Thermal-insulation blankets developed for use aboard the space shuttle can be adapted to a racing car to protect the driver against excessive cockpit heating. [Also see an earlier article under "Mission Accomplished," NASA Tech Briefs, Vol. 20, No. 8 (August 1996) page 20.] Thermal protection for the driver is necessary because, unlike the passenger compartment of a conventional automobile, the cockpit of a racing car is subject to intense heating as a result of unique racing-design features.
In particular, the exhaust pipes are routed so close to the sheet metal of the floor pan and transmission tunnel that a significant portion of the heat radiated by the exhaust system (at a power density of about 12 kW/m²) enters the cockpit, and even at high speed, the airflow is so limited that the cockpit is not cooled to a comfortable or even a safe temperature. Hotspots can develop near the driver's right foot and under the driver's seat. In the absence of thermal protection, a driver can sustain localized second- or third-degree burns. Although a cooling suit can be used to protect the driver, it adds undesired complexity and weight. In addition, a malfunction in the active cooling system could result in active heating of the driver.
Space-shuttle-type insulating blankets offer effective passive thermal protection, without contributing excessively to complexity or weight. The insulating blankets are of three different types: one type for installation on the exhaust and tailpipes, the other two types for installation in the cockpit. The exhaust-system blankets are made partly of a material called "advanced flexible reusable surface insulation" (AFRSI), which comprises a ceramic microfiber core between two glass-fabric face sheets quilted with a ceramic thread. The AFRSI of each blanket is covered with an outer nickel-alloy foil 0.001 in. (25 µm) thick. The foil cover is designed to increase the durability of the blanket, provide some shielding against radiation, and provide for mechanical attachment to enable safety wiring of the blanket to the exhaust-system components. The foil shell is closed along the edge of the blanket by a single fold (followed by rolling) and secured with stainless-steel staples. The single fold is designed to minimize thermal conduction while providing adequate strength. Grommets provide additional reinforcement for the seams and serve as attachment fixtures.
The blanket is contoured to the compound curves of the exhaust-system components. The entire blanket is less than 0.5 in. (1.3 cm) thick, yet acts as a highly efficient thermal-radiation shield with low thermal conduction. To prevent overheating of the exhaust and tailpipes, the blanket is installed only over the top of the exhaust system, leaving the bottom exposed to airflow. Because the blanket is made solely of metal, ceramic, and glass, it is nonflammable and does not outgas significantly during use.
The blankets of first cockpit-interior type are placed under the driver's seat and in floor areas to the left of the seat. Each blanket comprises a (1) a core of low-density, highly resilient glass-microfiber mat between 1 and 2 in. (between 2.5 and 5.1 cm) thick enclosed in (2) a radiation-barrier shell made from layers of an aluminized high-temperature-resistant film and sealed by a high-temperature-resistant adhesive tape, all enclosed in (3) a durable outer shell made of glass cloth impregnated with polytetrafluoroethylene (space-suit material).
The blankets of the second cockpit-interior type are used to insulate the transmission-tunnel/foot-well area. These blankets are made from AFRSI 0.5 in. (1.3 cm) thick, enclosed in glass cloth impregnated with polytetrafluoroethylene. AFRSI was chosen because of its ability to maintain known thickness over a range of compressive loads. The polytetrafluoroethylene-impregnated glass cloth provides durability. The blankets of both cockpit-interior types are designed to be lightweight, to provide maximum thermal insulation, to be nonflammable, and to provide additional protection to the driver in the event of a collision or fire.
This work was done by Bruce V. Lockley of Kennedy Space Center and Martin J. Wilson, Jean M. Charvet, and Suzanne M. Hodge of Boeing. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com under the Materials category, or circleno. 111 on the TSP Order Card in this issue to receive a copy by mail ($5 charge).
Inquiries concerning rights for the commercial use of this invention should be addressed to
the Patent Counsel
Kennedy Space Center; (407) 867-2544.
Refer to KSC-11938.