The RAM drill was developed for a particular seismic program. It is a system in which high-velocity air drives rotating cutters and blows the ice chips from the hole. The cutter drill motor hangs on a sonde that carries the air from the surface and is reeled out as the hole deepens. In typical firn/ice conditions in West Antarctica, two compressors in parallel are needed to provide enough air flow to overcome air losses in the firn. It has been used three times in West Antarctica, most recently during the 2009-10 field season, when it routinely attained depths of 90 meters. It has been tried out once in East Antarctica (at South Pole) with lesser success. The RAM drill is limited to a maximum depth of 95 m by the amount of hose that can be carried on the current configuration of its hose reel (one hose-width wide, no level wind), but in principle it could drill much deeper; once the penetration is below the firn/ice boundary there is little additional loss of return air and greater depths should come realatively easily. Factors affecting the drilling through the firn to the firn/ice boundary, however, are not well understood and methods of drilling consistently to below the firn/ice boundary remain to be found.
| Type: | Non-coring |
| Number in Inventory: | 1 |
| Max. Depth Possible: | 95 m (the depth being limited by the length of the hose) |
| Borehole Diameter: | 100 mm |
| Shipping Weight: | 22,664 lbs |
| Shipping Volume: | 2971 cubes |
| Comments: | Weight of drill system in operation about 20,000 lbs. |
| Subsystem | # in Inventory | Description | Weight | Cube |
| Crescent wheel w/ hose | 2500 lbs | |||
| Cresent sld w/ generator | 3000 lbs | |||
| Drill head | 900 lbs | |||
| Compressor sled | 7500 lbs | |||
| Spare hose on wooden reel | 800 lbs | |||
| Lubricants | 195 lbs | |||
| Electronics (2 boxes) | 250 lbs / 150 lbs | |||
| Spare motor | 113 lbs | |||
| Spares & Tools (2 boxes) | 155 lbs / 200 lbs |
System Overview
Major system components
- Two sled mounted diesel engine driven air compressors
- 400 cfm at 200 psi rated
- Hose reel sled
- Integrated drilling platform
- 100m of 1.5” air hose
- 6.5 kW generator
- Spares and tool storage
- Drill
- Drills a 4” hole
- Powered by compressed air
Deployment and Set-Up
- Requires two plus LC-130 flights not including the tow vehicle
- Heavy equipment support required to assemble the hose reel on the sled
- 1.5 days to set up with two people
- Shipping weight is ~22,664 lbs
- Weight of drill system in operation about 20,000 lbs
- Shipping volume is 2971 cubes
Drill System
- Two 1hp air motors coupled together drive a planetary gear reducer
- Head spins at 2500rpm
- Four tool steel cutters
- Two sets of centering blades
- Drills a 4” hole
- Adjustable booster nozzle at the top of the drill
- Exhaust air ejects the cuttings from the hole
- Weighs 200 lbs
Operation
- The rig is rough positioned by the tow vehicle and then drill is fine positioned via an adjustable carriage on the drill sled
- The speed and direction of the hose reel is controlled via a pendent
- Ethanol is injected into the air stream to prevent icing in the hose
- .7 L consumed per 90m hole
Past Deployment
- 2002-03 season at Onset-D, West Antarctica
- 226 holes drilled
- Target depth was 60m
- Average hole depth was 56m
- 12,686 total meters drilled
- 2008-09 season at upper Thwaites Glacier, West Antarctica (traverse from WAIS Divide)
- 176 holes drilled
- Target depth was 60m
- Average hole depth was 46m
- 8,109 total meters drilled
- 2009-10 season at lower Thwaites Glacier, West Antarctica (traverse from WAIS Divide)
- 132 holes drilled
- Average hole depth was 74m
- 9,782 total meters drilled
Performance
- Capable of drilling to 95m
- Firn permeability and conditions greatly effect the actual depth possible.
- 6m per minute maximum drilling rate
- 25 minute cycle time for a 90m hole
- ~5 gallons of fuel consumed per hole
