Description: Interest in civilian use of small Unmanned Aerial Vehicles (UAVs) with Vertical Takeoff and Landing (VTOL) capability has increased greatly in recent years, and is expected to grow significantly in the future. Research to date has focused on propulsion, batteries, sensors and autonomous control laws, but little attention has been paid to acoustic characteristics. The generation and propagation of noise associated with small VTOL UAVs are not well understood and prediction tools have not been developed or validated for this class of vehicles. Since public acceptance of these vehicles is crucial to their future in civilian roles, it is imperative that NASA acquire the analysis tools and an adequate understanding of the acoustic characteristics associated with these aircraft. The objective of the proposed effort is to create a base of experimental data to characterize the noise generated by this class of vehicle and then to use this data to evaluate and enhance existing rotary-wing design and analysis tools in this area.

Benefits: The proposed effort directly responds to NASA's SBIR solicitation goal to "develop and validate tools, technologies and concepts to overcome key barriers for rotary wing vehicles" citing in particular an objective to "develop design and analysis tools for the prediction of acoustics for small vertical lift UAVs." The proposed effort will provide valuable test data characterizing the acoustics generated by small VTOL UAVs – an area where current test data is sparse. The proposed effort will also see the enhancement of existing analysis methods to allow accurate prediction of small VTOL UAV noise. These advancements will support future NASA applications developing, designing and operating small VTOL UAVs in the civilian airspace – an area that NASA anticipates will grow significantly in the near future.

The new test database and the enhanced analysis tools for small VTOL UAV acoustics will be of great use to rotorcraft manufacturers, DoD agencies and private industry as well as NASA in the coming years. The DoD is seeing a growing use of small VTOL UAV aircraft in surveillance and tactical urban warfare. In these applications, stealth can be critical, and the ability to accurately characterize and predict the UAV noise will be invaluable. The analysis tools developed in this effort will be needed by manufacturers of small VTOL UAVs wishing to include acoustic analysis in their design work. Since the forecast for the implementation of these types of aircraft is burgeoning, not just for NASA and DoD but also for private industry, the market for analysis software and engineering services in this area has a tremendous upside for growth, leading to great potential for commercial applications beyond NASA's needs.