Instability-Based Structural Concept for Rollable Propeller Blades

Launching aircraft in highly constrained environments such as battlefields and undersea severely limits the dimension of the aerodynamic surfaces, limiting the range and efficiency. Deployable structures that can be packaged within small volumes for launch and expand rapidly and extensively midair for cruise present an effective solution to achieve performance while satisfying the stringent launch constraints. This paper introduces a novel structural concept for a rollable propeller blade, which results from combining a rollable skin and a rollable inner spar. The blade can be rolled up for packaging within a confined volume while maintaining sufficient stiffness when deployed in air. The design concept is based on the principle of propagating instability in thin-shell structures to achieve fast deployment without external actuation. The structural architecture design, prototype manufacturing, computational fluid dynamics and structural analysis, and propeller testing are presented to prove the concept. The proposed concept offers enhanced take-off and launching flexibility for aerial vehicles.