on the toy or model is undesirably
limited. They are also unsuitable for use indoors. The flames and sparks
emitted by conventional firework rockets and their ready ignitibility also
entail a certain risk of personal injury to the operator, especially a juvenile
operator, who may have at hand several rockets at a time in order to despatch
his toy or model on successive journeys. Moreover the firework character
of conventional rockets renders their packing, storage and transport in
bulk somewhat inconvenient and expensive.
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The flames and sparks emitted by conventional firework rockets […] entail a certain risk of personal injury to the operator, especially a juvenile operator
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According to the present invention an improved self-contained
gas-escape reaction propulsion device for a toy or model comprises a cylindrical
casing of heat insulating material closed at one end and provided with a
compressed compact charge of shorter length extending in close contact with
the cylindrical wall of said casing from its closed end, this charge comprising
a mixture of guanidine nitrate or nitroguanidine and a solid sensitiser
of the thermal decomposition thereof, in amount sufficient to enable the
mixture to propagate through itself a self-sustained exothermic gas-producing
non-explosive decomposition when a small amount of heat is locally applied
at the terminal surface of said charge at atmospheric pressure, said terminal
surface being spaced by an air space from a terminal wall element of heat
resisting rigid material perforated with one or more pressure controlling
gas-escape holes of predetermined dimensions, and a weakened portion of
the material of the length of the cylindrical wall not in contact with the
charge being deformable under a predetermined pressure in excess of the
desired working gas pressure so as to burst open the casing if said predetermined
pressure in excess of said working pressure should be attained.
The construction of the device is accordingly such as to establish an alternative gas-escape exit to the exterior should the effective gas-venting area in the terminal wall element be substantially reduced by clogging.
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The insulating material of the cylindrical casing wall
not in contact with the charge may have a weakened portion that will burst
itself open when a predetermined pressure in excess of the working pressure
is attained, but since in affixing the terminal wall element to the insulating
material forming said wall the latter must be deformed, for instance, by
turn- [sic]
its end over the rigid terminal wall element having the venting aperture,
it is convenient to arrange to form the cylindrical casing wall of such
material that this turnover fold will unfold itself if a predetermined pressure
in excess of the desired working pressure should be developed within the
device, this predetermined pressure being low enough to ensure that an emergency
gas-escape exit will thus be established before any danger of the charge
decomposing in an explosive manner could arise.
The said compressed compact charge if desired may be formed in situ in said cylindrical casing. On the other hand the said compressed compact charge may consist of a preformed pellet of a width to form a tight fit in said cylindrical casing.
The cylindrical casing may comprise a single tube capable of being provided with a turnover fold at each end or may comprise two telescopically closely fitting tubes one well inside the other and adhesively bonded together, each tube having a turnover fold at its free end.
In the case of guanidine nitrate the sensitiser of
its thermal decomposition may be for instance a polynitro-phenol or a polynitroso-phenol
or substitution derivative thereof, for example 2:4 dinitroresorcinol, 2:4
dinitroso-resorcinol, or 2:6 dinitropara-cresol in amounts ranging from
about 8-20% of the weight of the guanidine nitrate. It is desirable
to include preferably not more than 1 per cent. of vanadium pentoxide. An
aliphatic acid selected from the group consisting of tartaric, citric, fumaric
and maleic acids may be employed in partial replacement, or even in amounts
ranging from about 20-30% in complete substitution of the polynitro-phenol
or polynitroso-phenol or derivative thereof. There may also advantageously
be present in the composition preferably not more than 1 per cent. of asbestos
fibre which increases the available power by assisting the decomposition,
and if desired also preferably not more than 0.5 per cent. of potassium
nitrate, which assists the ignitibility. Charges suitable for the purpose
of the invention based on mixtures of guanidine nitrate and polynitrophenols
or polynitroso-phenols and certain substitution derivatives thereof are
claimed in the specification of British application No. 27240/47 (Serial
No. 644,073). Other sensitisers that may be used in the case of guanidine
nitrate include for instance, chromates, dichromates and polychromates of
alkali metals or ammonium, nitrocellulose; ammonium molybdate or molybdic
acid with asbestos, or couprous chloride or cupric oxide in amounts ranging
from about 3 to 12%. In the case of nitroguanidine, chromates, dichromates
or polychromates of the alkali metals or ammonium may be used.
When required local heating means is introduced through a controlling gas-escape hole by the operator and may consist for instance of a length of fuse or match composition in the form of a thread or mounted on a wire, the protruding portion of which is then lit. The local heating means may also take the form of a length of wire or the like that has been heated for instance in a domestic fire, gas flame or even match flame. It will be appreciated that the device as marketed does not have exposed fuse or like means of ignition. The gases generated by the decomposition of the sensitised guanidine nitrate or nitroguanidine composition are usually accompanied by little or no flame as they escape through a venting hole or holes. The terminal wall element may be made of temperature resisting metal construction, e.g., tinplate, aluminium alloys, nickel, stainless steel, non-porous refractory materials like silica, porcelain or compressed asbestos sheets. Since the devices as marketed are free from exposed fuse or like means of ignition they are particularly safe for children to handle.
