Stranger than you CAN imagine

[Rockin Robbins]

I think it was Issac Asimov who said that the universe was not only stranger than we believe but stranger than we CAN believe. Follow me into the twilight zone.

We have long been using Dick O'Kane with the instruction, bearing set, range who cares? But because of the short distance the torpedo travels straight out of the tube before it turns to the set bearing, a distance called reach, a slight angle is created from the apparent origin of the torpedo's path and the position of our submarine when the torpedo is fired. That means that the range in the TDC actually is meaningful even in a point and shoot shot....

Yeah, that's what I said too. OK, how bad can this get? Can't be too bad, right? So I set up an 8000 yard shooting gallery with tankers arrayed about every 10 degrees, with the center one on the zero bearing. Let's make boom-booms! This is MY kind of experimentation.

Through this whole thing I am using slow speed torpedoes for max range. Stupid me!

First, let's send six torpedoes up the zero line. We'll fire two on the default zero range, two on 3475, the manual setting I always use for Dick O'Kane, set 2 for 3000 and 2 for 8000 yards. Shoot times six!

Nasty finding number one! Of six torpedoes shot, only two reached 8000 yards. The rest crapped out between 3000 and 4500 yards. Also the torpedoes all ran different speeds, making spacing really important to tell which torpedoes were which. Which ones reached the target? I don't know. Set 'em up again.

This time I shot only the first two, set at zero range, up the zero line 30 seconds apart. They both made 8000 yards this time and they......both......missed right by about a target length and a half. What the????? Tried if again and again. When the torpedoes reached the 8000 yards (about half the time) they all missed right. These are zero gyro angle shots! Somehow the zero range predictable alters the path to the right far enough to miss consistently at 8000 yards. Play the scary music.

Any other range went up the zero line and struck the target if the torpedo got that far. I learned that experimenting at 8000 yards was darn frustrating and I'd better shorten up the shooting gallery. So I did.

I set up a new one at 3200 yards with target tankers on the 315, 320. 334, 346, 0, 14, 24, 35 and 49 bearings. That is more like it! I sent three torpedoes up the zero line with 1475, 2650 and 5008 ranges. What do you think happened?



Well that was refreshingly expected. They were very similar in path and all struck pretty much the identical spot.

Now let us leave the bounds of sanity and enter the darker realms. We'll aim at the 49º bearing boat. What happens with a shot set to 9843 yards?



It's a clean miss! The torpedo goes straight to the end of its reach, turns right but stops turning early so that 9843 yards it crosses the set bearing. Anywhere before there it's going to miss left by varying amounts depending on the distance traveled. So what ARE the allowable parameters at 3200 yards? I decided to find out by experimentation with the game, since a mathematical proof does not have to hold true there, especially after the zero bearing zero range shot consistently missed right earlier. I need a drink. NOW!

Turns out that a range of 5582 yards will just clip the left end of the target.



Of course, the correct range nails it



And 2625 clips the right end.



So there you have it. For a target sitting at bearing 49º the margin of error for this tanker was -575 to +2382 yards, 80% to 174% of the actual range would hit the target. Lesser deviations from zero bearing would be more tolerant, greater bearings would be even less tolerant to proper range being input into the TDC.

The conclusions we can make here are the following. Don't shoot Dick O'Kane shots from more than 2000 yards, with torpedo gyro angles much above 15º left or right. Between 345 and 15, you'll get your hits. Outside that you better put a rough range estimate into the TDC. There's plenty of slop, but the more accurate the better.

Inside of 2000 yards don't change a thing. You're a deadeye killer there. Proceed as normal. Of course you realize that one sonar ping will peg that range close enough for anybody's liking and you can shoot out to 3000 yards with perfect accuracy. Well not perfect but nobody on the target will care that the shot landed ten yards off the aiming point.

And don't bother shooting beyond 3000 yards with the stock game. Half the slow speed torpedoes run out of juice between 3000 and 4000 yards. You can't sink ships with a wimpy torpedo. Luke, what about RFB? Ducimus is in the slammer, so does anybody know the score with TMO?

Want to play? Here's my 3200 Yard Shooting Gallery for your listening and dancing enjoyment. Unzip into your Wolves of the Pacific\data\single missions folder.

[Arclight]

Haha, told you range was relevant. :p

Nice write up.

