Low intensity warfare had many impact on reducing logistic costs during field operations. It influenced the development of new large caliber HE projectiles. Concerning increasing lethal efficiency at target, the focus is at development of modern projectiles with natural, embossed and preformed fragmentation. Modern natural fragmentation projectiles characterize excellent aerodynamic properties, use of high strength steel with high fragmentation characteristics and denser high energy materials. Artillery projectiles with preformed fragments are usually equipped with large amount of preformed spherical or cubical fragments made of steel or tungsten. Modern unguided rocket warheads are based on embossed fragmentation or preformed warheads concept. There are limited data about real lethal effects of these projectiles. This paper presents available data and research results of embossed fragmentation warhead 122 mm and prefragmented warhead 128 mm, which are conducted in Bosnia and Herzegovina.

This work is focused on numerical simulations of air flow around a projectile in order to determine the influence of base shape on the drag coefficient. Simulations are made for transonic and supersonic speeds of air flow. Several shapes of projectile base is considered and the results are compared to drag coefficient of projectile with flat base. Base drag component can be as high as 50% or more of drag and any reduction in base drag can have a large payoff in increased range. Base drag is depended by flow characteristics and geometrical parameters. Influence of base shape to drag coefficient of projectile is studied by commercially CFD code FLUENT.

Base bleed is a system for base drag reduction of projectile by gas injection into base area. The gas injecting through orifice is generated by combustion of solid propellant grain. Base bleed output mass flow rate depends on the chamber pressure, the pressure into which jet exhausts, time and spin rate. An analytical interior ballistics model of base bleed developing in the paper is based on basic fluid dynamics and experimental results of measured time for base bleed burning in the field of radial acceleration. By iterative method, chamber pressure and mass flow rate can be estimated during the base bleed work. The model is verified by available experimental results.

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