Just for fun: Determining direct fire range to a large target instead of the ground

[Talespin Jim]

I have a question that someone might find intriguing to answer.

The reason I'm asking this question is because I'm interested in the reasoning process that leads to your answer.

I'm setting up my units and have a 50mm anti-tank gun that I've found the perfect spot to decorate with. It's among a couple of trees right behind a small gnoll, just big enough to make it hull down. It's also inconspicuous because there are actually more obvious placements for it, so chances are, the opponent won't immediately be looking for it there.

In my defensive planning, it becomes pertinent that I know at what point the AT gun will be about able to fire at approaching AFV's, such as a Sherman. From in front of the gnoll the ground elevation slowly falls maybe five meters in elevation over 200 meters, then it begins to rise again maybe seven meters over another 100 meters and then very slowly begins to drop back down a couple of meters over the next two hundreds meters. Thus there is a point between the AT Gun and where I expect a Sherman will eventually travel at which both the gun and the Sherman will be hull down from each other and some meters before it reaches that point, the Sherman will not be visible at all. (Note: these approximations of the slope and distances from where the slopes change are pretty wild guesses, or it would actually be a snap to calculate an exact answer.)

I can calculate, using the targeting tool that I can shoot the ground from the AT gun's position at exactly 300 meters distant and no further. But when a Sherman approaches, it will rise up from the ground perhaps what, maybe six feet or so? So without finding an old geometry schoolbook, how do I get a guestimate as to how far the AT gun will actually be able to see a Sherman approaching and shoot at it?

Now, I've also used another AFV I've been given, a Marder II, to determine that it can shoot the ground at an approaching Sherman at 402 meters, were it placed where the AT Gun will be. This gives me some idea of the effective difference in range a little height can mean. If I remember right a Marder II has a lower profile and the gun is lower still. So I'm guessing maybe the AT Gun's gun is 2.5 or 3 feet off of the ground and maybe the Marder's is 50% higher, increasing the range to ground by 100 meters. Therefore, as the slope continues to decline at an even rate for a long distance, I'm thinking the top of a Sherman would be maybe 50% higher than the difference between the height of the Marder II's gun, compared to the height of the gun of the AT Gun. Thus I'm guessing that maybe I could hit a Sherman at a maximum of fifty meters further than the Marder II could hit the ground were it in the AT gun's spot, and that would be 452 meters.

That's where I want to set up my ambush, the maximum range the AT gun can possibly snipe a Sherman. I'll put an infantry unit in the woods there to distract the Sherman so maybe the AT Gun can get a few shots off without being noticed and with any luck I'll fool the opponent into thinking the infantry unit somehow killed the Sherman and thereby maybe I can get another kill with the gun before he waxes me good.

How wrong am I?

Hint, the answer is not "You can shoot the gun any time you like, but you'll never hit anything because you're Italian." I would not find such an answer amusing and I would never say such a thing. It's not the average Italian's fault it was probably Mussolini's or many other people, far up the ladder from the average man on the street, who were making a lot of really bad and even corrupt decisions that all contributed to making the very brave Italian soldier's, who did not even want to be fighting in the war, or for the side they were on at the time, fight less effectively than they would have been able to, had they had the weapons, tactics, structure and leadership, optics, etc., of many of their counterparts. Still, I know some of you devilish souls will come up with that very comment.

Oh, and Oddball, the answer could be something other than, "This is not a tank simulator." Lol.

[Vanir Ausf B]

So without finding an old geometry schoolbook, how do I get a guestimate as to how far the AT gun will actually be able to see a Sherman approaching and shoot at it?

The point at which the text at the end of the target tool changes from "Reverse Slope - No Aim Point" to "No Line of Sight" would be a good approximation.

[A Canadian Cat]

I'm setting up my units and have a 50mm anti-tank gun that I've found the perfect spot to decorate with. It's among a couple of trees right behind a small gnoll, just big enough to make it hull down. It's also inconspicuous because there are actually more obvious placements for it, so chances are, the opponent won't immediately be looking for it there.

Sounds like a good place. One question - what if the Sherman tanks don't come that way? How good is your spot for other avenues of approach. Note I am not saying you should abandon the idea and look for a universal AT gun location because that probably would be a worse thing to do. Just be aware that a well placed gun often will not be part of the fight if the enemy comes at you in a different way. Once you accept that and make sure you have a plan to deal with those other enemy approaches you will be happy.

