Humanitarian Demining for the US Army Night Vision and Electronic Sensors Directorate Communications-Electronics Command.

From 1996 through 2002 CEG and Army Special Forces personnel conducted successful tests of prototype demining equipment at Ft. A.P. Hill. In these tests, the equipment was shown to be faster than existing hand methods of mine excavation and has the capability to increase operator safety.

Anti-personnel and anti-tank mine testing

During the tests, 140 anti-personnel and 120 anti-tank simulated mines were uncovered. The anti-personnel mines included: PMN, OZM, PMD-6, TS50, VS50, M-14, VAL-69; while the anti-tank mines included: M-6, M-15, M-19, TM-60, TM-62, TMD44, VS 1.8, and VS 2.2. The anti-personnel mines were shallow, buried less than 1 inch below the surface, while the anti-tank mines were buried up to about 0.5 foot deep. The mines were in the ground prior to the test a minimum of 30 days. The red clay soil at Range 71A was generally dry with an unconfined compressive strength from 2 to over 5 tons per square foot. The majority of the tests used a Mach 1.5, 30-scfm supersonic jet. Operating at 40 psig the jet exerts a force of 1.8 pounds, which is insufficient to set off the most sensitive PMN mine. Times to find and expose for identification as shown in the table below were much less than current practice. For the majority of times when a flagged indication is not actually a mine, use of the AIR-SPADE offers a significant time savings.

Times to Find and Expose Landmines

AIR-SPADE with Cart unit uncovering anti-personnel mines	AIR-SPADE with SAFEX utility on Deere GATOR uncovering anti-tank mines

Air powered brush removal tools

To address the real world need to remove underbrush that may have grown and covered a mined area, a line of commercial, air-powered brush and pruning tools has been located. The tools most complimentary to the demining system are: an underbrush trimmer, a pole pruner, and a pole saw. The underbrush cutter comes with both string and metal blade cutters. The underbrush cutter is very well suited to dense growth and thickets. The pruner can cut individual trunks or shoots up to 2 inches in diameter. Depending on the specific tool, the air requirements vary from 2 to 18 scfm. Figures show Special Forces Sergeants with the tools during testing at Ft. A.P. Hill.

The overall conclusion of the testing is that the addition of air tools to the AIR-SPADE package is very desirable. The chain saw and trimmer in particular have the most potential for consistent use. The air-powered tools, although costing more, appear to require less support and logistics in addition to being more rugged and tough. The trimmer, when used with a metal blade (recommended), cut all grass types and saplings up to 3-cm in diameter with ease. The blade works better than traditional string lines because it does not require bumping the head of the trimmer on the ground for additional string and because it does not need to be replaced as quickly as string. The chainsaw was much lighter than a commercial gas powered unit and far less temperamental. The light saw head allowed it to be extended a couple meters from the operator without seriously affecting its performance. The shears all worked well. Their major advantage over their manual counterparts is the decrease in fatigue and added control given to the operator.

Pole trimmer	Hand shear
Brush trimmer	Chain saw

Position Testing

Three operators equipped with various barrel sizes (0’, 2’, 3’, 4’, 5’) and with and without a 45° adapter conducted excavation testing using three common operator’s positions: prone, squatting, and standing. The time taken to uncover the top of the mine simulant and the time taken to uncover it completely were recorded. The mine simulants were buried 5-cm below the ground. Operators’ comments were recorded for each length, adapter, and position combination. The operators sought to identify levels of comfort, ease of use, confidence in tool, and fatigue factors. These results were used to rank the various combinations of tube length, adapters, and position.

Generally the 3 foot long barrel was preferred for the prone and squatting positions; while the 4 foot long tube was preferred for standing. Generally using the tool with the 45º degree adapter was preferred over without the adapter.

Water Jet Testing

The water jet was effective in cutting extremely hard soils. Preference was to use the water jet to cut narrow slits to section the soil and the air jet to break these off. In this manner, excess water was eliminated and no problems encountered with mud or puddles obscuring the view of the area to be probed for the mine. No particular synergism was seen when the air and water jets were used simultaneously in the specially combined head. Therefore, separate tools are preferred: the standard AIR-SPADE hand tool and a standard pressure washer gun with the appropriate nozzle. It is not recommended to exceed 1 ½ gpm at 1250 psi for demining purposes because of the risk of mine detonation.

Evaluating kneeling position	Combined air-water jet tool

Target Relocation

Concern has been expressed that use of the AIR-SPADE in demining will just scatter non-mine metallic indications so that they will just have to be found again. Special Forces operators tested a wide variety of dummy targets (metallic debris and the like) to see how much they might be dislodged and if they would be moved beyond safe recovery in a mine lane.

After excavation with the air jet, all targets except the paper clips were found through visual observations and without the use of a metal detector. The object that was verifiably displaced the furthest was the soda tab. Most of the metallic debris tested were not displaced more than 30-cm during excavation. Thus, it can be generally said that for small, light objects, like bicycle chain links often found in third world countries, the AIR-SPADE system will displace them, but not further than can be found visually. Thus, the speculation by the demining community that the AIR-SPADE system will increase false targets seems to be not a problem.

An interesting and unexpected observation gained from this test was that the operator had a tendency to manually pulse the system when using the non-pulsed AIR-SPADE in order to increase his visibility. Therefore, it can be said that not only does pulsing make more efficient use of the available air supply allowing more users to work simultaneously,but it also improves the operators performance when searching for targets.

Types of metal targets buried for relocation test. [#10 Bullet not shown]

Types of metal targets buried for relocation test.

Note: All units in centimeters

Summary of Demining Unit Specifications

Platform	AIR-SPADE® Hand Cart	SAFEX® Utility	SAFEX®Utility	SAFEX® Trailer
Air Flow (scfm)	30	60	30	60
No. of tools	1	2	1	2
Vacuum	No	3” dia hose	2.5” dia hose	No
Water Jet	No	No	Yes	Yes

To see video of the testing at Ft. A.P. Hill, please go to our reference library.