Measuring Up: NIST Calibrates Masses for Unique Air Force Deadweight Machines

This is NIST’s Million Pounds-Force Deadweight Machine. The two new Air Force devices, once assembled, will have a similar basic structure. The larger of the two new deadweight machines will be capable of measuring forces up to 453.7 kilonewtons (kN) (102,000 pounds-force). The smaller one will handle forces up to 133.4 kN (30,000 pounds-force). For comparison, the engine of a Boeing 787 has on the order of 245 to 335 kN (55,000 to 75,000 pounds-force) of thrust.

Credit: NIST

Mechanical engineers at the National Institute of Standards and Technology (NIST) have just finished calibrating several dozen large metal masses, which will be used to build a pair of unique force-producing machines currently being custom-built for the U.S. Air Force. The new Air Force machines will be about three times better than what they have now, though with larger uncertainties than NIST’s primary standards. They will support achieving peak performance of military aircraft that are the most advanced in the world.

When fully assembled, the devices – called deadweight machines – will consist of stacks of cylindrical masses, each between 500 and 8,000 pounds in weight. The deadweight machines will be used to calibrate force measurement devices, equipment that can be used to measure things like the thrust of a rocket engine or the weight of an aircraft before and after fueling.

The two new deadweight machines should improve efficiency and reduce the uncertainty of the Air Force’s force calibrations, said NIST’s Kevin Chesnutwood, who led the mass calibration effort.

“There are similar deadweight machines in the world but, truthfully, not all that many,” Chesnutwood said. “So any time one goes online, it is noteworthy.”

The Air Force’s deadweight devices are manufactured by Morehous ..

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