GB2263962A - Solid propellant rocket motor with fusible end closure holder - Google Patents
Solid propellant rocket motor with fusible end closure holder Download PDFInfo
- Publication number
- GB2263962A GB2263962A GB9122949A GB9122949A GB2263962A GB 2263962 A GB2263962 A GB 2263962A GB 9122949 A GB9122949 A GB 9122949A GB 9122949 A GB9122949 A GB 9122949A GB 2263962 A GB2263962 A GB 2263962A
- Authority
- GB
- United Kingdom
- Prior art keywords
- solid propellant
- motor
- propellant rocket
- rocket motor
- fusible
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000004449 solid propellant Substances 0.000 title claims abstract description 23
- 230000000717 retained effect Effects 0.000 claims abstract description 11
- 239000000155 melt Substances 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims description 18
- 239000003380 propellant Substances 0.000 claims description 12
- 229910052751 metal Inorganic materials 0.000 claims description 7
- 239000002184 metal Substances 0.000 claims description 7
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 5
- 150000002739 metals Chemical class 0.000 claims description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 3
- 229910052797 bismuth Inorganic materials 0.000 claims description 3
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 239000000374 eutectic mixture Substances 0.000 claims 1
- 230000008018 melting Effects 0.000 description 9
- 238000002844 melting Methods 0.000 description 9
- 238000012360 testing method Methods 0.000 description 8
- 239000002131 composite material Substances 0.000 description 5
- 238000009413 insulation Methods 0.000 description 4
- 229910001128 Sn alloy Inorganic materials 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 238000004880 explosion Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000001141 propulsive effect Effects 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
- F02K9/08—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using solid propellants
- F02K9/32—Constructional parts; Details not otherwise provided for
- F02K9/38—Safety devices, e.g. to prevent accidental ignition
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F42—AMMUNITION; BLASTING
- F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
- F42B39/00—Packaging or storage of ammunition or explosive charges; Safety features thereof; Cartridge belts or bags
- F42B39/20—Packages or ammunition having valves for pressure-equalising; Packages or ammunition having plugs for pressure release, e.g. meltable ; Blow-out panels; Venting arrangements
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Fuses (AREA)
- Portable Nailing Machines And Staplers (AREA)
Abstract
A solid propellant rocket motor comprising a motor case 1, solid propellant 6 and at least one end closure 2, 7, characterized in that at least one end closure is connected to the casing by at least one fusible connector 3, 4 which melts at temperatures below those that will cause autoignition of the motor but does not melt during normal propulsion, so that the end closure releases before the autoignition and is retained in place during normal propulsion. <IMAGE>
Description
The invention is a solid propellant rocket motor capable of withstanding the insensitive munitions cook-off test.
Heat can cause solid propellant to autoignite, causing the motor to explode, burst or move. In order to improve safety of solid propellant motors a relatively new requirement, referred to as "insensitive munitions cook-off test (hereinafter '11.M. testing), will soon be standard for all rocket motors. The test consists of heating the motor until autoignition occurs. To pass the test the ignited motor must remain passive while the propellant burns off, with no explosion, shrapnel or propulsion. This test ensures the safety of motors in case of fire or heat.
Current solid propellant rocket motors are not designed to withstand I.M. testing. Consequently, if a motor is subjected to cook-off temperatures, autoignition occurs, and the motor either explodes, bursts or becomes propulsive. This results because the motor is unable to relieve pressure build-up from the ignited propellant.
The invention is a solid propellant rocket motor comprising a motor case, solid propellant and at least one end closure, characterized in that at least one end closure is connected to the casing by at least one fusible connector which melts at temperatures below those that will cause autoignition of the motor but does not melt during normal propulsion of the motor" o that the end closure releases before the autoignition and is retained in place during normal propulsion.
In one preferred embodiment the fusible connector melts at a temperature in the range of 2700F to 3200F.
In a second preferred embodiment the fusible connector is selected from the group consisting of threaded or unthreaded rings.
Figure 1 shows a motor having two end closures, one retained by a threaded fusible ring and the second retained by an unthreaded fusible ring.
The term "end closure'1 refers to devices used to close the opening or openings of a rocket motor case. A nozzle assembly, typically comprising a nozzle, blast tube and exit cone, is used on the aft end. The nozzle assembly may be sealed, for instance, by a metal plate or foam igniter, or may be open. If the case has an opening at the forward end, a plate-like fixture is usually used to close it.
By "fusible" it is meant that the material is capable of being melted by heat. Any fusible material capable of meeting the structural and melting requirements for the connector may be used. Preferred are fusible metals alloys.
By "connector", reference is made to rings forming one or more interface of the case and end closure (which may be threaded (e.g., buttressed or so as to screw in) or unthreaded); receptacles with recesses provided for such retaining rings; pins or screws for securing the case to the end closure; and the like. The connector may be in contact with both the case and end closure, but does not have to be.
For instance, it may be connected to a support member. The key is that fusible connector(s) be in position and of a material such that during normal operation the end closure is retained on the rocket motor and when the fusible material melts before autoignition, pressure is released due to release of the end closure. Release of the end closure results in the end closure falling off or being pushed off the motor during autoignition.
