Passive deployment demonstration of shape memory alloy-type deployable aeroshell using a hypersonic wind tunnel

Deployable aeroshells are promising as a future aerodynamic entry technology to innovate space transportation systems for a round trip between Earth and Low Earth Orbit as well as for planetary explorations. Various types of deployable aeroshells have been investigated and tested, including mechanical and inflatable aeroshells. In this study, we propose a more innovative deployable aeroshell concept, which is a shape memory alloy (SMA) type. In this concept, the aeroshell can automatically deploy using an SMA as a structural member for the deployable aeroshell owing to aerodynamic heating during atmospheric entry and can produce a large aerodynamic drag. A scale model with a deployable aeroshell, such as an umbrella, was developed based on this concept. Hypersonic wind tunnel tests were conducted using the developed scale model to demonstrate the complete passive deployment of the aeroshell by aerodynamic heating. The test verified that the aeroshell was completely deployed in hypersonic flow by aerodynamic heating and produced a stable aerodynamic drag after its deployment. In addition, six-component aerodynamic forces, visualized flow field, and temperatures on the aeroshell were obtained during the test. As a result, the behavior of the deployable aeroshell during deployment was clarified.