Accession Number : ADA306847

Title :   Radiofrequency Transmission Characteristics of Candidate Ablation Materials for Planetary-Entry-Vehicle Heat Shields.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Gilreath, Melvin C. ; Chapman, Andrew J. ; Hatcher, Douglas M.

PDF Url : ADA306847

Report Date : DEC 1968

Pagination or Media Count : 63

Abstract : An experimental investigation was conducted to determine the radiofrequency properties of several candidate ablation materials for planetary entry vehicle heat shields. The radiofrequency transmissibility of each ablative material was determined by the real time measurement of the attenuation of a 35 GHz signal while each sample was exposed to a simulated planetary entry environment. The simulated planetary environment was produced by providing a heating rate, pressure, and free stream Mach number in an arc heated supersonic wind tunnel. Recordings of the transmission loss obtained through eacb material during the arc tunnel test and photographs of all test specimens before and after thermal exposure are presented. In addition to the transmission loss measurements, the dielectric properties of most virgin materials were measured at room temperature and are also presented.

Descriptors :   *ABLATION, *RADIATION ATTENUATION, *HEAT SHIELDS, *ELECTROMAGNETIC ENVIRONMENTS, THERMAL PROPERTIES, MEASUREMENT, ATMOSPHERE ENTRY, REAL TIME, TRANSMITTANCE, DIELECTRIC PROPERTIES, MACH NUMBER, FREE STREAM, HYPERSONIC WIND TUNNELS, TRANSMISSION LOSS, ABLATIVE MATERIALS, PLANETARY ATMOSPHERES.

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE