Testing of Flexible Ballutes in Hypersonic Wind Tunnels for Planetary Aerocapture

Abstract

Studies were conducted for the In-Space Propulsion (ISP) Ultralightweight Ballute Technology Development Program to increase the technical readiness level of inflatable decelerator systems for planetary aerocapture. The present experimental study was conducted to develop the capability for testing lightweight, flexible materials in hypersonic facilities. The primary objectives were to evaluate advanced polymer film materials in a high-temperature, high-speed flow environment and provide experimental data for comparisons with fluid-structure interaction modeling tools. Experimental testing was conducted in the Langley Aerothermodynamics Laboratory 20-Inch Hypersonic CF 4 and 31-Inch Mach 10 Air blowdown wind tunnels. Quantitative flexure measurements were made for 60 degree half angle afterbody-attached ballutes, in which polyimide films (1-mil and 3-mil thick) were clamped between a 1/2-inch diameter disk and a base ring (4-inch and 6-inch diameters). Deflection measurements were made using a parallel light silhouette of the film surface through an existing schlieren optical system. The purpose of this paper is to discuss these results as well as free-flying testing techniques being developed for both an afterbodyattached and trailing toroidal ballute configuration to determine dynamic fluid-structural stability. Methods for measuring polymer film temperature were also explored using both temperature sensitive paints (for up to 370 C) and laser-etched thin-film gages.

Low-Density Aerodynamics for the Inflatable Reentry Vehicle Experiment

“…If these technologies can be validated, then the inflatables will surpass [1][2][3] the capabilities of rigid aeroshells in several respects as follows: increased payload mass and volume fraction, postlaunch vehicle integration payload access, use of mission systems during both the in-transit phase and the entry, descent and landing phases, access to higher altitude landing sites upon entry, and provide a more benign payload thermal environment during entry. Included in the family of aerocapture inflatable decelerators [4] (Fig. 1) are trailing ballutes, afterbody attached ballutes, and forebody-attached inflatable aeroshells.…”

Aeroelastic and Aerothermoelastic Analysis in Hypersonic Flow: Past, Present, and Future

“…However, there was a 70% difference in axial displacement of the torus (i.e., the large inflatable ring that connects to the entry module via the membrane structure). In a similar study, Wang et al [251] incorporated Newtonian impact aerodynamics [1,71] into the open source DYNA3D [153,154] structural solver, and they showed good agreement with the static aeroelastic experimental data measured by Buck [239].…”

“…NASA's goal of manned space exploration has reinvigorated research into IADs [236][237][238][239][240][241][242][243][244][245][246][247][248][249][250][251]. These devices are desirable for planetary entry, since they can provide a significant increase in drag during the entry phase while being packaged in relatively small volumes during the launch and transit phases of space travel.…”

“…structure was modeled using temperature-dependent material properties. Partial validation of the developed framework was carried out using experimental observations by Buck [239] for a flexible tension cone placed in a hypersonic wind tunnel. A comparison of experimental and computational results for the flow over the deformed membrane is shown in Fig.…”

Static Aeroelastic Analysis of Thin-Film Clamped Ballute for Titan Aerocapture

“…Both tests were performed at the NASA Langley Research Center under contract from the In-Space Propulsion group at NASA Marshall Spaceflight Center [20]. The first tests used both the hypersonic CF 4 tunnel and the 31 inch Mach 10 Air tunnel, and the second test only used the Mach 10 Air tunnel.…”