...

Now, I can calculate, using the targeting tool that I can shoot the ground from the AT gun's position at exactly 300 meters distant and no further. But when a Sherman approaches, it will rise up from the ground perhaps what, maybe six feet or so? So without finding an old geometry schoolbook, how do I get a guestimate as to how far the AT gun will actually be able to see a Sherman approaching and shoot at it?

Well your way is much more analytical than mine - which is eyeball it. See this:

which has the advantage that the enemy tank is already there. Which brings me to...

Now, I've also used another AFV I've been given, a Marder II, to determine that it can shoot the ground at an approaching Sherman at 402 meters, were it placed where the AT Gun will be. This gives me some idea of the effective difference in range a little height can mean. If I remember right a Marder II has a lower profile and the gun is lower still. So I'm guessing maybe the AT Gun's gun is 2.5 or 3 feet off of the ground and maybe the Marder's is 50% higher, increasing the range to ground by 100 meters. Therefore, as the slope continues even for a long distance, I'm thinking the top of a Sherman would be maybe 50% higher than the difference between the height of the Marder II's gun, compared to the height of the gun of the AT Gun. Thus I'm guessing that maybe I could hit a Sherman at a maximum of fifty meters further than the Marder II could hit the ground were it in the AT gun's spot, and that would be 452 meters.

Sounds totally reasonable - I like it. It will probably turn out to be incorrect but hey what else can you do? Actually one suggestion is to play test it. Use the same map and see what the AT gun can see when Shermans come driving across the map. If that is too gamey for you use the Marder. Since if this were real live you could order the Marder to drive to the ambush location and the AT gun crew could sight it. You can setup a red vs red game and drive the Marder around letting the AT gun crew see what they can see.

That's where I want to set up my ambush, the maximum range the AT gun can possibly snipe a Sherman. I'll put an infantry unit in the woods there to distract the Sherman so maybe the AT Gun can get a few shots off without being noticed and with any luck I'll fool the opponent into thinking the infantry unit somehow killed the Sherman and thereby maybe I can get another kill with the gun before he waxes me good.

Again I like it - good plan.

How wrong am I?

Hint, the answer is not "You can shoot the gun any time you like, but you'll never hit anything because you're Italian."

Does that imply that you are Italian? It does not really matter because "no plan survives first contact with the enemy" anyway. But it does sounds like a solid plan.

[A Canadian Cat]

The point at which the text at the end of the target tool changes from "Reverse Slope - No Aim Point" to "No Line of Sight" would be a good approximation.

Ooo I totally forgot about that. Yes, I use that often once you realize what it is telling you it is very helpful.

[Talespin Jim]

The point at which the text at the end of the target tool changes from "Reverse Slope - No Aim Point" to "No Line of Sight" would be a good approximation.

Ah, I always forget about that because it seems to not work so well, so I don't use it, but for just an approximation it would help. The problem is not so much determining the no aim point though, it's determining how much farther the distance will be to a Sherman than it is to the ground. So I can use the no aim point to figure out the pinnacle of the gradual peak that will serve to give the Sherman the hull down position, but somehow I have to calculate how far beyond that I can still shoot at a Sherman, which is standing, what, maybe six feet high? The slope is so gradual that I know a Marder makes 102 meters past the no aim point for the AT Gun, but how much farther will the top of a Sherman first appear than the height of the Marder's gun? Usually an eyeball with a tool like that is close enough. But in this case, we know that the difference in height between a Marder's gun and an AT gun makes a 102 meter difference as to where you need to place your units. How much more difference will the top of the Sherman make? it could be fifty, a hundred meters or more. That's a big margin of error when the decoy has to be a slow moving infantry unit close assaulting a tank. Eyeballing it won't cut it in this situation.

Sounds like a good place. One question - what if the Sherman tanks don't come that way? How good is your spot for other avenues of approach. Note I am not saying you should abandon the idea and look for a universal AT gun location because that probably would be a worse thing to do. Just be aware that a well placed gun often will not be part of the fight if the enemy comes at you in a different way. Once you accept that and make sure you have a plan to deal with those other enemy approaches you will be happy.

Ian, you also make some excellent comments. This one is the most intriguing to me, because it shows something about how I think.

The appeal of this spot is more than what I've said. The spot also fits my thinking for things like AT Guns and sometimes machine guns or other direct fire weapons. I sometimes like a limited lane of fire. If I put the AT Gun where it will sweep the whole board, it will get one shot or two, then something, somewhere will suppress it or destroy/kill it. But if I put it where it can only see or be seen from one narrow direction, then it can only be shot at from a few targets, probably just one, that can see it too and it then it lives to fight another day.

So this gun protects a side road, on my right flank, through the forest that the enemy is unlikely to use, but if they do use this access, they have to go down this road, single file. Nothing else can see them there, they won't be able to see anything else, because I won't waste any more units there. But if they did go that way and I didn't protect it, I would get blind sided. This way maybe I can slow them down or even deny them access this way.

To make this even more perfect, there are some guns in the center of my line, which the enemy absolutely has to destroy and then take their position for the victory points. I am definitely facing an overrun no matter what I do. So if I turn this little 50 mm gun 90 degrees to the left, it has a tight lane of fire to the center of my line where those other guns are and where the enemy must go to get the victory points. So even if the enemy never goes down the road this gun is protecting in the forest, it will still get a flank shot on something going to the center of my line--maybe infantry, maybe tanks. It will become important one way or another and will not go to waste. In my opinion, it is the perfect situation for a gun of this size.

[Vanir Ausf B]

Ah, I always forget about that because it seems to not work so well, so I don't use it

Hmm, I rely on it heavily.

but somehow I have to calculate how far beyond that I can still shoot at a Sherman, which is standing, what, maybe six feet high?

Unless my understanding of the game mechanic is wrong I don't think you can ever spot a unit in an action spot to which you have "No Line Of Sight" with the target tool, except through tree foliage sometimes. LOS through trees is weird.

There are, IIRC, 5 height levels (or maybe six, my memory fails me here) that a unit can be at. Prone soldier is one, kneeling soldier is two, standing soldier is three and then there are two more for vehicles of varying heights. AFAIK, when the target tool says "Reverse Slope - No Aim Point" it is saying that you don't have LOS to the ground in that action spot, but do have LOS to at least the top height level above it. Since Shermans are a tall vehicle -- 9 feet tall -- they are probably classified at being the tallest height level possible for spotting which means you should always have LOS to one in a "Reverse Slope - No Aim Point" action spot (although you would not necessarily have LOS to shorter vehicles or infantry in the same spot).

At least that's how it works from my experience.

[sburke]

You can shoot the gun any time you like, but you'll never hit anything because you're Italian.

Somebody had to say it.

2 serious items.

The 50mm also benefits by being harder to spot. You may find if given a good enough concealed flanking position that your opponent will be gnashing their teeth trying to figure out what hit them. That in itself can disrupt their plans significantly.

Regarding your initial targeting planning I would also try to make sure I wasn't creating a situation where I was firing too early and potentially missing a partially hull down vehicle. To maximize your concealment you don't want them too close but you also do not want to be firing too many ranging shots.

[A Canadian Cat]

The appeal of this spot is more than what I've said. The spot also fits my thinking for things like AT Guns and sometimes machine guns or other direct fire weapons. I sometimes like a limited lane of fire. If I put the AT Gun where it will sweep the whole board, it will get one shot or two, then something, somewhere will suppress it or destroy/kill it. But if I put it where it can only see or be seen from one narrow direction, then it can only be shot at from a few targets, probably just one, that can see it too and it then it lives to fight another day.

Good. I think that means you are using your AT guns and heavy weapons well. So many people put them in an over-watch position and then complain that they get spotted too easily. Limited sight lines covering particular avenues of approach is the right thing to do. I recently finished a game where I had a 75mm AT gun covering a ford - it could see pretty much nothing else and it killed two or three tanks (I forget) and was never spotted the whole game. I love it when that happens.

So this gun protects a side road, on my right flank, through the forest that the enemy is unlikely to use, but if they do use this access, they have to go down this road, single file. Nothing else can see them there, they won't be able to see anything else, because I won't waste any more units there. But if they did go that way and I didn't protect it, I would get blind sided. This way maybe I can slow them down or even deny them access this way.

