The swinging counterweight trebuchet. Experiments on inner movement and ranges

The inner movement of a trebuchet with swinging counterweight was measured inside a laboratory by the use of rotation sensors to determine angular coordinates for beam, counterweight and sling. Data collection was started before the trebuchet was fired and lasted until some time after the projectile was released and flung into ground right in front of the machine. A single measurement is then sufficient for a semi-empirical determination of longest range and kinetic energy at target as well as mechanical energies and internal forces throughout the entire shot. Loss of mechanical energy was ascertained and attributed to friction. Measurements of actual ranges performed on a flat field with little wind are presented and compared with the semi-empirical determinations and ab initio calculations.