Dirt Cratering (Chapter 12) Flashcards
1
Q
- What is explosive requirement for Dead stumps?
A
1lb of explosive is used per 1’ of diameter
2
Q
- What is the spacing between deliberate crater boreholes?
A
5 feet between boreholes, center to center
Same as hasty crater
3
Q
- An expedient cratering charge should be primed with what?
A
Prime with 1lb of TNT (dual priming is recommended)
4
Q
- What is formula to calculate number of boreholes for a relieved face crater?
A
N_fr = ((L-10) / 7) + 1
Calculates number of charges for friendly row of boreholes.
Round any fractional numbers to next higher number
N_er = N_fr - 1
5
Q
- What is characteristics of deliberate crater?
A
V shaped
7-8 feet deep
25-30 wide
37 degree slope
6
Q
- What is measurement requirement for boreholes at the end of a deliberate crater?
A
End boreholes are 7’ deep
7
Q
- What is explosive requirement for live stumps?
A
2bls of explosive is used per 1’ of diameter
8
Q
- What is measurement and explosive requirement for an enemy row in a relieved face crater?
A
4’ deep
30 lbs explosive
9
Q
- How do you measure for stump removal?
A
Stumps are measured 12-18” above ground level then diameter is rounded to next higher ½ foot
10
Q
- What is the spacing between hasty crater boreholes?
A
From center to center 5’ between boreholes
11
Q
- An effective craters takes _______ allowing time to employ anti-tank weapons
A
4 or more passes
12
Q
- How do you improve craters?
A
Digging face vertically on friendly side
Mining
Filling with water
Any other means to further delay the enemy
13
Q
- What are the geometric characteristics of hasty crater?
A
V shaped
6-7 feet deep
20-25 wide
25-35 degree side slope
14
Q
- What is the fuel oil requirement to mix with fertilizer?
A
1 quart per 25lbs of fertilizer
15
Q
- What is minimum weight of explosive per borehole used in hasty craters?
A
At minimum 50 lbs of explosive per borehole
DOES NOT MATTER WHICH EXPLOSIVE
Do not convert using RE factor, only divide by pounds per unit
16
Q
- To construct relieved face crater, which row will be fired first?
A
Enemy row
1/2 to 1 1/2 second delay
17
Q
- For breaching hard surface pavement, how many pounds of explosives should be used?
A
1 pound for every 2 inches of pavement
Tamp charge twice the breaching radius (thickness of the pavement) (2 x Br)
18
Q
- What is depth of deliberate crater boreholes?
A
A combination of 5’ and 7’ deep
19
Q
- What is the placement/spacing between friendly and enemy rows when constructing a relieved face crater?
A
On Dirt or Gravel roads: 8 feet apart
On Hard surface road: 12 feet apart
20
Q
- What is explosive requirement for complete tree?
A
3lbs of explosive is used per 1’ of diameter
21
Q
- How much nitrogen must be contained in Ammonium nitrate fertilizer?
A
33 1/3% of nitrogen
22
Q
- What is hasty crater blowout distance?
A
Approximately 8 feet beyond the end boreholes
23
Q
- What are the three methods of boulder removal?
A
Snake-hole, mudcapping, and block-hole method
24
Q
- What is the shape/characteristics of a relieved face crater?
A
Trapezoidal shape
7-8 deep
25-30 feet wide
Unequal side slopes
25
7. For hasty crater, what is average traverse attempts of modern tanks?
Average of 4 attempts
26
37. What is taproot hole depth equivalent to?
Equal to stump diameter
27
20. What is measurement and explosive requirement are a friendly row in a relieved face crater?
5’ deep
| 40 lbs explosive
28
25. For relieved face crater, where would you place first borehole?
5 feet in from the desired edge of the crater
29
23. What is the spacing between relieved face crater boreholes?
7 feet between boreholes, center to center
30
38. What is lateral hole depth equivalent to?
Equal to stump radius
31
16. What is minimum explosive requirement of deliberate crater boreholes?
5’ holes will have 40 lbs of explosive
| 7’ holes will have 80 lbs of explosive
32
18. What is formula of deliberate crater?
N = ((L-16) / 5) +1
L = length of crater in feet
Round up any fractional hole to next higher number
33
4. For hasty craters, what is minimum depth of boreholes?
At least 5 feet deep
34
1. What is the requirement of effective craters?
Must be too wide for track vehicles to span and too steep-sided for vehicles to pass
35
12. For deliberate crater, what is the average number of traverse attempts of modern tanks?
Average of 8 attempts
36
10. What is the formula for hasty crater?
N= ((L-16) / 5) + 1
Round up any fractional number of holes to next higher number
L is length in feet
37
19. What are the two types of rows required to construct relieved face craters?
Friendly row and Enemy row
38
11. What is deliberate crater blowout distance?
Approximately 8’
39
What do repeated attempts to traverse do to a crater?
Pull loose soil into the crater, reducing both depth and angle of the crater.
40
What should you do for hasty boreholes?
Stem all boreholes with a suitable material
41
Can you have two 5 foot boreholes next to each other on a deliberate crater?
No
No two 5 foot holes side by side
42
What is the resulting number of 5' and 7' boreholes for an EVEN number of boreholes in a deliberate crater?
Difference of 2, 7 foot holes being the higher number
43
What is the resulting number of 5' and 7' boreholes for an ODD number of boreholes in a deliberate crater?
Difference of 1, 7 foot holes being the higher number
44
What is the blowout for a relieved face crater?
Approximately 5 feet
45
How should you prime the rows for a relieved face crater?
Prime separately
| Allow for a 0.5 to 1.5 second delay between firing each row
46
For a relieved face crater, will the friendly and enemy sides have an equal number of boreholes?
No
N_er = N_fr - 1
47
How much should you tamp a charge to breach hard surface pavement?
2 times the breaching radius
| 2 x thickness of the pavement
48
What is an expedient cratering charge?
Mixture of ammonium nitrate fertilizer and fuel oil (Motor oil, diesel, gas)
49
How long should you soak an expedient cratering charge for?
1 hour
50
What is important when working with an expedient cratering charge?
Protect from moisture
Never leave the charge in the borehole for long periods of time, charge will accumulate moisture, reducing its effectiveness
51
Procedure for expedient cratering charge
Measure and mix fertilizer and fuel for desired charge
Mix thoroughly
Allow to sit for 1 hour
Place half of mixture in borehole or container
Place two primed 1 lb blocks of explosive in borehole or container
Add remaining mixture
Tamp remaining space with dirt
52
What is the snake hole boulder removal method?
Dig a hole under the boulder large enough to hold the charge, then stem the charge
53
What is the mudcapping boulder removal method?
Place the charge on a crack in the boulder and cover with 10 to 12 inches of mud or clay
54
What is the block-hole boulder removal method?
Drill a hole in the top of the boulder deep and wide enough to hold the amount of explosives required
Prime the charge with det cord and tamp firmly
55
Do you ever use RE when calculating for dirt cratering?
No, pounds of explosives is the same, no matter what type.
