August 19, 1960: Inertia Measuring Test Platform

  • Published
  • Air Force Flight Test Center

A vein of silver ore was discovered beneath the weight and balance hangar during the course of excavating for the massive foundation of the Inertia Measuring Test Platform. The discovery ignited a brief but intense excitement in the local area. To recover the ore, however, would require destroying the costly new facility. Three weeks later, the footings were poured and the vein was buried beneath 986 cubic yards of concrete. This was the largest continuous pouring of concrete in the history of the Antelope Valley.

The Dynamic Inertia Measurement method uses a ground vibration test setup to determine the mass properties of an object using information from frequency response functions. Most conventional mass properties testing involves using spin tables or pendulum-based swing tests, which for large aerospace vehicles becomes increasingly difficult and time-consuming, and therefore expensive, to perform. The DIM method has been validated on small test articles but has not been successfully proven on large aerospace vehicles. In response, the National Aeronautics and Space Administration Armstrong Flight Research Center conducted mass properties testing on an “iron bird” test article that is comparable in mass and scale to a fighter-type aircraft. The simple two-I-beam design of the “iron bird” was selected to ensure accurate analytical mass properties. Traditional swing testing was also performed to compare the level of effort, amount of resources, and quality of data with the DIM method. The DIM test showed favorable results for the center of gravity and moments of inertia; however, the products of inertia showed disagreement with analytical predictions.

News Search