Exploratory Wind Tunnel Tests Of A Shock Swallowing Air Data Sensor At A Mach Number Of Approximately 183 PDF Download

Wind tunnel tests were made using various designs of pressure probes mounted ahead of three different nose designs. These probes included the measurement of static pressure, ram pressure, and angle of attack and yaw in various combinations with each other in an angle of attack range up to 23 degrees. In addition, studies were made of the effect of hole size on the static pressure reading, effect of high angle of attack on these readings, the effect of flow out of the static holes, and the effect of the proximity of a shock wave, and the use of a unique slotted type probe design to minimize variations of static pressure reading with roll angle. It was found that, as the hole sizes were increased from .040 to .125 inches, the static pressure decreased very slightly so as to cause the indicated Mach number (when calculated from measured ram and static pressure) to vary from 1.77 to 1.79 (tunnel M = 1.73) at zero angle of attack. This discrepancy disappears at 6 degrees angle of attack at zero roll angle. A Mach number variation of less than .01 exists up to 5 to 6 degrees angle of attack with the NACA type probe (S). With the hemispherical type probe the indicated Mach number increases with angle of attack at a rate of approximately .01 for every 5 degrees angle of attack up to an angle of 8 degrees, after which it rises slightly more rapidly. (Author).