Finding Range

corsair15 · 11-20-10, 08:59 PM

I have a question about finding range to target without the stadimeter.

First, I wanted to mention that I cannot stand the fact that I can't just input range, speed, and angle on bow with the numpad. It would be so much cooler if I could.

However I actually do not know how to find range without the stadimeter. There was an equation in the instruction manual, and I actually do not know how to use it. I can do math fairly well, but I can't make out what the equation says in the manual. It says something like (Number of degrees divided by [cos] multiplied by [tan] etc etc)

Anyway, I wouldn't actually know how to use that equation anyway even if I did know what it said. So could anyone give me the equation in simple terms that I could do with a calculator or a piece paper preferrably?

I realize that the lines on the periscope represent a specific number of degrees to help you find range. What is the math I'd need to do after I find the degree and bearing to target?

Any replies would be welcomed.

Diopos · 11-21-10, 01:57 AM

R=H/tan(φ)

R - Distance to target
H - Height from top of mast to waterline
φ - angle you observe the top of mast through the periscope

You must know H beforehand (identified target or own estimation)
For small φ's you can use R=H/φ as long as φ is in radians not degrees.

corsair15 · 11-21-10, 05:42 PM

Is that Tangent, multiplied by the number of degrees?

So: Height divided by Tangent multiplied by Angle = Range ????

I'm still not exactly sure (I never took Geometry or Trig in school, I wish I would have though, because now I'm trying to learn it by myself)

razark · 11-21-10, 06:09 PM

It's height divided by the tangent of the observed angle (I'm guessing degrees for the angle).

You'll either need to memorize the tangents of angles, have a table to look it up, or have some device for calculating it.

Pisces · 11-22-10, 08:38 AM

If you use the "TGT Dial AOB Fix" mod or whatever it is called, then you can click on the range dial an turn it until whatever range you desire lines up with the range indicator. Basically you don't measure the observed height of the target (the two overlaid images of the scope are not used), but force it to use it's default (hidden) heigt angle.

Let me see if I can find a link to it.

[EDIT] It's called the "Easy AOB" mod. Go figure:

http://www.subsim.com/radioroom/showthread.php?t=152945

What I meant was, that to set a range (that I presume you know, like by eyeballing, or I misunderstood) it doesn't matter if the mast is small and the optical size is big, or the mast is large and optical size is small. If you know the range, and just want to set it, just fumble with the dials until it is set.

[EDIT 2]Sorry, I re-read the thread and I obviously misunderstood.

tomoose · 11-22-10, 11:06 AM

I must be missing something here. Even with the formula mentioned you're still missing some info, aren't you?

You want to find the range and you've identified the ship and got the mast height from the ID manual. That part is clear enough. How do you determine the verticle (observed) angle without the stadimeter? Which hash mark etc do you use in the periscope/TBT? You need at least two pieces of info in order to solve the equation.

If
Y = mastheight (as given by ship ID book), and
X = angle (observed angle fm sub to mast top, from the horizontal), and
Z = range

Range(Z) = Height (Y)/tan X
How is X determined without the stadimeter or some other device?

11-20-10, 08:59 PM	#1
corsair15 Watch Join Date: Sep 2010 Posts: 21 Downloads: 6 Uploads: 0	Finding Range I have a question about finding range to target without the stadimeter. First, I wanted to mention that I cannot stand the fact that I can't just input range, speed, and angle on bow with the numpad. It would be so much cooler if I could. However I actually do not know how to find range without the stadimeter. There was an equation in the instruction manual, and I actually do not know how to use it. I can do math fairly well, but I can't make out what the equation says in the manual. It says something like (Number of degrees divided by [cos] multiplied by [tan] etc etc) Anyway, I wouldn't actually know how to use that equation anyway even if I did know what it said. So could anyone give me the equation in simple terms that I could do with a calculator or a piece paper preferrably? I realize that the lines on the periscope represent a specific number of degrees to help you find range. What is the math I'd need to do after I find the degree and bearing to target? Any replies would be welcomed.

11-21-10, 01:57 AM	#2
Diopos Ace of the Deep Join Date: Jul 2008 Location: Athens, the original one. Posts: 1,226 Downloads: 9 Uploads: 0	R=H/tan(φ) R - Distance to target H - Height from top of mast to waterline φ - angle you observe the top of mast through the periscope You must know H beforehand (identified target or own estimation) For small φ's you can use R=H/φ as long as φ is in radians not degrees. __________________ - Oh God! They're all over the place! CRASH DIVE!!! - Ehm... we can't honey. We're in the car right now. - What?... er right... Doesn't matter! We'll give it a try anyway!

11-21-10, 06:09 PM	#4
razark Ocean Warrior Join Date: Mar 2007 Location: Houston, TX Posts: 2,731 Downloads: 393 Uploads: 12	It's height divided by the tangent of the observed angle (I'm guessing degrees for the angle). You'll either need to memorize the tangents of angles, have a table to look it up, or have some device for calculating it. __________________ "Never ask a World War II history buff for a 'final solution' to your problem!"

11-22-10, 08:38 AM	#5
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	If you use the "TGT Dial AOB Fix" mod or whatever it is called, then you can click on the range dial an turn it until whatever range you desire lines up with the range indicator. Basically you don't measure the observed height of the target (the two overlaid images of the scope are not used), but force it to use it's default (hidden) heigt angle. Let me see if I can find a link to it. [EDIT] It's called the "Easy AOB" mod. Go figure: http://www.subsim.com/radioroom/showthread.php?t=152945 What I meant was, that to set a range (that I presume you know, like by eyeballing, or I misunderstood) it doesn't matter if the mast is small and the optical size is big, or the mast is large and optical size is small. If you know the range, and just want to set it, just fumble with the dials until it is set. [EDIT 2]Sorry, I re-read the thread and I obviously misunderstood. __________________ My site downloads: https://ricojansen.nl/downloads

11-22-10, 11:06 AM	#6
tomoose Grey Wolf Join Date: Aug 2005 Posts: 930 Downloads: 23 Uploads: 0	Hieght, angle, range I must be missing something here. Even with the formula mentioned you're still missing some info, aren't you? You want to find the range and you've identified the ship and got the mast height from the ID manual. That part is clear enough. How do you determine the verticle (observed) angle without the stadimeter? Which hash mark etc do you use in the periscope/TBT? You need at least two pieces of info in order to solve the equation. If Y = mastheight (as given by ship ID book), and X = angle (observed angle fm sub to mast top, from the horizontal), and Z = range Range(Z) = Height (Y)/tan X How is X determined without the stadimeter or some other device?

11-21-10, 05:42 PM	#3
corsair15 Watch Join Date: Sep 2010 Posts: 21 Downloads: 6 Uploads: 0	Is that Tangent, multiplied by the number of degrees? So: Height divided by Tangent multiplied by Angle = Range ???? I'm still not exactly sure (I never took Geometry or Trig in school, I wish I would have though, because now I'm trying to learn it by myself)