Beech Starship Interior Noise Experimental Studies

Beech Starship is an all-composite airplane - the first of its kind to get FAA certification. When Beech decided to produce this airplane, a lot of engineering properties of the materials that the Company was planning to use were still unknown. One of those was the acoustic property. Even with the new materials Beech planned to make Starship cabin as quiet as possible. With this in view the Company conducted acoustic research test on two fuselage composite panels towards the end of December 1983. Both the panels were made of graphite-epoxy, the same material that Starship fuselage is made of. One panel was a honeycomb construction with NOMEX core and the other was a conventional skin-stringer type construction. The two panels were tested as they were as well as in conjunction with three composite interior panels, with some sound-proofing materials. One panel was also tested with Vibration Isolators isolating the interior panel from the main panel. This paper presents the details including instrumentation and pertinent results of this acoustic research test. The graphite panels demonstrated a higher level of noise reduction than any aluminum panel previously tested. The honeycomb panel in combination with a 1/4 inch interior panel and 1/2 inch NOMEX insulation produced the best results.