Recent Development and Test of Inflatable Wings

Abstract

In recent years the Departments of Defense and Homeland Security have had a desire to tightly pack small Unmanned Aerial Vehicles (UAVs) in order to allow them to be launched via gun, by hand, or air dropped for reconnaissance or munitions delivery. Inflatable components enable compact packaging and rapid deployment on the ground or in flight, while minimizing system mass and complexity. Inflatable structures also provide UAVs with a significant amount of robustness as they can sustain hard landings without damage due to their inherent inflatable nature, in essence functioning as airbags. The combination of these two factors, compact packaging and damage tolerance, can be combined to provide UAVs that are easily transportable and cost effective. Numerous laboratory and flight tests have been performed to demonstrate the damage tolerance of inflatable wings. The survivability rate has remained at 100% beyond one hundred flight test impacts, and has been verified by similar laboratory testing. The resilience of the inflatable components manufactured from engineered materials is outstanding and tracks well with related inflatable structures such as the Pathfinder and MER airbags, which landed on the rocky surface of Mars. Inflatable wings have also demonstrated two aspects of morphing for UAVs or other flight platforms (such as airships). These are high aspect ratio changes via the deployment of inflatable tip extensions, and camber morphing for aerodynamic control. Inflatable wings with embedded actuation systems have been developed that are deployable and can easily be shape morphed to provide the required aerodynamic control for small UAVs. The flexible composite materials used in inflatable wings also allow for the inclusion of multi-functional elements to augment performance. Multi-functional elements for deployable wings include those that perform structural or aerodynamic functions, but are also used for functions such as aerodynamic control, power generation, power storage, and communication. Key tests conducted during this research and discussed herein include: rapid simultaneous wing deployment, gust and impact loading survivability tests, and wing shape vs. inflation pressure as characterized through wind tunnel testing. This paper discusses the various morphing concepts in detail and the subsequent development and testing of various components for UAVs. The design and fabrication of a small UAV with embedded actuation technology on the inflatable components is also detailed along with flight-test data.