Name: AFRSI-2500 Blanket
Database: NASA Ames Thermal Protection Materials
Category: Silicon-Based Reusable Composites: Composite Flexible Blankets
Composition: extel 440 outer fabric, Saffil alumina insulation, and S-glass inner fabric, sewn together with a Nextel 440 thread.
Manufacturer: HiTemp Insulations, Oceaneering Thermal Systems
Technical Readiness Level: 9
Last Modified: 2001-10-01

Description:

• A development of the basic AFRSI TPS architecture, AFRSI-2500 is a quilted blanket TPS consisting of a woven alumina-borosilicate outer fabric, a woven glass inner fabric, and fibrous alumina batting sewn together with alumina-borosilicate thread. For most applications, a water-proofing agent would typically be applied to AFRSI-2500 at the factory and again between flights. Also, a surface coating of a ceramic material such as C-9 would most likely be required. In addition to meeting emittance requirements, the coating makes the outer surface more rigid and helps to protect the blanket's top surface fibers from aerodynamically-induced abrasion. <BR><BR> Compared to tile-type TPS, AFRSI-2500's installed cost is low, but its aerodynamic capabilities are far more limited. It has a much rougher surface finish than most tiles and therefore has an increased propensity to force a laminar boundary layer into turbulence. This increased roughness can also produce markedly amplified local heating where boundary layers are relatively thin, such as the windward side of most reentry vehicles. Additionally, AFRSI-2500 has lower tensile and shear strength compared to tiles, making it less applicable in areas of high aerodynamic loading; especially rapidly fluctuating aerodynamic loads. Although the blanket is very flexible during installation, its surface becomes hardened after application of the C-9 coating and brittle after thermal exposure. This material has a higher thermal conductivity when measured parallel to the blanket surface than when measured through the blanket. Only data for thermal conductivity normal to the plane of the blanket is given below. Data shown is for a .967" thick, 9.36 lb/ft3 blanket from an EMTL Final Report No. 1817. Conductivity data for AFRSI-2500 of other thicknesses may vary due to its non-uniform density construction. The same report documented some tests on a similar thickness of AFRSI where it had 3-5% lower thermal conductivity at higher pressures and 15-25% lower thermal conductivity at lower pressures than AFRSI-2500.

Point of Contact:

• Marc Rezin
• NASA Ames Research Center
• mrezin@mail.arc.nasa.gov

Pictures:

• AFRSI Sample

Notes:

• 1. Value given is for the blanket batting (fill). Blanket bulk density varies with thickness. Bulk density = density + additive areal weight / thickness. AFRSI-2500 has a nominal thickness of 1.0 inch and a minimum demonstrated thickness of 0.25 inches.
• 2. Total areal weight = density * thickness + additive areal weight.
• 3. Unknown, but assumed to be similar to the data for AFRSI.
• 4. Average hemispherical emissivity of uncoated Nextel 440.
• 5. Based on preliminary findings of Arcjet testing done at NASA ARC.
• 6. Based on material manufacturer's published temperature use limit.
• 7. Cost for C-9 coated standard AFRSI blanket.
• 8. These values based on similar experience from NASA's Shuttle flights of AFRSI and may vary drastically.
• 9. These values based on similar experience from NASA's Shuttle flights of AFRSI and may vary drastically.

Property References:

• 1. S. Amanda Chiu, William C. Pitts: Reusable Surface Insulations for Reentry Spacecraft:AIAA Paper 91-0695:Jan. 1991:TPSX Ref. #3.
• 2. D.J. Rasky: Thermal Protection Systems for Future Reusable Launch Vehicles:25th International Conference on Environmemtal Systems, No. 951618:Jul. 1995:TPSX Ref. #7.
• 3. anon: Shuttle Operational Data Book:Boeing Document:Boeing:TPSX Ref. #28.
• 4. anon: Final Report on Measurements of the Apparent Thermal Conductivity and Thermal Resistance of Ceramic Flexible Insulations:EMTL Final Report No. 1817 FMI-EMTL-W/A 3276, for NASA ARC:Oct. 1996:TPSX Ref. #29.

General References:

• 1. S. Amanda Chiu, William C. Pitts: Reusable Surface Insulations for Reentry Spacecraft:AIAA Paper 91-0695:Jan. 1991:TPSX Ref. #3.
• 2. D.J. Rasky: Thermal Protection Systems for Future Reusable Launch Vehicles:25th International Conference on Environmemtal Systems, No. 951618:Jul. 1995:TPSX Ref. #7.
• 3. C. Ehrlich, et al.: Advanced Manned Launch System Study (AMLS); Reusable Cyrogenic Tank Design:Contract NAS1-18975 DRD-9:Rockwell International, Space Systems Division, Downey, CA:Jul.-Sep. 1993:TPSX Ref. #8.
• 4. anon: Current Technology for Thermal Protection Systems:NASA Conf. Pub. 3157:Feb. 1992:TPSX Ref. #9.
• 5. D.A. Kourtides, S.A. Chiu, D.J. Iverson, D.M. Lowe: Thermal Response of Rigid and Flexible Insulations and Reflective Coating in an Aeroconvective Heating Environment:NASA TM-103925:Mar. 1992:TPSX Ref. #26.
• 6. D.A. Kourtides, J.L. Bandfield, N. Pakrasi, W.C. Pitts: Effect of Ceramic Coatings on Thermal Performance of Flexible Insulations:26th International SAMPE Technical Conference, Atlanta, GA:Oct. 24-27, 1994:TPSX Ref. #27.
• 7. anon: Shuttle Operational Data Book:Boeing Document:Boeing:TPSX Ref. #28.