An in-flight technique for wind measurement in support of the space shuttle program

Abstract

A technique to use an aircraft to measure wind profiles in the altitude range of 1,500 to 18,200 m was demonstrated at NASA Ames-Dryden. This demonstration was initiated to determine if an aircraft could measure wind profiles in support of space shuttle launches. The Jimsphere balloon is currently the device used to measure pre-launch wind profiles for the space shuttle. However, it takes approximately an hour for the Jimsphere to travel through the altitudes of interest. If these wind instruments could be taken with an aircraft closer to launch in a more timely manner and with the same accuracy as a Jimsphere balloon, some uncertainties in the measurements could be removed. The aircraft used for this investigation was an F-104G which is capable of flight above 18,000 m. It had conventional research instrumentation to provide air data and flow angles along with a ring laser gyro inertial navigation system (INS) to provide inertial and Euler angle data. During the course of 17 flights, wind profiles were measured in 21 climbs and 18 descents. Preliminary comparisons between aircraft measured wind profiles and Jimsphere measured profiles show reasonable agreement (within 3 m/sec). Most large differences between the profiles can usually be explained by large spatial or time differences between the Jimsphere and aircraft measurements, the fact that the aircraft is not in a wings-level attitude, or INS shifts caused by aircraft maneuvering