ENABLING OBJECTIVE
1. Produce fire control data with the plotter.
MAIN TEACHING POINTS
2. Prepare the plotter for firing:
a. description;
b. maintenance;
c. preparation for the pivot method; and d. preparation for the alternative method.
PREPARATION
3. Time Required. Two 40-minute periods.
4. Method. Theoretical and practical.
5. Administration.
6. Stores:
a. one plotter per candidate;
b. firing tables; and
c. cleaning materials.
7. Training Aids:
a. chalkboard;
b. large-scale plotter;
c. firing tables; and
d. computer with PowerPoint®.
CONDUCT OF THE LESSON
8. Introduction:
a. Review. As required.
b. What. You will learn the preparation of the plotter for firing.
c. Why. So that, as a control post operator (CPO), you can perform your work correctly and produce accurate fire control data.
d. Where. On the course, at your unit and in combat.
9. Stage I—Description:
a. Description. As has already been seen, there is a clear difference between the fire orders given to the CPO by the fire controller (FC) and passed to the CPO and those given to the mortar by the CPO. The orders have to be converted by the CPO with the mortar computer or the plotter. As the mortar computer is a machine, it is liable to mechanical breakdowns. As CPO, you must therefore know all aspects of producing fire control data using the plotter.
b. With the mortar, the plotter is used to calculate fire control data and convert the fire controller’s orders into:
CHARGE BEARING ELEVATION
c. Components. The plotter includes five main parts:
(1) The Bag. It is mounted in a bag with a strap and containing pockets for maps, papers, firing fans and registration table.
(2) The Base. The base represents 1000 metre plotting grids subdivided into 100 metre squares. A line, which goes from the centre point to the top of the base, is called the indicator line. This line is numbered from 1 to 6 to indicate the distance from the position of the pivot point.
(3) The Rotating Disk. The rotating disk turns on the base by means of a pivot. The outside edge of the disk is graduated in mils from 0 - 6400 mils, numbered every 100 mils and marked every 10 mils.
(4) Firing Fans. These are various types of fans depending on the ammunition you use.
Their usefulness is to determine the charge and elevation for the various firing ranges.
(5) Registration Table. Allows the CPO to register target data and have them within reach.
Figure 2-1: The Plotter
10. Confirmation of Stage I:
a. questions from the class; and b. questions to the class.
11. Stage II—Maintenance. The plotter is made of plastic and scratches easily, especially underneath the disk. If dirt is allowed to accumulate on the plotter, it very quickly becomes unusable. The CPO must make sure to follow these instructions:
a. Before Use. The plotter must be clean and free of dirt, especially sand. The disk must be removed and carefully cleaned. Typewriter cleaners are suitable
for removing marks, but liquid silicon may be used.
Dry it with a flannel cloth or paper towel.
b. During Use. Only graphite, omnichrome or fine point pencils erasable with water are recommended for use. To erase, do not use materiel such as rubber to erase ink but only silicon. When the plotter is not being used for a short period of time, make sure it is placed in a safe place so no one sits or walks on it.
c. After Use. Clean it properly and dry it thoroughly before putting it away. Always put it away flat in a cool, dry and protected place. Do not expose it to the sun or place it near the heater of a vehicle.
12. Confirmation of Stage II:
a. questions from the class; and b. questions to the class.
13. Stage III—Preparation of the Plotter:
a. Introduction. There are two methods of preparing the plotter, the pivot method and the alternative method.
b. The Pivot Method. The pivot method consists of making the grid lines of the base correspond to the grid lines on the map, so that the position of the mortars corresponds to the pivot. You must proceed as follows:
(1) Determine the position of the mortars on the map with a six-figure grid reference, for example 150 650.
(2) Make the pivot of the plotter coincide with the map (grid reference) (see Figure 2-2).
(3) Note the easting at the top of the indicator line, for example 150.
(4) Note the northing facing the line 1600-4800 for example, 650.
(5) Once the starting point has been entered on the plotter as indicated above, number the other lines.
(6) Easting: move towards the east from 150 - 160, 170, 180, etc. and vice versa towards the west -140, 130, 120, etc.
(7) Northing: move towards the north from 650 - 660, 670, 680, etc. and vice versa towards the south, - 640, 630, 620, etc.
(8) Later, the CPO can enter on the disk data such as safety limits in future periods, arcs of fire, etc.
(9) The CPO must then install the appropriate firing fan, if applicable. The practice base plate will be:
114 506 998 107 123 124
c. Alternative Method. When the mortars must be moved large distances, the pivot method cannot be used because it takes too much time. Then proceed as follows:
(1) In choosing the grid references to determined the starting point, the firing CPO must allot 3000 metres to the area not covered by the disk, otherwise the line of departure would not be covered. To do this, it suffices to add or subtract 3000 metres to or from the place on the map where the mortar was originally.
(2) Determine the position of the mortar and assign it a six-figure grid reference. Mark it on the plotter as one would do on a map and draw a mortar symbol. The point of the symbol indicates the exact position.
(3) Once the above preparation has been completed, it is no longer necessary to change the numbering of the grid lines during the operation. You have only to erase the former mortar positions and trace the new ones as on a map.
Figure 2-2: Preparation of the Plotter—Pivot Method 14. Confirmation of Stage II:
a. questions from the class; and
b. questions to the class.
15. Final Confirmation:
a. questions from the class; and b. questions to the class.
CONCLUSION
16. You have just learned how to describe and maintain the plotter and also how to prepare for firing using the pivot and alternative methods.
17. The next lesson will be…
LESSON 2