The specific melting temperature(s) suitable for materials useful in this invention depends on the autoignition temperature of the motor and the temperåtúres which the fusible connector will experience during propulsion and storage. The motor configuration, insulation, propellant, load(s) and other well known design features will dictate the preferred melting temperature and material.
Generally, the autoignition temperature of the motor will be the autoignition temperature of the solid propellant. That is, if (a) the motor is stored without an igniter, (b) the igniter does not contain pyrotechnic material or (c) the igniter contains a pyrotechnic material having a higher autoignition temperature than the propellant, the fusible connector material may be selected based on the propellant autoignition temperature. However, if the igniter has a lower autoignition temperature than the propellant and either (a) the motor is stored with the igniter in place or (b) the motor may experience high temperatures after installation of the motor, the fusible connector material should be selected so that it has a lower melting temperature than the autoignition temperature of the igniter.
Suitable fusible materials will have a melting temperature of from 2000F to 1000oF. For most applications, the melting temperature of the fusible material will be in the range of 250oF to 550oF. Most conventional tactical motors will require fusible materials which melt at a temperature in the range of 2700F to 3200F.
The motors of this invention are made with conventional rocket motor materials. The case may be made of composites, metals or both, and may be insulated using conventional materials. The nozzle and forward end closures are also made with conventional materials, such as composites and metals.
The propellant can be any conventional propellant, such as composite propellants. Autoignition temperature is specific to the propellant used and may be in the range of 375OF to 575oF. Generally, solid propellant autoignition occurs at temperatures of 450 to 500oF.
Figure 1 is an illustration of a motor having two end closures, one retained by a threaded fusible ring and the second retained by an unthreaded fusible ring. The motor is similar to that used for tactical applications, but has a reduced configuration for testing.
Case (1) is a metal case 15 inches long and 5 inches in diameter. The walls of the case are insulated with approximately 90 mil thick paper phenolic. (The insulation is not shown.)
The forward end-closure (2) is plastic and is retained by unthreaded, fusible metal alloy retaining ring (3) (split ring). The retaining ring is made of a eutectic metal alloy of bismuth and tin with a melting point of 281oF. Rubber
O-ring (4) is a pressure seal. Thermoplastic insulation (5) protects the forward end closure from heat of propulsion. The insulation will be pushed from the case upon autoignition of the motor if the forward end-closure is released by melting of the retaining ring. The propellant (6) is composite having an autoignition of 4500F+.
The aft-end closure is nozzle assembly (7). It has a foam weatherseal and burst disc (this may be part of an assembly, including an igniter), which is not shown.
The nozzle assembly is composite and is retained by threaded, fusible metal alloy retaining ring (8). The retaining ring is made of a eutectic metal alloy of bismuth and tin with a melting point of 281oF. Nozzle support member (9) is made of plastic which is retained by the nozzle and fusible retaining ring. Rubber O-ring (10) is a pressure seal.
An igniter is not shown but normally would be located in the forward or aft end of the motor.
While the invention has been described with respect to specific embodiments, it should be understood that they are not intended to be limiting and that many variations and modifications are possible without departing from the scope and spirit of this invention.
Claims (11)
1. A solid propellant rocket motor comprising a motor
case, a propellant and at least one end closure characterized in that at least one end closure is connected to the casing by at least one fusible connector which melts at temperatures below those that will cause autoignition of the motor but does not melt during normal propulsion of the motor, so that the end closure releases before the autoignition and is retained in place during the normal propulsion.
2. A solid propellant rocket motor as claimed in claim 1 wherein the fusible connector melts at a temperature in the range of 270oF to 320at.
3. A solid propellant rocket motor as claimed in any of the preceding claims wherein the fusible connector is selected from the group consisting of threaded or unthreaded rings.
4. A solid propellant rocket motor as claimed in any of the preceding claims wherein the end-closure connected to the casing by a fusible connector is a nozzle assembly.
5. A solid propellant rocket motor as claimed in any of claims 1 - 3 wherein the end-closure connected to the casing by a fusible connector is a plate-like fixture in the forward end of the motor.
6. A solid propellant rocket motor as claimed in any of claims 1, 2, 4 or 5 wherein the fusible connector is selected from the group consisting of rings, recesses for retaining rings, pins and screws.
7. A solid propellant rocket motor as claimed in any of the preceding claims wherein the fusible connector is made of a fusible metal alloy.
8. A solid propellant rocket motor as claimed in claim 7 wherein the metals alloy is a eutectic mixture of bismuth and tin.
9. A solid propellant rocket motor as claimed in any of the preceding claims wherein the fusible metal melts at a temperature lower than the autoignition temperature of the solid propellant.
10. A solid propellant rocket motor as claimed in any of the precedeing claims wherein the motor contains an igniter comprising a pyrotechnic material and the fusible connector melts at a temperature lower than the autoignition temperature of the pyrotechnic material.
