NALYTIC studies of the hypersonic near wake problem often make use of base pressure measurements and resulting correlations in order to verify and/or upgrade calculated results. Although an extensive amount of base pressure data have been obtained from wind-tunnel test experiments only a limited amount of results are available for interference free data under high Mach number conditions.J ~ 3 In addition, because available flight test data on base pressures have been obtained with pressure gages whose full scale ranges were 0.1 psia or greater, published results on flight test base pressures4 ~ 8 correspond primarily to moderate or high Reynolds number conditions. The purpose of the present Note is to present additional base pressure results obtained through use of low range gages (0.01 and 0.05 psia full scale) on three conical flight vehicles of 8° half angle. These data represent a set of unique flight test base pressure measurements extending to low Reynolds number and are shown herein along with other results, also previously unpublished, for 8° half-angle conical vehicles as obtained through use of 0.1, 1.0 and 2.0 psia gages. All data correspond to zero angle-of-attack conditions at a freestream Mach number of (M^ ~)20. Results are available for three types of heatshield material which can be categorized as high, medium, and nonablators corresponding to turbulent mass loss parameters of \_(m/pAv)T~~ 0.05, 0.01, and 0.0, respectively. Taken together, the complete set of data represents a composite summary of flight test base pressure data for 8° half-angle cone vehicles covering a range of Reynolds number of (Re^L ^) 2 x 105 to 3 x 108. 2. Experimental Technique The low range data discussed herein were measured through use of dual range gages which were located for each vehicle at a radial location of (r/R = ) 0.54. For this stretched diaphragm gage the dual output feature was accomplished through use of two amplifiers which independently provided 5 v d.c. outputs at pressure levels of 0.01 psia and 0.05 psia. Response time tests and analyses determined that a small (10%) bias correction to the local raw data was appropriate in order to account for time lag effects associated with the pressure gage assembly. This correction has therefore been applied to all the low range data presented herein. Since final results have been validated to ± 5% full scale, only data greater than 5% full scale are presented. The data obtained with the 0.1,1.0, and 2.0 psia gages, as shown herein, correspond to results which were 10% full scale or greater. Data are presented for each of three radial locations (r/R = 0, 0.33, and 0.46) and for the three mass loss parameters previously described. The noted results were determined from measured