[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