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[…] an emergency gas-escape exit will thus be established before any danger of the charge decomposing in an explosive manner could arise.
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An embodiment of the invention is illustrated in the
diagrammatic drawings accompanying the provisional specification whereof
Fig. 1 represents on an increased scale a longitudinal axial section and
Fig. 2 an end plan of a device suitable for the driving of a toy vehicle.
In the diagrammatic drawings 1 is a cardboard cylinder
turned over a thick cardboard disc 2 as shown at 6, 8 is the main gas producing
charge of a composition consisting for instance of a mixture of:—
Guanidine nitrate -
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91.0%
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by weight
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2:4 dinitroresorcinol
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8.0%
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,, ,,
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Asbestos fibre - -
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0.3%
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,, ,,
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Vanadium pentoxide
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0.5%
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,, ,,
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Potassium nitrate -
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0.2%
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,, ,,
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strongly compressed into the resulting container wall whereof the base and
sides are supported in a press. 3 is a small charge of ignition composition
consisting for instance of 2:4 dinitroresorcinol. Into the open end of the
container a tinplate disc 4, which is provided with a cylindrical hole 5
of a diameter approximately one-tenth of that of the disc, is forced for
a short distance, and the end of the wall 1 extending beyond the disc 4
is turned over as shown at 7. The internal. diameter of the device is 1.9
cm. and the weight of the charge 8 is 8 grams and that of the charge is
0.1 gram; their combined length being approximately 2.1 cm., and the space
between the end of the charge 3 and the terminal disc 4 being approximately
0.75 cm. The diameter of the orifice is 0.19 cm. The external diameter of
the device is 2. 05 cm. and the turnover at the forward end of the device
unfolds if the difference between the internal pressure built up and that
of the atmosphere exceeds 4 atmospheres. After the ignition has been brought
about by means of a hot wire introduced through the hole 5, the steady working
pressure in the space between the charge 8 and the disc 4 may range from
2.67 to 3 atmospheres, depending on the fineness of the ingredients, especially
the dinitro-resorcinol and the guanidine nitrate, the tendency being for
finer original particle sizes and longer milling to give the higher pressures[.
T]he corresponding thrust delivered as the gases escape through the hole
5 is from 21 to 28 grams weight and the time for which this is maintained
is 15 seconds.
Another embodiment of the invention is illustrated
in the diagrammatic drawings attached hereto whereof Fig. 3 represents on
an increased scale a longitudinal axial section and Fig. 4 an end view of
a device suitable for the driving of a toy vehicle.
In the diagrammatic drawings 9 is a cardboard cylinder
turned over a thick cardboard disc 10 as shown at 11 and telescopically
fitting into and adhesively bonded to another cardboard cylinder 12 turned
over a tinplate disc 13 as shown at 14. The disc 13 is supported at the
end 15 of the inner cardboard cylinder 9. The tinplate disc 13 is provided
with a cylindrical hole 16 of a diameter approximately one-tenth of that
of the disc. The inner and outer cylinders have each a length of 3.8 cms.
The internal diameter of the inner cylinder 9 is 1.9 cm. and the external
diameter of the outer cylinder 12 is 2.05 cm. The diameter of the orifice
is 0.19 cm. 17 is a preformed gas-producing pellet closely fitting in the
inner cylinder 9 and is of the same composition and weight as 8 of Fig.
1. 18 is a piece of wire gauze fitting tightly in the inner cylinder and
placed over a wick 19 one end of which is bent over said gauze. The combined
length of the pellet 17, gauze 18 and wick 19 is approximately 2.1 cm. and
the space between the end of the charge 17 and the terminal disc 13 is approximately
0.75. cm. The turnover at 14 unfolds if the difference between the internal
pressure built up and that of the atmosphere exceeds 4 atmospheres. The
ignition of the bent over portion of the wick 19 can be brought about by
inserting another length of wick through the jet orifice and igniting the
protruding portion when required. The ignited wick 19 ignites the pellet
charge 17 and a steady working pressure which may range from 2.67 to 3 atmospheres
is attained in the space between the pellet charge 17 and the disc 13. The
corresponding thrust delivered as the gases escape through the hole 16 is
from 21 to 28 grams weight and the time for which it is maintained is 15
seconds.
The device according to this embodiment of the invention
is very easily assembled. The cylinders 9 and 12 are each provided with
a turned over end 11 and 14 respectively. The cardboard disc 10 is pushed
into cylinder 9 against the turned over end 11. The preformed pellet 17
is pushed down into cylinder 9 against the cardboard disc 10. The wick 19
is then placed on the preformed pellet 17, and the metal gauze 18 is placed
over the wick 19 arranging that a portion of the wick 19 is bent over the
gauze 18. The tinplate disc 13 is inserted into the cylinder 12, the exterior
surface of the cylinder 9 is coated with an adhesive composition and the
cylinder 9 is then pushed into the cylinder 12 so that its rim 15 pushes
the tinplate 13 well up against the turned over end 14 of the outer cylinder
12.
