hank327
Member
Mr. Humphrey has it right. I was an 11C for four years in a line company using 81 mm mortars. We usually laid the section in using an aiming circle, which is basically a surveyors instrument. An M2 compass could be used to lay the guns, but that was not the preferred method. Once the guns were laid in, the sights were set to 2800 mils in deflection and 1100 mils in elevation and the two aiming posts were set out.
The aiming posts were used as a reference point for the sight. The posts were set out in such away as to appear as only one post when the sight was
referred deflection and elevation settings of 2800 and 1100. Before setting out the aiming posts, the gun is both level in deflection and elevation according to the spirit levels on the sight. When a fire mission is called, the FDC takes the information provided by the forward observers and translates it to fire command to the guns. The fire command goes like this.
FDC: "SECTION!"
The Section (aka the guns) repeats all the commands back to the FDC. Everbody yells: "SECTION!"
FDC: DEFLECTION...3210!
Section repeats : DEFLECTION...3210
FDC: ELEVATION... 1255
Section repeats: ELEVATION...1255
1 round HE QUICK, CHARGE 7
The gunners then dial the deflection and elevation settings onto the sight. Only the sight moves, not the gun.
Once the sight has the proper settings on it, the gunners then must physically move the mortar back to the aiming posts. If it is only a small shift, then you can make the adjustment with the traversing and elevation mechanism on the bipod. If it is a large shift, then the whole gun must be picked up and shifted. The assistant gunner will get down on his knees in front of the gun and with a hand on each bipod leg, lift the bipod up just enough to clear the ground. The gunner while looking through the sight with his left hand on the traversing handle and his right hand holding the gun tube at the muzzle then moves the mortar until the sight is back onto the aim posts. The gun is then releveled for deflection and elevation and then minor adjustments are made with the T&E mechanism with more releveling until the vertical crosshair of the sight is back in its proper position in relation to the aiming posts.
One note of interest. When a mortar makes a large deflection shift and the sight is brought back to the aiming posts, the aim posts will no longer be perfectly aligned on behind the other. You will now have two aiming post in your sights field of vision. what you do then is lay the gun in such away that the vertical cross hair is equal distant from the farthest aiming post as the farthest aim post is from the closest aim posts. That sight picture looks something like this: l l l
In mortar gunnery the horizontal crosshair is not used, only the vertical. When the gun is properly laid onto the aiming posts, the vertical cross hair is aligned along the lefthand edge of the aimposts.
Once the guns are laid on the firing coordinates, then the #2 gun (mortar sections have three mortars and the #2 gun is the center gun) fires the adjusting round. All the guns in the section follow the FDC commands, but only the #2 gun fires until the fire is adjusted onto the target. Once that occurs, the FO (forward observer) will tell the FDC to "Fire For Effect".
The FDC will then relay the command of "Fire For Effect" to the guns along with the number of rounds to be fired. After each round is fired, the guns are relaid upon the aiming posts. In my section, the gunner kept his eye on the sight as the rounds were fired and made the adjustments quickly. Once the baseplate is settled in, it only takes a minor twist of the T&E mechanisms to relevel the gun.
It takes a lot of teamwork and practice to be a good mortar section. But you can bring alot of steel on target in an amazingly short period of time if you have a well practiced crew.
A disclaimer: The last time I fired a fire mission was in the spring of 1982. There was no such things as GPS or electronic computers. What we called computers were men with M16 plotting boards and firing tables physically computing the FO's call for fire into commands for the guns. I heard of a couple of section sergeants buying the then brand new Texas Insturments programmable calculators with their own money to use in the FDC but I never saw one.
The aiming posts were used as a reference point for the sight. The posts were set out in such away as to appear as only one post when the sight was
referred deflection and elevation settings of 2800 and 1100. Before setting out the aiming posts, the gun is both level in deflection and elevation according to the spirit levels on the sight. When a fire mission is called, the FDC takes the information provided by the forward observers and translates it to fire command to the guns. The fire command goes like this.
FDC: "SECTION!"
The Section (aka the guns) repeats all the commands back to the FDC. Everbody yells: "SECTION!"
FDC: DEFLECTION...3210!
Section repeats : DEFLECTION...3210
FDC: ELEVATION... 1255
Section repeats: ELEVATION...1255
1 round HE QUICK, CHARGE 7
The gunners then dial the deflection and elevation settings onto the sight. Only the sight moves, not the gun.
Once the sight has the proper settings on it, the gunners then must physically move the mortar back to the aiming posts. If it is only a small shift, then you can make the adjustment with the traversing and elevation mechanism on the bipod. If it is a large shift, then the whole gun must be picked up and shifted. The assistant gunner will get down on his knees in front of the gun and with a hand on each bipod leg, lift the bipod up just enough to clear the ground. The gunner while looking through the sight with his left hand on the traversing handle and his right hand holding the gun tube at the muzzle then moves the mortar until the sight is back onto the aim posts. The gun is then releveled for deflection and elevation and then minor adjustments are made with the T&E mechanism with more releveling until the vertical crosshair of the sight is back in its proper position in relation to the aiming posts.
One note of interest. When a mortar makes a large deflection shift and the sight is brought back to the aiming posts, the aim posts will no longer be perfectly aligned on behind the other. You will now have two aiming post in your sights field of vision. what you do then is lay the gun in such away that the vertical cross hair is equal distant from the farthest aiming post as the farthest aim post is from the closest aim posts. That sight picture looks something like this: l l l
In mortar gunnery the horizontal crosshair is not used, only the vertical. When the gun is properly laid onto the aiming posts, the vertical cross hair is aligned along the lefthand edge of the aimposts.
Once the guns are laid on the firing coordinates, then the #2 gun (mortar sections have three mortars and the #2 gun is the center gun) fires the adjusting round. All the guns in the section follow the FDC commands, but only the #2 gun fires until the fire is adjusted onto the target. Once that occurs, the FO (forward observer) will tell the FDC to "Fire For Effect".
The FDC will then relay the command of "Fire For Effect" to the guns along with the number of rounds to be fired. After each round is fired, the guns are relaid upon the aiming posts. In my section, the gunner kept his eye on the sight as the rounds were fired and made the adjustments quickly. Once the baseplate is settled in, it only takes a minor twist of the T&E mechanisms to relevel the gun.
It takes a lot of teamwork and practice to be a good mortar section. But you can bring alot of steel on target in an amazingly short period of time if you have a well practiced crew.
A disclaimer: The last time I fired a fire mission was in the spring of 1982. There was no such things as GPS or electronic computers. What we called computers were men with M16 plotting boards and firing tables physically computing the FO's call for fire into commands for the guns. I heard of a couple of section sergeants buying the then brand new Texas Insturments programmable calculators with their own money to use in the FDC but I never saw one.
