An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle re-entry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800 degrees Fahrenheit. The environmental pressure was varied from 0.0001 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of Saffil, Q-Fiber felt, Cerachrome, and three multi-layer insulation configurations were measured.Daryabeigi, KamranLangley Research CenterTHERMAL CONDUCTIVITY; MULTILAYER INSULATION; REUSABLE LAUNCH VEHICLES; REENTRY EFFECTS; THERMAL INSULATION; AERODYNAMIC HEATING; TEMPERATURE GRADIENTS; NITROGEN; THERMAL ANALYSIS; REENTRY SHIELDING; TEMPERATURE EFFECTS...