Mar 20, 2019

Frangible Fence Equipment Test Developed

By Leslie Mintz - USEA Staff

Dr. David Vos and the USEA’s Cross-Country Safety Subcommittee have developed a low cost, easily constructed testing system in order to test obstacles with frangible fence equipment to ensure that the fence will collapse when impacted under ap­propriate conditions.

The only materials needed for the test are:

  1. A 40 kg kettlebell
  2. 10ft of stainless steel chain of 5/32”
  3. Hooks and clevis
  4. Tractor and tractor bucket

“The whole point is to come up with an approach or means in which we can not only test future devices, but also current devices,” explained Vos. “In the field it is often not very obvious why [a frangible device] didn’t release. The point is to get to very strongly physics based solutions that are really easy to use in the field.”

The full parameters for the test are available here.

Watch Dr. Vos demonstrating the test:


If you are interested in learning more about Dr. Vos’ calculations behind how he developed the system and why the test works, watch his presentation from the 2018 USEA Annual Meeting & Convention during the Safety Open Forum here:



Learn more about frangible technology from Dr. Vos and Andy Griffiths in their article “Exploring Collapsible Technology for Cross-Country Jumps.”

About Dr. David Vos
Dr. Vos led Project Wing at Google [X] through Nov 2016, culminating in the world's first month long drone delivery service at Va Tech. Prior to joining Google [X], Dr. Vos was Senior Director at Rockwell Collins after the acquisition of Athena Technologies – a leading flight control and navigation systems company – in April 2008. Vos was Founder, CTO and CEO of Athena Technologies. Having worked in the unmanned systems industry since its inception, he is a pioneer and a thought leader in the area of Unmanned Aerial Vehicles (UAVs). Born in South Africa and now a U.S. citizen, Vos is the inventor and developer of Rockwell Collins Control Technologies core technology. He holds patents in nonlinear control systems and other areas and has broad experience in guidance and control systems. From August 2007 thru 2014, Vos was appointed by Virginia’s Governor to Commissioner of the Vint Hill Economic Development Authority’s Board of Commissioners. In June of 2007, Vos was named by Ernst & Young as an Entrepreneur of the Year winner in the Greater Washington area. Vos holds a B.S. in Engineering with Honors in Aeronautical Engineering from the University of Stellenbosch, South Africa, an M.S. in Dynamics and Control from MIT, and a Ph.D. in Estimation and Control from MIT, in the Department of Aeronautics and Astronautics.

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