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Most Recent Prototypes - January 2000
Prodder Developments 1997 - 1999 at HARC
The early UWA prototypes were reproduced at HARC in Islamabad, Pakistan, for simulated field tests. A number of important factors emerged from a careful study by two experienced Afghan deminers with HARC engineers. The mark 3 design was an attempt at an improved excavation tool. Initially it was a simple U-shaped channel section, but the front opening was later widened (mark 3a) to prevent stones and mud from clogging the throat. The mark 1 design was difficult to use as the deminers wanted to place the blade sideways into the ground, so part of the guard was removed to make it easier to use (mark 2).
These photographs show deminers using the Mk 2 prodder on flat and sloping ground using squatting and lying positions. (left, centre, right). Photographs at Risalpur testing area.
Left, centre: deminer showing use of bayonet (note hand pose carefully: it is intended to allow the bayonet to fly out of the hand in the event of an accidental explosion), Right: awkward pose required for Mk 2 prodder when excavating. All these photos show the helmet weight support which was invented to relieve the 2.2 kg weight of the ballistic helmet.
Mark 3 prodders evaluated by deminers. (left, right) The T-shaped handle was preferred to the original saw handle design. The blade has been mounted at a different angle too, so the normal usage position is with the T bar vertical. The prodder is a right-handed design.
Mark 4 prodder with powder coated handle. This was considered as the "ideal" design by Afghan deminers who evaluated it in simulated field tests in Pakistan. However, when it was issued to a demining team for use in the field it was found to be too weak. The prodders bent too easily according to the deminers. it took us some time to work out why this was so, after the careful testing by the Afghan deminers in our own field tests. The reason emerged when we held an entirely unrelated simulated field trial, again with Afghan deminers, but not to evaluate the prodders. The deminers used the prodders for many excavation other than investigating metal targets, and even when investigating targets, they initially used the prodder much more forcefully than our original deminers. The prodders did not bend, but they nearly did. From that point on we used much stronger steel blades and strength was never an issue after that. Fredrick Palsson, technical adviser with Mine Action Program Afghanistan (UNOCHA) suggested a different blade design and this was made and tested with a polycarbonate guard. The deminers found it was good as a probe, but for stony or hard ground (by far the most common in Afghanistan) it was much more difficult to dig with than the Mark 4 prodder. The Mark 5 prodder has a T shaped handle, and the Mark 6 has a axial handle, also suggested by Fred Palsson. Again, the deminers only favoured this design as a probe.
Mark 5 Prodder with metal handle (left) and wooden handle (right).
Mark 6 Prodder with wooden handle
Fixture for making polycarbonate hand guards. The polycarbonate blank is heated in the visor making oven at about 150 degrees C, and transferred to the fixture where it is bent by hand. (full-size)
Some different handle designs evaluated in a second series of trials with deminers. The palm-shaped handle(left) was comfortable for digging but extra pressure and friction with the palm was uncomfortable in extended prodding work. The rubber composition handle on the right was also uncomfortable in extended use. Some different handle designs evaluated in a second series of trials with deminers. This one (full-size) was based on a moulded handle cast from plasticine gripped by a medium sized hand. It works fine for a single hand position but was fatiguing in extended use with different hand positions.
Some different handle designs evaluated in a second series of trials with deminers. Another design shaped for the palm, and again discarded in favour of the T-shaped design for the Mark 4. (left, right). For a summary of these more recent trials, see the top of the page and Trials in Pakistan - January and June 1999 (to be continued) |
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