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F305-Z4551 and Z4552 - Rope Tension Forces

Customer: National Aeronautics and Space Administration (NASA)
Loadcell: F305-Z4551 50,000lbf and F305-Z4552 5,000lbf
Generic Type: Rope Tension Loadcell
Special Features: Low mass, 2-piece titanium construction

Working closely with NASA and its subcontractors, Novatech Measurements Limited has designed and built a number of custom loadcells for use in space flight applications. One such loadcell was required to provide cord tension measurement in the most unobtrusive manner possible. This necessitated a two piece, titanium construction.

The loadcell could be assembled around the cord such that there was no need to de-tension or decouple the cord and no need to manufacture special end terminations. Two versions were manufactured for different sizes of rope. The total mass of the 50,000lbf sensor was no more than 1.25kg, with an overall diameter no more than 50% larger than the cord itself.

In addition to minimising the physical impact on the dynamics of the system, the loadcell was required to ensure against physical damage to the delicate woven cord. The design needed to be completely rounded, with smooth flowing curved surfaces on all internal and external features to avoid abrasion or snagging. The resulting geometry was too complex to be machined by a human operator and needed the integration of special CAD/CAM software working in conjunction with state-of-the-art, semi-automatic, 4-axis milling machines.