VaS and crossing the enemy's 'T' suggestion
- Thread starter BuShips
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DM said:The more I think about it the more I'm tempted to either remove the +1 for beam-on attacks, or just apply it to firing from any angle
I'd really like to see a proven analysis combining the effects of range, caliber, projectile trajectories (ballistics), armor and target profile, although I've found something close. :wink:
Keith said:
In a way of backing up those comments Keith, let me offer up a tidbit of info that I have that's historic and something to "chew on". At about a range of 14,000 yds. side hits and deck hits are equally numerous, but at 30,000 yds. 80% of the hits are deck hits. What I do not know yet is the range at which those deck hits cease, but I'd guess after just a few miles the shells' trajectories would begin dropping. Target aspect angle would seem to be variable, and that's the justification that Mongoose has placed upon their "large silhouette" modifier, but I'd only give that any real due consideration at point blank ranges (maybe around 5"?). I'll admit that the real barb was seeing no way to execute a line-of-sight usage of crossing the T (limiting return fire to the T's top with just the van ship's forward guns) while at the same time seeing the inferior tactical position getting a reward for getting itself outflanked. :?
Hugbiel said:
I'm of the opinion that having more target seen doesn't give any great advantage to a ship firing upon it (unless it is sitting at close range). From what I've read, the range to the target is plotted and the guns are fired. Since most of the time the guns are under the control of a gun director and not under any local control, you really don't have time to spread the angle of the turrets out sideways to take any real advantage from a side profile. Most of the salvoes deviate anyway in three dimensions and can fall short, long or to either side and that isn't really something that can be planned for. I do see where you are coming from, as the game designer thought much the same and gave it a bonus to hit. In a short period of time I'll post a historical chart that would seem to support my contention that target profile doesn't seem to calculate much into hit percentage.
Hugbiel said:
The distinction between ballistic and flat trajectory is was trying to make was that for a ballistic shot the range is critical. on a flat trajectory (age of sail ranges and torpedo tracks) it can almost be ignored. with ballistic attacks the size of a taget is determined by deck area which is unaffected by aspect.
Your point on ease of targetting is one for someone with more historical knowlegde than me.
Keith said:
Keith, you humble yourself too much, me thinks :wink:. You are dead-on right about what you speak. I've even modified my own previous beliefs and now fully believe that target aspect angle doesn't modify the odds of a hit, unless the target is laying alongside at less than a few miles at most.
Keith said:
Or me too.
But IMHO it's where Mongoose find the +1. So I try to notice it.
AFAIK the possibility seem logical. As a technician i know that's a factor. But one among other.
(knowing opponent ship spec, distance betwenn turets for exemple is an other, size and efficience of the gun director is an other realy more important )
For history of radar i can say that politics has thinking that having the best firing solution is important. Having a bigger view of the target help, but i can't tell if in WWII it's a pratical thing or a something to little to be considered.
But i'm sure that gunners correct the firing of their guns by estimating the difference betwen the planed center of the salvo and the real one. They try to negate the constants deviations, and place the target in the center of the variables ones where probability of hit is maximum. ( Not an easy thing on a moving target from a moving firing platform.)
So having a better firing solution and salvo report is a matter of the times. But I have no idea how mutch it's affect what.
Hugbiel said:
Hugbiel, I appreciate your comments. I understand where you are thinking, and it sure makes some sense. I've been doing some exhaustive digging around and I am getting an idea that while to you and even me that the side profile would be best to view, in the age of fast steel ships and the longer range gunnery from just beyond a few miles to over the horizon that the target aspect wasn't even mentioned in the documents that I've been looking at. You have however given it some additional thought and what you just said regarding deviations and hit probabilities is exactly what was considered to a great degree in naval gunnery. I'll shortly be posting some charts that contain how actual naval gunnery was calculated in World War 2. For me, there is nothing better that can be used for calculating for a game what hit probabilities might be than actual naval gunnery procedures and tables. I just wish that my mind was a bit more trained so that I could break down all of the data, but from what I've been reading target angle wasn't anywhere in their calculations. I had said the other day that at 30,000 yards 80% of the hits were deck hits (and ones that most likely all penetrated), but at 14,000 yards side hits and deck hits were about 50/50. I still do not find additional information that is stated like that was, as it would help out greatly with any general understanding of how the shells fell at closer ranges. At least I have the tables with which we can study the hit probabilities on targets in a real-world proven method. I consider this material to be a naval game designer's best method of recreating in miniature naval gunfire probabilities with accuracy. It's not critical for the game of Victory at Sea though, as it is functioning well for the level of game that it is targeted for, and that is fast-play. I still want to study this information a bit more, and then I'll share it here with any that are interested.
