looking for the manual of BearingRateComputer

[makman94]

Hello subsimers,

does anyone knows where i can find the manual of Bearing Rate Computer? (http://www.subguru.com/BRC.jpg)

[B_K]

Hi! I spent a lot of time to find something while I was playing dangerous waters. I recommend you ask on DW forum too. The best document so far was https://www.globalsecurity.org/military/library/policy/navy/nrtc/14308_ch10.pdf

As far as I know, the BRC allows to calculate range based on bearing rate and speed across the line of sight. To calculate speed across the LOS you should add both your and your target speed component using sine on the innermost disk, knowing target bearing and angle on bow. If I remember well, 1 degree of bearing rate at 1 mile (2000 yards) and aob 90 means the speed across the LOS is 1 knot.

Edit: remember, for historrical accuracy, that BRC was introduced during Cold War.

[makman94]

Hi! I spent a lot of time to find something while I was playing dangerous waters. I recommend you ask on DW forum too. The best document so far was https://www.globalsecurity.org/military/library/policy/navy/nrtc/14308_ch10.pdf

As far as I know, the BRC allows to calculate range based on bearing rate and speed across the line of sight. To calculate speed across the LOS you should add both your and your target speed component using sine on the innermost disk, knowing target bearing and angle on bow. If I remember well, 1 degree of bearing rate at 1 mile (2000 yards) and aob 90 means the speed across the LOS is 1 knot.

Edit: remember, for historrical accuracy, that BRC was introduced during Cold War.

hello B_K,

thank you for your reply mate but i know about this document. At all documents i have found so far about it on internet none of them is explaining the use(s) of this tool thats why i am trying to find its own manual.

i am more interested to see if the Ekelund range can be calculated with this tool and what features can be calculated with this sliderule. ( i don't care if it ,firstly, was presented at cold war, i want to understand its use )

Very nice idea to ask about it at DW forum. In fact, there is the proper place to make this question.

Thank you B_K :up:

[B_K]

From what I read and managed to figure out, the BRC works like this:
1) construct LOS diagram
2) you know target relative bearing - you know the first angle of which sine is needed
3) find target's AOB - you now know the second angle of which sine is also needed
4) find target's speed
5) find target's bearing rate

now:
- since you know ownship speed, point 90 degree mark (innermost disk) on that speed and read speed across the LOS where target bearing angle is - this is the first speed component. You multiplied your speed by sinus of target bearing angle.
- do the same with target's speed and AOB

- add both speeds to get total relative speed across the LOS

- turn bearing rate value to that calculated speed

- read the range estimation

In my opinion that is the basic principle of BRC operation. OFC this is only my guess from what I read, but it's quite possible they did it like this.