Measuring the center of gravity (CG) location of large spacecraft presents many of the same challenges encountered when measuring small objects. Common requirements for the measuring device include: establishing known geometry, maintaining geometry over the full range of load conditions, selecting force transducers with appropriate sensitivity to support the desired measurement performance, preserving that sensitivity throughout the measurement, and devising a method to relate the spacecraft’s datum to the instrument’s datum.
The WCG High-Accuracy Series tests items up to 2,850 lbs, with ultra-high sensitivity models available. These instruments use a load cell system to measure the location of center of gravity using a weighted average. To measure an object, simply lower it onto the triangular table and position it relative to machine zero. The third CG coordinate can be measured after rolling an object 90 degrees. CG accuracy depends on test object weight, center of gravity height, fixture accuracy and leveling. Less than one minute is required to make a measurement, so these instruments are ideally suited to high volume production. This type of instrument is often used to measure “black boxes” used in aircraft and missiles. The five standard C series models are a lower-cost alternative and suitable for general purpose applications. We recommend them for laboratories that don’t require the highest precision.
Our hardware enabled the Boeing CST-100 Starliner team to take highly accurate mass properties measurements ahead of flight testing.