US2617251A

US2617251A - Gas escape reaction propulsion device

Info

Publication number: US2617251A
Application number: US73364A
Authority: US
Inventors: Alexander C Hutchison; Wilson Matthew
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1948-03-03
Filing date: 1949-01-28
Publication date: 1952-11-11
Anticipated expiration: 1969-11-11
Also published as: NL145064B; NL78664C; GB645897A; DE908353C; FR981035A

Description

Nov. 31, 31952 A. c HUTCHISON El'AL 2 537 253 GAS ESCAPE REACTION PROPULSION DEVICE Filed Jan. 28, 1949 FIG.

. 7 W095: Alexander Carzzlay fizdc/zz'sozz 2 Ma zzhezw W'Zson.

Patented Nov. 11, W52

UNlTE GAS ESCAPE REACTION PROPULSION DEVICE Great Britain Application January 28, 1949,.Serial No. 73,364 In Great Britain March 3, 1948 8 Claims. (c1. Bil-35.6)

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, model or the like to which it is attached. 7

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 emcient 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' ignitability 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 inorder 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.

According to the present invention an improved self-contained gas escape reaction propulsion device for a toy, model or the like comprises a cylindrical casing of heat insulating material closed at one end and provided with a compressed compact charge comprising a mixture'of guanidine nitrate and/or nitroguanidineand a solid sensitizer 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, which terminal surface is 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.

2 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 accordance with a preferred form of the invention, a portion of the insulating material of the cylindrical casing wall not in contact with said charge is deformable under a predetermined pressure in excess of the desired working gas 7 more than 1 percent of vanadium pentoxide. An

aliphatic acid selected from the group consisting of tartaric, citric, fumaric and maleicacids may be employed in partial replacement, or even in amounts ranging from about 20-30% in complete substitution of the polynitrophenol or poly.- nitrosophenol. There may also advantageously be present in the composition preferably not more than one percent of asbestos fibre which increases the available power by assisting the decomposition, and if desired also preferably not more than 0.5 percent of potassium nitrate which assists the ignitability; Charges based on mixtures of guanidine nitrate and polynitrophenols or polynitrosophenols are claimed in co-pending application Ser. No. 42,948. Other sensitizers that may be used in the case of guanidine nitrate include 101 instance, chromates, dichromates and.

polychromates of alkali metals or ammonium; ,ni'

trocellulose; ammonium molybdate or molybdic acid with asbestos, or cuprous chloride or cupric oxide in amounts ranging from about 3to 12%. In the case of nitroguanidine, chromates, dichromates or polychromates of the alkali. metals or ammonium may be used. j

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 theform of a length of wire orthe 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 sensitized guanidine nitrate or nitroguanidine composition are usually accom-.

predetermined pressure in excess of the workin pressure is attained, but sinee in affixing the terminal wall element to the insulating material forming said Wallthe latter must be deformed, for instance, by turning itsend over the rigid terminal wall element, 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 shouldbe developed withinthe device, this predetermined pressure being low enough to ensure. that an emergency as escape exit will thus be established before any dangerof the, charge decomposing in an explosive manner could arise,

An embodiment oi tha invention is illustrated in the diagrammatiodrawings accompanying the specification, whereof ,Fig. 1 represents on an increased scale alongitudinalgaxial sectionand Fig.

2- anflend plan of a, devicesuitablefor the drivcylinder turned .overathickcardboard disc Zas shown at 6, B isthemain gas producing charge of-a composition consisting. for instance. of av strongly, compressed into the resulting container wall whereotthe .baseand sides are. supported in the press. 3 is. asmall. charge of. ignition composition consisting for instance of 2:4 dinitro-v resorcinol. Intothe .open end of the container a tinplate disc .4, which is-provided with a cylin-.

drical hole 5 of. a.diameterapproximately.onetenth of thatof the disc, isforced for a short dis-. tance, and the end of. the .wall Lextending. beyondthe disc 4. is-.turned-over as shown at l. The internal diameterofrthe..device.is1.9 cm. and the weight ofthecharge Bis 8Vgrams and that of the charge3 is.0;1 gram, theircombinedlength being approximately. 2.1 cm. and the. space, be.

tween the end of the charge. 3 and theterminal disc 4 being approximately'0fl5'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 an internal pressure exceeding 5 atmospheres is built up. After the ignition has been brought about by means of a hotwireintroduced through the hole 5, the steady'working pressurein the space between the charge 8 and the disc 4 is 3 atmospheres; and the thrust delivered as the gases escape through the hole 5 is 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 alongitudinal axial section and Fig. 4 an end view of adevice suitable for the driving of a toy vehicle.

