BALLISTICS COMPUTER - ARTILLERY

[sketchh 11]

I created a ballistic computer (external Excel spreadsheet) for artillery.  The difference between what I created and what I have seen elsewhere is that I added a calibration function.  The concept is that you provide the initial inputs and fire the first round, then input the coordinates of where that round impacts, and the sheet automatically updates the yellow cells for the adjusted bearing and elevation.  This calibration is valid as long as you consider the following assumptions:

1. As you drive the vehicle, any change in position AND/OR change in elevation will throw off your calibration by the same amount.

2. The calibration value is most accurate at the bearing you used during the calibration process, and your results deviate more as your turret deviates from that initial bearing (if you target something 90° from the original target, don't get mad when it's not accurate). 

 

All of the testing was completed using the M4 Scorcher, however the M5 MLRS and the MK6 Mortar is included in the file.  The equations don't change, only the muzzle velocity values, so if there is any issue with the results start by verifying the velocity values.  Using the M4 Scorcher, I drove to a distance of 5.6km, entered my cords and the cords of the target, fired the first round, entered the impact cords, and put rounds on target consistently after that.

 

Remember, the performance of the computer is dependent on the accuracy of the data entry.

 

Calibration process:

NOTE: ONLY CHANGE VALUES IN THE GREEN CELLS.

1. Enter your vehicle type in cell B6.

2. Enter your cords in cells B7:B9, using the 4-digit format.

3. Enter the target cords in cells B10:B12.

4. Adjust your firing mode according to the value shown in cell B17.

5. Adjust your bearing according to the value shown in cell B18.

6. Select an elevation value to use for your calibration shot; in theory the "high" value will result in a more accurate calibration (this isn't real life btw), although in practice the difference seems small.  Fire your calibration shot.

7. Determine the impact cords of the calibration shot, either by watching the map (King of the Hill) or by utilizing a forward observer.

8. Enter the impact cords of the calibration shot as follows:

         a. If you fired the calibration shot using the "high" elevation value, enter the impact cords into cells E10:E12.

         b. If you fired the calibration shot using the "low" elevation value, enter the impact cords into cells F10:F12.

9. The calibrated bearing and elevation values automatically populate into the yellow cells B18:B20.  Adjust your turret to the corrected bearing and elevation values and fire at will.

 

Notes:

-Re-calibrate any time the vehicle is moved, or if you change target cords and the bearing changes changes more than a couple degrees.

-If you can't get the system to work and you are following the steps above, verify that you are in the correct firing mode by pointing at something far away and cycling firing mode until you locate the short range mode, then cycle forward from there.

-The computer is set up such that:

       -You can keep the same calibration values in E10:F12 and change to different targets in cells B10:B12 without affecting the calibration.  Remember the assumptions listed above when doing this.

       -You must clear all of the contents in cells E10:F12 before you can accurately RE-calibrate your firing. (Actually clearing the contents from cells E10 and F10 will remove the calibration effect from the yellow cells, if you are in a hurry).

       -The computer will return an error message if there are values present in BOTH cells E10 and F10 at the same time.

 

Click on the link below to go to the (locked) public version of the spreadsheet, click on File, and Download As, then Microsoft Excel.  If you want, re-upload this file to Google Docs and share the link with your friends, then you can all see the same data if you are in the same vehicle or working together as a crew.

 

Link below.

 

https://docs.google....dit?usp=sharing

[Mozkelby 39]

Good work mate!

[skyline 1]

Great Work! I was looking for this.

 

Lately I've been using one that I've created but it's not as complete as yours. But there is a problem with the MK6 Mortar. I'm not sure what it is. Your calculation is spot on, I get the same results in mine and very close results when comparing with the automatic calculation ( the REV value on mortar when you have sight of the target).

 

But the shots are landing too short, yesterday I tried to hit a target 1.600m away. The REV was giving me 61.45, your calculator: 61.30 (same as mine). But to hit the target I had to use 59.60 - 60.00.

 

I don't know if I'm doing something wrong, or did BIS change the velocity / added drag / or wind on a recent patch, maybe?

[x3kj 1247]

If the underground of your vehicle/static weapon is not perfectly flat you are going to miss. The elevation only shows barrel elevation relative to the vehicle origin, not to the ground. Also g = 9.81, not 0.9805something

[sketchh 11]

x3kj, the value of g is negligible, I went ahead and changed it in the online document.  There are conflicting reports of what the value is, I'm not sure how to verify it.

 

skyline, did you try putting in the impact coordinates and seeing if the adjustment that the sheet calculates will get you on target?  He is right that the vehicle (or mortar) has to be perfectly flat to match the spreadsheet, which is why I needed to develop the calibration functionality.

 

In addition to having to be on flat ground, it is possible that the horizontal axis of the vehicle does not match the horizontal axis of the "world".  That is the case with the M4 Scorcher; there is approximately 2° offset from horizontal on flat ground.  Basically, if your inputs are very accurate, including the impact point of where the first round lands, you should be on target by the second round.

 

BTW I just verified that the muzzle velocities for the mortar are correct.

 

Glad to see people are using this   :dancehead:  

[Freghar 73]

x3kj, the value of g is negligible, I went ahead and changed it in the online document.  There are conflicting reports of what the value is, I'm not sure how to verify it.

The short answer is - it depends on where you measure it.

 

At different points on Earth, objects fall with an acceleration between 9.78 and 9.83 m/s2 depending on altitude and latitude, with a conventional standard value of exactly 9.80665 m/s2 (approximately 32.174 ft/s2).

https://en.wikipedia.org/wiki/Gravitational_acceleration

[skyline 1]

x3kj, the value of g is negligible, I went ahead and changed it in the online document.  There are conflicting reports of what the value is, I'm not sure how to verify it.

 

skyline, did you try putting in the impact coordinates and seeing if the adjustment that the sheet calculates will get you on target?  He is right that the vehicle (or mortar) has to be perfectly flat to match the spreadsheet, which is why I needed to develop the calibration functionality.

 

In addition to having to be on flat ground, it is possible that the horizontal axis of the vehicle does not match the horizontal axis of the "world".  That is the case with the M4 Scorcher; there is approximately 2° offset from horizontal on flat ground.  Basically, if your inputs are very accurate, including the impact point of where the first round lands, you should be on target by the second round.

 

BTW I just verified that the muzzle velocities for the mortar are correct.

Glad to see people are using this   :dancehead:

 

In my first test I was using the mortar on the airfield, that should be a flat surface, but it was missing. Then I tried placing the mortar at Camp Rogain, shot a target at 1600m (without direct sight) and missed by only 10m! So, the calculations are indeed correct. I did some research and it seems there is 0 drag on mortar shells in A3.

 

My conclusion is: It will be very hard to hit the target with the first shot, because we can't know for sure if we are in a flat horizontal surface. But, if we use the impact coordinates, the second shot should easily hit.

Thanks again for this spreedsheet! Too bad I don't remember how to program in Visual Basic using Excel, or I would do a little .exe to calculate this.

 

[NoBodie 0]

Trying to get that newbie forums checked off so I can start a new thread.  Read almost all Arty related post i could find.

 

I'm trying to get an artillery battery to fire on a support request. I have 6 units (same type) grouped sync to a arty support provider which in turn is linked to a support requested and in turn sync to the player. Every time I call for fire only 1 gun fires. How do I get all six to fire?

Pics below of setup.

http://s1356.photobucket.com/user/NoBodie1/slideshow/ARMA%203