INTRODUCTORY NOTES1. Accurate shooting from the map is only possible when a map of scale 1/25,000 or larger is available. Where accuracy is not essential, for example for the engagement of areas well removed from the position of our own troops, maps of smaller scale can be used, but it should be noted that the detail on such maps is not usually surveyed in.
2. The principle of map shooting is that all calculations both for direction and for elevation are made from the map. The method has certain advantages, namely:-
- No observation is necessary.
- Targets can be engaged that cannot be seen from the ground.
- Preparations can be made to open fire before the actual targets have been located.
- Any number of targets can be engaged by switches.
- It is just as flexible by night as by day.
It also has certain disadvantages, namely:-
- 1/25,000 maps are not always available.
- Maps are liable to distortion.
- Accurate location of points on map is often difficult.
- Corrections by observation of fire are not possible, there being no OP.
3. The method entails:-
- (a) Location of the pivot gun on the ground, and marking its position on the map.
- (b) Laying out the zero line for the pivot gun, or for all guns if a night shoot is required.
- (c) Location of target or targets on the map and calculating the data to hit them.
The processes (a) and (b) must be carried out in daylight, though the guns themselves need not be brought into action until after dark. Therefore, orders for a map shoot to be carried out at night must reach the group in sufficient time before dark.
LESSON 116.- MAP SHOOTING, DIRECTION
A INSTRUCTOR’S NOTES
Aim
1. To teach how to lay out the gun position and to obtain from the map the direction to hit the target.
Class and instructors
2. Lecture – One officer instructor and not more than 30 in the class. Practice – Squads under squad instructors.
Periods
3. One 45-minute period, lecture. One 45-minute period, practice.
Stores
4. Blackboard and chalk, for lecture. The class require range tables, maps, sharp pencils and tracing paper. Practice – Director, compass, zero posts, direction pegs, gun flags and a short wooden post.
Preparation
5. Prepare a map shoot to be used as an example when teaching this and the ensuing lesson. The class should work out the example on their maps after each stage of the lesson.
B – CONDUCT OF LESSONApproach
6. Give the aim of the lesson (see para 1 above).
7. Explain the introductory notes to the chapter.
Location of the pivot gun on the map
8. State that the position of the pivot gun can be fixed on the map by:-
- (a) Resection, using one of the following methods:-
- (i) Resector protractor.
- (ii) Tracing paper.
- (iii) Compass.
- (b) By comparing the detail on the ground with the detail on the map.
- (c) By artillery survey, if available.
9. Revise, by questions, resection by the resector protractor (see Lesson 44).
10. Make sure that the class understand how to resect by compass (see Manual of Map Reading, Photo Reading and Field Sketching 1929).
11. Explain and demonstrate resection by tracing paper. This is done by drawing on a sheet of tracing paper three lines meeting at one point and making angles measured by the director as in the resector protractor. The three lines on the tracing paper are then used as if they were the three arms of the resector protractor.
12. State that, when time permits, a greater accuracy is attained by employing one method and checking with another.
Placing guns on zero lines
13. Tell the class that a zero line is selected on the map in the centre of the target area. The pivot gun can be placed on this zero line by either:-
- (a) Use of a reference point which can be seen on the ground and located on the map, or
- (b) If no suitable reference point can be found, by compass.
14. Explain how to place the pivot gun on its zero line by the use of a reference point:-
-
- On the map, draw the lines joining the pivot gun to the point selected for its zero line. One the map, draw the line joining the pivot gun to the reference point. Measure the angle between the two lines with a protractor.
Mount a director over No. 1 gun flag with its drums and dials at zero. Lay it on the reference point still at zero, and then swind it through the angle measured. Place a zero post and a direction ped using the hairline as in Lesson 108.
15. Explain how to place the pivot gun on its zero line by compass:-
-
- On the map draw the line joining the pivot gun to the point selected for the zero line. Measure the grid bearing of the zero line with a protractor. Convert this to a magnetic bearing by adding the magnetic variation if the variation is West – by subtracting if the variation is East. Add or subtract the compass error (if any).
Place a wooden peg in the position of No. 1 gun and rest the compass on this peg, rotating it until it is laid on the required bearing. Align a zero post and a direction peg, using the hairline on the compass in the same way as the hairline of the director.
16. State that when the guns arrive, they are paralleled on their zero lines in the normal manner. If the guns are not coming into action until after dark, posts and pegs must be put out for all guns as in Lesson 108.
Obtaining direction
17. Explain the method of obtaining direction, which is as follows:-
- Draw a line between the pivot gun and the centre of the target and measure the angle between this line and the zero line, with a protractor. Work out the switch required to lay the line of fire of No. 1 gun 22½ yards to the right of the centre of the target, in the normal manner.
18. Confirm the methods of locating the pivot gun, of placing the guns on their zero lines and of obtaining direction, by questioning the class.
Practical pegging
19. Demonstrate pegging using a reference point.
20. Practice the squad.
21. Demonstrate pegging using a compass.
22. Practice the squad.
23. Practice the squad in resecting a position and pegging it for a night shoot.
Conclusion
24. Questions to and from the squad.
25. Sum up main points.
LESSON 117.- MAP SHOOTING – ELEVATION, CREST CLEARANCE AND SAFETY
A – INSTRUCTOR’S NOTES
Aim
1. To teach how to calculate from the map the elevation required to hit the target.
2. To teach how to determine from the map whether guns will clear the crest.
3. To teach how to ensure from the map that fire can be delivered over the heads of our own troops with safety.
Class and instructors
4. One officer instructor and not more than 30 in the class. Squad instructors, if available, can be of use in helping backward members of the class to work out map problems.
