|The load cell George brought along. Here it reads 0.67kn of maximum force for the test on the snow anchor.|
A shear fail of a buried axe (1) from Max Hunter on Vimeo.
A shear fail of a reinforced buried axe from Max Hunter on Vimeo.
|A bullhorn arrangement for the nomics|
A shear fail of a Bullhorn arrangement buried axe from Max Hunter on Vimeo.
We tested 2 Deadmen snow anchors, and these proved to be very strong, but were very dependent on the angle of insertion into the snow. They did seem to be repeatedly stronger than a reinforced axe anchor. Deadmen have a very large SA and are perfectly symmetrical down a vertical axis through the cable.
We moved on to build bucket seats. We managed to destroy an obviously weak bucket seat, but could not destroy the second seat.
We moved on to measure the impact force on a climber as they fall past a belayer in a bucket seat. The load cell was attached directly to the falling climber. We used body belaying (with a non dynamic arrest and with a very dynamic arrest), and a belay plate (at least 3 belay plates were tested) with dynamic and non dynamic arrests. With non dynamic arresting the maximal force was over 1kn, but with a hugely dynamic arrest (with body belaying or belay plate) the maximal force was down to 0.4kn. The skill of the belayer seemed crucial here to reduce the maximal impact force.
An impact force test on a falling climber+a belayer in a bucket seat using dynamic belaying from Max Hunter on Vimeo.
We built 2 snow bollards. The first was what we would like to build, for successful abseiling, and the second was of a size that we thought would probably fail. The smaller bollard is in the photo below. Both bollards withstood abseils (without belay plates). Finally we tried to fail the larger bollard, and measure the maximal force we could apply to it. We could not fail the anchor.
|Abseiling off the 2 snow bollards|
|The smaller of the 2 snow bollards|
|Trying to destroy the larger of the 2 snow bollards|