Hypersonic flow over bodies in tandem and its relevance to ballute design

A computational study of hypersonic flow over two bodies in tandem shows that if the second body is simply connected, the flow is violently unsteady in a similar way as in spiked body flow. The worst part of the unsteadiness can be avoided by making the second body in the shape of a ring. If this arrangement is used for aerocapture of a spacecraft, the ring requires significantly less gas than the simply connected body for the same drag. The ring could be given radial lift to counteract radial tether force.