Examination of dynamic characteristics of a CONEX container in dual point carriage from simulation and wind tunnel test

This paper discusses the observations and results from wind tunnel tests and simulations of an isolated 6x6x8 ft CONEX cargo container carried in a 2-point inverted-V suspension with a laterally active forward cargo hook (ACH). Wind tunnel tests on a model-scale configuration showed a growing roll-yaw limit cycle oscillation in forward flight with a progressive shifting of the load from the rear hook to the forward hook as the speed increased and eventual rear cable slackening. A simulation model of the full-scale load-suspension configuration was developed and achieved good agreement with the wind tunnel results after including the nonlinear stretching properties of the test cables and accounting for the unsteady aerodynamics of the CONEX. A lateral ACH controller design based on the linearized simulation model showed good load stabilization performance using lagged load attitude feedback. Load distribution to the two hooks could be controlled by cable length adjustments at the rear hook.