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At 11 grains per foot, tube splits occurred in the dual-cord configuration, venting explosive products. Separate tests revealed that the tube in the single-cord configuration could easilywithstand much higher explosive loads. The mechanism that produced tube rupture was the impact of65the tube against the end ring nearest to the cord fired, inducing a thinning of the tube wall. As the tubecontinued to expand, it failed in tension at this thinned site.Figure 47.
Severance performance, comparing web thickness to explosive load, of several configurations of the Super*Zip seperation joint.Explosive margin for this separation joint was established by ratioing loads:minimal flight load----------------------------------------------------------------------------------min. load to break thickest doublerFor the Shuttle/IUS:9.5------- = 1.277.5A second margin was established by ratioing the plate bending moments for successful severance (platethicknesses cubed) at the minimum flight load to the maximum allowable flight thickness.3(minimum severed thickness)------------------------------------------------------------------------------3(maximum allowable thickness)3For the Shuttle/IUS:66( 0.098 )----------------------- = 1.713( 0.082 )Chapter 18 - DISPOSAL METHODS• Environmental restrictions• Burning to atmospheric discharge• Burial in land fills• Discharge into streams/water• Biggest Military problem = base cleanup/weapons disposal• Government approach• Closed-cycle burning, minimal discharge• Chemically dissolving/separation/recycling• U.S.
Army Defense Ammunition Center and School Savanna, Illinois 61074-9639 (815) 273-890167CONCLUSIONS/RECOMMENDATIONSApplying pyrotechnic (explosive and propellant-actuated) devices has been considered to be an art,rather than an engineering science.
When failures occurred after completing qualification, past designers had few test methods that quantitatively defined performance and functional and structural containment margins. Their recourse was limited, other than to provide more pyrotechnic energy. However, ifthis scenario was true, why has the application of pyrotechnics been so successful? What is the need forchange if so few failures have occurred? Finally, with the failures that have occurred, why haven’t clearresolutions been made and specifications improved to prevent recurrence?Over the years a number of justifications have been offered.
Pyrotechnic devices contain explosives,which really can’t be measured because of their high energy levels and dynamics. These devices are justlike electronic “black boxes;” it is not necessary to understand the internal components. This is the waywe’ve always tested these devices. These people know what they’re doing; they have been making andapplying these devices for a lot of years. Besides, the devices we’re using now are just like the designsthat have been flying for years.
We don’t have time to do research. We have to fix this failure quickly tomeet flight schedules. Don’t worry, once we get this system together, it’ll work. Trust me.Success with pyrotechnic devices has been achieved through large functional margins. Even thoughfunctional margins were not defined, it is not difficult to use plenty of explosive or propellant to makeeach device work.
The major problem with widely cited requirements (go/no-go testing and +/−15%pyrotechnic loads) is that functional or containment margins are not defined. Without failures there is noway to determine how close the device is to failure. That is, when the device has a minimal energysource, if all the devices within a group (usually numbering less than 200) function, the assumption ismade that functional reliability is adequate. However, should system parameters vary in an amount thatwould be trivial in pneumatics or hydraulics systems, such as surface finish, o-ring lubrication or theinitial free volume into which the energy source is fired, failure can occur.
Similarly, when the devicehas too large a charge, which could introduce structural failure, the assumption is made that since all testunits maintained structural integrity containment reliability has been achieved. More than 2000 “identical” devices must be subjected to simple go/no-go testing to assure functional and structural reliability.The primary purpose of this manual is to alter the concept that the use of pyrotechnics is an art andrefute the above- stated “justifications” that applications don’t need to be understood by providinginformation on pyrotechnic design, development and qualification on an engineering basis. Included areapproaches to demonstrate functional reliability with less than 10 units, how to manage pyrotechnicunique requirements, and methods to assure that the system is properly assembled and will perform therequired tasks.68REFERENCES1.
Lake, E.R.; Thompson, S. J.; and Drexelius, V.W.: A Study of the Role of Pyrotechnics on the Space Shuttle Program.NASA CR-2292, September 1973.2. Bement, Laurence J. and Schimmel, Morry L.: Integration of Pyrotechnics into Aerospace Systems. Presented at the 27thAerospace Mechanisms Symposium, May 12-14, 1993, NASA Ames Research Center, California.3.
Bement, Laurence J.: Pyrotechnic System Failures: Causes and Prevention. NASA TM 100633, June 1988.4. Bement, Laurence J. and Schimmel, Morry L.: Determination of Pyrotechnic Functional Margin. Presented at the 1991SAFE Symposium, November 11-14, 1991, Las Vegas, Nevada.5. Schimmel, Morry L.: The F-111 Crew Module: Major Challenge for Thermally Stable Explosives. Presented at the Symposium on Thermally Stable Explosives, U.S.
