Help aiming a mortar

[Blaster]

HELP!!  Within the last month or so, someone posted some directions on one of the methods to aim a mortar.  I believe there were a series of stakes pounded in the ground nearby to accomplish this sighting/aiming.  I kind a messed up by not just printing those instructions at the time I read them.  I have been using the search process but get nothing.  Can someone please remind me what thread contained that information?  Any help will sure be appreciated.  Thanks from Blaster (Yeah, at age 72, it looks like my memory is just THE very first thing to go) 

[dominick]

Blaster,

I brought the post to the front page for you and others to see.  It is titled "Testing the soda can mortar"

[Blaster]

Blaster,

I brought the post to the front page for you and others to see.  It is titled "Testing the soda can mortar"

Thanks for that Dom. 
Blaster (Bob in So. CO -  just one of your many customers who is very satisfied with your great products, communications and service).

[Double D]

I am posting this here as it will be easier to find in a search. 

Artlleryman has helped me find the aimng directions in Gibbon's. 

244 PRACTICE OF FIRE.
by inserting the arm in the bore, or placing it against the face of the piece, and afterwards the
direction is given.
Mortars are fired either over the parapet or through embrasures. In the former case, to
establish the vertical plane of fire passing through the object, a short stake is driven in the
interior crest, as near as possible opposite the middle of the platform. Sighting by this stake
a long one is planted about one yard in front, and in line with the target, and a cord being
attached to the top of it, is stretched to the rear of the piece over the head of the first stake,
and a third planted directly under the cord one yard in rear of the platform. The large stake is
then removed, the cord is attached to the small one; and, when stretched over the rear one,
gives the proper direction of the mark. It is not so liable to be disarranged by the enemy's
shot as if attached to
the large stake. When so stretched, a plumb -line attached to it will determine the vertical
plane of fire passing through the object, and the centre of the platform. The axis of the piece
being placed in this plane, by means of the line of metal, will evidently have the proper
direction; but should the shells fall habitually out of line, the direction of the piece is
corrected by means of the pointing-board, a strip of wood with a notch on one edge to fit on
the rear stake, and graduated both ways from the middle, by means of which the mortar may
be directed farther to the right or the left. Should the shell fall too far to the right, the cord is
put to the right of the rear stake, and by varying the position, several times in succession, the
proper direction will be finally reached.
If the mortar is to be fired through an embrasure, drive a stake in the middle of the
embrasure, near the interior crest, and attach a cord to it, and a second in rear of the
platform, as near as possible in line with the first, and the object; the last one being high, to
clear the mortar with the cord, and allow the sighting. By means of the cord, and a
pointing-board nailed to the rear st ake, correct the shots as before. The cord is kept in its
place by a little picket, which is attached to the end, and driven in rear of the rear stake.
Another method for" directing a mortar, is for the gunner, with a plumb -line, to mount any
object in rear of the platform, and cause a stake to be driven near the interior crest, and
another in rear of the platform, in line with the first, and the
POINTING MORTARS. 245
object. Then, with the cord and pointing -board, rectify the firing as before .
The angle of elevation of a mark, is the angle which the line drawn frown the object to the
breech of the piece makes with the horizontal.
When the object fired at and the mortar are not on the same level, the angle of greatest
range, instead of being 45ºis 45º+or -½ the angle of elevation or depression of the object.
Thus to reach an object elevated 15º above a mortar, the angle of greatest range would be
45º+ 7 ½ =52 ½ ºwhile, if the object was depressed 15º ,the angle would be 45º -7½= 37½ º.
The advantages of the angle of greatest range are: - 1. Economy of powder. 2. Diminution of
recoil, and less strain on the piece and its platform. 3. More uniformity in the ranges. 4.
Differences of a few degrees above or below cause only a slight difference in the ranges.
Should the distance to the object be very short, and the velocity of the shells not great
enough on the descending branch, they must be fired under an angle of 60 º; when, of course,
greater charges must be used for the same distance, the ranges obtained with 60 degrees
elevation being about one -tenth less than those with 45 º. A shell fired at 60 º elevation, as it
goes higher and obtains a greater velocity in falling, will strike more directly and with
greater violence upon the vaults of the magazines and shelters of the enemy, and will have a
greater force of penetration.