11. A solid propellant rocket motor substantially as hereinbefore described with reference to the drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/593,725 USH1144H (en) | 1990-10-04 | 1990-10-04 | Solid propellant rocket motor with fusible end closure holder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9122949D0 GB9122949D0 (en) | 1993-06-16 |
| GB2263962A true GB2263962A (en) | 1993-08-11 |
Family
ID=24375891
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9122949A Withdrawn GB2263962A (en) | 1990-10-04 | 1991-10-30 | Solid propellant rocket motor with fusible end closure holder |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | USH1144H (en) |
| FR (1) | FR2690205A1 (en) |
| GB (1) | GB2263962A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1635054A2 (en) * | 2004-09-14 | 2006-03-15 | AVIO S.p.A. | Solid-propellant engine casing, and solid-propellant engine featuring such a casing |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5735114A (en) * | 1991-08-15 | 1998-04-07 | Thiokol Corporation | Thermostatic bimetallic retaining ring for use in rocket motor assembly |
| US5542688A (en) * | 1992-10-27 | 1996-08-06 | Atlantic Research Corporation | Two-part igniter for gas generating compositions |
| US5398498A (en) * | 1994-05-06 | 1995-03-21 | Bei Electronics, Inc. | Joint construction between components of military projectile and releasable by melting of fusible eutectic helical member |
| US7578122B1 (en) * | 1995-02-24 | 2009-08-25 | Aerojet General Corporation | Rocket motor case using plank sections and method of manufacture |
| US6035631A (en) * | 1995-07-04 | 2000-03-14 | Royal Ordnance Public Limited Company | Safety in solid fuel rocket motors |
| US5792981A (en) * | 1996-10-28 | 1998-08-11 | Thiokol Corporation | Gun-launched rocket |
| US5976293A (en) * | 1997-02-10 | 1999-11-02 | Universal Propulsion Company, Inc. | Method for making a case for combustible materials |
| US6321656B1 (en) * | 2000-03-22 | 2001-11-27 | The United States Of America As Represented By The Secretary Of The Navy | Thermally actuated release mechanism |
| US6619029B2 (en) * | 2001-11-01 | 2003-09-16 | Alliant Techsystems Inc. | Rocket motors with insensitive munitions systems |
| US6752085B2 (en) * | 2002-05-06 | 2004-06-22 | Lockheed Martin Corporation | Method and apparatus for releasably attaching a closure plate to a casing |
| US8082846B2 (en) * | 2002-08-12 | 2011-12-27 | Qinetiq Limited | Temperature responsive safety devices for munitions |
| GB2391899A (en) * | 2002-08-12 | 2004-02-18 | Qinetiq Ltd | Shape memory alloy connector and an overwound munition casing |
| US7331292B1 (en) | 2004-03-23 | 2008-02-19 | The United States Of America As Represented By The Secretary Of The Navy | Venting system for explosive warheads |
| ES2352881T3 (en) * | 2007-06-28 | 2011-02-23 | S.E.I. Societa Esplosivi Industriali S.P.A. | SECURITY DEVICE FOR EXPLOSIVE CONTAINERS, EXPLOSIVE CONTAINERS AND METHOD FOR PREPARING SAFE CONTAINERS FOR EXPLOSIVES. |
| GB0714440D0 (en) * | 2007-07-25 | 2007-10-17 | Qinetiq Ltd | Rupturing device |
| US9964387B2 (en) * | 2009-08-19 | 2018-05-08 | Orbital Atk, Inc. | Insensitive munitions swaged vent plug |
| US8578855B2 (en) | 2009-08-21 | 2013-11-12 | General Dynamics Armament And Technical Products, Inc. | Rocket motor tube with safety features |
| US8550004B1 (en) * | 2009-10-21 | 2013-10-08 | The United States Of America As Represented By The Secretary Of The Army | Riveted cartridge venting |
| WO2015175608A1 (en) * | 2014-05-14 | 2015-11-19 | Fike Corporation | Vented-at-temperature igniter |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5036658A (en) * | 1990-03-05 | 1991-08-06 | The United States Of America As Represented By The Secretary Of The Army | Pressure relief device for solid propellant motors subjected to high external temperatures |
-
1990
- 1990-10-04 US US07/593,725 patent/USH1144H/en not_active Abandoned
-
1991
- 1991-10-30 GB GB9122949A patent/GB2263962A/en not_active Withdrawn
- 1991-12-13 FR FR9115525A patent/FR2690205A1/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5036658A (en) * | 1990-03-05 | 1991-08-06 | The United States Of America As Represented By The Secretary Of The Army | Pressure relief device for solid propellant motors subjected to high external temperatures |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1635054A2 (en) * | 2004-09-14 | 2006-03-15 | AVIO S.p.A. | Solid-propellant engine casing, and solid-propellant engine featuring such a casing |
| EP1635054A3 (en) * | 2004-09-14 | 2006-11-15 | AVIO S.p.A. | Solid-propellant engine casing, and solid-propellant engine featuring such a casing |
| NO342013B1 (en) * | 2004-09-14 | 2018-03-12 | Avio Spa | Solid motor housing and solid motor housing showing such housing |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9122949D0 (en) | 1993-06-16 |
| FR2690205A1 (en) | 1993-10-22 |
| USH1144H (en) | 1993-03-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |