REQ - torpedo speed chart for SHIV

[Tigershark624]

Ahoy,

I've been scouring the boards looking for a mod that includes a chart for zero-angle torpedo shots as appears in the MaGUI mod for SHIII. If one already exists, can someone direct me to it? If there is none, is there a historical source for such a chart that I might just save a screen shot of and print out? I use the zero-angle method in SHIII with a fair amount of success and wanted to use it in SHIV.

Thanks,
Tigershark

[razark]

Originally Posted by Tigershark624

I use the zero-angle method in SHIII with a fair amount of success and wanted to use it in SHIV.

I'm not familiar with this. Can you explain what it is?

on the torpedo loadout screen there is a box that gives you the details for each torp including speeds warhead and such

[Tigershark624]

Originally Posted by razark

I'm not familiar with this. Can you explain what it is?

What I'm looking for is this, from Makman's excellent MaGUI mod:



It shows the lead angle for firing a torpedo, in this case set to 44 kts, at a gyro angle of zero to intercept a target moving at the speed indicated on the left and the anticipated AOB at impact, indicated above. I get target speed by taking the length of the vessel and dividing it by the time it takes it to cross the vertical line in the scope. I then multiply that by 1.95 and it gives me the target's speed in knots. I guesstimate the AOB and try to get as close as possible to the target's anticipated track to minimize errors. It works pretty well, especially since range isn't really a factor, unless the target is beyond the range of the torpedo.

So, the question remains, perhaps correctly asked this time, is there any kind of chart like this for American torpedoes? I think they'd be just as handy in SHIV as in SHIII.

Regards,
Tigershark

[BigWalleye]

Try the Submarine Torpedo Fire Control Manual,

www.hnsa.org/doc/attack/index.htm

Plates XVII and XVIII have the information you are looking for, although in a rather less user-friendly format than your SH3 chart. But if you take the trouble to pick points off the curves, you can roll your own table for any target speed and track angle, not just a normal approach.

[razark]

Originally Posted by Tigershark624

What I'm looking for is this, from Makman's excellent MaGUI mod:
<snip>
It shows the lead angle for firing a torpedo, in this case set to 44 kts, at a gyro angle of zero to intercept a target moving at the speed indicated on the left and the anticipated AOB at impact, indicated above.

Ah, that. Never seen anyone upload one.

Originally Posted by Tigershark624

So, the question remains, perhaps correctly asked this time, is there any kind of chart like this for American torpedoes?

Do you have Excel?
OpenOffice works, too. Good enough to send a Jap battleship to the bottom, but I make no claims that it's perfect.

[Tigershark624]

Originally Posted by razark

Do you have Excel?
OpenOffice works, too. Good enough to send a Jap battleship to the bottom, but I make no claims that it's perfect.

Yes, thank you! This is exactly what I was looking for. A little work with the cell colors to make it easier to read quickly and I'm set.

[gmetzo]

Originally Posted by Tigershark624

What I'm looking for is this, from Makman's excellent MaGUI mod:



It shows the lead angle for firing a torpedo, in this case set to 44 kts, at a gyro angle of zero to intercept a target moving at the speed indicated on the left and the anticipated AOB at impact, indicated above. I get target speed by taking the length of the vessel and dividing it by the time it takes it to cross the vertical line in the scope. I then multiply that by 1.95 and it gives me the target's speed in knots. I guesstimate the AOB and try to get as close as possible to the target's anticipated track to minimize errors. It works pretty well, especially since range isn't really a factor, unless the target is beyond the range of the torpedo.

So, the question remains, perhaps correctly asked this time, is there any kind of chart like this for American torpedoes? I think they'd be just as handy in SHIV as in SHIII.

Regards,
Tigershark

Hi , I know this is a post from like a decade ago , but could you possibly elaborate on how you are utilizing this card? Or if someone can point me to documents about it? I am not sure I understand how it functions.

[razark]

Originally Posted by gmetzo

Hi , I know this is a post from like a decade ago , but could you possibly elaborate on how you are utilizing this card? Or if someone can point me to documents about it? I am not sure I understand how it functions.

The chart is set up for firing a zero gyro angle shot (torpedo running straight ahead, to hit as the target crosses your bow).


This one is specifically for a torpedo running at 44 knots, and you'd need different charts for different speed torpedoes.


Across the top is the torpedo track angle (the angle between the target's course and the torpedo's course). Because the torpedo is running straight ahead, this is also the angle on the bow when the target is directly ahead of you, since the line of sight at this time would be the same as the torpedo track.


Down the side is the speed of the target in knots.


Each cell in the chart is the lead angle at firing time.




So, to fire a torpedo at a ship doing 1 knot on a course that is directly perpendicular to your course, you would aim your scope at 1.3 degrees (port or starboard, in the direction the ship is coming from), and when the ship crosses the center wire, you fire.


For a ship traveling 12 knots on a course that is 70 degrees off of yours (it is coming towards you slightly), the lead angle would be 13.2 degrees.
A 20 knot target crossing you at 140 degrees (headed away from you somewhat), the lead angle is 24.1 degrees.



In the situations described, G=0, so Ta and TTa would be the same. Because of the way the math works out, range is completely irrelevant.


For a little light reading:
https://maritime.org/doc/attack/index.php

[ElCid97]

It's just a table to help you determine your lead angle on the periscope when firing a shot using the sub itself perpendicular to the path of the ship.

If you want to hit a target right at 90* and it's traveling at 5kts, then you would turn the periscope towards the target and fix it at 6.5 degrees (353.5 degrees if it's coming from the left). When you see a part of the target you want to hit cross the centerline of the periscope, you fire your torpedo(s) and they'll hit.

What this chart in particular allows you to do is set it up so that you can hit the target at something other than 90* on.

For example, if you want to hit a target doing 9 kts at an angle of 80* (to reduce the chance of a dud, for example) then you would set the "lead" at 11 degrees towards the target.

Keep in mind you should still put your boat perpendicular to the track the target is traveling for this to work as it should.

Also keep in mind this particular chart is for the "fast" setting of the German torpedo. There are two other charts from what I'm seeing in this screenshot for the "medium" and "slow" settings (40 and 30 at the bottom).

This is similar to what has been dubbed the "Dick O'Kane Method" for US fleetboats. This chart is just a bit more "in-depth" than what we have on the US side.

I have a similar chart for 90* only in the gramaphone chart I made a while back using some formulae, etc. It's just not as advanced as this one.

Regards,

ElCid97

[gmetzo]

Thank you very much for the fast and informative responses , I appreciate it a lot!

[smm]

It's commonly called Dick O'Kane method.




There's quite a few YT videos on this. You can actually do this w/o scope even - I have a video in a storm where used radar (hah, like that would work in that sort of a storm I had there.. ) to plot the ship's course, get my 90d normal, and then used the crew hydrophone readings to fire the torpedoes..







--smm