Mathematical Question concerning Firing Solutions - what am I doing wrong?

vindex · 06-15-07, 03:11 AM

Okay, I admire your devotion.

(shaking his head in wonder)

HMS Vanguard · 06-16-07, 07:03 AM

Fellow Virtual Skippers, I got her:

First confirmed kill in Silent Hunter 4, and this one is dedicated to those who have helped me work out my calculations in this thread. Needless to say, I'm pretty happy at putting this tin can on the bottom through a fully manual firing solution. I'm going to practice this a few more times and then go into the main campaign.

One minor thing I did have an issue with though - I was trying to work out the precise AOB using the details put forward in the guide I originally linked to, and came back with a completely wrong number. My precise figures were:

Sin of Bearing Change = 0.54
0.54 x 804 (Range 2) = 434.16
434.16 divided by 804 = 0.778
0.778 Sin-1 = 51.1 degrees

So the calculations were telling me that my AOB to the Cruiser was 51.1 degrees. However, that was clearly wrong from visual observation, as I was sitting at roughly 90 degrees to her starboard at the time. Using this 90 degree estimate I was successful, and I realise from reading elsewhere that estimating was done quite a bit on the RL boats, but I would be interested if anyone could tell me how I got this particular bit of calculating wrong?

Good hunting!

joea · 06-16-07, 12:21 PM

Good work Vanguard, but you do realise the real boats had slide rules and a TDC don't you? It's not unrealistic to use the TDC (unless you are in an S-boat).

HMS Vanguard · 06-17-07, 02:54 AM

Quote:

Originally Posted by joea

Good work Vanguard, but you do realise the real boats had slide rules and a TDC don't you? It's not unrealistic to use the TDC (unless you are in an S-boat).

Fair point - however, with the lack of a working stopwatch until 1.3, I figure knowing this info is a good idea. And seeing as I seem to be getting better at it, I may just try rattling around in an S Class at the start of the war for the sake of it.

And thankyou for the praise - I've taped the precise calculations I did to my wall to remind me of my first kill. :P

Powerthighs, I'll dig up the calculations later today - gonna go try shooting at the training convoy first with my estimated AOBs.

Xelif · 06-17-07, 07:43 PM

Vanguard, the AOB calculated is from your initial observation. Add the number of degrees he's moved across your field of view to arrive at a final AOB (ie, add the bearing change to the AOB). At least, I believe that's your trouble...

Final AOB = calculated AOB + bearing change

Also, yes, it looks like the explanation was flipped like Powerthighs stated. The equation should have you subtracting (2 * cos bearing change * range 1 * range 2) from (range1 squared + range2 squared)... or the whole equation:

c^2 = a^2 + b^2 - 2 * a * b * cos C

Powerthighs · 06-16-07, 12:38 PM

Can you provide both your range\bearing measurements?

06-16-07, 07:03 AM	#2
HMS Vanguard Swabbie Join Date: Aug 2004 Location: England, United Kingdom Posts: 11 Downloads: 0 Uploads: 0	Fellow Virtual Skippers, I got her: First confirmed kill in Silent Hunter 4, and this one is dedicated to those who have helped me work out my calculations in this thread. Needless to say, I'm pretty happy at putting this tin can on the bottom through a fully manual firing solution. I'm going to practice this a few more times and then go into the main campaign. One minor thing I did have an issue with though - I was trying to work out the precise AOB using the details put forward in the guide I originally linked to, and came back with a completely wrong number. My precise figures were: Sin of Bearing Change = 0.54 0.54 x 804 (Range 2) = 434.16 434.16 divided by 804 = 0.778 0.778 Sin-1 = 51.1 degrees So the calculations were telling me that my AOB to the Cruiser was 51.1 degrees. However, that was clearly wrong from visual observation, as I was sitting at roughly 90 degrees to her starboard at the time. Using this 90 degree estimate I was successful, and I realise from reading elsewhere that estimating was done quite a bit on the RL boats, but I would be interested if anyone could tell me how I got this particular bit of calculating wrong? Good hunting! __________________ "Submariners are a bunch of intelligent misfits that somehow seem to get along, understand each other and work well together. -- submitted by Red Hanley who overheard a skimmer officer say this while talking to a non-navy type

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06-15-07, 03:11 AM	#1
vindex Planesman Join Date: Apr 2007 Posts: 192 Downloads: 17 Uploads: 0	Okay, I admire your devotion. (shaking his head in wonder)

06-16-07, 12:21 PM	#3
joea Silent Hunter Join Date: Jul 2002 Location: At periscope depth in Lake Geneva Posts: 3,512 Downloads: 25 Uploads: 0	Good work Vanguard, but you do realise the real boats had slide rules and a TDC don't you? It's not unrealistic to use the TDC (unless you are in an S-boat).

06-17-07, 07:43 PM	#5
Xelif Seaman Join Date: Dec 2006 Posts: 37 Downloads: 0 Uploads: 0	Vanguard, the AOB calculated is from your initial observation. Add the number of degrees he's moved across your field of view to arrive at a final AOB (ie, add the bearing change to the AOB). At least, I believe that's your trouble... Final AOB = calculated AOB + bearing change Also, yes, it looks like the explanation was flipped like Powerthighs stated. The equation should have you subtracting (2 * cos bearing change * range 1 * range 2) from (range1 squared + range2 squared)... or the whole equation: c^2 = a^2 + b^2 - 2 * a * b * cos C

06-16-07, 12:38 PM	#6
Powerthighs Beach Leaf Join Date: Apr 2007 Location: Seattle, WA Posts: 287 Downloads: 11 Uploads: 0	Can you provide both your range\bearing measurements?