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View Full Version : Improving the 4-bearing method (with ownship moving) using Spiess TMA formula


ljqcn101
04-25-19, 05:10 AM
I just found that by using a specific map tool in Wolfpack would make the plotting of 4-bearing method much easier, and also less error prone (i.e. you don't need that triangle formed by the 3 bearing line anymore).

Let's say you have taken 3 bearings while moving, as shown in the video for illustration purpose. And the core methodology behind the 4-bearing method is to find the imaginary 4th bearing line (also called the Spiess Line).

In Wolfpack, there's a handy map tool function called 'draw from midpoint', which can help you find a line splitted equally by the 3 bearing lines. By randomly picking two points on the 2nd bearing line as a starting point, you can extend the lines with equal length to define the Spiess Line.

https://www.subsim.com/radioroom/picture.php?albumid=1215&pictureid=11076

https://www.youtube.com/watch?v=_pN8x3nHJIg

ljqcn101
04-25-19, 06:14 AM
Then, we can use the imaginary 4th bearing and the real 4th bearing to triangulate the target position.

Let's check the solution using the automatic TMA solver:
https://www.subsim.com/radioroom/picture.php?albumid=1215&pictureid=11049

Elphaba
04-25-19, 07:47 AM
Alternatively, two Uboats in a wolf pack can triangulate very quickly (6mins?) and get true course and speed.

Did it last night with McDewgle and it worked brilliantly.