is it ok to compute a solution at long range then close in?

lostsm · 07-01-09, 08:06 PM

i was wondering if it's generally okay to compute a solution with (what i believe to be) accurate data that I can manually enter into the TDC while I have a target locked in my UZO/periscope, and then get in at a nice firing position

everytime I do this, I can see the TDC adjusting bearing and the gyroangle as our relative positions change, but the range always stays the same, in this case, a very long range. this always leads me to doubting my solution and then rushing at reaquiring solution data and often enough missing due to my last minute haste

so given 100% accurate TDC data, at say 8-10km away, and getting into a 90degree intercept position, keeping the target locked as often as possible, is the solution computed at 8+km still valid?

Alien1099 · 07-01-09, 08:14 PM

I'm no expert but I would think it would be valid as long as you calculated the exact time you needed to fire after taking into account the target's speed if it's moving along a very exact path (of course). I would not recommend moving ahead to close the distance yourself as that would probably throw the calculations off too much since you're not traveling at a constant speed and would require more math than it would be worth to account for it in my estimation. Get the target's vector then get into position and wait and fire when your calculations say you should. I'd just use the periscope though.

TigerShark808 · 07-01-09, 10:31 PM

I always have this problem with computing a target at long range then closing in and exspecting the same "NUMBERS" to work.
With me..I just continue to update my data.Its works better that way.

vorosgy · 07-02-09, 02:21 AM

As far as I know, only the AOB is updated automatically, but I think it's correct only if you're not moving, and the target is moving straight ahead. You've got to update the range manually.

However, skookum mentions an excellent intercept method during which you can safely ignore target range in this thread:
http://www.subsim.com/radioroom/showthread.php?t=151842
To make it short, IF the AOB and speed you enter is correct, and the gyroangle is 000, and the target's path is perpendicular to yours, then range does NOT matter.

Fincuan · 07-02-09, 04:34 AM

Quote:

Originally Posted by vorosgy

To make it short, IF the AOB and speed you enter is correct, and the gyroangle is 000 then range does NOT matter.

Fixed it for you. Regardless of your or the target's courses range does not matter if the gyroangle is zero.

vorosgy · 07-02-09, 04:51 AM

Quote:

Originally Posted by Fincuan

Fixed it for you. Regardless of your or the target's courses range does not matter if the gyroangle is zero.

Yes, you're right! I didn't think it through first... having perpendicular path is indeed not neccessary.

lostsm · 07-02-09, 06:36 AM

what exactly does range do? sets off the torpedo once it reaches that range?

if so, if you get your sub close enough to a ship's path, might as well set the range really high so even if you miss, it might hit another one behind it, right?

joegrundman · 07-02-09, 06:47 AM

no it doesn't do anything like that.

Range affects the computed gyro angle in cases where the gyro is not 000. This is because the line of sight from the periscope and the torpedo track are not the same thing with non 000 gyros. in practice however the difference is small enough to be ignored with gyros of +/- 15 degrees at reasonably short ranges.

And this is because the periscope is in the center of the boat, whereas torpedoes are launched from the front, go ahead for a whlie then begin a turn with a turn radius before following the computed path.

But with larger gyros, accurate range readings become necessary

Hitman · 07-02-09, 07:01 AM

Quote:

what exactly does range do?

Range is important for convergence, see this thread here: http://www.subsim.com/radioroom/showthread.php?t=121744

lostsm · 07-02-09, 07:07 AM

thanks!

Pisces · 07-02-09, 10:02 AM

The range is indeed not updated, so old range measurements are useless at shoot time. But as is allready said, if you fire with near-0-gyro angle, than it doesn't matter.

If you turn during the intercept/closing process then the solution is not valid anymore. Because the AOB on the dial doesn't match wat you see anymore.

Keeping the target locked as long as possible isn't even nescesary, just point the scope at the target when you want to fire. With good TDC settings it's WYSIWYG, no matter how long you looked at it.

