Supporting Test Aircraft with Lift Airbags

Innovators at NASA’s Armstrong Flight Research Center have developed a method of using aircraft lift airbags to support test aircraft during wing strain gage load calibration. In calibration testing, a set of known loads is applied to the wing, and the loads and strain gage responses are then recorded. Multigage shear, bending, and torque load equations can then be derived from linear regression analysis of the data. The method aims to address challenging strain measurement conditions present in certain aircraft with particular landing gear geometries. For example, the Gulfstream III test aircraft has main landing gear attached to the inboard wing at the rear spar. In aircraft with this type of landing gear geometry, the main gear load reaction into the wing changes as the applied test load changes, corrupting the test data and compromising the accuracy of the load equations.