Active Acoustic Blankets for RLVs

CSA Engineering proposes the development of active blankets for the attenuation of acoustic disturbances in reusable launch vehicles. The active blanket is composed of a conventional, passive, sound absorbing blanket conbined with an active layer that is used to increase the effectiveness of the passive treatment at frequencies below 500 Hz. The active layer is a thin, lightweight material driven by a compact actuator that controls the velocity of the material's surface. A microphone is mounted close to the surface of the active layer, and sound pressure levels are reduced through feedback between the microphone and the control actuator. The combination of active and passive control enables the active blanket to overcome the low-frequency performance limitations of current technology.The Phase I effort is divided into four tasks. System-level requirements for the concept will be determined using information obtained from two RLV contractors. Materials will be determined for the passive component of the blanket and actuators developed for the active layer. Low-cost microcontroller-based control electronics will be designed. A prototype of the concept will be fabricated and a series of experiments will be performed to measure its effectiveness at low frequencies. A follow-on Phase II effort will involve larger-scale technology demonstration.