Having now particularly described and ascertained the
nature of our said invention and in what manner the same is to performed
[sic],
we declare that what we claim is : -
l. An improved self-contained gas-escape reaction propulsion
device for a toy or model comprising a cylindrical casing of heat-insulating
material closed at one end and provided with a compressed compact charge
of shorter length extending in close contact with the cylindrical wall of
said casing from its closed end, this charge comprising a mixture of guanidine
nitrate and/or nitroguanidine and a solid sensitiser of the thermal decomposition
thereof in amount sufficient to enable the mixture to propagate through
itself a self-sustained exothermic gas-producing non-explosive decomposition
when a small amount of heat is locally applied at the terminal surface of
said charge at atmospheric pressure, said terminal surface being spaced
by an air space from a terminal wall element of heat-resisting rigid material
perforated with one or more pressure-controlling gas-escape holes of predetermined
dimensions, and a weakened portion of the material of the length of the
cyclindrical wall not in contact with the charge being deformable under
a predetermined pressure in excess of the desired working gas pressure so
as to burst open the casing if said predetermined pressure in excess of
said working pressure should be attained.
2. An improved self-contained gas-escape reaction propulsion
device as claimed in claim 1 wherein the weakened and deformable portion
of the cylindrical wall material consists of a turnover fold over a terminal
wall element.
3. An improved self-contained gas-escape reaction propulsion
device as claimed in claim 2 wherein the turnover fold is formed over the
rigid terminal wall element having the venting aperture.
4. An improved self-contained gas-escape reaction propulsion
device as claimed in any of the preceding claims wherein the cylindrical
casing is formed from a single tube capable of being turned over into a
fold at each end.
5. An improved self-contained gas-escape reaction propulsion
device as claimed in any of claims 1 to 3 wherein the cylindrical casing
comprises two close fitting tubes telescoped one inside the other and adhesively
bonded together, each tube having a fold at its free end turned over a terminal
wall element.
6. An improved self-contained gas-escape reaction propulsion
device as claimed in any of the preceding claims wherein the compressed
compact charges are based on mixtures comprising guanidine nitrate and a
polynitro-phenol or a polynitroso-phenol or substitution derivative thereof
as claimed in the specification of co-pending British Application No. 27240/47
(Serial No. 644,073).
7. An improved self-contained gas-escape reaction propulsion
device as claimed in claim 6 wherein the polynitrophenol derivative is 2:4-dinitro-resorcinol.
8. An improved self-contained gas-escape reaction propulsion
device as claimed in any of claims 1 to 5 wherein the compressed compact
charge consists of a mixture comprising guanidine nitrate and a chromate,
bichromate or poly-chromate of an alkali metal or ammonium.
9. An improved self-contained gas-escape reaction propulsion
device as claimed in any of claims 1 to 5 wherein the compressed compact
charge consists of a mixture comprising guanidine nitrate and nitro cellulose.
10. An improved self-contained gas-escape reaction
propulsion device as claimed in any of claims 1 to 5 wherein the compressed
compact charge consists of a mixture comprising guanidine nitrate, asbestos
and ammonium molybdate or molybdic acid as sensitisers.
11. An improved self-contained gas-escape reaction
propulsion device as claimed in any of claims 1 to 3 wherein the compressed
compact charge consists of a mixture comprising guanidine nitrate and cuprous
chloride or cupric oxide.
12. An improved self-contained gas-escape reaction
propulsion device as claimed in any of claims 1 to 5 wherein the compressed
compact charge consists of a mixture comprising nitroguanidine and a chromate,
bichromate or poly-chromate or an alkali metal or ammonium.
13. An improved self-contained gas-escape reaction
propulsion device as claimed in any of the preceding claims wherein the
perforated terminal wall element is made of temperature resisting metal.
14. An improved self-contained gas-escape reaction
propulsion device as claimed in any of the preceding claims wherein the
compact charge is one compressed in situ against the cylindrical
casing wall.
15. A method for the production of an improved self-contained
gas-escape reaction propulsion device as claimed in any of the preceding
claims wherein the compact charge is formed in situ before the said
perforated terminal wall element is incorporated into the structure.
16. An improved self-contained gas-escape reaction
propulsion device substantially as described and with reference to the diagrammatic
drawings accompanying the provisional specification.
17. An improved self-contained gas-escape reaction
propulsion device substantially as described and with reference to the diagrammatic
drawings attached hereto.
Dated the 28th day of January 1948.
E. A. BINGEN,
Solicitor for the Applicants.
Leamington Spa: Printed for His Majesty's Stationery Office,
by the Courier Press.—1950.
Published at The Patent Office, 25, Southampton Buildings. London, W.C.2,
from which copies, price 2s. Od. each (inland) 2s. 1d. (abroad) may be
obtained.
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Fig. 1
Fig. 2
Fig. 3
Fig. 4
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