>> >rocket has no built-in tendency to amplify a perturbation, departing >> >faster and faster from the desired attitude once nudged off center. >> >> ...other than sloshing propellant, which may be a significant >> factor in a real system. > >True, depending on design and conditions. Also, that will generally be an >oscillating disturbance rather than a simple one-sided instability, so the >analogy remains weak.
Right. It's possible for it to be non-oscillating; if you hover at an angle the free surface effect may be constant, but that is probably rare on rockets as opposed to say ships, where I first learned about the significance of the effect. Particularly significant in damaged stability calculations when part of a ship has flooded... The natural slosh frequency should be avoided in the control loop systems, however, as getting into a slosh/maneuver feedback loop would quite possibly be a Bad Day. -george william herbert [EMAIL PROTECTED] _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
