Flexible heat shields deployed by centrifugal force

Abstract

Atmospheric entry aerodynamic decelerators which also provide thermal protection do not scale well for smaller payloads (e.g. CubeSat) or where the planets atmosphere is significantly less dense than the Earth's (e.g. Mars entry). Both cases require heat shields larger than can be accommodated either within the launch vehicle fairing, or within acceptable payload volumes, so deployable shields are required. Unlike previous designs proposed to fulfil this requirement like inflatable structures or deployable solid mechanisms, the presented research addresses this by utilising inertial force, or specifically, centrifugal force generated from autorotation to deploy and stiffen a flexible heat shield. Structural dynamic analyses including the trajectory simulation on a CubeSat sized system has shown that the autorotation and deployment form a closed loop which reliably leads to an equilibrium of deployment, while the heat shield is near fully deployed at altitudes higher than 30 km with tolerable spin rate (< 6 rps) and oscillation. Thermal analysis suggests that a front surface temperature reduction of 100K is achievable on a CubeSat sized vehicle as unlike inflatable structures, no thermal insulation is needed around the flexible material. This design concept can realise a lightweight, compact and concise entry system.

Folding analysis for thin-walled deployable composite boom

“…Limitation of storage capacity in launch vehicles drives the growing usage of deployable structures for large space structures such as solar sails and reflector antennas etc. These structures can be packaged into a small volume before launch and unfolded into large configurations during their working state in space [1][2][3][4][5] . Due to the superior stiffness and strength as well as ultralight weight characteristics, thin-walled deployable composite structures made of high strain composites are a potential solution for launching large constructions for space missions [6][7][8] .…”

Downrange manoeuvre and oscillation suppression of a self-regulating centrifugally deployed flexible heat shield using a controlled reaction wheel

“…5. Since you build on the heat shield's structural dynamics explained on [20], in order to have this paper more self-contained, you should present a summary of the main statements of that work.…”

“…The structural dynamic behaviour explained by [20] was briefly summarised in paragraph 3 of Introduction, p2.…”

“…With the revisions made, the paper is now self-contained without requiring further detailed information from reference [20]. 6.…”

“…To clarify the statement and eliminate the necessity to mention reference [20] here, this paragraph (on p5) is revised to: "Where ! is the rate of autorotation, q is dynamic pressure, and !…”