Community Ballistics

[bakerman 247]

.....

Edited April 9, 2014 by Bakerman

[kremator 1064]

What a great idea, and I hope those very experienced will help to share their knowledge too.

[das attorney 857]

As Kremator says, really good initiative. Thanks for sharing - will contribute if I find anything useful to add.

[da12thMonkey 1943]

w/r/t acceleration used in the calculation of airfriction, what's the best way to derive that? If memory serves me correct, v/t plot for most projectiles isn't linear, so the instantaneous acceleration (deceleration) gradient changes. Do you just average it out as total change in velocity over total time?

[bakerman 247]

w/r/t acceleration used in the calculation of airfriction, what's the best way to derive that? If memory serves me correct, v/t plot for most projectiles isn't linear, so the instantaneous acceleration (deceleration) gradient changes. Do you just average it out as total change in velocity over total time?

The acceleration used in the ballistics calculator gets the v0 and v1 of every tick. So every tenth millisecond I take the (new) v0 and v1 and calculate the drag for that time frame. This solves the issue of the drag not being linear.

[chops 111]

An excellent initiative Bakerman.

There was a similar mod (Joint Ammo & Magazines) back in the OFP days that became the default config system for addon weapons. It becomes so frustrating when you're trying to play an mission with addons that have wildly different ammo values. Is the plan to release an addon for which weapon addons can use the values, or is it more a matter of using the agreed values in each config?

Cheers

[Fr3eMan 16]

Nice idea!! :rolleyes:

[Guest]

Release frontpaged on the Armaholic homepage.

Community Ballistics

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We have also "connected" these pages to your account on Armaholic.

This means in the future you will be able to maintain these pages yourself if you wish to do so. Once this new feature is ready we will contact you about it and explain how things work and what options you have.

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[roberthammer 582]

Nice , but one question

Does the weapon Initspeed really overrides the muzzle velocity from magazine class?

If yes then we dont need this > http://feedback.arma3.com/view.php?id=12125 (vote it anyway)

Edited April 7, 2014 by RobertHammer

[Spartan0536 188]

UPDATE, I have now offically stopped using D2D's ballistic calculator and am now using Bakermans Calculator, thanks again buddy!

[th3flyboy 0]

Nice idea, but I see a flaw in implementation, the weapon velocity could easily cause problems with subsonic rounds. If I were to fire a subsonic round, and the weapon is tuned for supersonic ammo, that would *speed up* the subsonic round to supersonic levels.

[zelectec 10]

Awesome contribution to the community and thanks for your credit.

[da12thMonkey 1943]

Nice , but one question

Does the weapon Initspeed really overrides the muzzle velocity from magazine class?

If yes then we dont need this > http://feedback.arma3.com/view.php?id=12125 (vote it anyway)

Muzzle-device MagazineCoef modifies the initSpeed from the cfgMagazines by a scale factor (percentage of magazine initSpeed).

Bakerman's description of cfgWeapons initSpeed seems to suggest that it completely overwrites the initSpeed from cfgMagazines definition, so that all rounds would fire at the same MV from that weapon, rather than as a percentage of the assigned MV from the mag. So for example if you loaded a magazine configured for "subsonic" rounds, it would fire at the same MV as a regular ball round.

If that's the case, making the initSpeed parameter for the weapon act the same as MagazineCoef, like the ticket is suggesting would still be preferable.

[Robalo 465]

Nice , but one question

Does the weapon Initspeed really overrides the muzzle velocity from magazine class?

If yes then we dont need this > http://feedback.arma3.com/view.php?id=12125 (vote it anyway)

Think about shooting various types of ammo from the same weapon (eg. 62 gr. vs 77 gr.). We need to be able to set a coefficient that would be applied to the magazine's initspeed. The engine already supports this, but it's only for muzzle devices.

[bakerman 247]

Thank you for pointing that out. I will do a proper investigation on the effects of cfgWeapons initSpeed on muzzle velocity. The description I have there is mostly paraphrased from the VBS wiki, so this may not be true for Arma. I will report back with the findings ASAP.

@Foxhound

Thank you for hosting. :)

@Spartan0536

Thanks, I hope it helps!

