SBIR-STTR Award

This research addresses a deployable wing for a rapid response high altitude long endurance aircraft that is delivered to a high altitude over a location of interest in a low volume stowed configuration. The challenges are multi-disciplinary and relate to aerodynamics, structures, materials and manufacturing technology. The proposed technical approach is a high L/D inflatable wing with a number of innovations, including: the use of thin film materials for low volume storage, the use of structural fiber reinforcement for tailored strength and stiffness characteristics, a design that transfers of tension from the inflatable spar to the wing skin to promote airfoil accuracy, inflatable ribs, and compatibility with a Hydrazine-based inflation subsystem. A feasibility assessment is made, based on a baseline configuration that uses a high-TRL propulsion system to remain at 90,000 ft altitude for 24 hours. The feasibility assessment is supported by analysis and by a subscale demonstration article. A development plan is created that addresses all technical challenges necessary for a full scale flight demonstration with wing deployment at 90,000 ft. altitude.

Keywords:
Inflatable Wing, Thin Film Materials, Low Volume Storage, Structural Fiber Reinforcement, High Altitude, Long Endurance, Hydrazine Based Inflation Subsystem

DARPA’s Rapid Eye program requires a large wing capable of deployment from a small stowed volume while at high altitude. Once deployed this wing must have extremely high aerodynamic efficiency. Out Phase I technical approach was based on an inflatable structure and a high tension membrane surface. We were able to prove feasibility of the structure by analysis with validation by similarity to numerous large inflatable structures using proprietary AirBeam technology. Aerodynamic efficiency was verified by wind tunnel testing of membrane wing models. The values of rib spacing and membrane tension were shown to be critical for aerodynamic performance. The proposed Phase II research addresses the next most critical technical challenge: in-flight wing deployment. We will use a subscale inflatable wing to develop packing and deployment methodology that leads to reliable, controlled, repeatable wing deployment from a relevant annular stowed volume to a fully deployed, structurally and aerodynamically complete wing. The test articles will include all relevant deployed elements, inkling cable bracing, control surfaces and actuation means. All tests in this phase will be ground-based. The objective of this research is to provide a reduced-risk basis for in-flight deployment of a full scale wing in the next phase of development.

Keywords:
Inflatable Structure, High Tension Membrane, Inflight Deployment, Stowing Methods, Packing Methods, Inflation System, Subcsale Testing