[gutted]

I called it 90AOB on my table due to the fact that in the U-baot (re: SH3) the periscope and aob dials were linked. so to take this kind of shot all one had to do was put the scope at 0 degrees.. set 90AOB (or any AOB for that matter), then train the scope left or right until the gyro read 0. thus taking a 90AOB shot. though techincally, it was less than 90AOB at the aim point becaues the AOB would change autommically with the scope in SH3.

this table was my attempt to simplify this for SHIV, since the two dials were not linked as in SH3.

As for arctan, invtan.. im no mathemetician, but aren't they are the same thing. i put inverse tangent because the windows calulator doesn't have an arc tangent function. to get the same effect you do inverse tangent. .ie 1 / tan(x). to be honest, i dont remember why i have the "90 -" part of the formula there. This was done some years ago. Basically what i did was worked it out using the windows calculator.. then whipped up a quick C++ program to spit out the numbers, then dropped it into an XML file to print it.

in windows calculator you'd do this for fast mk.14 vs 9 kt ship:
46 / 9
hit the = button
hit the Tan button
hit the 1/X

again i cant remember what the "90 - " was for.

anyway, i need to update that table one of these days. First off the table assumes Mk.14 torpedos (31kt slow, 46kt fast). and secondly i need to extend it off to the right for Impact AOB's other than 90, as i dont really try to set up for perfect 90AOB shots anymore now that i've grown found of the american TDC and find myself actually using it. .ie i dont line up perfectly at 90AOB and wait like a duck.. i'm always on the move manuevering now. though every now and then i find myself in a situation where i fall back on the table for hip shots. gives me a rough idea of how much i need to lead for a given target speed.