Modifications to the 1972 ROBIN Program

The Robin system is used to derive density, temperature, pressure, and winds from the radar track of an inflatable falling sphere. The system consists of a rocket vehicle, sphere, radar, and software program utilized to process and derive the atmospheric parameters. The computer program (called ROBIN 72) used for the derivation of the data was subjected to extensive field tests and has subsequently been modified. The new program resulting from the modifications (designated ROBIN 77) eliminates a number of problems encountered in the earlier version such as: supersonic bias, Mach one spike, Cd exceedance, and subsonic bias. The new program includes a better estimate of filter errors resulting from radar tracking errors. The 1976 US Standard Atmosphere replaced the 1962 US Standard Atmosphere for a first guess of temperatures used to calculate density. Rocketsonde-derived density errors due to radiosonde data are discussed and a summary of the accuracy of thermodynamic data and winds using the ROBIN 77 program is presented. (Author)