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An investigation into developing better additives for reducing gun barrel erosion was initiated by this laboratory. The investigation was prompted by the higher energy/density propellant formulations currently under development because these new propellants possibly could exacerbate gun barrel erosion. This report is a progress report that describes the initial results obtained with the U.S. Army Armament Research, Development and Engineering Center's, Picatinny Arsenal, New Jersey erosion test fixture. Some erosion mechanisms and proposed ways to reduce or interfere with them are discussed. Three candidates were selected: K2CO3, CaCO3, and ZnCO3 and compared with the customary wear additive, TiO2. Based on the data, it was concluded that all selected candidates reduced wear caused by both M3O and JA2 propellants, but K2CO3 was ranked as most effective. The additives were also dispersed in silicone oil to form pastes. Five samples of K2CO3 paste was loaded into an experimental obturator design and test fired in a 155-mm gun. The resulting 4% decrease in heat flux suggested that paste loaded obturators may be a feasible method to reduce gun barrel wear, but further investigation is necessary to verify this assertion.

The barrel life of a solid armature rail gun is a critical issue, Arcing along the barrel pathway at the interfaces between the armature and the rails produces severe damage The ability to protect the rails and yet provide sufficient electrical contact to sustain arc-free high-current flow is desirable, This thesis investigates the use of liquid metal as an interface material between the sliding electrical contact surfaces of the armature and the barrel rails, Experiments were conducted with the Naval Postgraduate School's 4-inch Rail Gun and liquid metal interface coatings were applied to the armature Results indicated that the liquid interface protects the rails and projectile surfaces for static electrical contact, Apparatus has been design to investigate sliding electrical contact between armature and rails in a controlled manner New rails with a novel Adamy-Maier grooved rail design were fabricated to facilitate coating rails, Various groove patterns have been designed to control the current flow through the rails and across the interface surfaces, while maintaining lateral stability and interface integrity, These experiments are still in progress at the time of this writing, "The original document contains color images"

In the interests of environmental responsibility, the Navy is seeking replacements for lead decoppering agents. These agents are necessary to remove the copper deposited on the barrel surface of a gun firing copper-banded projectiles. A brief review of the theory of decoppering will be presented to provide the rationale for our choice of bismuth as the replacement for lead. Our test program was being conducted in the 5"/54 gun because the problem of lead toxicity poses two problems in this system: not only the environmental discharge during firings, but the propellant, Naco, contains a lead salt, rather than using lead foil. Protection of the workers manufacturing Naco from the lead salt incurs significant additional expense. Naco was made without lead, fired in a pair of barrels in an attempt to copper the barrels. Though 156 rounds were fired from each barrel, neither showed any measurable coppering. One barrel did show moderate amounts of copper in bore-search examination. After a single round of either a charge loaded with 5 g of bismuth/tin foil or the standard Naco, the barrels were completely cleaned of copper.

This report details the testing conducted to determine the amount of variation which exists in the 5.56-mm ballistic test results between U.S. Army Armament Research, Development and Engineering Center, Lake City Army Ammunition Plant, and Olin Ordnance, St. Marks, Florida. The testing included using the same 5.56-mm M856 tracer lot; test equipment; and 5.56-mm electronic pressures, velocity, and action time test barrels at all three sites and concluded that there was less than a 2% variation.

Muzzle devices for reducing the blast and flash levels received by the AC-130 gunship were investigated. A noise suppressor design decreased the blast levels only minimally while the flash level increased compared to the standard flash hider. Extension tubes with 6-inch and 8-inch exit diameters were also tried with no better results. A flash hider with an 8-inch exit diameter brought the flash levels down to new lows but the peak overpressure levels on the airplane were not improved. Finally, a 22-inch barrel extension was tried. The use of a barrel extension resulted in decreased levels of flash and reduced peak overpressures at all microphones except one positioned in the most forward position. Muzzle blasts, Muzzle flash, Interior ballistics, Muzzle devices, Shock waves.

An investigation was undertaken to examine electromagnetic (EM) gun- barrel projectile interaction. the RASCAL code was used in this study because of its ability to easily manipulate relevant parameters such as gun tube centerline, projectile contact stiffness, and projectile design geometry. This work compares the projectile performance in the 9-MJ EM railgun at the University of Texas Center for Electromechanics (UTCEM) to that in a double- travel conventional gun. This comparison was made by varying the parameters listed above for two projectile designs, one projectile being the M829 Link round, the other, a preliminary EM design. It was believed that adoption of this format would identify specific areas of the EM gun-projectile system that excite transverse loading, with the results of this analysis presented here. RASCAL, Transverse acceleration, EM Railgun, In-bore projectile dynamics, Velocity, Electromagnetic guns.

Repeated gun firings can steadily elevate the barrel temperature. The firing heat input and the resulting barrel temperature rise depend on the thermal properties of the barrel material. In particular, they depend on the thermal conductivity, specific heat, and mass density. Since conductivity and specific heat depend on barrel temperature, gun barrel heating becomes a nonlinear problem. If the temperature range is large, this temperature dependence can have an effect on the predicted barrel temperature change. We shall show how these effects are modeled by use of a finite difference solution to the one-dimensional (Fourier) equation of heat conduction. Our findings indicate that for the limited number of rounds stowed in a tank, the inclusion of temperature-dependent thermal properties does not have a significant effect on the predicted barrel temperature change. gun barrels; finite difference theory; thermal properties; M256 120-mm gun; multiple rounds; tar gun heating.

This report, details testing done on ultra-pure filtered diesel fuel and unfiltered diesel fuel. Several barrels of filtered fuel, shipped from the manufacturer--Sterling Technology, Inc., Jacksonville, Florida--had been tested using the 690-in. Deutz F-8L-413A Air Cooled V8 Engine. No significant difference had been found, but due to a delay in starting the tests, it was suspected that some deterioration might have occurred in the fuel. The objective was to investigate the possible benefits of the ultra-pure filtered diesel fuel in power improvement and reduction of exhaust smoke.

Twenty papers on various aspects of analysis, design and instrumentation of gun dynamics are presented by authors from five universities, five industrial research laboratories and various laboratories of the U.S. Army, Navy, and Air Force.

This report presents the results of an experimental program to evaluate a full-scale Borsic aluminum composite structure spar/titanium propeller barrel retention system and a high-contact-angle duplex tapered roller bearing for an advanced technology 2000-SHP propeller system. (Author)

The United States met virtually all of its oil needs from domestic sources until the early 1970s. This self-sufficiency gradually eroded as our internal production failed to keep pace with rising levels of energy consumption. As a result, our new energy needs have been satisfied primarily by petroleum imports. The 1973 Arab oil embargo and supply curtailments associated with the Iranian Revolution in 1979 were painful experiences for the nation. By 1980, the United States was importing 8.5 million barrels of oil per day at a cost many times higher than the going rate in earlier years. Dependence on Middle East oil had become a frightening reality. During the same period, trade deficits, inflation, interest rates, and balance of payment problems were increasing at an alarming rate. Since that point in time, the United States has made progress in building a strong foundation for energy security. Despite these gains the United States is rapidly approaching another critical juncture in its battle to reduce dependency on imported oil. It also suggests national economic strategies that could be employed to improve America's energy prospects for the future.