Design, Manufacturing, Testing, and Analysis of a Highly-Constrained Single-Use UAV Wing 2018-01-1958

Unmanned aerial vehicle (UAV) design aspects are as broad as the missions they are used to support. In some cases, the UAV mission scope can impose design constraints that can be difficult to achieve. This paper describes recent work performed at West Virginia University (WVU) to support repeated flight testing of a single-use UAV platform with emphasis on the highly specialized wings required to help meet the overall airframe mass properties constrained by the project sponsor. The wings were fabricated using a molded polyurethane (PU) foam as the base material which was supported by several different types of rigid and flexible substructures, skins, and matrix-infused fiber elements. Different ratios of infused fiber mass to PU foam were tested and additional tungsten masses were added to the wings to achieve the correct total mass and mass distribution of the wings. Expected accelerations were applied to the wing designs analytically and numerically to establish appropriate test limits and explore potential structural loading aspects, and static and dynamic experimental tests were employed to determine the suitability of the wing designs for the UAV airframe. Likely wing design candidates that survived all experimental tests in the lab were subjected to final experimental tests on the UAV platform in outdoor high-G field launches. High speed cameras revealed several types of failure modes in these applied tests, indicating design sensitivity both in wing bending and in torsion under extreme acceleration. Because the wings were designed to eventually support a large number of single-use free flight experiments, the wing designs were also subjected to detailed cost analysis to ensure the final designs would meet the imposed economic as well as physical constraints. A final design with a steel-and-braided line-reinforced box-frame carbon fiber substructure, fiberglass-infused PU foam with >50% by mass fiber content, and fiberglass skin was found to exhibit the best combination of survivability, mass properties, cost, and ease of manufacturing.