To make this even more perfect, there are some guns in the center of my line, which the enemy absolutely has to destroy and then take their position for the victory points. I am definitely facing an overrun no matter what I do. So if I turn this little 50 mm gun 90 degrees to the left, it has a tight lane of fire to the center of my line where those other guns are and where the enemy must go to get the victory points.

Sounds good. I like the bonus that you can rotate 90 degrees and fire into another key location. Those spots don't come along every day but they are nice when they do.

Once we get the ability to move AT guns short distances in all the current games I think you will be able to find more spots where the gun can be moved a short distance and cover a different tight lane. I am really liking that feature in CMRT.

[Talespin Jim]

Wow, thanks all. So much great information. I'm glad I asked the question.

[Talespin Jim]

There are, IIRC, 5 height levels (or maybe six, my memory fails me here) that a unit can be at. Prone soldier is one, kneeling soldier is two, standing soldier is three and then there are two more for vehicles of varying heights. AFAIK, when the target tool says "Reverse Slope - No Aim Point" it is saying that you don't have LOS to the ground in that action spot, but do have LOS to at least the top height level above it. Since Shermans are a tall vehicle -- 9 feet tall -- they are probably classified at being the tallest height level possible for spotting which means you should always have LOS to one in a "Reverse Slope - No Aim Point" action spot (although you would not necessarily have LOS to shorter vehicles or infantry in the same spot).

This is something I would never have figured out if you hadn't told me. I don't think I saw it in the rules or anywhere, and I just would not have thought to categorize into levels. So now I understand better what you are saying because if it says, "...reverse slope," I can actually see some height levels in that action space, now it's just up to me to figure out how high I can see and since a Sherman is so tall, I can just about for sure see it, I suppose.

A walking man would be different. In this case where the slope is so mild, I could get a rough idea of that by how far I am from the point at which the text changed to "...reverse slope." All I have to do is go to a topographical viewing mode and close in, so I'm looking at the unit and it's immediate surroundings as though I were above it in a helicopter. Then I use the target tool to find the farthest space toward the target space where I could see the ground "Area target" and count how many spaces it says "...reverse slope," and stop counting when it changes to "No line of sight." There probably isn't anything above 9 feet tall (call it ten feet to make the math easy), so I can now divide the number of spaces by ten and then multiply the dividend by the approximate height in feet of the target, (which is maybe five feet if I'm shooting at a man) and the resultant product will tell me about how many "...reverse slope" spaces to count back from the farthest "area target," and that is about the first space I can expect to see the enemy infantry unit. So actually this is incredibly useful now that I understand it. It's something you can do in your head, if I'm making myself clear.

For example, let's say we want to figure out how far away we can see infantry "hunting" toward us from the position we place our gun, when they will be walking up the slope of a small rise between us. We use the target tool to find the last action space where it says "area target," and that tells us where the pinnacle of the rise is. The first space beyond that will say, "Reverse Slope, no aim point," and we count that as space number one. We continue to count spaces as you move the targeting tool away from your unit, until you reach the point to where it says "No line of sight." Let's say that number of "reverse slope" spaces is 15, because it is a gentle slope. You take the number of spaces and divide it by ten (to make it easy), giving you 15/10 or 1.5. Then you guestimate how tall your target it, and I'd say an infantryman's head sits between four and five feet tall when they are hunting. So let's say five feet. So you multiply 1.5 times 5 to get the product of 7.5. You count back 7.5 "reverse slope" spaces and you have the approximate spot where they will come into view.

To make it more useful, but more complicated, and yet simpler, then let's abstract the distance of the size and number of spaces. In other words, what if you are not firing directly down a line of spaces? What if you are shooting across rows of spaces at a diagonal? So you simply look at where your first and last "reverse slope" points are along that straight line of fire, and guess at how many feet tall your target is, then imagine that line segment of "no aim points" broken up into ten equidistant segments, and count about that many tenth's along that line starting with the first "reverse slope" segment. Keep counting one segment for each foot high your target is, and that will get you pretty close to where you will be able to first see the target.

I think you would very quickly get to the point to where you can look top down on a unit and say to yourself, "It says no reverse point from here to here, and I want to shoot at something that is two and a half feet tall, so now I just guestimate about two and a half tenths of this line (which happens to be one quarter--so one quarter of the way down the line) and there is where the target comes into view. In a very short while, you could look at any line segment and make a fairly accurate guess as to where the enemy will come into view, based upon how tall the target will be.