[roberthammer 582]

Thx for the info - i forgot about subsonic vs supersonic + various ammo

and yes that feature would be great

Edited April 7, 2014 by RobertHammer

[lukrop 10]

Thanks for the writeup. I'm really looking forward to your config database. I'm sure lkr_ammo will profit from your findings and hopefully even feedback something to this project. ;)

[da12thMonkey 1943]

The description I have there is mostly paraphrased from the VBS wiki, so this may not be true for Arma. I will report back with the findings ASAP.

I wouldn't be surprised if its inclusion in cfgWeapons is one of those things that's implemented in VBS but not Arma, so it may not work at all.

What grips me the most about MagazineCoef initspeed is that BIS have actually set them all to 1 now in the muzzle-device configs because the effect it was "simulating" (instant subsonic ammo with when suppressors are attached) was pretty much horseshit and nobody liked it because it was unrealistic and had a poor effect on gameplay. They have this rather useful function in the engine that is going to waste because they chose to implement it in a less practical place in the config than they could have done.

It seems BIS have finally reviewed the ticket today though. Fingers crossed they will see the opportunity to adapt it to make good use of the decent work that the programmers did, which is currently not being put to any use by the game.

Edited April 7, 2014 by da12thMonkey

[bakerman 247]

Tests concluded.

cfgWeapons initSpeed has no effect on muzzle velocity.

I will be amending the first post to reflect this.

[bakerman 247]

I will try to do at least one ammunition per day, if time permits.

Here's the first bullet, a 6.5mm Grendel, which is the closest thing we have to A3's caseless 6.5mm.

This specific 6.5mm is a Lapua Scenar 123gr OTM with a G1-BC of 0.527.

The final airFriction is the average of the airFriction determined at 100 and 400 yards, shot from a simulated muzzle @ 2750 FPS.

Hit was calculated with a bullet form of 5, because it is a FMJ. The high typicalSpeed takes any long barrel into account.

Caliber was determined from report one and two that the 123gr 6.5mm is able to penetrate slightly less than a M80 at medium ranges and slightly more at 1000m.

class B_65x39_Caseless: BulletBase
{
  typicalSpeed = 900;
  airFriction = -0.0007195;
  hit = 11.36283415;
  caliber = 0.972;
};

Any cfgWeapons modders would be interested to know that this article also contains a recoil comparison between the 6.5mm OTM, M885 and M80.

[olds 15]

Awesome Bakerman. So that would be a cfgMagazine initSpeed of 838 vs. BIS' 800.

[sarcasm] P.S. Could you please provide more significant digits for the hit and caliber values? Some of use like to be precise you know.:232: [/sarcasm]

Edited April 8, 2014 by Olds

[da12thMonkey 1943]

This specific 6.5mm is a Lapua Scenar 123gr OTM with a G1-BC of 0.527.

The final airFriction is the average of the airFriction determined at 100 and 400 yards, shot from a simulated muzzle @ 2750 FPS.

Hit was calculated with a bullet form of 5, because it is a FMJ. The high typicalSpeed takes any long barrel into account.

Scenar is a bit of a tough one. It's marketed as Hollow Point Boat Tail (HPBT) in the EU, and most military this side of the atlantic shy away from using it as anything but a target-shooting round (anything described as "hollow-point" is generally considered a no no under the Hague Convention), but in the US it's described as Open-Tip Match, where such rounds are permitted for use in combat by snipers, (and snipers only AFAIK) because they don't really have the characteristics of traditional HP ammunition: The aperture if much narrower, and the jacket tends to be much more strongly bonded to the core than on a HP.

The US cleared OTM due to the fact Sierra Match King bullets were proven to have similar terminal effect on soft targets to standard FMJ ball, but AFAIK the terminal effects against hard targets are much less likely to penetrate than FMJ.

Is there any capacity in the calculator to reflect this small difference between FMJ, OTM and HP?

[bakerman 247]

@da12thMonkey

Thanks for the information. :)

I guess I should get more sleep or something if I'm missing stuff like that, but that's why I haven't posted it on the first post and that's what this thread is for.

Yes the calculator can do exactly what you asking, adjust bullet form for soft targets and caliber for hard target performance.

I choose the 123gr OTM because it's the closest thing I could find to the fictional A3 round.

[Trauma.au 10]

I will continue working on this as time permits, in the next update something spotted orbiting around Jupiter may be included, who knows?

Titan.

[bakerman 247]

Yes I'm going to add a large moon into the ballistics mod.

/s