Hitting a moving target

[greycat]

I sometimes think that the games makes it too easy for a tank/anti-tank gun to hit a moving target with it's first shot. Very often the first indication of the location of the enemy is when one of your recce vehicles is suddenly 'brewed up' - a situation all players will be familiar with! I'm in two minds about it as I don't how often this used to happen in reality but I would be interested to know what factors the game considers when calculating the hit probability. In particular, does it allow for deflection? Hitting a target moving directly towards/away from the shooter should be easier than hitting one moving (possibly rapidly) across his field of view.

[Michael Emrys]

In particular, does it allow for deflection? Hitting a target moving directly towards/away from the shooter should be easier than hitting one moving (possibly rapidly) across his field of view.

All true. I kind of doubt that the game has matured to the point where this is calculated, but I would be happy to be shown that I am wrong about that.

Michael

[Vanir Ausf B]

Yeah, I would love to know what effect, if any, target movement has on accuracy. If I ever have several days with nothing else to do I may make a test to find out. But my own anecdotal observations have led me to suspect that that it may not have any effect at all.

[JasonC]

Range matters a lot for this - that is, whether target apparent motion matters or doesn't matter.

The typical AP round velocities are around 750 meters per second. A typical off road vehicle speed is round 7 meters per second (15.66 mph), on a road you might occasionally see 15 meters per second. Then you only get the cosine of that vector projected onto the line perpendicular to the line of fire, which can cut the apparent speed in half or (perfectly 90 degree motion) leave it unchanged. The apparent motion speed is thus in a range of 3-7 m/sec for off road movements, occasionally doubled for fast movement on a road; though the last is rare in tactical situations it does happen with recce cars etc.

At 750 meters the vehicle might move 1-2 times its own length in the shell's flight time and thus require some "lead", but at 400 meters its motion might move the point of impact but not the "fact of impact", if I can put it that way. When the angle of movement is highest the vehicle is also presenting its longest axis and thus the largest target, with the cosine effect making the "un-led, targetable width" about the same.

Truly long range fire - 1.5 km shots and the like - definitely require a proper "lead" if the target is moving across the field of view. But how common is that in CM? How common are first shot hits at those ranges, even with a stationary target?

At the knife fight ranges common on most CM maps, speed really isn't much protection if the shooter aligns the gun and gets the shot off. If he can't "track" the target it protects you, that is the way it can help in close. Tracking angle change is largest at close range. At long range the flight time is longer so you can miss if you don't "lead" properly, but the angle to sweep through is small.

FWIW...

[Killkess]

I might be wrong but isnt lead in the azimuth only dependent on the motion vectors?

[sburke]

All true. I kind of doubt that the game has matured to the point where this is calculated, but I would be happy to be shown that I am wrong about that.

Michael

During our Hamel Vallee fight I had a PzShk team fire off a round at one of Broadsword's Shermans in the last few minutes of the game. The round impacted on where the Sherman would have been if you projected it's movement at the time the round was fired. The Sherman had however stopped in the meantime. Until Steve says otherwise (and even then I'd probably politely suggest he double check with Charles ) I am absolutely convinced the game factors it in. I don't think it is a "probability issue". The game doesn't roll die, it figures the flight path and then looks for the intersection. In the flight time of my rocket, the Sherman halted - the paths did not intersect. In this particular example I think the factors involved are better graphically portrayed as the flight time is so much slower. I do not think however the mechanics are any different for tank rounds.

What would concern me more is if Corporal Nerd pulled out his handy dandy slide rule and figured the intersection point was outside of his covered arc and therefore decided he'd been told not to fire. I'd probably run him into a minefield were I to discover that.

[mjkerner]

During our Hamel Vallee fight I had a PzShk team fire off a round at one of Broadsword's Shermans in the last few minutes of the game. The round impacted on where the Sherman would have been if you projected it's movement at the time the round was fired. The Sherman had however stopped in the meantime. Until Steve says otherwise (and even then I'd probably politely suggest he double check with Charles ) I am absolutely convinced the game factors it in. I don't think it is a "probability issue". The game doesn't roll die, it figures the flight path and then looks for the intersection. In the flight time of my rocket, the Sherman halted - the paths did not intersect. In this particular example I think the factors involved are better graphically portrayed as the flight time is so much slower. I do not think however the mechanics are any different for tank rounds.