So let's take a vote. Who thinks I'm OCD?

[PhilM]

This is something I would never have figured out if you hadn't told me. I don't think I saw it in the rules or anywhere, and I just would not have thought to categorize into levels. So now I understand better what you are saying because if it says, "...reverse slope," I can actually see some height levels in that action space, now it's just up to me to figure out how high I can see and since a Sherman is so tall, I can just about for sure see it, I suppose.

A walking man would be different. In this case where the slope is so mild, I could get a rough idea of that by how far I am from the point at which the text changed to "...reverse slope." All I have to do is go to a topographical viewing mode and close in, so I'm looking at the unit and it's immediate surroundings as though I were above it in a helicopter. Then I use the target tool to find the farthest space toward the target space where I could see the ground "Area target" and count how many spaces it says "...reverse slope," and stop counting when it changes to "No line of sight." There probably isn't anything above 9 feet tall (call it ten feet to make the math easy), so I can now divide the number of spaces by ten and then multiply the dividend by the approximate height in feet of the target, (which is maybe five feet if I'm shooting at a man) and the resultant product will tell me about how many "...reverse slope" spaces to count back from the farthest "area target," and that is about the first space I can expect to see the enemy infantry unit. So actually this is incredibly useful now that I understand it. It's something you can do in your head, if I'm making myself clear.

For example, let's say we want to figure out how far away we can see infantry "hunting" toward us from the position we place our gun, when they will be walking up the slope of a small rise between us. We use the target tool to find the last action space where it says "area target," and that tells us where the pinnacle of the rise is. The first space beyond that will say, "Reverse Slope, no aim point," and we count that as space number one. We continue to count spaces as you move the targeting tool away from your unit, until you reach the point to where it says "No line of sight." Let's say that number of "reverse slope" spaces is 15, because it is a gentle slope. You take the number of spaces and divide it by ten (to make it easy), giving you 15/10 or 1.5. Then you guestimate how tall your target it, and I'd say an infantryman's head sits between four and five feet tall when they are hunting. So let's say five feet. So you multiply 1.5 times 5 to get the product of 7.5. You count back 7.5 "reverse slope" spaces and you have the approximate spot where they will come into view.

To make it more useful, but more complicated, and yet simpler, then let's abstract the distance of the size and number of spaces. In other words, what if you are not firing directly down a line of spaces? What if you are shooting across rows of spaces at a diagonal? So you simply look at where your first and last "reverse slope" points are along that straight line of fire, and guess at how many feet tall your target is, then imagine that line segment of "no aim points" broken up into ten equidistant segments, and count about that many tenth's along that line starting with the first "reverse slope" segment. Keep counting one segment for each foot high your target is, and that will get you pretty close to where you will be able to first see the target.

I think you would very quickly get to the point to where you can look top down on a unit and say to yourself, "It says no reverse point from here to here, and I want to shoot at something that is two and a half feet tall, so now I just guestimate about two and a half tenths of this line (which happens to be one quarter--so one quarter of the way down the line) and there is where the target comes into view. In a very short while, you could look at any line segment and make a fairly accurate guess as to where the enemy will come into view, based upon how tall the target will be.

So let's take a vote. Who thinks I'm OCD?

Very impressively reasoned and explained - I understand!

Whilst I'd like to give the impression that I'm far too polite to vote "yes" in your poll, I would nevertheless say that, in my - sadly, mostly chastening - experience of CM, this is .... erm ... WAY ott!!

Given the vagaries of spotting first (or, often, not first, or at all), missing with the first few shots, and the reaction of taking cover / cowering in response to return fire, I count myself lucky if my guys hit anything at all in a likely target zone, let alone wondering where they may be able to hit something that is six feet high as opposed to something that is four feet high ...:eek:

[Talespin Jim]

I agree. It is down the list of priorities and thus just for fun. But think on this--the more factors you can figure out how to control, the more effective you become. Isolating factors one at a time will gradually improve our effectiveness.

[Vergeltungswaffe]

This reminds me of CMx1. I had all the LOS distances on a chart (ie you can see infantry 26m into dense woods, or whatever the distance was) and you always took full advantage of that knowledge in PBEM.