Alright, I'm ready to release the fruits of an exhaustive search for anything that would backup the +1 AD hit bonus for a Large Silhouette. Those peering over my shoulder should know that this concerned me to the level that it did mainly because of a lack in the rules to use LOS for ship counters like is used with smoke counters. The Large Silhouette bonus was sitting there all fat and happy and seeming to give a reverse benefit to being at the bottom of the T, especially with the lack of restricting the forward return fire of ships following the target of the enemy ships crossing its bow. When I decided to evaluate the "beam bonus" as a separate item and not as appearing to compound the absence of a "full" crossing bonus, I at first saw the logic of the possibility that it could be validated. While not coming from Hugbiel's perspective of optical rang-finding advantage, I thought it might be that as long as the two ships were exchanging fire on a line parallel to each other there would seem to be an advantage. My reasoning was that if one were to view the arrangement of a typical Hood/Bismarck primary weapon layout, one could surmise that the parallel track of the target would present more area to be hit, regardless of range. This is somewhat displayed in the second graphic on the beginning page of this topic. As range increases, the percentage of hits to the side armor shifts over into a higher number of deck hits. Although a few days ago after finding some actual naval gunnery salvo dispersion charts and their lack of considering the target's hull angle in them, I was swung over into thinking that the hull angle wasn't a factor. Now I now that the chart that I was studying was just focusing upon the salvo pattern itself without regard for what was "under" that shot pattern. Although I have not found a like-set of guidelines specifically for ship target angle, what I have found now confirms at least that I have solid backing to defend the author's inclusion of the silhouette firing bonus. DM will find this "interesting", as I had pretty much convinced him of the lack of its import except perhaps at very close ranges. 
Thus, I have swung back and forth several times, based upon the data that I had absorbed. Although initially "angry" at the bonus, I drew up the chart previously mentioned as a way to give it some credibility, separate from my study of arguing for inclusion of a better representation of crossing the T.
Understand also that I am taking the following quotes on faith, due to the good reputation of the website that the data is taken from (http://www.navweaps.com/):
I feel that this finally gives those that are interested or even those critical of the Large Silhouette bonus something to think about. If you take the average of the three range ratios, you basically can say that there is a 2:1 advantage in hitting a broadside target as to hitting an end-on target.
As far as my main subject area for this topic being a discussion on Crossing the T, I am now pretty much satisfied that it has run its course (no pun intended, well OK pun intended!) as it comes down to using Line of Sight on counters or ship models in order to simulate the full tactical benefit of limiting an enemy line's return fire while concentrating your own firepower upon its lead ship (called the guide in formation changes). I'll invite any further use of the topic for additional discussion on my offering and I will try to post additional gunnery data that I found to be fascinating.
Thus, I have swung back and forth several times, based upon the data that I had absorbed. Although initially "angry" at the bonus, I drew up the chart previously mentioned as a way to give it some credibility, separate from my study of arguing for inclusion of a better representation of crossing the T.Understand also that I am taking the following quotes on faith, due to the good reputation of the website that the data is taken from (http://www.navweaps.com/):
Code:
Accuracy During World War II
A Naval War College study performed during World War II estimated that an Iowa Class (BB-61) battleship firing with top spot against a target the size of the German battleship Bismarck would be expected to achieve the following hit percentages.
Range Percentage hits against a broadside target Percentage hits against an end-on target Ratio
10,000 yards (9,144 m) 32.7 22.3 1.47:1
20,000 yards (18,288 m) 10.5 4.1 2.56:1
30,000 yards (27,432 m) 2.7 1.4 1.92:1I feel that this finally gives those that are interested or even those critical of the Large Silhouette bonus something to think about. If you take the average of the three range ratios, you basically can say that there is a 2:1 advantage in hitting a broadside target as to hitting an end-on target.
As far as my main subject area for this topic being a discussion on Crossing the T, I am now pretty much satisfied that it has run its course (no pun intended, well OK pun intended!) as it comes down to using Line of Sight on counters or ship models in order to simulate the full tactical benefit of limiting an enemy line's return fire while concentrating your own firepower upon its lead ship (called the guide in formation changes). I'll invite any further use of the topic for additional discussion on my offering and I will try to post additional gunnery data that I found to be fascinating.
Here is another interesting bit that I found. This is a naval gunnery hit dispersion chart. At first this influenced me to think that a ship profile did not matter because when you study the pattern it gives an equal percentage of error to direction X and Y. As it does not give a hint as to the scale of the error over a set distance here, I was originally placing the entire target ship well into this pattern, and would give the impression that the profile did not matter. From the information presented in my earlier post above, it would seem to be in a sort of conflict. While nothing is perfect, the table is still interesting from a gamer's perspective. For example, using two 8-sided dice of two colors we could duplicate the chart and use it for a game. Though it at first was used to calculate salvo dispersion "for real", now it's a game aid. 8)
Waow That's a good search, that you made BuShips.
This give me some thinking. I don't know your mathematical base so I will try not to go too fast.
