Cost effective two component balance for a subsonic wind tunnel

Abstract

Wind tunnels are used extensively for the aerodynamic testing of vehicles (airplanes, cars, trains etc), balls (tennis ball, golf ball etc), buildings and other objects; to simulate their behavior at different speed while in motion. Wind tunnel balances are used to measure different forces and moments (lift, drag, side forces, yaw, pitch, roll) acting on these objects when move past air. Wind tunnel balances are instrumented in different ways like using potentiometer, load cell, discrete strain gauges etc, with each instrumentation scheme having is advantages and disadvantages with respect to cost, accuracy, sensitivity, complexity and ruggedness. In this report, different existing wind tunnel instrumentation schemes are analyzed with an emphasis on low cost with reasonable accuracy. The resulting optimal sensor configuration for the lift and drag are presented. A two component balance, designed and built, on the resulting scheme was calibrated and subjected to wind tunnel testing of aerodynamics forces on standard shapes. The findings of this benchmark case were compared to published results and it was found that the two component balance designed in this work provides reasonably accurate measurements, while being providing ease of manufacture and cost effectiveness.