SUBSIM Radio Room Forums - Looking for a link for calculating speed.

SUBSIM Radio Room Forums (https://www.subsim.com/radioroom/index.php)

- SHIII Mods Workshop (https://www.subsim.com/radioroom/forumdisplay.php?f=195)

- - Looking for a link for calculating speed. (https://www.subsim.com/radioroom/showthread.php?t=145837)

Quote:

Hitman, if you could help create one. By all means!

Done. Link posted in the new thread opened by Lanzfeld. The bearing indcator comes directly from my NYGM optics mod, so I'm unsure if you will like the result (I have not tested it because I don't have OLC Gui installed, but should work OK) but anyway it's better than nothing.

Quote:

Originally Posted by geosub1978

Oh yes, the paralleling of target's coarse is a very satisfactory methode. Nevertheless, I insist that the best way is to "KEEP THE BEARING CONSTANT". If you use a BRC wheel, a MUST HAVE for real life lovers and 100% manual targeting. You can obtain the best speed of the target, even for convoys.

This means:

Subspeed*sinusBearingAngle=TargetSpeed*sinusAoB

So:

TargetSpeed=Subspeed*sinusBearingAngle/sinusAoB.

All you have to do is to keep the bearing of the target constant by adjusting your speed and coarse (for targets with AOB < or = 35 DEGREES only). This has the benefit that you don't have to be on serface while the target makes 12kts.

Finally you need an electronic hand calculator to do the mathematical equation, if you don't use a real life BRC wheel which is quite common in this forum.

This works fine for me for submerge attacks untill the end of the war, while keep silent speed 3-4knots.

i do not understand it right, but it sounds interesting. can you clarify this meethod a little bit please?

Constant Bearing Method

When two ships are in collision coarse the bearing between them is constant. The Angle on Bow (AOB) is also constant in this case, while the distance is reducing. It is exactly the same thing when you shoot a torpedo. The deflection angle (firing angle) is chosen according to target AOB-Speed and torpedo speed in order to have a constant bearing between them which is the collision coarse of the torpedo.

How to use this in SH3:

When the target is still not visible and you have a hydrophone contact, you try to much your speed and coarse in order to have the target on a constant bearing and distance CLOSING! You will notice this either by the sonarman report or (better) by manually operating the hydrophone. Now in this situation the vectors A and B of the picture below are equal. Of coarse if initially the target has great AOB (more than 30-35), this situation is difficult to happen, as the target travels rapidly ahead. When the target is finally visible and so determining it’s AOB, you have to resolve the following mathematic equation which is obvious from the picture below:

SubSpeed x Sinus(Target Bearing)= TargetSpeed x Sinus(TargetAOB). The only thing that you don’t know is TargetSpeed.
So:

TargetSpeed={SubSpeed x Sinus(Target Bearing)}/ Sinus(TargetAOB)

http://img187.imageshack.us/img187/4528/95440968en2.jpg

In order to resolve this, you need a calculator (which accepts sinus input). Or you can use the Bearing Rate Computer (BRC) wheel. For this, use these links.
http://www.subsim.com/radioroom/show...+Rate+Computer

http://www.subsim.com/radioroom/show...+Rate+Computer

Notice:

1. After determing the AOB and Speed, estimate immediately the distance you want to shoot and start maneuvering.

2. In bad whether or at night, the target will get too close to be visible and you will not have the time to set a firing coarse. So you need other plotting techniques.

3. In case of a convoy, pick up a ship and try to do the above mentioned things.

4. A benefit is that you don’t have to identify the target.

5. The method is very accurate and simple, if you want to simulate a TDC break down or a Weapon Officer is “KAPUT” and you do everything manually.

HMmm, interesting. If you managed to get into a course that results in a constant bearing situation you allready have enough information to fire, except with a hit uncertainty due to gyro-parallax (for which you need range), and crude aiming (bearing per whole degree, nothing you can do about withoout visual in the periscope).

If you point the periscope to the bearing of the target, and set AOB to 90 (port/starboard in the direction the target is moving), and targetspeed to the length of your vector B (=ownspeed * sin(targetbearing) ) , then the torpedo should be going in the right direction. This gyro-parallax effect is only large at short ranges so might not be a big problem. You only need to gamble on if your torpedos can reach it.

Next time I'm in the game I'm going to try and see if I can 'fire blind' this way.

@Pisces

1. You can use this method also to approach the target, without fear that the target will pass "CONSTANT DISTANCE" and then "MOVING AWAY". When you manage to have constant bearing (target invisible) the target is always "CLOSING" untill it is on top of you.

2. The blind adjustments that you do if the target is invisible are:

If the bearing of the target moves TO your bow, you increase speed and alter your coarse in order to open the bearing. If the bearing MOVES BEHIND you do the oposit.

I remind you that if the target has AOB greater than 30-35degrees this method may be impossible to be implemented.

3. Your solution setting seems logical.

The U-jagd tools mod includes this sliderule and instructions for getting speed with the constant bearing method - it also includes instructions for getting a speed estimate on an intercept course when you DON'T have a constant bearing too - although in this case you do also require a rough range estimate too

Someone, i forget who (could be h.sie) made a mini-mod adding it to OLCGUI

http://img136.imageshack.us/img136/1...derule1mw2.jpg