Abstract: Lightweight acoustic absorbers. The acoustic absorbers absorb energy during launch of a vehicle by a rocket, and are adapted to line the inside of a cavity of a fairing containing a vehicle. The absorbers comprise acoustic absorbing members, and a layer substantially surrounding the acoustic absorbing member which is substantially impermeable to contaminating particulates found within the fairing, and substantially impermeable to any contaminants which may be emitted by the acoustic absorbing member. A plurality of vents are cut in the layer, and a filter is placed over the vents to filter out any contaminants. The vents allow the gases within the fairing and the acoustic absorbing member to pass therethrough, thereby compensating for differential pressure.

Abstract: A vibration damping assembly for a wheel or the like that undergoes rotation is achieved by providing an annular groove in a surface of the wheel coaxial with the wheel axis. An annular metal ring formed from a channel member generally U-shaped in cross-section is positioned with one of its legs within the annular groove substantially encased therein by a vibration damping material. The remainder of the channel member extends close to areas of the wheel that are adjacent to the groove, and vibration damping material is sandwiched between the wheel and the channel member. Vibration damping material subject to shear deformation during rotation of the wheel is used, along with vibration damping material subject to deformation in tension and compression.

Abstract: A multilayered sound absorbing panel formed from aramid cloth and aramid felt layers. An intervening film between the cloth and felt layers may be included, bonded to those layers in interrupted patterns so as to leave portions of the film non-bonded to the cloth and felt layers.

Abstract: A vibration damping assembly for a wheel or the like that undergoes rotation is achieved by providing an annular groove in a surface of the wheel which is coaxial with the axis of the wheel. A viscoelastic damping material subject to shear deformation during rotation of the wheel is positioned within the groove against the surface of the groove, and an annular metal ring is positioned in the groove against the viscoelastic damping material with the damping material sandwiched between the ring and wheel.