Starting on page 289 you can get some additional information on the impliments used in aiming.


If you don't have a copy of Gibbons Artillerist's Manual you can get it here.  Gibbons Artillerist's Manual   It is a PDF file so it may take a minute or so to open.  After it opens you can save to you computer.

Thanks Norm!

[Blaster]

Thanks DD.  In my old age, I have no problem reading but comprehending is my hangup.  I'll have to read that piece numerous times to really understand it's contents.   
Blaster (Bob in So. CO)

[Double D]

Bob,

Since nobody has stepped forward and volunteered to present the mortar aiming seminar at the shoot this summer, i am going to lear how to do that myself.

I could not understand the three stakes, one short un the middle until Norm explained the mortar was shot behind a parapet.  One stake goes in front of the parapet the short stake goes on top of the parapet and the third goes behind the the mortar. 

Stakes one and two are aligned so looking down the string between them points at the target.  The third stake and string is then used to extend this line of sight.  The mortar is aligned unde the string.

Come to Montana and we all learn it together.

[Artilleryman]

If you aren't shooting from behind a wall just use two stakes, one several feet in front of the mortar and one a couple of feet behind the mortar. 

[Cat Whisperer]

Who needs stakes when you have a forward observer?

[GGaskill]

The real question is "does the FO have a radio?"   

[Blaster]

The real question is "does the FO have a radio?"   

AND a hard hat

[Cat Whisperer]

The real question is "does the FO have a radio?"   

AND a hard hat

It might be called adjusting fire under "danger close" conditions.

[seacoastartillery]

     Tim, Montana is just crawling with varmints, so I know we will convince you of the opportunities afforded you by attending the Montana Model Cannon Shoot.  Now, not knowing or understanding the stick and string method of mortar aiming and considering that DD will NOT be mowing the grass all the way out to the 100 yard stake, Mike and I will be needing an FO very close to the target to allow us to correct for short, long, left and right deviations.  Because of the tall grass around that two foot long, regulation NSCSCA target stake we will be using, we figure the FO should be within, say, about 15 paces of the stake.

     So, the second real question is, "are you volunteering?"

He, he, he, a hard hat won't help you with the Paihans' projectile.   

Tracy and Mike 

[Cat Whisperer]

    ...
     So, the second real question is, "are you volunteering?"
...

That is a job that we ALL share - per the Duty Roster - each will have his/her turn.

[Double D]

You guys worry me.  The range sloops down and away from the firing line and if you can't see where an 11 inch 130 lb projectile impacted the dry Montana prairie....hint look at the base of the mushroom cloud!   

[Cat Whisperer]

It's not a matter of seeing roughly where it hit.

I've shot with M & T before.  They shoot with precision.

So you've just GOT to have an FO to be able to adjust fire when they're 1" to the left or right!

 

[Blaster]

CW says,
"That is a job that we ALL share - per the Duty Roster - each will have his/her turn".


Ouch! CW, suddenly the Montana Cannon Shoot doesn't seem "quite" as attractive to me anymore with that F.O. duty......

[Cat Whisperer]

CW says,
"That is a job that we ALL share - per the Duty Roster - each will have his/her turn".


Ouch! CW, suddenly the Montana Cannon Shoot doesn't seem "quite" as attractive to me anymore with that F.O. duty......

On the contrary - it should inspire you!  To be able to see the rounds hit up close and personal ! 

I can still remember (FA OCS) seeing 105mm rounds hit about 60-80 yards in front of us - one a dud - kicking up dirt and cutting a narrow, short but deep trench in the ground.