Rotational isolation with neutrally buoyant suspension

Rotational vibration isolation is of critical importance for many airborne instrumentation applications. Such isolators require very low frequency isolation for the rotational degrees of freedom combined with translational rigidity and negligible translation to rotation coupling. This paper describes a vibration isolator using neutrally buoyant flotation to provide high translation rigidity combined with very low rotational rigidity. The isolator reduces the rotational vibration at all frequencies above its resonance (0.18 ± 0.01 Hz) and has a large dynamic range (±30°) suitable for airborne surveying. Viscous, inviscid, and mechanical coupling inside the isolator have been analyzed. A recent fixed wing flight test shows the isolator reducing the rotational vibration by more than a factor of 1000 at frequencies above 10 Hz.