In the diagrammatic drawings 9 is a cardboard cylinder turned over a thick cardboard disc I0 as shown at II and telescopically fitting into and adhesively bonded to another cardboard cylinder- I Zturned, overa tinplate disc l 3 as shown at l4. The disc 13 is supported at the,

end l5 of theinner cardboard cylinder 9. The tinplate disc I3 is-provided witha cylindrical hole [6 of a diameter approximatelyone-tenth ofthat of the disc. The inner and outer; cylinders have.- each alength; of 3.8 cms, The internal diameter of the inner cylinder 9,is.-1-. 9 cm. and theex-v ternal diameterofthe outer cylinder I2 is 2.05 cm. The diameter oftheorificeis 0.19 cm. I? is a preformedgasrprodncing pellet closely fitting in the inner cylindereii and is of the same, composition and weight as 8 of Fig. 1. I8-is a piece of wire gauze fitting tightly inthe inner cylinder and placed over-a wick or igniting fuse t9. one end of-which isbent over said gauze. The combined length of the. pellet I1, gauze I8 and wick l9 isapproximately 2-.1 cm. and the space between the end of-tlrieclr1argev I] and the tere minal disc. I3- isapproximately 0.75, cm. The turnover at I4;unfolds if an internal pressure exceeding 5 atmospheres .is built up... The ignition.

wick. through the jetand igniting. the protruding. portion. when required... The: ignited wick. l9;

ignites. the. pellet charge I 1 :and a steady work;

ing pressure of 3zatmospheres isattained in the space. between .the-pellet charge lr'l and the disc. I3. The thrust deliveredaasthe gases escape:

through the hole. I Gris. 28. grams weight and. the

timefor. which .it.is.maintained is .15 seconds.-v

The. device according to this embodiment of 2 the invention is very. easily: assembled. The cy1+- inders. 9 "and 12. are. each .providedwith a. turned; over end ll and-Mrrespectively- The cardboard disc 10 is. pushed into cylinder 9 against." the turned overend. ll.

board disc The wick. I9;isthen placed .on

thepreformed pellet. l1 and the. metal gauze I8;

tin-platedisc |3 isinserted into the cylinder- I2, the exteriorsurfaceofthe cylinder -9"is coated:

with an adhesive-composition and; the cylinder;

9 is-- then pushed into .tlfe.cylinder. l2 :so that:

its -rim.l5. pushes the ;tin.-.:plate..- l3 well up against the turned over end, I lrlofctheqouter. cylinder l2 action propulsion .device 101:; a; toy; model i013 :the;

like: o risin an y nd ical.. as na utilis in:

sulati materia nd:; a. ompr ssed. o a t The preformed pellet I! is; pushed down-into. cylindertagainst thecard-M gas-generating charge in intimate contact with the cylindrical wall of said casing, said casing being closed at one end and provided at the other with a terminal Wall element of heat resisting rigid material perforated to provide at least one pressure-controlling gas escape hole of predetermined dimensions, said compacted charge being of such length with respect to the casing as to leave an air space between a terminal surface of the charge and said terminal wall element, said cylindrical casing wall not in contact with the charge being deformable along a weakened portion which allows said casing to burst open under a predetermined pressure in excess of the desired working pressure, said compacted charge comprising in admixture a predominant proportion of a com ound selected from the group consisting of guanidine nitrate, nitroguanidine and mixtures thereof, and a minor proportion of a solid sensitizer of the thermal decomposition of said compound in amount sufiicient to enable the mixture to propagate through itself a self-sustained, exothermic, gas-producing, non-explosive decomposition at atmospheric pressure when a small amount of heat is locally applied at said terminal surface of said compacted charge.

2. An improved self-contained gas escape reaction propulsion device as claimed in claim 1, wherein the weakened portion of said casing consists of a turnover fold of said insulating material which is capable of being unfolded by a predetermined pressure in excess of the desired working pressure within the device.

3. An improved self-contained gas escape reaction propulsion device as claimed in claim 1, wherein the cylindrical casing comprises a single tube provided with a turnover fold at each end.

4. An improved self-contained gas escape reaction propulsion device as claimed in claim 1, wherein the cylindrical casing comprises two telescopically closely fitting tubes adhesively bonded together, each of said tubes having a turnover fold at its free end.

5. An improved self-contained gas escape reaction propulsion device as claimed in claim 1, wherein said charge comprises guanidine nitrate and said sensitizer is a derivative of phenol containing a plurality of substituent groups each consisting of a nitrogen atom attached exclusive to at least one terminal oxygen atom and to one of the nuclear carbon atoms of phenol, said sensitizer being present in substantial amount not exceeding about 20% of the weight of the guanidine nitrate.

6. An improved self-contained gas escape reaction propulsion device as claimed in claim 5, wherein said phenol derivative comprises 8 to 20% of the weight of the guanidine nitrate.

7. An improved self-contained gas escape reaction propulsion device as claimed in claim 5, wherein the phenol derivative is 2:4 dinitroresorcinol.

8. An improved self-contained gas escape reaction propulsion device as claimed in claim 5, wherein the phenol derivative is 2:4 dinitrosoresorcinol.

ALEXANDER C. HUTCI-IISON. MATTHEW WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 826,293 Unge July 17, 1906 2,165,263 Holm July 11, 1939 2,229,208 Holm et a1. Jan. 21, 1941 2,440,271 Hickman Apr. 27, 1948 FOREIGN PATENTS Number Country Date 2,554 Great Britain A. D. 1877 360,787 France Mar. 10, 1906 502,560 France Feb. 24, 1920 831,496 France June 7, 1938