|Acquisition Program: ||PM Future Combat Systems Brigade Combat Team|| Objective: ||Develop and test lightweight combustible polymer cased small arms ammunitions to replace brass cased ammunitions without sacrificing ballistic performance and long-term reliability.
|| Description: ||Weapon system advances have resulted in the infantry soldiers carrying additional gear to enhance their combat effectiveness, but at the cost of increased logistics burden. To ensure that America’s soldiers maintain their overwhelming combat edge into 21st century, decreasing soldier loads has moved to the top of the priority list in the Army. In this regard, one of the heaviest load pieces for soldiers is their ammunition. However, the high cost of lightweight metal materials and the associated manufacturing costs represent a significant part of the affordability challenge faced by these efforts. Attempts in the past 50 years to use lightweight polymers to replace brass can only reduce the weight by about 25% and has not yet proven successful to achieve the ballistic performance and long-term reliability. Combustible cartridge case technology is successfully used in large caliber ammunition systems to eliminate the logistical burden of disposing of unconsumed packaging after firing. Combustible cartridge cases bring additional advantages in comparison to metallic cartridge cases or old bag charges such as reduction in barrel wear, enhanced firing energy, increased firing rate and reduction in charge costs. At the same time the combustible polymer case materials offers protection of the propellant charge in the handling, storage, and loading phases, making it the better candidate to replace metallic packaging than caseless cartridges.
Recently there is significant interest to pursue combustible cartridge case technology in small caliber weapon systems to achieve the lightweight ammunition goal. However, it is challenging to apply the combustible cartridge technology used in large caliber ammunitions to small arms ammunition to replace the conventional brass case. The technical hurdles include the combustible resin inherently lacking mechanical strength, high porosity, vulnerability to penetration of water and water vapor, and problems related to materials used for fabrication, and complete combustion. Therefore, despite numerous advantages of the combustible cased cartridge to the conventional metal cased cartridge, enough attentions should be given to characterizing the potential problems associated with the production and use of combustible cases.
The program shall accomplish specific performance objectives. A multidisciplinary research and development effort, focusing on mechanics, materials science, physics, chemistry, design and numerical modeling and simulations, shall be conducted to identify and characterize the combustible polymer materials, optimize small caliber cartridge case design, as well as production feasibilities. First, this effort shall develop or identify combustible polymer materials for polymer cartridge case applications. Included in this development is the study of the material residue after burning of the selected combustible polymeric materials. Analysis on mechanical and physical properties of the combustible materials at various temperature, humidity and treatments shall be performed. Secondly development efforts for small arms cartridge case design using combustible polymer materials shall be carried out. Dynamic finite element analysis simulations to validate the internal and exterior ballistic performance of the proposed cartridge case designs shall be conducted. Lastly, investigations on the environmental effects on the mechanical and physical properties of the selected combustible polymer materials shall be accomplished. Assessment of the production capabilities and feasibilities of the proposed lightweight combustible polymer cased small arms ammunitions need to be addressed.
The success of this combustible small arms cartridge case technology will deliver the lightweight ammunition solution to US Army. By reducing the ammunition weight, solders can have the same or more fire power with a stronger armor protection and additional gear without compromising their mobility, thus achieving tactical objectives and protection of our soldiers.
Parameters/Metrics which these cartidges must meet:
* No residue should be left behind after combustion
* The ballistic performance should be similar to legacy rounds
* The weight should be 50% of that of legacy rounds
* There should be no toxicity issues with the cartidge
* The cartridges should be able to withstand standard operating conditions.
* Aging should not have significant effects on the performance or safety of the cartidge cases.
|| ||PHASE I: Identify, develop and test combustible polymer materials for small arms polymer cartridge case applications. Study the material residue after burning of the selected combustible polymeric materials. Perform analysis on mechanical and physical properties of the combustible materials at various temperature, humidity and treatments. Develop novel small arms cartridge case design concepts using combustible polymer materials. Conduct dynamic finite element analysis simulations to validate the internal ballistic performance of the proposed combustible cartridge case designs.
|| ||PHASE II: Review the results from the Phase I feasibility study. Optimize the combustible material selections and refine the cartridge case designs. Investigate environmental effects on the mechanical and physical properties of the selected combustible polymer materials. Develop proper tooling and molds and build actual prototype cases on proposed combustible small arms cartridge case designs. Conduct advanced 3-D finite element analysis modeling and simulation to validate the ballistic performance of the proposed cartridge case with combustible material at extreme low temperature or cook-off temperature in hot weapon chamber. Conduct ballistic testing to measure chamber pressure and muzzle velocity and inspect the residue material. Assess production capabilities and feasibilities of the proposed lightweight combustible polymer cased small arms ammunitions.
|| ||PHASE III: If this program is demonstrated to be successful, this combustible polymer casing technology can be applied to military and civilian applications. Military application includes lightweight cartridge cases for small arms (5.56mm, 7.62mm and .50 calibers), medium caliber (20mm, 25mm, 30mm and 40mm) as well as large caliber (60mm, 81mm, 105mm and 120mm) ammunitions. Civilian application includes ammunitions for hunting and law enforcement.
|| References: ||
1. Chesonis, Kestusis G.; Smith, Pauline M.; Lum, WIlliam S., “Investigation of Residue and Coating Stoichiometry on 120-mm Combustible Cartridge Cases”, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005, ARL-TR-2337, 2000,
2. Fedoroff, B. T. and Sheffield, O. E., “Encyclopedia of Explosives and Related Items”, Picatinny Arsenal, Dover, NJ, Rept. No. PATR-2700, Vol. III, p. C611-C621, 1966, CPIA Abstract No. 68-0238, AD 653 029.
3. Hannum,, J. A. E., Editor, “Hazards of Chemical Rockets and Propellants”, Volume 2, Solid Propellants and Ingredients, Chemical Propulsion Information Agency, Laurel, MD, CPIA Pub. No. 394, Vol. II, Jun 1985, p. 11-3, CPIA Abstract No. 86-0027, AD A160 812|
|Keywords: ||Structural, energetics, lightweight, ammunition|