Advanced High-Temperature Flexible TPS for Inflatable Aerodynamic Decelerators

Abstract

Typical entry vehicle aeroshells are limited in size by the launch vehicle shroud. Inflatable aerodynamic decelerators allow larger aeroshell diameters for entry vehicles because they are not constrained to the launch vehicle shroud diameter. During launch, the hypersonic inflatable aerodynamic decelerator (HIAD) is packed in a stowed configuration. Prior to atmospheric entry, the HIAD is deployed to produce a drag device many times larger than the launch shroud diameter. The large surface area of the inflatable aeroshell provides deceleration of high-mass entry vehicles at relatively low ballistic coefficients. Even for these low ballistic coefficients there is still appreciable heating, requiring the HIAD to employ a thermal protection system (TPS). This TPS must be capable of surviving the heat pulse, and the rigors of fabrication handling, high density packing, deployment, and aerodynamic loading. This paper provides a comprehensive overview of flexible TPS tests and results, conducted over the last three years. This paper also includes an overview of each test facility, the general approach for testing flexible TPS, the thermal analysis methodology and results, and a comparison with 8-foot High Temperature Tunnel, Laser-Hardened Materials Evaluation Laboratory, and Panel Test Facility test data. Results are presented for a baseline TPS layup that can withstand a 20 W/cm 2 heat flux, silicon carbide (SiC) based TPS layup, and polyimide insulator TPS layup. Recent work has focused on developing material layups expected to survive heat flux loads up to 50 W/cm 2 (which is adequate for many potential applications), future work will consider concepts capable of withstanding more than 100 W/cm 2 incident radiant heat flux. This paper provides an overview of the experimental setup, material layup configurations, facility conditions, and planned future flexible TPS activities.

Flutter Analysis of the Thermal Protection Layer on the NASA HIAD

“…Specifically, the proposed TPS configuration consisting of Nextel 440-BF20, Pyrogel 6650, and Kapton Kevlar Laminate was studied. Three theoretical structural models were developed based on photographic observations of the experimental test setup as described in previous conference proceedings 1,2 . The piston theory hypersonic flow approximation was used for the aerodynamic pressure in all cases.…”

“…Thus, as a first step, the present analysis is based on the current NASA wind-tunnel tests of rectangular TPS articles 1 , which are mounted on metallic tiles and exposed to hypersonic flow. A flutter analysis of this geometric shape is less complex, and it may help explain why oscillations could be observed during testing.…”

Surface Catalyzed Recombination Efficiencies for Flexible Thermal Protection Materials in Air Plasma

“…NFLATABLE Aerodynamic Decelerators (IAD) offer an advantage over rigid aeroshells owing to their ability to incorporate a larger heat shield diameter in the same size launch vehicle shroud [1]. The IAD is stored in a densely packed configuration until just prior to atmospheric entry where it is deployed to significantly increase the forebody surface area to provide greater drag at higher altitude, which is a more manageable heating environment.…”

“…However, flexible TPS systems have additional requirements that must be considered. The material must withstand high packing densities of 400kg/m 3 , sharp creases of near zero bend radii and sustain its physical properties and flexibility after long durations [1]. Currently, non-ablative woven fabrics and ablative impregnated weaves are being considered as possible solutions.…”

Nonlinear Oscillations of a Fluttering Plate Resting on a Unidirectional Elastic Foundation

“…This model can be used to approximate that of a plate resting on a foundation but not actually bonded at any point on its surface. This work may be of interest in several aerospace applications, especially for flexible thermal protection systems [5] on inflatable aerodynamic decelerators. In this case, an insulating thermal protection blanket is draped over a flexible substructure, with no middle surface connections between the two components.…”