07-01-09, 08:06 PM	#1
lostsm Sailor man Join Date: May 2005 Posts: 47 Downloads: 2 Uploads: 0	is it ok to compute a solution at long range then close in? i was wondering if it's generally okay to compute a solution with (what i believe to be) accurate data that I can manually enter into the TDC while I have a target locked in my UZO/periscope, and then get in at a nice firing position everytime I do this, I can see the TDC adjusting bearing and the gyroangle as our relative positions change, but the range always stays the same, in this case, a very long range. this always leads me to doubting my solution and then rushing at reaquiring solution data and often enough missing due to my last minute haste so given 100% accurate TDC data, at say 8-10km away, and getting into a 90degree intercept position, keeping the target locked as often as possible, is the solution computed at 8+km still valid?

07-01-09, 10:31 PM	#3
TigerShark808 Engineer Join Date: Jun 2007 Location: 2074 nautical miles south west of San Francisco! Posts: 212 Downloads: 71 Uploads: 0	I always have this problem with computing a target at long range then closing in and exspecting the same "NUMBERS" to work. With me..I just continue to update my data.Its works better that way. __________________ GWX3GOLD OLC "Gold" MkIId SH3 Commander D.I.D 100% Realism ! SWCs-AtlanticReaper Skin <---because it is badass!

07-02-09, 06:47 AM	#8
joegrundman Ocean Warrior Join Date: May 2007 Posts: 2,689 Downloads: 34 Uploads: 0	no it doesn't do anything like that. Range affects the computed gyro angle in cases where the gyro is not 000. This is because the line of sight from the periscope and the torpedo track are not the same thing with non 000 gyros. in practice however the difference is small enough to be ignored with gyros of +/- 15 degrees at reasonably short ranges. And this is because the periscope is in the center of the boat, whereas torpedoes are launched from the front, go ahead for a whlie then begin a turn with a turn radius before following the computed path. But with larger gyros, accurate range readings become necessary __________________ "Enemy submarines are to be called U-Boats. The term submarine is to be reserved for Allied under water vessels. U-Boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs." Winston Churchill

07-02-09, 10:02 AM	#11
Pisces Silent Hunter Join Date: Dec 2004 Location: AN9771 Posts: 4,904 Downloads: 304 Uploads: 0	The range is indeed not updated, so old range measurements are useless at shoot time. But as is allready said, if you fire with near-0-gyro angle, than it doesn't matter. If you turn during the intercept/closing process then the solution is not valid anymore. Because the AOB on the dial doesn't match wat you see anymore. Keeping the target locked as long as possible isn't even nescesary, just point the scope at the target when you want to fire. With good TDC settings it's WYSIWYG, no matter how long you looked at it. __________________ My site downloads: https://ricojansen.nl/downloads

07-01-09, 08:14 PM	#2
Alien1099 Watch Join Date: Jun 2009 Posts: 23 Downloads: 16 Uploads: 0	I'm no expert but I would think it would be valid as long as you calculated the exact time you needed to fire after taking into account the target's speed if it's moving along a very exact path (of course). I would not recommend moving ahead to close the distance yourself as that would probably throw the calculations off too much since you're not traveling at a constant speed and would require more math than it would be worth to account for it in my estimation. Get the target's vector then get into position and wait and fire when your calculations say you should. I'd just use the periscope though.

07-02-09, 02:21 AM	#4
vorosgy Swabbie Join Date: Jun 2009 Location: Hungary Posts: 11 Downloads: 18 Uploads: 0	As far as I know, only the AOB is updated automatically, but I think it's correct only if you're not moving, and the target is moving straight ahead. You've got to update the range manually. However, skookum mentions an excellent intercept method during which you can safely ignore target range in this thread: http://www.subsim.com/radioroom/showthread.php?t=151842 To make it short, IF the AOB and speed you enter is correct, and the gyroangle is 000, and the target's path is perpendicular to yours, then range does NOT matter.

07-02-09, 06:36 AM	#7
lostsm Sailor man Join Date: May 2005 Posts: 47 Downloads: 2 Uploads: 0	what exactly does range do? sets off the torpedo once it reaches that range? if so, if you get your sub close enough to a ship's path, might as well set the range really high so even if you miss, it might hit another one behind it, right?

07-02-09, 07:07 AM	#10
lostsm Sailor man Join Date: May 2005 Posts: 47 Downloads: 2 Uploads: 0	thanks!