Computational testing of inflatable airfoils for improved design

Chambered inflatable airfoils offer an alternative wing design for unmanned aerial vehicles. A key advantage of these types of airfoils is their ability to be initially compacted, then inflated to a full wing, and then potentially re-compacted as necessary. Some types of these wings naturally yield a surface that is inherently bumpy, as the center of each inflation chamber expands further compared to its edges where the interior baffles link the upper and lower wing surfaces. Connected with the design and flight testing of inflatable wing unmanned aircraft, there have been a series of computational studies of the inflatable airfoil shapes used for the actual wings to gauge the effects of the bumpy surface versus a smooth surface airfoil. Two main foils have been used on these aircraft, the Eppler 398 and NACA 4318. In current computational testing, the two foils have illustrated some common trends and some differences in terms of the shift from a smooth to a bumpy surface. Further comparative investigation of these airfoils should improve our understanding of the effects of the inflatable surface on the aerodynamics.