Periods
5. One 90-minute period, lecture and practice.
Stores
6. Blackboard and chalk. The class required range tables, maps marked up with the example used in Lesson 116, resector protractors and sharp pencils.
Preparation
7. Draw the diagram given below on the blackboard. Prepare two map shoots.
B – CONDUCT OF LESSONApproach
8. Give the aims of the lesson (see para 1, 2, 3 above). Revise Lesson 116, by questions.
Obtain elevation
9. Explain that:-
- (a) The range gun-target is obtained from the map using the scale on the resector protractor, or dividers in conjuction with the scale at the bottom of the map.
- (b) The angle of sight is obtained by determining the difference in height between the guns and target and converting this vertical height by an angle. (See Fig 53 below).
The procedure is as follows:-
- (i) Examine the contours and note the height of the guns and the target above sea level and thus determine the difference in height between the two, eg,-
Target 450 ft. Guns 400 ft. Difference +50 ft. - (ii) Convert this figure to the nearest number of yards and from the VI graph discover the angle it subtends at the range gun-target, eg,-
- Range 2700 yards.
- 17 yards at 2700 yards subtends 20 minutes.
- Angle of sight is plus 20 minutes.
- (c) Errors in elevation are covered by the combined sight rule in the normal manner.
10. Get the class to work out an elevation problem.
Crest clearance
11. Explain that it may be necessary to ascertain whether the bullets will clear a crest which is not visible from the gun position. The line on the map between the gun line and the target should always be examined to see if it passes through a contour higher than the guns. If such a crest is found, the procedure is:-
- (a) By comparison of the contours, determine the difference in height between the crest and the guns, and measure the range guns-crest.
- (b) From the VI graph discover what the height of the crest above the guns subtends as an angle. This is the angle of sight to the crest.
- (c) From the range tables, find the crest clearance angle for the range guns-crest.
- (d) Add these two angles together and the MQA is obtained. By comparing the MQA with the lowest quadrant angle required to engage the target, it can be ascertained if the guns will clear the crest.Example:-
Range guns-crest 1200 yards Gun contour 400 ft. Crest contour 500 ft. Difference 100 ft. 33 yards at 1200 subtends 1 degree 35 minutes Crest clearance angle at 1200 yards 1 degree 36 minutes MQA is 3 degrees 11 minutes From the previous example, the elevation to hit the target was 2700 plus 20 minutes. Lowest elevation required would be 2600 plus 20 minutes. Tangent angle for 2600 yards is 5 degrees 24 minutes Angle of sight is 20 minutes Lowest quadrant angle is 5 degrees 44 minutes By comparing this with the MQA it can be seen that guns will clear the crest by 2 degrees 33 minutes.
12. Get the class to work out a crest clearance problem.
Safety
13. Explain that it may be necessary to ascertain whether the guns can be fired with safety over the heads of our own troops in the line of fire. The procedure is identical to the procedure for ascertaining if guns will clear a crest, except that the safety angle for the range guns-own troops is employed in place of the crest clearance angle for the range guns-crest.
Example:-
| Range guns-own troops | 850 yards. |
| Gun contour | 400 ft. |
| Own troops contour | 640 ft. |
| Difference | 240 ft. |
| 80 yards at 850 yards subtends | 5 degrees 20 minutes |
| Safety angle at 850 yards is | 1 degree 57 minutes |
| Guns must not fire lower than | 7 degrees 17 minutes |
14. Get the class to work out a safety problem.
15. The class should now be practised in the whole procedure of making calculations and preparing positions for map shoots. It is advisable for the instructor to check that the class have obtained the correct data before allowing them to prepare the fire order.
Conclusion
16. Questions to and from the squad.
17. Sum up main points.
LESSON 118.- FIRE CONTROL CHARTS
A – INSTRUCTOR’S NOTES
Aim
1. To teach the guse and method of compiling fire control charts.
Class and instructors
2. One officer instructor and not more than 30 in the class.
Periods
3. One 45-minute period, lecture.
Stores
4. Blackboard and chalk and a supply of fire control charts, Army Form B 2668 (see Plate 24).
Preparation
5. Draw a specimen fire control chart on the blackboard.
B – CONDUCT OF LESSONApproach
6. Give the aim of the lesson (see para 1 above).
7. State that for the conduct of programme shoots, when fire is required at stated periods on one or more targets, it will generally be preferable to issue charts for the control of fire. Such charts are usually desirable for shooting off the map and firing by night.
Compiling fire control charts
8. Fire control charts are made up by group commanders. They are prepared from data obtained during reconnaissance. Normally during programme shoots by day or night section commanders command their own sections under the supervision of the group commander. Fire control charts are therefore required for the group commander showing the data for all four guns, and for each section commander showing the data for their respective guns.
9. Explain each heading of the fire control chart. The charts contain the actual detail of switches, timings and rates of fire and the elevations and number of taps to be employed for each target.
State that time must be allowed in the chart for the lifts and switches to be put on the guns. At night a pause of 30 seconds should be allowed for each list and 60 seconds for each switch. When tapping right and left is required, the time taken to complete the series of bursts and taps should also be allowed for.
In prolonged shoots, pauses should be allowed for the maintenance of the guns. These pauses should be arranged so that never more than one gun is stopped for that purpose.
An example of a completed fire control chart is shown in Plate 24. Columns 7 and 9 should not be completed initially, as the angle of switch and the elevation should not be corrected for climatic conditions until the guns are about to fire on a task.
Conclusion
10. Questions to and from the class.
11. Opportunity should be taken of practising fire controllers in compiling fire control charts, when working out map shooting or night firing problems.
12. Sum up main points.
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