What would concern me more is if Corporal Nerd pulled out his handy dandy slide rule and figured the intersection point was outside of his covered arc and therefore decided he'd been told not to fire. I'd probably run him into a minefield were I to discover that.

I've seen that behavior too, but also have seen the rounds land behind the tank (slide rule calc a little off, I guess!) but still forward of the vehicle's starting point. So it seems that the shooters are applying good ol' Kentucky windage.

Get Some!

[YankeeDog]

I'm not aware of a definitive statement by Steve & Co. on the matter, but I'm fairly certain that target movement is modeled in CM's hit calculations. In fact, based on how detailed everything else is in the CM hit modeling, I'd guess the modeling in this area is fairly complex and detailed.

But if you're interested in knowing more, why not run some tests? Should be a pretty straightforward test to run.

As JasonC has already noted, most WWII combat vehicles don't move very quickly, and the engagement ranges you see in CM are usually relatively short, so under typical conditions I'd expect the effect to be fairly subtle. To make it easier to see in tests, I'd suggest starting with a test of a relatively low velocity gun (such as am Allied 75mm pack howitzer or German 75mm infantry gun), and targeting a relatively small, fast target like an armored car at a distance of 750m+ -- this should make the effect of moving vs. not moving easier to see.

[Vanir Ausf B]

But if you're interested in knowing more, why not run some tests? Should be a pretty straightforward test to run.

Why not? Because designing the test isn't the problem. The time investment required is the problem. Assuming we are testing first shot accuracy you only get one date point per target per test run. And the difference in accuracy may not be large, per JasonC's post. So to establish a high confidence level in the results would likely require a large sample size; several hundred for each test. And you would need two tests: the control group with stationary tanks and the test group moving. We're talking days, not hours.

But hey, if you think it's so easy to do let us know your results

[YankeeDog]

But hey, if you think it's so easy to do let us know your results

Because I'm not the one who is particularly curious to know the answer; I'm not going to do someone else's work for them.

[Vanir Ausf B]

It's not my work either, for the reasons stated.

[Guest]

I'm not aware of a definitive statement by Steve & Co. on the matter, but I'm fairly certain that target movement is modeled in CM's hit calculations. In fact, based on how detailed everything else is in the CM hit modeling, I'd guess the modeling in this area is fairly complex and detailed.

This is putting it very mildly. We don't use hit probabilities, or even hit calculations. We use the ballistics system to its fullest. Gunners aim their weapons using their available equipment (optics, etc.). They make decisions about some factors, guesses about others, and pull the trigger when they think their projectile is going to hit their target - and of course their thinking will be influenced by stress and other factors like experience and training.

Whether they hit, penetrate, etc., is purely down to physics.

So... WAY more complex than rolling dice!

In this example, a large angular movement would be more difficult to make guesses and decisions about, and that should be reflected in how often they hit. In-game shots are very often taken, however, as pointed out above, at essentially point-blank range for their guns / optics.

[greycat]

This is putting it very mildly. We don't use hit probabilities, or even hit calculations. We use the ballistics system to its fullest. Gunners aim their weapons using their available equipment (optics, etc.). They make decisions about some factors, guesses about others, and pull the trigger when they think their projectile is going to hit their target - and of course their thinking will be influenced by stress and other factors like experience and training.

Whether they hit, penetrate, etc., is purely down to physics.

So... WAY more complex than rolling dice!

In this example, a large angular movement would be more difficult to make guesses and decisions about, and that should be reflected in how often they hit. In-game shots are very often taken, however, as pointed out above, at essentially point-blank range for their guns / optics.

:cool: Good to know, many thanks!

[Michael Emrys]

This is putting it very mildly. We don't use hit probabilities, or even hit calculations. We use the ballistics system to its fullest. Gunners aim their weapons using their available equipment (optics, etc.). They make decisions about some factors, guesses about others, and pull the trigger when they think their projectile is going to hit their target - and of course their thinking will be influenced by stress and other factors like experience and training.

Whether they hit, penetrate, etc., is purely down to physics.

So... WAY more complex than rolling dice!

In this example, a large angular movement would be more difficult to make guesses and decisions about, and that should be reflected in how often they hit. In-game shots are very often taken, however, as pointed out above, at essentially point-blank range for their guns / optics.

Well, I guess I get my wish then.

Michael