Development of a device for reduction of low‐frequency sound transmission reduction in small launch vehicles

Abstract

Launch acoustic loads have the potential to damage sensitive payloads within a payload fairing, often requiring more structural mass to withstand these loads than would otherwise be necessary to survive launch. A typical payload fairing will exhibit several cavity resonance modes related to its axial length. These modes are excited both by the vibrations transmitted through the structure during launch, and by acoustic ground reflections coupled into the system during the initial launch phase. Conventional acoustic blankets mitigate the acoustic environment within a payload fairing, but are generally only effective above 250 Hz. In this work we present an Adaptive Vibro‐Acoustic Device (AVAD), which is designed to actively and passively absorb acoustic energy in a payload fairing at frequencies below 250 Hz. To date, a prototype has been designed and tested for application to a sounding rocket experiment, Vibro‐Acoustic Launch Protection Experiment (VALPE), being conducted by the Air Force Research Laboratory. Prototype test results as well as projected performance in flight will be presented.