Naval Ordnance Laboratory-White Oak, Silver Spring, Maryland. June 23-25,1970.6. Bement, Laurence J.: Rotor Systems Research Aircraft (RSRA) Emergency Escape System. Presented at the 34th AnnualNational Forum of the American Helicopter Society, Washington, DC, May 1978.7. Simmons, William H.: Apollo Spacecraft Pyrotechnics. NASA TM X-58032, October 1969.8.
Falbo, Mario J. and Robinson, Robert L.: Apollo Experience Report. NASA TN D-7141, March 1973.9. Graves, Thomas J.: Space Shuttle - A Pyrotechnic Overview. Presented at the European Space Agency Conference onExplosives and Pyrotechnics, Space Applications, October 23-25, 1979, Toulouse, France.10. Ellern, Herbert: Modern Pyrotechnics. Chemical Publishing Company, 1961.11. MIL-P-46994/B, Amendment 3: General specification for boron/potassium nitrate12. Drexelius, V. W. and Schimmel, M. L.: A Simplified Approach to Parachute Mortar Design.
Presented at the Seventh Symposium on Explosives and Pyrotechnics, Philadelphia, Pennsylvania, September 7-9, 1971.13. Design and Performance Specification for NSI-1 (NASA Standard Initiator-1), SKB26100066, January 3, 1990.14. Meyer, Rudolph: Explosives. Printed by Verlag Chemie, 1977.15.
Properties of Explosives of Military Interest. AMCP 706-177, AD 764340. U.S. Army Materiel Command, January 1971.16. Rouch, L. L. and Maycock, J. N.: Explosive and Pyrotechnic Aging Demonstration. NASA CR-2622, February 1976.17. Material Specification for HNS Explosive, WS5003J.
Naval Surface Weapons Center, February 1981.18. Kilmer, E. E.: Heat-Resistant Explosives for Space Applications. Journal of Spacecraft and Rockets, Vol. 5, No. 10, October, 1968.19. MIL-STD-1576 (USAF): Electroexplosive Subsystem Safety Requirements and Test Methods for Space Systems, July 31,1984.20. DOD-E-83578A (USAF): Explosive Ordnance for Space Vehicles (Metric), General Specification for, October 15, 1987.21. NSTS 08060, Revision G: Space Shuttle System Pyrotechnic Specification.22. Lake, E. R.: Percussion Primers, Design Requirements. McDonnell Douglas Corporation Report MDC A0514, Revision B,April 5, 1982.23. Schimmel, Morry L.
and Kirk, Bruce: Study of Explosive Propagation Across Air Gaps. McDonnell Aircraft CorporationReport B331, December 24, 1964.24. Schimmel, Morry L.: Quantitative Understanding of Explosive Stimulus Transfer. NASA CR-2341, December 1973.25. Bement, Laurence J.: Helicopter (RSRA) In-Flight Escape System Component Qualification. Presented at the Tenth Symposium on Explosives and Pyrotechnics, San Francisco, California, February, 1979.26. Persson, Per-Anders: Fuse. U.S. Patent 3,590,739, July 6, 1971.27.
Chenault, Clarence F.; McCrae, Jr., Jack E.; Bryson, Robert R. and Yang, Lien C.: The Small ICBM Laser Ordnance FiringSystem. AIAA 92-1328.28. Ankeney, D. P.; Marrs, D.M.; Mason, B. E.; Smith, R. L. and Faith, W. N.: Laser Initiation of Propellants and Explosives.Selected Papers, SP93-09, on Laser Ignition. Published by the Chemical Propulsion Information Agency, September 1993.6929. Drexelius, V.
W. and Berger, Harold: Neutron Radiographic Inspection of Ordnance Components. Presented at the FifthSymposium on Electroexplosive Devices, Philadelphia, Pennsylvania, June 13 and 14, 1967.30. Bement, Laurence J.: Monitoring of Explosive/Pyrotechnic Performance. Presented at the Seventh Symposium on Explosives and Pyrotechnics, Philadelphia, Pennsylvania, September 8-9, 1971.31. Schimmel, Morry L. and Drexelius, Victor W.: Measurement of Explosive output.
Presented at the Fifth Symposium ofElectroexplosive Devices, the Franklin Institute, June 1967.32. Bement, Laurence J. and Schimmel, Morry L.: Cartridge Output Testing: Methods to Overcome Closed-Bomb Shortcomings. Presented at the 1990 SAFE Symposium, San Antonio, Texas, December 11-13, 1990.33. Bement, Laurence J.; Schimmel, Morry L.; Karp, Harold and Magenot, Michael C.: Development and Demonstration of anNSI-Derived Gas Generating Cartridge (NGGC).
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