Ballistics external

In the propulsion of a solid propellant rocket relatively small masses of materials are ejected through the nozzle at a very high velocity while the relatively higher mass of the rocket is propelled forwards at a correspondingly lower velocity. 

The product of mass and velocity is called momentum and the law of conservation of momentum tells us that the total momentum of an isolated system (such as a rocket) is constant. For example, if two bodies collide, then their total momentum before impact is equal to their total momentum after impact. 

In the case of a rocket, the chemical reaction between the fuels and oxidisers in the propellant forces product gases through the nozzle at a certain momentum, while the momentum of the rocket increases in the opposite direction. 

Newton s third law of action and reaction is somewhat less fundamental than the conservation law and states that action and reaction are equal and opposite. Hence, if a body A exerts a force (action) on a body B, then B will exert an equal and opposite force (reaction) on A. Applied to a rocket, the downward force on the product gases from the nozzle is equal to the upward force on the rocket. 

The primary function of the nozzle is to convert the gunpowder heat energy into thrust with the minimum conversion loss. 

In external ballistics there is a range of equations associated with the flight of the rocket. Each equation contains certain parameters that, collectively, may be used to predict the flight path. For firework rockets, the most important factors include the weight of the rocket, the weight of the propellant, the specific impulse of the propellant and the shape and size of the rocket in accordance with equation (3.9), 

The specific impulse is a figure of merit for a particular propellant and is defined as the thrust that can be obtained from an equivalent rocket which has a propellant flow rate of unity. 

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In sending a rocket into the sky we are calling into action several laws of physics and chemistry, and the same laws apply whether the application is a small firework rocket weighing a few ounces or a solid propellant booster for the space shuttle containing around 300 tons of propellant. These fundamental processes may be conveniently divided into internal ballistics and external ballistics. 

The simplest external ballistics calculation is that in which a shell is hred vertically. This type of calculation has also been extended to include the case where a dud shell falls back to earth. 

B. Exterior or External Ballistics- the study of the motion of the projectile after it leaves the muzzle of the weapon... 

There is a wide range of firearms, and the choice of ammunition available presents a very large number of gun/ammunition combinations. The reason for such a variety of projectiles encompasses internal and external ballistics, nature of target, and wound ballistics, all of which are beyond the scope of this text. 

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