Hi John,

Thanks for taking the time to read through the tutorial. 0 AOB is the moment the target is pointing directly at you, i.e. the moment you cross his track. If he is pointing directly away from you he is at a 180 deg AOB. In other words, AOB is the the bearing to your boat if you were standing on the deck of the target.

Great, thanks again.

hello Derstosstrupp,
I was looking at these two presentations and i want to ask you something


at this point of first presentation, i think that i am missing it.

How do you know that, at this bearing (collision bearing you’ve been maintaining), the AoB is always 90° ?

Look at the following pic (the spoken AoB at this bearing can be anything else):

http://i68.tinypic.com/wlrsz5.jpg

how can be ignored the above and consider the AoB to be always at 90° at this bearing? what am i missing here ?



ps: Therefore, for calculate target speed:

target speed = [Own speed / sin(AoB)] x sin(target bearing)



Same question for the second presentation

Hi Makman,

This post is back when I was using these methods as shooting methods, that is, to derive a gyro angle. I now use these methods to derive target speed (see my stuff in my sig as well as this that I made for Wolfpack https://drive.google.com/file/d/1isf...w?usp=drivesdk. That is a more evolved way of using the methods and is more in line with historical procedures.

To your question, the setting of 90 is simply for simplicity’s sake. Setting 90 allows you to set the target speed = own speed in the TDC, that’s all. Since the formula is

own speed x sine(brg) / sine(AOB) = target speed,

Then setting TDC speed to equal own speed yields the same result since the sine of 90 is 1.

Again, antiquated method and superseded by my subsequent stuff.

i see , thank you for the reply Derstosstrupp :Kaleun_Salute:

No problem Makman, thank you for all your great work all these years!:Kaleun_Salute:

In so far as it isn't clear yet (to other readers), I think this image may clarify why you set AOB to 90 degrees when looking to the target, and use ownspeed*sin(constant_bearing) as target speed.

http://ricojansen.nl/image/intercept_angles2.JPG

As far as the TDC is concerned when the bearing is fixed to the target, to know the torpedo lead-angle it only needs to know what that sideways speed is perpendicular to the target bearing. Hence why you set the AOB to 90, and target speed to ownspeed*sin(constant_bearing). The TDC will calculate the lead angle for the torpedo by taking a right-angled triangle with that sideways-speed as opposing side, and the torpedo speed as the hypotenusa. So torpedo lead-angle will then be:
arcsin( ownspeed * sin(constant_bearing) / torpedospeed )
And then further corrections for gyro-angle parallax based on (rough) range.


The real target speed and actual AOB isn't so important to get the torpedo on the target as it will only provide additional information on the speed components along the line of bearing. This will only tell the closure rate of the torpedo to the target, Read: correct time to impact. The time to impact calculated by the TDC cannot be relied upon in this Ausdampfverfahren setup. Without knowing the actual AOB and speed, the torpedo would be lead onto the target anyway. (assuming measurements are exact without error) The idea behind the Ausdamphverfahren is to fire as soon as this constant bearing is established and the calculation of the sideways speed is done. Or whenever you got up to a sufficiently close range.

If you want to fire on a different bearing to another target (than the one on the established constant bearing) at a later point. Then you need to have the scope on the established constant bearing, correct target speed to the real target speed based on the observed AOB (targetspeed = 'sideways speed' / sin(observed_AOB) ) and set the observed AOB in the TDC. Now the TDC is calibrated to aim wherever with proper torpedo lead. (As long as range is entered appropriate to the target) This was explained in derStosstrupp's documents too iirc.

Probably a stupid question, but what is the overhaul maneuver? :oops:

When you're getting in front of, or "overhauling" a convoy/ship.

Got it now, thanks!

For the first method, how do you usually proceed with acquiring a collision course? Do you go by first adjusting your boat's course port or starboard, until the bearing remains constant, then trim slightly as you proceed or is there a formula that can be used which assigns a probable bearing difference between the two ships' bow, for a given target speed?

What do you do if the bearing suddenly changes by 1-2 degrees after more than 15 minutes? For example, in situations in which you are intercepting a target by hydrophones over long range.

I keep it simple. No math, no formulas, etc. Just keep a visual on them, and when the ship/masts are barely in view, that's where I want them.
So I adjust my course accordingly to keep it that way.

I don't intercept via hydrophones, sorry. Maybe someone else can help there.

The bearing accuracy is not good enough to do this by hydrophone. Visual sighting by periscope or UZO line is required.

I'm at work now replying on my phone. It is hard to describe the method I have in mind. Will do later today.

Derstosstrup did make videos with wolfpack showing the procedure some months ago.

This is simply trial and error. I found it best to first adjust your speed until the bearing just barely changes and then fine-tune it with course changes. It really only needs to be held constant over the course of a few minutes. Also, just be aware of that the closer you are to a 90° angle on bow, The more accurate the results, since the formula divides by the sine of the angle on bow, and the further away you are from 90° the more effect small AOB estimation errors will have.

I use these methods primarily for finding target speed, whereas when I first made this post it was a way to calculate a Gyro angle for purposes of shooting, but using it to compute speed is much more useful.

The method I had in mind this afternoon was by recording own movement while on a constant course, but with changing speed faster then slower. One has to record one's own position on the map, point the scope to a fixed point on the target hull, be at an overtaking speed making the target creep backwards, and at some time slow down letting the target catch up to the line. Then the distance own ship moved over the time until it catches up gives you your average speed. With own ship and the bearing of the scope being constant, the target returning to the line as it catches up is effectively a constant bearing at two moments in time. And since the scope bearing and own course is kept constant you can easily calculate your speed component across the line of sight by multiplying it by the sine of the bearing. As shown in my image above, this is the same as the 'speed across' of the target. Then the real target speed results from dividing it by the sine of the AOB.

For the Wolfpack game this should work out nicely (barring the current time-dilation bug), since you can easily record your own movement by the difference in the odometer value at both times down to the meter. But I forgot that in SH3 you can't measure distance as precisely. You are limited to the 100m units that is displayed by line length or circle radius. The latter would require longer time periods to get any meaningful precision in the average speed. Trial and error as derstosstrup advocated is then easier and better done in reasonable time.

I can't remember. Does SH3 have an odometer? If so, probably a crude scale though.

Another question : is there a "maximum bearing" in the Ausdampfverfahren method?

For example, in one of my attack due to the target both "moving away" from me on his course and both our difference in speed my bearing was remaining constant at 40-42 degrees. But, from what I understand the wider the gyro angle, the higher the risk of the torpedo missing its target. Am I wrong in thinking that?