Lego Brick-Inspired Physics Can Make Flights More Fuel-Efficient

Torque wrenches - and the people who use them to build and maintain planes - are unsung heroes of the skies.

Torque wrenches measure the force that causes an object to rotate. Aircraft mechanics use torque wrenches to ensure that bolts and fasteners on planes are correctly tightened. Without them, a plane could come apart midflight.

But like any measurement tool, torque wrenches need to be calibrated regularly to make sure they're giving accurate readings. If these measurements are off, the results could be disastrous.

Calibrating these tools is expensive and time-consuming. That's because these calibrations are typically done on a large device in a lab, not on-site, where airplanes are being maintained. So that requires shipping the wrenches to the lab and then waiting for them to be calibrated and returned.

Thanks to advances in measurement science at NIST, calibrations may soon be performed locally instead. And it all started with … Lego bricks?

The Lego Kibble Balance Leads to Calibration Improvements

More than a decade ago, NIST researcher Leon Chao and his team were building a precise machine, known as a Kibble balance, for directly measuring a kilogram using quantum physics. Chao's supervisor suggested they try creating a tiny version of it out of Lego bricks. The resulting paper was a scientific hit and even inspired copycat Kibble balances around the world!

But the story doesn't end there. The team applied scientific principles in this project to develop a similar technology for calibrating small torque tools - such as precision fasteners used in night vision goggles - using electrical standards via a much smaller device. Eventually, the military plans to use these devices to calibrate torque wrenches for planes and vehicles.

The tool, known as the Electronic NIST Torque Realizer (ENTR), is a calibration tool that can be used anywhere - no shipping or waiting required. The device works by using rare-earth magnets, among other electronic and mechanical components, to generate torque that can be measured with high-tech electrical measurement devices.

The researchers partnered with Snap-on Industrial, a tool manufacturer that contracts with the U.S. military. Currently, one ENTR device is being tested at Nellis Air Force Base in Nevada, with plans to build and distribute several more.

"Snap-on took our design and made some very helpful improvements to it. We are working closely with the company to help them build more and deploy them out to U.S. Air Force bases," said NIST researcher Zane Comden.

The Air Force uses hundreds of thousands of torque wrenches that all have to be calibrated to a particular standard with a robust chain of traceability, said Air Force Mechanical Engineer Anthony Gaughan. The equipment that calibrates those wrenches has to be checked in a lengthy process every three months.

But ENTR could make it possible to check the equipment much less often and still have it work as intended. This could save time and money.

Most importantly, it could help the military be more prepared. Moving calibration away from U.S. bases and toward the areas where planes are being flown and maintained would make military operations more agile.

"This further ensures military readiness, and that doesn't just mean the plane takes off. It means our weapon systems, and their critical subsystems, work as intended because their measurements are accurate and traceable," said Air Force Technical Expert for Metrology Jeremy Latsko. "That means the mission is accomplished safely and effectively."

Bringing Local Calibrations to the Airplane Hangar

Once this technology is adopted by the government, other companies that need to use torque tools, such as commercial airplane manufacturers and automakers, may shift to this new approach as well.

Fewer screws and bolts could be required on airplanes because torque tools are calibrated so precisely, said Andrew Lobo, president of Snap-on Industrial, NIST's partner in the effort. This could mean the planes have fewer screws and bolts and be lighter and more fuel-efficient.

"My belief is that this technology has the potential to transform entire industries. Anything that rolls or flies could benefit from removing uncertainty in the measurement chain," Lobo said. "When you remove uncertainty, you raise confidence. And that confidence allows engineers and developers of planes, trains and automobiles to improve the efficiency of how they operate. It's our privilege to be a part of that."

The current version of ENTR can measure to 1 newton meter, a unit of torque, with a very high degree of accuracy. While this is only a fraction of the torque needed to, say, tighten the lug nuts on your car tire, it's proof of concept that the team is continuing to improve upon.

For scientists whose research mostly stays within expert circles, it's exciting to see their work's impact in the world.

"This is a thrill for us and for NIST. It's an important part of NIST's mission to disseminate the technology and scientific advancements we make here out into the wild," Chao said. "Our expertise is working in labs and writing technical manuscripts, so this is new and exciting for all of us involved."

Editor's note from the U.S. Air Force: Approved for public release, public affairs case number AFLCMC-2026-0076.