Meso-scale Mission Adaptive Compliant Wing

The flow environment of small rotary-wing and fixed-wing Unmanned Air Vehicles (meso-scale UAVs), is conducive to the formation of laminar separation bubbles which significantly degrades their performance - a phenomenon that is typical of low Reynolds number flight regimes (50,000 to 300,000). This "bubble drag" can be alleviated over a wide operational lift coefficient range and Reynolds number range by altering the geometry of the airfoil and deploying turbulators to transition the boundary layer. Properly implemented, variable geometry airfoils can potentially improve the lift-to-drag performance of meso-scale UAVs by as much as 80%. The key challenge is to physically realize these novel variable geometry adaptive structures for meso-scale vehicles with severe limitations on space, weight, and power. FlexSys, a pioneer in adaptive compliant structures technology, has successfully designed, fabricated, and tested several variable geometry flaps in recent years. Through aerodynamics analysis and experimental testing, we propose to first identify the most effective means to realize performance gains using variable geometry and deployable turbulators to reduce low Re airfoil drag over broad operating regimes. We also propose to design, fabricate, and test a "proof-of-concept" model to demonstrate the feasibility of the approach and mature variable geometry wing technology for meso-scale UAVs.