Summary
Highlights
Progressive grains are suitable for long-barreled artillery for high velocity. Degressive grains are better for short-barreled weapons like mortars or pistols, providing quick maximum pressure. Rockets use special neutral grains for low, steady pressure. Propellants must be chosen to match tactical purposes, providing desired velocity with minimal smoke, flash, and wear.
Ballistics is a complex science dealing with the technical problems of hitting a target and achieving desired tactical results. It's divided into three main areas: interior ballistics (launching), exterior ballistics (in-flight behavior), and terminal ballistics (action at the target).
Launching ammunition involves simple principles. Pressure from burning propellant creates gas that propels a projectile, while also causing recoil in the gun. Rockets operate similarly, where gas expulsion propels the rocket forward.
Propellant, often nitrocellulose powder, is designed in various grain forms. Grain size and design significantly affect burning rate and pressure. Smaller grains burn faster, providing a sharp thrust, while larger grains give a sustained push.
There are three main types of grains: degressive (solid, fast burn, high initial pressure), neutral (one hole, constant burning surface, moderate pressure), and progressive (multiple holes, increasing burning surface, sustained pressure, ideal for high-velocity weapons). Different weapons require specific grain types for optimal performance.
Exterior ballistics studies projectile behavior in flight. Without external forces, a projectile would fly straight. Gravity pulls it down, and air resistance (drag) slows it and shortens its range. Streamlining and boat-tailing can reduce drag. Stabilization is achieved with fins (mortars, rockets) or spin (rifled barrels), though spin causes drift, which is accounted for in aiming.
Beyond gravity and drag, other factors influencing long-range fire include air density, temperature, wind, and Earth's rotation. The goal of exterior ballistics is to predict and improve projectile flight, leading to accurate firing tables for maximum direct hits.
Terminal ballistics focuses on the projectile's effect at the target. Projectiles are designed for different effects: blast (high explosives for shattering and tearing), penetration (high-velocity, tough-nosed projectiles), fragmentation (breaking into flying pieces for personnel and light structures), and incendiary (starting fires).
Fuzes control the timing and action of projectiles at the target. Types include impact fuzes (instant or delayed), time fuzes, and proximity fuzes. Fuse location (front, base, side) also influences the resulting effect.
For enemy planes, fragmentation is desired, using proximity fuzes. Against armored targets or reinforced concrete, armor-piercing projectiles with base fuzes and a short delay are used for penetration and subsequent fragmentation. Shaped charges can also achieve penetration by focusing explosive force.
Terminal ballistic experts determine the most destructive combination of effects for each target. Additionally, ammunition must be suitable for mass production, safe to handle, transport, and store, and technically feasible across all phases of ballistics.