Laboratory test fixture for nonrigid payloads (projectiles)

A laboratory test fixture for nonrigid payloads is described which allows payload arrangements to undergo the simultaneous spinning and coning motions experienced by a projectile in flight. The fixture enables the destabilizing phenomena associated with the nonrigid payload to be created in a controlled laboratory environment where special instrumentation can measure the physical effects of interest. The results are used to evaluate the potential destabilizing influence of the payload and to support the evolution and validation of theoretical analyses describing the associated fluid dynamics situation. The author describes the operational aspects of the fixture and reviews several research and development projects for which it has been used. Engineering design aspects of the XM761 and M825 smoke screening projectiles are described. In addition, the role played by the fixture in evolving a general theory for homogeneous viscous liquid fills is reviewed. Studies associated with payloads composed of viscoelastic fluids and other unconventional compositions are addressed including methods of reducing or eliminating the problem.<>