[Sledgehammer427]

and thats why i hate broad angles...

hey Rockin Robbins...i need some help with a term paper :rotfl:
just kidding

[Rockin Robbins]

Originally Posted by Sledgehammer427

and thats why i hate broad angles...

hey Rockin Robbins...i need some help with a term paper :rotfl:
just kidding

Man! I was thinking that I had finally written something that NOBODY cared about.

Arclight, the general principle still holds. If you're shooting under 2000 yards, that's all but about 3 of my shots ever, it really doesn't matter so long as you pull the triangle down and have the normal 1475 yards in the system. If you're shooting 3000 yards or more, find a way to put 3000 yards in the TDC. That's close enough.

If you're shooting 4000 yards or more it doesn't matter because half your torpedoes aren't getting there anyway.:rotfl: That was the real shocker for me.

[Arclight]

I know it doesn't really matter. I'm just a perfectionist, so I couldn't resist.

I always set the range as high as I can get it (requires some fidling with the stadimeter). Then the "deviation" is never more then the distance the tubes are from the centerline (at least when firing at 0 bearing ). At first I set the range as low as it would go, but then you notice the issue when firing at longer ranges.

Like you suggested, a quick ping for range will solve the issue.


But I never noticed torpedo's running out of steam too early. :hmm:
Longest (RFB) shot for me was 4 fish running more then 6000 yards, with 2 hits and actually detonating, the other 2 going in front and behind the target.

Was this while you were testing the new RFB?

[Orion2012]

Originally Posted by Arclight

I know it doesn't really matter. I'm just a perfectionist, so I couldn't resist.

I always set the range as high as I can get it (requires some fidling with the stadimeter). Then the "deviation" is never more then the distance the tubes are from the centerline (at least when firing at 0 bearing ). At first I set the range as low as it would go, but then you notice the issue when firing at longer ranges.

Like you suggested, a quick ping for range will solve the issue.


But I never noticed torpedo's running out of steam too early. :hmm:
Longest (RFB) shot for me was 4 fish running more then 6000 yards, with 2 hits and actually detonating, the other 2 going in front and behind the target.

Was this while you were testing the new RFB?

If it was I've had a few fail to start, or the motor dies before they reach 100 yards, but haven't really shot over 1800 yards.

Those pictures though aren't from the RFB 1.52 unless RR is using a HUD overhaul.

[Sledgehammer427]

that gui looks like TMO...
the PK button would have GSP labeled on it if it were RFB

[Skyhawk]

"Man! I was thinking that I had finally written something that NOBODY cared about." -RR-

LOL @ RR, you'd be surprised! :rotfl:

"Much Ado About Nothing" mean anything? Ring any bells? :hmm:

Now, to make sure I understand correctly:

You mean to say that the O'Kane method of torpedo firing solutions is less than accurate at long ranges?

That torpedoes both real and simulated sometimes fail to perform to specs?

And speaking of "reach", while we are mixing simulated reality with reality itself . . .

What about the effect of ocean currents on a 1.5 mile / 8,000 yd. shot? Or a 4,000 yd. shot?

What about the effect of wave action on a 1.5 mile / 8,000 yd. shot? Or a 4,000 yd. shot?

You mean to say, that even though the O'Kane method of torpedo firing solutions is highly reliable, that it is not foolproof at extreme/long range?

Wow, who woulda thunk? I can't imagine!

longshot - 1. an entry, as in a horse race, with only a slight chance of winning. 2 a. bet made at and against great odds. b. A risky venture that will pay off handsomely if successful.

Maybe that's why they call them "longshots"? Geeze Louise, lol.

Thank you for enlightening us oh mighty "Self-Proclaimed and Self-Righteous Protector of the Subsim Forums". Here's hoping your sense of humor is still intact.

Ever so respectfully submitted with best regards (in spite of the risks involved) ,

"Skyhawk"

[Munchausen]

:hmm: The O'Kane method still requires you to set the target's AOB +/- lead angle. From the looks of the TDC in your screenshots, it doesn't seem like you did it. Please clarify, 'cause I'm confused.

[Mush Martin]

Who Knew

[SteamWake]

While programming all this logic keep one thing in mind.

Its a pristine ocean. No currents, no 'real' kelp, and so on..

[Diopos]

Originally Posted by SteamWake

While programming all this logic keep one thing in mind.

Its a pristine ocean. No currents, no 'real' kelp, and so on..

General sim comment not specific to SH4.

