PRESSURE MEASUREMENTS ON A SPINNING WIND-TUNNEL MODEL BY MEANS OF TELEMETRY

The Magnus force is a side force which exists on spin stabilized projectiles at angle of attack. Although its absolute magnitude is small, it has a destabilizing effect. A large part of the Magnus force arises from an asymmetric pressure distribution caused by the distorted boundary layer. This paper discusses a possible technique for measuring the pressure distribution about a spinning body and obtaining the force by integration. It also would serve as a check for three-dimensional boundary-layer calculations. The technique involves imbedding pressure transducers into the model surface and the use of a miniature, self-contained telemetry system to transmit the pressure data out of the tunnel. Data with spin and without spin have been obtained at a single axial location on a tangent-ogive-cylinder. The data without spin compared favorably with theoretical calculation. Data with spin indicated an anomaly in the pressure distribution. The test were carried out in a wind tunnel at Mach 2. 0 to 3. 5 in increments of 0. 5.