Bullet velocity - inaccurate ?

[fincuan 0]

SVD

[Spokesperson 0]

Excellent. That's exactly what's needed. Would be great if that's averaged over maybe 10 shots too.

If you send me the data table with the parameters I can plot it together with the forumla (or if you want to do it).

Let's say we compare the M16. Anyone need the correct bullet weight for that?

[fincuan 0]

That data is from single shots only, as the variances were so small I didn't see a need for more. Remember, dispersion and most other external factors are disabled in these tests, so there's not much that can bring any variance. Doing a 10-shots average on one weapons shouldn't take long though, I'll see if I can get it done for M16A4 later tonight.

[Spokesperson 0]

Also, please post your data. Preferably a table with two columns. One for flight time, and one for range.

Maybe bullet drop too if you want.

Then I'll make a combined graph with values from "theory".

[InqWiper 0]

I compared the the results from my testings with a program I found on the internet: http://www.federalpremium.com/resources/ballistics_application.aspx

It did not have all the ammo types but I compared 5.56x45, 7.62x39 and 7.62x51.

Press show spoiler to show results:

M16 shot at 500 meters (5.56x45):

Initial velocity: 929.997m/s

-Initial velocity: 920m/s

Final velocity: 453.482m/s

-Final velocity: 519m/s

Distance travelled: 498.799m

-Distance travelled: 500m

Velocity maintained: 48.7617%

-Velocity maintained: 56%

AKM shot at 500 meters (7.62x39):

Initial velocity: 709.963m/s

-Initial velocity: 716m/s

Final velocity: 268.571m/s

-Final velocity: 386m/s

Distance travelled: 498.939m

-Distance travelled: 500m

Velocity maintained: 37.8433%

-Velocity maintained: 54%

DMR shot at 500 meters (7.62x51):

Initial velocity: 899.975m/s

-Initial velocity: 860m/s

Final velocity: 568.629m/s

-Final velocity: 558m/s

Distance travelled: 499.447m

-Distance travelled: 500m

Velocity maintained: 63.1828%

-Velocity maintained: 65%

As you can see 7.62x51 was a good match, 5.56x45 was an ok match and 7.62x39 was a bad match.

Very nice graphs Fincuan :)

Pretty much the exact same results I got at 500 meters which shows the accuracy of the results in both tests IMO.

[galzohar 31]

Isn't the SS109 5.56 round 4 grams?

In any case, the best thing to do to get the correct values is, as hinted by other posters, to adjust the flight time as close to RL as possible and then use proper values for gravity. Of course if you have RL bullet drop values to use to choose your model's constants, then based on gravity calculations you can instantly interchange between flight time and bullet drop.

Gravity's effects shouldn't need anywhere near as complex modeling as drag does. A simple fixed acceleration formula should probably work more than fine in most situations, since the vertical speeds are low and thus the vertical portion of the drag is rather negligible - be it in a model where it is linear to the speed or something more complex, if the (vertical) speed is small then the effects of drag (on the vertical speed) are small as well... At least for bullets that don't have fins/wings/other crazy stuff ;)

[Spokesperson 0]

http://en.wikipedia.org/wiki/5.56x45mm

Yes about 4 grams.

I entered m16 params. Still Constant C_d=3, but it agrees quite well with arma2.

I also found a great article that uses variable C_d (that follow power law - with an exponent taken from experiments).

It also agrees ok at 500m.

http://www.arl.army.mil/arlreports/2005/ARL-TR-3620.pdf

Arma2 M16 bullet drop and flight times are more or less ok in other words.

[maturin 12]

If you want anecdotal evidence that excessive air resistance is the problem, drop an LGB. It explodes well behind the aircraft as opposed to underneath as a normal reasonably aerodynamic object would.

[cartier90 0]

Could we expect this to be sorted by next patch ?

[max power 21]

I doubt it, but who knows.

[max power 21]

If the ballistic path is correct but the travel time is not, wouldn't that indicate that there is something wrong with gravity as well?

[galzohar 31]

If the ballistic path is correct but the travel time is not, wouldn't that indicate that there is something wrong with gravity as well?

Yes, that would basically mean that they adjusted the bullet drag value to compensate for the incorrect gravity.

[cartier90 0]

Has anyone tried the tests on ACE ?, or is the prolem engine related...

[cartier90 0]

*bump* - would like to hear other peoples experiences...

[cartier90 0]

Just got ACE today, doesnt seem to solve the issue - 1000 m shot taking 2 full seconds - Im sure 1.4-1.5 is nearer what it should be.

[SWT_Janowich 10]

Are sou sure?

[cartier90 0]

Usually Im not a stickler for these things, but this issue I am ..:p

I stand corrected, its actually 1.8 seconds time of flight IRL for a 1000 m shot - wheras its more like 2.2 - 2.3 in game - not huge , but it is significant.

[node_runner 0]

Does the AI rely on your support for bounding movements while in combat mode? Sometimes when they start saying "Go, I'm covering", I'm not sure if one AI is talking to another AI, or if he is talking to me and just won't move until I move up.

In other words, when you give your team a move command in combat mode and they start to bound toward that position, do they care at all or take into account where the player is standing or what arc the player is covering?

[max power 21]

Does the AI rely on your support for bounding movements while in combat mode? Sometimes when they start saying "Go, I'm covering", I'm not sure if one AI is talking to another AI, or if he is talking to me and just won't move until I move up.

In other words, when you give your team a move command in combat mode and they start to bound toward that position, do they care at all or take into account where the player is standing or what arc the player is covering?

I believe that they take groups of 2 and bound like that. It's the reason why they are so slow to keep up when they are in combat mode, I think. Patch 1.05 has reduced this behaviour based on their distance from the squad commander, I believe. To make absolutely for certain how the behaviour translates practically, I think you'd have to make a test mission and observe them.

[mr.g-c 6]

Any news about this one?

If a change is coming, i'd like to advertise for my "old" ticket about bullet speeds defined in magazine configs:

http://dev-heaven.net/issues/2411

[cartier90 0]

Any closer to a resolution ?

[LJF 0]

This is definitely an issue I'd like to see resolved, serious problem in my mind. I always felt something was a little off.

[maturin 12]

Are we sure we have the numbers correct? This article says a 7.62 round takes "about" a second to travel just 600m.

[forum troll 4162 18]

Does anyone have any input about this? I don't really know what I'm talking about, so it's not worth a thread, but according to wikipedia the effective range of the bushmaster is 3000 meters. So shouldn't the 25mm cannon on the Cobra be able to reach targets at 1500-2500 meters without lobbing rounds like a catapult?

Everything falls at the same rate, a piece of paper falls at the same rate as a car.

[Michael Withstand 10]

I just want to comment that without ACE 2 I found for example that the sniper rifle SVD Dragunov which I use often in multiplayer has quite a weak killing power.

Often than not the target would be hit but not killed or even appeared dying.

And I just think ACE 2 should become the standard version :rolleyes:

it just brings too many vital improvements.