The fact that say an important environmental parameter such as currents is not explicitely and "continuesly" simulated in the game, does not mean that it is not taken into account in specific game aspects or events. If you had collected the perfect data set on a target which is "steady on its course" it wouldn't be important if it is close or further away. You're only concern would be if the impact point would be within your selected torp's range. But long shots were... longshots! They missed. Still assuming perfect target data, there are other parameters that influence a longshot (and currents seems to be an important one). In many sims paremeters not explicitely simulated maybe implicitely simulated, through the use of tables or random numbers that influence the specific game situation.
So if even if we don't "feel" the currents, that doesn't mean that there are not ingame situations that somehow take them into account.

Again I say that my comments are not specific for SH4.
(I don't know how the darn thing works! )

[Hitman]

Hello

I think that's the old convergence problem :p See this thread I opened long ago:

http://www.subsim.com/radioroom/show....php?t=121744&

Since your optics are not right above your torpedo tubes, there is a convergence correctiion needed, and there's where range matters.

[Rockin Robbins]

Actually, Hitman, your posts were what set me off to experiment to determine just how much difference it made. The answer: not much but plenty to cause muchas misses if you aren't careful.

I was using the stock game so I could see on the nav map exactly where I hit the target and determine where the boundaries were for accuracy in range. Although the aiming parameters would be the same in RFB and TMO, the premature shutdowns may be different in those two mods. That's why I asked for info in my first post. I'll do the research myself if nobody steps up.

@Munchausen: Actually I WAS set up for a Dick O'Kane, because the speed of those puppies really was zero. My Shooting Gallery Test Mission has them anchored out there so the only error can come from the inherent geometry of the torpedo course itself. My own submarine was also stationary.

The parallax between the position of the torpedo tubes and the position of the periscope or TBT has nothing to do with the problems. That difference is automatically compensated for by the TDC. In fact, the distance between periscope and torpedo tubes, both fore and aft, were adjustable! Now why would that be? Well, fleet boat lengths varied from the 253' length of the Gar class to the 311' length of the Gato and Balao classes. The adjustable parallax parameter made the TDC equally deadly in each.

And in the virtual ocean there are no currents. The wave action does not make surface currents that offset the aim of the torpedo at all. Our sim would have to be much bigger to account for those parameters. But if you think about it, since your submarine, torpedo and the target are both immersed in the same current conditions, the effect cancels out and it is just as if there were no current at all. Wave action, being very localized, would be different.

Originally Posted by Skyhawk

Now, to make sure I understand correctly:

You mean to say that the O'Kane method of torpedo firing solutions is less than accurate at long ranges?

Yup. But you can fix that by entering a range in the 2500-3000 yard area if you are firing a long shot.

Originally Posted by Skyhawk

That torpedoes both real and simulated sometimes fail to perform to specs?

No, the specs call for a certain percentage of failures. That way, just like Microsloth, the anomalies become features, and actually raise the price of the product!

Originally Posted by Skyhawk

And speaking of "reach", while we are mixing simulated reality with reality itself . . .

Well, that's what I'm left with after the research. The devs did incredible research into the implications of TDC operation and actual torpedo placement that just about perfectly "mixed reality and simulation" here. This implies weeks or months work modeling an aspect of the game that nobody would ever appreciate (until crazy me came along with my shooting gallery). You know, the Mark 18 had a shorter reach and a tighter turning radius. I'll bet my shooting gallery would show the difference of the lesser parallax! The devs we often criticise are geniuses!

I fully expected that none of this complex and hidden geometrical quagmire would be there at all!

The biggest surprise for me: Awhile ago, someone asked why they could not set their TDC to range zero. He was all upset about it. So in my tests I tried some 8000 yard shots at the zero bearing with the TDC set to zero range. All the shots missed right. Any other range hit the target if the tropedoes got there. Anybody have any idea why that should be so? I think that is the only situation where the simulation yields different results than the real TDC.

[Hitman]

The parallax between the position of the torpedo tubes and the position of the periscope or TBT has nothing to do with the problems. That difference is automatically compensated for by the TDC. In fact, the distance between periscope and torpedo tubes, both fore and aft, were adjustable! Now why would that be? Well, fleet boat lengths varied from the 253' length of the Gar class to the 311' length of the Gato and Balao classes. The adjustable parallax parameter made the TDC equally deadly in each.

But the TDC can't automatically compensate everything. True it will take into account one side of the triangle, which is known -distance from the optics to the torpedo tube- but it still will lack the variable of distance to target in order to set the proper correction for parallax.