Manual firesolution

[Raskil]

Hi everyone,

i've noticed that the fire solutions (heading of the torpedo) that are assigned to a torpedo tbe seem to be very bad (i need to resteer the torps very soon after launch). So i tried to calculate my own solutions. I just wanna post them here, cause i don't know if they are correct. Maybe someone has additional suggestions / corrections.

First Step:
What do i know for my triangle?

Distance from OS to Contact => b
Speed of own Torpedo => c
Speed of Contact => a
Bearing from OS to Contact => d
Course of Contact => e

Other things used:
OS Position => A
Contact Pos => C
Intercept Point => B


So i can contruct a triangle if i can get an angle for trigonometry. As i know bearing to Target and Target Course, i can calculate gamma with the following formula:
gamma = 180 - e + d

To get the other two values missing (otherwise trigonometric formulas won't work), i use a little trick. I simply assume target speed and torp speed as distances in my triangle. This will give me a smaller triangle then the one i want to calculate, but this way i evade a much more complicated vector calculation.

So i've a triangle with the following values:
gamma
Side a
Side c

Now i can apply the congruency theorems (don't know if they a really called like that in english):

alpha = asin(a * sin(gamma) / c)

So we get Alpha. From Alpha i can calculate Beta, as all 3 inner angles in a triangle sum up to 180°.

Beta = 180 - Alpha - Gamma

With Alpha we already got what we need to calculate our snapshot bearing, so why bother calculating Beta? Beta is used for two things:
1. it gives us an idea from which angle our torp will hit its target
2. Remember that i simplified the triangulation by shrinking the triangle to the speed of own torp and Contact? We now need to calculate a new triangle with the same inner angles, but larger sides. Therfor we will need Beta.

So what values ares given for our new traingle (Triangle with the same inner angles as simplified triangle above)?
Alpha from triangle above
Beta from triangle above
Gamma from triangle above
Side b (distance from OS to contact)

Here is the calculation:
a = b * sin(alpha) / sin(beta)
c = b * sin(gamma) / sin(beta)

With a we get the distance traveld by tontact till the torp impacts.
With b we get the disttance the torp must travel till impact (very usefull for eastimating RTE ranges)

Last thing to do is calculate our Snapshot bearing:

if Bearing to contact > Course of contact:
Snapshot bearing = Bearing to contact - Alpha
else
Snapshot bearing = Bearing to contact + Alpha

Sorry for my bad english, its not my native language.

P.S.:
I'm currently working on a scipt which does theese calculations for me.

Greets Raskil

[TLAM Strike]

Question: Do you have the autocrewman for the Firecontrol system on? Turning him off and using Auto TMA does improve torpedo accuracy. :hmm:

[Raskil]

Nope, manual TMA and manual torp control

[Janus]

Hey "rasputin", you figured all that out just with calc.exe?

[Dr.Sid]

I did these computation once but without angles, only with parametric vector equations. That leads to quadratic equation, where you get time of the impact. Knowing that it's easy to extrapolate target's movement and adjust torpedo heading.

On larger distances there is very simple solution which omits closing/opening speed of the target. You just take distance of target divided by torpedo speed which will give you impact time. Then again you just shoot at extrapolated target position.
Exactly with this algorithm I made champion for few weeks in guntactyx bot programming game, where leading your shots was essential.

But hey .. the torpedoes in DW are guided. These computations are only good for targets moving straight, constant speed, no reaction. Expect him to flank away when he hears the torpedoes.

Then much more important thing is to know if he can run away from the torpedoes. With surface boats, very often, they really can do that (and human players do that all the time).

Knowing max speed of the target, max speed of the torpedo and torpedo's max range, you must compute safe distance, from which the target can't make it.

Sometimes target will also change course to 'clear the datum'. You must predict this and use more torpedoes .. like 3 .. one to the left, second to the right .. and one straight at the target for the case he will simply run away.

[Raskil]

Not every Torp is guided. I found this calculations quit usefull for getting my wakehomers, etc on target