95 replies to this topic

[Felicitatem Parco]

Bump to merge with mwomercs.com/forums/topic/6200-projectiles-how-will-they-work

[JP Josh]

Ghost, on 05 December 2011 - 08:22 AM, said:

I'm against bullet drop for several reasons. The most prominent reason I'm against ballistics being involved is the fact that the deck is already stacked against projectiles. I'm all for anything that keeps the laser boats at bay.

somebody doesnt know how to make a ARTY BOAT!!!!!!

[Steamroller Stig]

Prosperity Park, on 04 December 2011 - 10:10 PM, said:

the Dev's would certainly find one way or another for you to adjust for the drop.

why not just have it so the player accounts for the drop? any form of auto aim is going to be counter productive on moving targets even the convergence is an issue.

[Johannes Falkner]

I would say the projectiles should follow true ballistic arcs, but the computers would get calibrated for the arc ahead of combat. So I think that the gravity should be visible in terms of arc to target, but not necessarily become dramatically more difficult to use.

[Nik Van Rhijn]

Devs have said that drop will occur after max range. It would seem that with convergenge etc that lead and drop for ballistics are catered for by the computer. It will still involve time to target but if you assume that a projectile is doing 1500m/sec. At 750m it takes 1/2 sec. A mech doing 65 kph (many mediums and heavies) is doing 18m/sec. In other words it would move 9m at 750m. Much combat would take place at much shorter ranges, with correspondingly lower lead necessary.

[Dragux]

Truth be told, if the drop was enabled, i would personally say that the longer the distance and the drop... the more damage the bullet would have since its reaching terminal velocity and pulling down towards the planet (wont say earth since MOST BATTLES ARENT ON EARTH).
would be interesting too since it would take a great deal of skill to aim the weapon and fire, or can impliment a guided aiming system to show where to aim for the bullet to drop at the specific point (similar to what Chrome Hounds did at one point)

Would be an interesting mechanic added to the MW series as well

[syngyne]

Dragux, on 28 March 2012 - 08:48 AM, said:

Truth be told, if the drop was enabled, i would personally say that the longer the distance and the drop... the more damage the bullet would have since its reaching terminal velocity and pulling down towards the planet

Projectiles are almost always launched at faster than terminal velocity. They're constantly being slowed by whatever medium they're travelling through towards their terminal velocity.

[Johannes Falkner]

Air friction slows a projectile relative to it frontal area and surface area. The equations can get nasty, but projectile diameter is one major factor, surface area of the projectile is another and projectile velocity rounds out the projectile factors. Add in factors for the atmospheric conditions such as density temperature and pressure and (obviously) gravity and you have yourself some lovely equations. You can add things like atmospheric motion (wind and turbulence), projectile shape factors............................................

So ye, projectiles should drop. But the computer should account for it.

[docmorningstar]

I have a handy little program that calculates projectile behavior for battletech weapons (I'm a huge geek) - they are somewhat balanced for real life (the explosive/kinetic energy damage for ACs are based on a 185mm russian arty piece for shell size and explosive content - 180mm is one of the caliber examples for AC20s.. & a 75mm howitzer for muzzle velocity because why not...) and the Gauss rifle damage is based off of that using pure kinetic energy models;

I ended up with an AC20 projectile being equivalent to a 80kg shell with 20KG of HE traveling 400 m/s (slow) and a GR slug being a 250 kg lb slug with a muzzle velocity of 2500 m/s.

My program assumes realistic bullet profiles and ballistic coefficients. The velocity loss is minimal for any of the projectiles we are using (stupid 1km max range). (the KE change in an 80kg projectile@1km with an v0 of 400ms is less than 2% of the total energy (assuming a HE component)) The windage is pretty darned small, too.

I thought alot about this, and here is what I came up with.

Ballistic projectiles follow a realistic trajectory.
Your mech displays a 'fixed' aimpoint for each reticle - this is the point that your weapons will hit at a particular range. This aimpoint range can be tweaked to whatever range you want. This is equivalent to sighting in your weapon.
The battlemech targeting computer automatically calculates the 'proper' amount of bullet drop @ the range to the current target.
This is displayed as a secondary aimpoint within the targeting reticle.
'Lead' is not calculated, normally.
if you outfit your mech with a targeting computer, it displays an aim-point in the reticle which will guarantee a hit IF the target continues at the exact same speed/path

Ballistic projectiles follow a true ballistics path, because it looks good, and will add alot of skill into hitting targets that you DON'T have 'locked up'. A basic ballistic path is really easy to calculate. Over the ranges we are talking about, projectiles experience virtually no loss of forward velocity, which means that the ballistic path can be easily calculated from basic physics equations.

