Thuresson Marcus. Development and evaluation of a six degrees of freedom model of a 155 mm artillery projectile

Master of Science Thesis. — Stockholm, Sweden: KTH Royal Institute of Technology. — 56 p.A crucial part of any army, today and historically, has been its artillery. In the ancient world, the roman legions fielded mechanical equipment such as the ballista that could hurl boulders or large arrows hundreds of meters into the enemy ranks. The discovery of gunpowder in China in the 9th century led to the development of artillery that used gunpowder as propulsion to launch projectiles. Today, the general role for artillery on the battlefield is to provide fire support, defined by NATO as «the application of fire, coordinated with the maneuver of forces to destroy, neutralize or suppress the enemy».
Artillery is a term for any long range cannons that can fire unguided and guided projectiles for many kilometers, with mixed accuracy. In a modem army precision is sought-after, as it is both more cost effective (fewer artillery pieces and projectiles needed) and also minimizes the risk of hitting friendly or non-combatant units. In order to hit a target at long range with good accuracy, the trajectory of the projectile must be calculated. This was done by using different models that takes into account the current conditions at the firing site, such as weather, projectile mass, earth’s rotation and aerodynamic properties of the projectile. Modem artillery shells are spin-stabilized, which puts higher demands on the number of freedoms needed to accurately model the trajectory. Different models approach this problem in different ways, and this work will focus on the Six Degrees Of Freedom model (6-DOF) and the Modified Point Mass Model (MPMM). The MPMM is a simplification of the 6-DOF model, and has fast computing speeds; the 6-DOF model is more complex and should be more precise. The MPMM for an m/sgr77 projectile already exists at the Swedish Defense University, abbreviated FHS in Swedish, since it was made as a part of a thesis project in 2014. However, no 6-DOF model of an m/sgr77 artillery projectile existed at the beginning of this thesis project at the Swedish Defense University.