Bullet Drops

[Qaiex]

Originally Posted by Dreadnought1984

showing my noobness here, but what's the mp?



isn't the wiki currently down?

The wiki has been down since late .85
It was useful even with some informaiton being false, I wish it was back up.

[RHYS4190]

Originally Posted by puppezed

Either I misunderstood what you wrote or you are mixing up length units and angle units.

Let´s take for example the flight path of an 7.62x39 AK round from Lapua and presume the gun is zeroed to 150m. The flight path is:
50m : +3.2 cm
100m: +4.8 cm
150m: 0 cm
200m: -9.0cm
300m: -64.3cm
http://www.lapua.com/fileadmin/user_...ridges2009.pdf
So if you are shooting at ranges of 300m the drop is 64.3cm and you have to aim that much above the target in order to hit it dead on.

With a mildot sniper scope, milradian angle unit comes into play. 64,3cm@300m equals 2.2 milradians. Since the angle between dots in a mildot reticle is 1 milradian, using the second dot under the cross section of the scope would mean a hold over of 2 milradians which equals 60cm@300m which is pretty close the required 64.3cm hold over. 1 milradian angle equals the length of 10cm@100m and 30cm@300m.


I can tell by first hand experience that hitting a man sized target with an AK (well, at least with a Finnish AK) is quite easy but you do have to take bullet drop into account either by aiming above the target or by manually adjusting sights.

I´d like to see Project Reality putting more emphasis to ballistic flight paths of all projectiles (bullets, RPGs, cannon round etc). In my opinion Red Orchestra (previously WW2 Unreal Tournament mod, now a stand alone game) has implemented ballistic flight paths pretty well and the bullets really do drop. It makes hitting targets more challenging but much more realistic and rewarding.

Yeah that but that in RL not in game, im talking about ingame physics, in game there a smaller bullet drop i think then that it only a few millimetres, IF there is a drop at all.

[TheLean]

Originally Posted by Jonny

Wrong.

They follow a parabolic trajectory whose starting velocity is parallel to the barrel of the rifle (discounting deviation). It is NOT a 'linear' drop.


The DEVs do not approve of any of the workarounds that have been found to this day, and zeroing only some of the guns is not acceptable, apparently.

Thank you for that information. Just to clarify by an example, the Designated Marksmans rifle kit is zeroed at 600 meter according to the manual. Does this mean that we have to aim at the chest of a soldier at 300 to hit him in the head because of a parabolic bullet path?

[nedlands1]

Originally Posted by TheLean

Thank you for that information. Just to clarify by an example, the Designated Marksmans rifle kit is zeroed at 600 meter according to the manual. Does this mean that we have to aim at the chest of a soldier at 300 to hit him in the head because of a parabolic bullet path?

Nope. The weapons in the game aren't really "zeroed" as such (see diagram below). The whole "zeroing" thing is an arbitrary way of saying that you need to take into bullet drop at that range. In general the deviation has much greater influence on hitting your target than bullet drop.

[TheLean]

Aha, that picture explain everything. It is so much win it should be in the manual.

[[R-DEV]Rudd]

I suspect it will be in the guide when its back up seems alot of great work is hiding from us behind that password :P

[Dreadnought1984]

Originally Posted by [R-CON]nedlands1

Nope. The weapons in the game aren't really "zeroed" as such (see diagram below). The whole "zeroing" thing is an arbitrary way of saying that you need to take into bullet drop at that range. In general the deviation has much greater influence on hitting your target than bullet drop.

I believe I understand what you're saying. Correct me if I'm wrong, but it seems that you're saying that in PR, bullets DO drop for all distances including those less than their stated "zeroed" range, but the scopes accommodate for this at these stated "zeroed" ranges?

I had previously understood that in PR, bullets, in essence, act as lasers until the stated range and then began to drop. But it seems that because the scope is accommodating for the expected range, you could shoot over targets closer than that accommodated range.

[nedlands1]

Originally Posted by Dreadnought1984

I believe I understand what you're saying. Correct me if I'm wrong, but it seems that you're saying that in PR, bullets DO drop for all distances including those less than their stated "zeroed" range, but the scopes accommodate for this at these stated "zeroed" ranges?

Yes. Bullets drop for all distances unless the gravity modifier for the projectile is set to zero in which case the projectile doesn't drop at all (unless you shoot downwards of course). The only weapons with a gravity modifier of zero, that come to mind, are the guided missiles. Most weapons have a fairly low gravity modifier, decent muzzle velocities and lots of deviation which makes the drop hard to see. Bullets come out of the centre of the screen, for most weapons, and the crosshairs/ironsight have been aligned with the centre of the screen as well. I represented this on the lower part of the diagram. Both the point of aim (red line) and the path of the projectile (black line) originate from the same point.

The whole "weapon X is zeroed to Y meters" in PR has nothing to do with real world zeroing. It's just an opinion that the drop is negligible up to that range.

I hope I answered your question.

[Dreadnought1984]

Originally Posted by [R-CON]nedlands1

Yes. Bullets drop for all distances unless the gravity modifier for the projectile is set to zero in which case the projectile doesn't drop at all (unless you shoot downwards of course). The only weapons with a gravity modifier of zero, that come to mind, are the guided missiles. Most weapons have a fairly low gravity modifier, decent muzzle velocities and lots of deviation which makes the drop hard to see. Bullets come out of the centre of the screen, for most weapons, and the crosshairs/ironsight have been aligned with the centre of the screen as well. I represented this on the lower part of the diagram. Both the point of aim (red line) and the path of the projectile (black line) originate from the same point.

The whole "weapon X is zeroed to Y meters" in PR has nothing to do with real world zeroing. It's just an opinion that the drop is negligible up to that range.

I hope I answered your question.

thank you! that finally clicked for me, I'm relaying this the TG forums.

[Just_A_Thought]

Jonny,
I am pretty new to the game, and probably a year and a half too late to this discussion. In reading through your posts from early 2008, it was really nice work that you, Nedlands, CAS-117, Mosquill and Zangoo did for ballistics. (But this all seemed to stop when Zangoo left.) At the risk of telling you something you already tried, and of flogging (selling) a dead horse, there might be a way to get around the tracer bug:

There must be something telling the program whether each round is a tracer or not. If this information can be passed to the ballistics equations, here is a possibility. In the ballistics equations, replace all instances of velocity v with (v + 10/9 * v * Tracer_Flag), where Tracer_Flag = 1 for tracer rounds and 0 for regular rounds.

For regular rounds, the position of each round would be as you already have them (i.e. the 10/9 * v * Tracer_Flag becomes 0, leaving only v). For tracer rounds, the physics in the PR universe would make them move in the same trajectory as regular rounds, even though the velocity is apparently lower. (Note: Some posts on the message boards suggested that real tracers tend to fall a little short of where the non-tracer rounds fall. This could be modeled by using a constant like 1.11 instead of 10/9.)

If damage is based on bullet velocity, and I'm NOT sure that it is, the above velocity modification could be applied for damage calculation as well.

Just a thought. Hope it helps.