Bettsometer control

The measurement is taken on the upper surface of the wing in three cells: centre (half of wing span), 1/4 wing span and the last open cell (closest to the stabiliser).

The device is mounted at midpoint on the wing chord. Before commencing measurement this place must be checked, as even the smallest tears can drastically alter the results. It is advised to look at the cloth against the light.

One needle with a sharp tip is straight and mounted in the head of the device. With this needle the cloth resistance is tested.

The other needle has a blunt tip and is hooked. With this one the stitching strength is tested.

What we measure with this device is the force needed to break the cloth fibres, and practically its tear resistance under a minimal, predetermined force.
In order to take the measurement, the straight needle is driven into a stretched piece of cloth, and then the balance is loaded up to 600 g. If the cloth will not tear, the test is considered positive (passed). It is to be made in three places on the top surface above the air intakes, and in three places on the lower surface near the suspension points of the A row.
If the cloth breaks in any of tested places, the paraglider is no longer considered airworthy.
The stitching is examined with hooked needle. The hook is driven between the folds, and balance is loaded up to 1000 g. If the stitching holds, the test is successful. It is to be made in three places on the top surface in the vicinity of leading edge.