The air bearing balance described has been designed to support the dynamic force measurement requirements of virtual e ight testing. This balance is a single-degree-of-freedom air bearing spindle. The bearing gas e lm is instrumented with fast-response pressure sensors that enable the determination of forces and moments. The device thus permits the measurement of unsteady aerodynamic loads on spinning test articles. The balance also incorporates a supply of high-pressure air, delivered to the model without friction, for pneumatic actuators or reaction control jets. Spin at up to 20,000 rpm is made possible with a brushless motor. The focus is on calibration properties of the balance, particularly the ine uence of rotation angle and spin rate on the calibration parameters. Combined linearity and repeatability errors less than 0.5% full scale are achieved at a e xed angle. Spin rate and angle deviations introduce calibration variations as large as 20%, but angle and speed curve e tting are shown to reduce this error to less than 1.5%.