Saab Bofors Dynamics commissioned FOI to build a dynamic testing device to measure the momentum caused by misalignment of the axial thrust force of a rocket. The dynamic testing device consists of a steel disc with a 30 mm wide groove. This 1.30 mm thick membrane rests on a liquid and on the membrane surface strain gauges are glued. The motor type tested has a thrust force of 20 kN and a burning time of 20 ms.