Author Topic: Gun Convergence calculator  (Read 3010 times)

Offline mustng2

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Gun Convergence calculator
« on: August 02, 2014, 02:11:23 PM »
https://app.box.com/s/bc3tfxhvchy3e7khej4m
The link above will take you to an Excel or Open Office spread sheet to illustrate gun convergence and vertical convergence based on a linear velocity drop per foot of travel which is better than assuming no velocity drop, but I don't know how it compares to the velocity drop calculation used in the game.  Suggestions are appreciated.
« Last Edit: August 02, 2014, 02:13:06 PM by mustng2 »

Offline bustr

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Re: Gun Convergence calculator
« Reply #1 on: August 02, 2014, 06:56:59 PM »
What are you attempting to accomplish?
bustr - POTW 1st Wing


This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline FLS

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Re: Gun Convergence calculator
« Reply #2 on: August 02, 2014, 10:40:24 PM »
You can use the .target command to investigate AH ballistics.

Offline mustng2

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Re: Gun Convergence calculator
« Reply #3 on: August 03, 2014, 07:47:28 AM »
Bustr,
Just giving a visual representation of how the vertical and horizontal streams look before and after the convergence point.  It seems to agree with target shooting results.  May not be of use to anyone else but thought I would share.  Let me know if you see something that could be improved.

Offline Scca

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Re: Gun Convergence calculator
« Reply #4 on: August 04, 2014, 11:38:22 AM »
What are you attempting to accomplish?
Someone does something they feel is useful and this is what they get...

Tx mustng2 for the contribution to the community. 
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Working on my bbs cred one post at a time

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Offline bustr

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Re: Gun Convergence calculator
« Reply #5 on: August 04, 2014, 05:29:32 PM »
Scca,

It's missing components used in the game's gunnery physics calc. You can find many of the formulas and tables from a WW2 AAF gunnery harmonizing manual. Do a search for the following and you will find it in a PDF download somewhere on the internet.

AAF Manual 200-1

Fighter Gun Harmonization
----------------------------------------

IN game as FLS pointed out you can do many things to see your convergence and drop.

Use full zoom for all of this. You may even need to change the offline arena time to 05:00 so you can see your gunsight over the white target.

.time 05:00

1. - fly auto level to about 300IA and pull up the target. Just remember shooting for an extended time slows your plane and raises the nose. Remember offline to set ammo to 10x.

2. - sitting on the runway pull up the target. You will need to use all of the target command.

.target range heading azimuth

With many fighters azimuth will be between 7 and 15 to place the target center lined up with your gunsight center. Heading will end up being slightly off from the runway heading. But you can use fractions of the heading for example.

.target 400 269.7 11.9

That way if you are a stickler about the center of the target lining up center of your gunsight, you can nudge it there.

3. - use the TA terrain offline and park your fighter with it's main gear just down the slope on either end of the main runway. By slowly easing your main gear down slope and watching the artificial horizon. You can reasonably level the fighter like jacking the rear end up at a gunnery hardstand shooting range. This is one of the ways I create long range calibrated gunsights for the 37mm in the YakT, 50mm in the 410, and 75mm in the B-25H. Or any old cliff off the end of a runway will do.

4. - speed, altitude, and G forces will change the IP point and dispersion of your bullet streams. Especially shooting past 1200ft.

So what was the OP trying to accomplish with a formula sheet missing major components of Hitech physics?
bustr - POTW 1st Wing


This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline Skuzzy

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Re: Gun Convergence calculator
« Reply #6 on: August 05, 2014, 09:55:26 AM »
Bustr, if I may.  The approach you are taking is one that will put off most people from even trying to help others.

Anyone showing an interest in helping improve the Aces High experience is welcome to do so.  If the implementation of said help falls short, in any way, then it everyone should pitch in and help show how something could be made more helpful.

I would counter your question with, "What could be done to help improve the program being offered by this player?".
Roy "Skuzzy" Neese
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Offline bustr

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Re: Gun Convergence calculator
« Reply #7 on: August 05, 2014, 06:33:54 PM »
Sorry Skuzzy, now you want us to be gentle with the new guys. Ok.....

That ballistic calculator is missing altitude, air density, temperature, total G, horizontal acceleration G, true airspeed, bullet (drift\jump\yaw). It is missing the relationship between the fuselage level lug line, relative bore line and gunsight line of sight when parked on the spawn point. And flight path when testing in auto level.

Some of this can be minimized by shooting sitting at the spawn with your engine off. You will have to use all three parameters of the .target command to line up the offline target with the center of your gunsight. Or you can observe all of this by flying auto level at sea level, 7k, 15k, and 20k at about 300-350IA to see gunnery at many of the altitudes you will fight in the game.

The offline target is a better tool to observe your convergence choices at range because you will see most of the physical factors programmed into gunnery in effect for Aces High. Along with their differences between different rides.
bustr - POTW 1st Wing


This is like the old joke that voters are harsher to their beer brewer if he has an outage, than their politicians after raising their taxes. Death and taxes are certain but, fun and sex is only now.

Offline mustng2

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Re: Gun Convergence calculator
« Reply #8 on: August 05, 2014, 09:10:17 PM »
Sorry Skuzzy, now you want us to be gentle with the new guys. Ok.....

That ballistic calculator is missing altitude, air density, temperature, total G, horizontal acceleration G, true airspeed, bullet (drift\jump\yaw). It is missing the relationship between the fuselage level lug line, relative bore line and gunsight line of sight when parked on the spawn point. And flight path when testing in auto level.

Some of this can be minimized by shooting sitting at the spawn with your engine off. You will have to use all three parameters of the .target command to line up the offline target with the center of your gunsight. Or you can observe all of this by flying auto level at sea level, 7k, 15k, and 20k at about 300-350IA to see gunnery at many of the altitudes you will fight in the game.

The offline target is a better tool to observe your convergence choices at range because you will see most of the physical factors programmed into gunnery in effect for Aces High. Along with their differences between different rides.
Bustr,
It was of course never intended to replace the target.  The target work can be very time consuming and this gives a player a quick illustration of grouping before and after the convergence point particularly if they are using different convergence for gun pairs .  As stated in the instructions it is for level flight only and assumes level line of sight (LOS).  It does have an input for vertical difference between pilot LOS and guns (cell F7).  Obviously it is based on simple gravity drop and a linear velocity drop per foot based on 3 input parameters, muzzle velocity, range for know velocity and velocity at that range.  I was hoping someone would point out errors or improvements something like:
Is 4 feet a reasonable vertical distance between LOS and guns?
What is the center line spacing on the guns for wing mounts for various aircraft?
Based on target tests, does the horizontal convergence agree with target work?  I used just straight lines like shown in the hanger.  Is there a better way?
Does the vertical trajectory agree with target tests within a foot or so?  I checked it against a Barrett 50 cal post.  It was off about a foot at the 1000 yard point.  That is where I got the 2751 fps muzzle vel and the 1483 fps at a 1000 yards.  Does anyone have a similar plot from in game tests?  You can set the vertical difference to 0 to get a horizontal trajectory drop which is a more familiar format to most.  I was surprised it was that close.
I had a time scale on it, but took it off to keep it simple.  Should I put it in?

Offline Skuzzy

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Re: Gun Convergence calculator
« Reply #9 on: August 06, 2014, 09:09:01 AM »
Sorry Skuzzy, now you want us to be gentle with the new guys. Ok.....

Not really.  This forum is the "Help and Support" forum.  Not the "Gig em with a hook and drag em around over a bed of nails" forum. :)
Roy "Skuzzy" Neese
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