The dispersion chart look like a gaussian curve with no difference for direction. ( A gaussian curve is the kind of curve who link value to probability you get with lot of little hazard factor. It have a flat hight probability plateau in the center and deacrease fast after it. )
It could be a scalled pattern : the shape stay the same but the base distance change.
If as I estimate the deviation probability is only different for the distance of the target course of the shell and the same in all direction , we can see the 50% zone as a tube. This tube will not give the same shape if it cross sea with a flat trajectory or a ballistic one. So the dispersion pattern. Unless there's other factor.
mmm not sur if i am understandable.
This give me some thinking. I don't know your mathematical base so I will try not to go too fast.
The dispersion chart look like a gaussian curve with no difference for direction. ( A gaussian curve is the kind of curve who link value to probability you get with lot of little hazard factor. It have a flat hight probability plateau in the center and deacrease fast after it. )
It could be a scalled pattern : the shape stay the same but the base distance change.
If as I estimate the deviation probability is only different for the distance of the target course of the shell and the same in all direction , we can see the 50% zone as a tube. This tube will not give the same shape if it cross sea with a flat trajectory or a ballistic one. So the dispersion pattern. Unless there's other factor.
mmm not sur if i am understandable.
Yes, you are correct that my math is a bit rusty. What I was taught years ago has faded from memory without keeping a use for it. That is sort of how it goes, lol :roll:. Of course the center point is called the "Mean Point of Impact". From what I can observe on the chart, the greater the distance is from the "MPI" the faster it drops off into insignificance. They mentioned that "wild shots" are not considered for this purpose. Things are assumed to be as stable as possible, not counting for curve of the Earth, wind, course, etc. Just for fun, I think I will make a new version of the chart and fill in the boxes with tints that show what I already recognise; that it forms a thick plus sign, and fades the errors into the corners more that to the solid X & Y locations. I might even add the "game" condition of 8-sided die rolls too. :idea:
I guess that all trajectories with over a mile range are liable to have a large ballistic element (I think that's about the limit given muzzle velocity and the effect of gravity on the projectile) so this dispersion pattern is likely to be for "ballistic gunnery".
One interesting consideration ifs the targetting of a moving ship, assuming it travels throught the aimed point it will be its angle of approach that will be most important. If it is runnung parallel or perpendicular to the firing ship is corridor of traval will be through the bands with the highest prbability of a hit. If the vessel approaches at 45 degrees much of its corriodor will travel through areas with a lowerhit probability
One interesting consideration ifs the targetting of a moving ship, assuming it travels throught the aimed point it will be its angle of approach that will be most important. If it is runnung parallel or perpendicular to the firing ship is corridor of traval will be through the bands with the highest prbability of a hit. If the vessel approaches at 45 degrees much of its corriodor will travel through areas with a lowerhit probability
Keith said:
Yes, that would be the case if the ship were going at a speed that had it moving through the pattern as the shots fell, but I don't think that it should be used that way. Of course you would be correct if the scale of the ship was the size of the entire width or length of the chart, but I do not think that is the case either. From what I've read, this chart uses the idea that a salvo will vary and disperse with range, considering there are a lot of things acting upon a ship that is firing (and there are). Each of the 64 sections is defined as being "one probable error" wide, using the fact that 50% of the shots fired will end up near the Mean Point of Impact, either in range or deflection. The ones that are more distant from the MPI (the other 50%) will be because of additional errors in either range (left to right on the chart) or deflection (top to bottom). Those corners that you saw were a lot safer-appearing are areas where shots are "off" in both range and deflection of course. Your contention that the chart is basically for ballistic gunnery should be a correct one.
If you have the time to kill, here is the very informative page I have been viewing.
http://www.navweaps.com/index_inro/INRO_BB-Gunnery_p2.htm
This is page one, so you don't have to poke about for it.
http://www.navweaps.com/index_inro/INRO_BB-Gunnery_p1.htm
DM said:
All shell trajectories have an entirely ballistic element at any distance
I'll change it for you DM. He meant to say that "I guess that all trajectories with over a mile range are liable to have a larger ballistic element than trajectories that are less than a mile."
How's that? :wink: Thanks for the help, btw. It's hard to wrap one's mind around the idea that a projectile that has just begun its flight is not travelling a straight path right out of the barrel, and I'm sure that is what he was thinking about. There is perhaps one exception that you might think about (and I'm saying this for fun and not seriousness), but it does start one to think about it. There should be a point during flight where the downward trajectory of the projectile is perfectly cancelled out by the 'downward' curvature of the Earth, thus synchronising the projectile arc with the curve of the Earth's sphere (for just a part of a second). :lol:
DM said:Instantaneously, yes I guess so. For longer durations I guess thats called "orbit"
You mean like this??? :lol:
The article is below. Now that's what I call trajectory! :wink: The sweet thing about this is that they used 16" battleship guns to test satellite launches. I'll bet you know about Gerry Bull. Sad ending for a guy with dreams of space.
http://www.astronautix.com/articles/abroject.htm