Edited by docmorningstar, 04 April 2012 - 12:26 AM.

[Jesper]

Good to see this topic, but come on its the 3rd milenium I too think bullets have come far in their evolution in technology, and fast shots such as the gauss and AC2 and 5 should not be affected. The Long Tom is by its nature a hard to use weapon and that is because its arc trajectory which I agree, but not the rest. The machine gun should also have a split fire type...

[Johannes Falkner]

Doesn't matter how advanced your bullet is so long as the cops can pull it over for breaking the law of gravity.

[Shai tan]

Anything that can drop, should do so, as it brings skill factor into play. Anyone remember those games where peeps are all the way across the map ala Soldier of Fortune???? And they aim and shoot and kack peeps from all the way across the map. Rediculous.

[docmorningstar]

So, here is an illustration for how I think that targeting and ballistic fall off should work.

You pre-set (maybe make it easily adjustable in-mission) your 'default' targeting range (this is the distance where all of your weapons converge IF you don't have a target locked up). This will be essential in shooting at targets that you can 'see' but your sensors can't lock up, Or shooting at targets at super-long range, or shooting ballistic weapons 'over' intervening terrain. This creates a virtual 'aim point' (you can keep it virtual, or make it visible)

When you 'lock up' a target, you automatically get a rangefinder which calculates range-to-target and adjusts the convergance of your weapons, as well as generating a new aimpoint.

When you fire, a ballistic path is created between the aimpoint and your mech's weapon, based on things like the muzzle velocity (actualy, for battlmech sized weapons, loss of projectile speed is negligble due to wind drag). That is the path that the shell/beam/missile takes.



The dragon is targetting the middle catapult (with the aim point) - The target is 'locked up' so the dragons targetting system feeds him an aimpoint of 500m and his weapons re-calibrate to aim there.

The forward/rear catapult illustrate what happens if you are 'aiming' at the middle target, and it moves forwards or back before your rounds get there.

You can see that it is 'impossible' to generate a miss with a laser weapon by moving only forwards/backwards - but the shooter needs to keep the beam 'on target' to do max damage
You can also see that for low caliber AC (AC2) the trajectory is very, very flat, meaning that if the target moves forwards/back, the shell might not hit exactly where aimed, but will probably hit the target. Not shown is that because the AC2 has such a huge velocity, it will carry very far beyond range, letting you shoot at targets at great distances. As AC weapons get larger, they lose muzzle velocity, and take more of an arced path to the target. This means that you can now generate misses for the big guns by simply moving forward or back. BUT it would also let high caliber AC lob shots over stuff.

[MaddMaxx]

Nice Graphic doc. One issue I have is based on this statement made earlier.

Quote

"and a GR slug being a 250 kg slug with a muzzle velocity of 2500 m/s."

The Gauss Rifle gets 8 shells per ton. Thus 1 shell would weigh in at 250lbs, not Kg's. A kilo is 2.2 lbs so a 250kg slug would actually weight 550lbs thus reducing the ammo per ton to less than 4.

GR's don't get many slugs per ton as is, let's keep it at 8 eh...

Edited by MaddMaxx, 03 April 2012 - 10:58 AM.

[docmorningstar]

derp

That's a typo - the MV is correct at 2500m/s

[RedDragon]

I think bullet drop would be a neat and new feature for MW. We'd have to see how it could be implemented since we don't even know how convergence will work. Compensating for bullet drop is quite the same as convergence, just vertically. So why not combine those two?
An idea that seems quite logical to me is this: You have one specific key that sets all (selected? grouped?) weapons to hit a target that is x metres away, where x is the distance your currently selected enemy is away from you. Naturally that means if you can't get a lock on your enemy, you won't be able to hit him with all weapons in an instant. In that case you could either fire all weapons manually (aiming higher for ballistcs) or you bring your reticule over the enemy mech and after some time your weapons are aligned to the current range.
This naturally doesn't compensate for lead on a moving target, although if you're able to get a lock on a mech there could be an indicator where to shoot in front of your target and the mech will fire all weapons along a horizontal line so that lasers hit the target instantly, ACs are fired with a small lead, missiles with a larger one, so all weapons will hit the target if it moves in a constant tempo. But maybe that would be a bit too much work done by the computer so the pilot doesn't need much skill (unless he tries to hit erratic moving targets or targets he can't get a lock on).
Any drawbacks to this?