Hybrid Rigid/Inflatable Wings for Low Volume Wing Storage

Inflatable wings have proven themselves to be a viable option in unmanned aerial vehicle (UAV) flight in certain applications. There are several advantages when using inflatable wings. Foremost among these is the ability of the aircraft to be stored, fully assembled, in a smaller volume for ease of transportation and quick launch capability. Example applications currently being pursued include backpackable UAVs and extra-terrestrial aircraft, as well as HALE UAVs deployed from rapid delivery systems. This paper discusses the design options between using a folding wing system that is volume limited and an inflatable wing system that is mass limited. There should be an optimum between the two that provides the lowest packed volume and weight combination for the highest deployed span. The concept of hybrid rigid/inflatable wings appears to be feasible for UAVs that combine both systems. The goal of this research is to determine the feasibility of a high aspect ratio (>20) aircraft using the hybrid wings capable of flight at high altitude using inflatable wings. In comparison with high aspect ratio folding wings, such designs require advanced lightweight and strong materials to maintain structural integrity due to increasing loads as the wing span increases. It also requires advanced folding techniques to reduce the deployment dynamic loading. Another aspect that this research focuses on is the issues of packaging of folding wing vehicle into the small deployment systems for planetary exploration or for high altitude flight. Therefore, the hybrid rigid/inflatable wing concept should provide sufficient wing structural bending stiffness and also remain suitable for low volume wing storage based around an inflatable framework. Several concepts will be discussed, including both span-wise and chord-wise hybrid designs.