Ekelund Range

[PeriscopeDepth]

Now that I'm getting into manual TMA, I remember (at least I think it was) Bill Nichols posting it in the old SC forum, but I don't remember it and I think a lot of that forum was wiped. So would you mind posting it for us all again Bill, or anybody else who knows it? Thanks. Googled but couldn't seem to find the formula, just the history behind it.

[Bill Nichols]

Look here:

http://www.haptonstahl.org/ppt/tma_files/frame.htm

[Rip]

Excellent link Bill. Amazing how when I was a plot coordinator I hated this method of range determination, and now I love them.

It sucks having an officer with a programmable calculator come up with a better range than I have on the plot.

Somebody needs to put the formula into a webpage that we can feed the variables to. The that can stay open right beside the Ship Database webpage that I use extensively when playing.

[PeriscopeDepth]

Thanks for the link, now let's see if I interpreted it correctly.

My thinking is total speed across LOS=OSSpeedAcrossLOS+TgtSpeedAcrossLOS . And bearing rate is just the rate of degress per minute change you observe in the sonar station.

So, I'm calculating ekelund doing this:

sinLA+[TgtSpdXsin(90-AspctAng)]/BrgRate

That X is me multiplying, not a variable BTW. And LA=Lead Angle.

My head hurts.

Got my definitions from this page http://www.tpub.com/content/combat/14308/css/14308_170.htm

[PeriscopeDepth]

Another question. When a speed across LOS is moving left, it is a negative value, right?

[Bellman]

Bill that link, as the Bishop said to the actress -
' Its not working for me '

' Its gone dead'

' Nothings happening and its mighty frustrating'

' Anyways I'll keep trying'

[PeriscopeDepth]

Try http://www.haptonstahl.org/ppt/tma_files/v3_document.htm , go through the slides till you get to the TMA ones.

[Bellman]

:D Thanks -

' Now its up' ;)

[Bellman]

' But now i've got a real headache '

Thats some real bedtime reading. :hmm:

[Bill Nichols]

The book, "Naval Operations Analysis" (3rd edition) has an excellent discussion of target motion analysis (Chapter 11), including details on Ekelund ranging. The book is published by Naval Institute Press, but you can probably get it through your local library system.

[Bellman]

Thanks Bill.

Rip - an interesting suggestion. But what are the limits to the software 'support' to the windowed game ?
Another thread here considers 'synthesizer' assistance.

Some place, some time, some how, these issues need airing and an agreement reached on accepted MP practise ? :hmm:

[Rip]

Thanks Bill.

Rip - an interesting suggestion. But what are the limits to the software 'support' to the windowed game ?
Another thread here considers 'synthesizer' assistance.

Some place, some time, some how, these issues need airing and an agreement reached on accepted MP practise ? :hmm:

Well the ship database is just a refined implementation of something that works poorly in the game. Trying to identify contacts with the narrowband tools in the game is a nightmare.

Something like Ekelund Range while not in the game is nothing more than a mathematical manipulation of information you already have. So I don't think it harms any balance or anything, and you have to remember that it isn't perfect. Even give perfect imput the range is ballpark. I see it much like using cross bearing to give you min and max ranges. While a lot of people may not use it, it can be very useful and easy.

Personally I hope the game goes a little more the SHIII route and they give me a virtual crew someday. Then I can just press the button for asking the weapons officer what the Ekelund Range is :up: , followed by ordering him to make the weapons in tubes 1 and 2 ready in all respects.

I think if all the technical stuff could be abstracted and let the player just play captain would open the game to a whole new audience. If somehow you could give them the ambience and feel of being a nuclear submarine captain there is not a man alive that would not want to suspend reality for a few hours and try it out.

I doubt there will ever be anyone with deep enough pockets and the vision to pull off such a thing, but just imagine a fleet full of virtual captains, not trying to do everything on their vessels but doing just like a real captain. Looking at his displays, getting reports, and barking orders. Then add to that crew members that improve as you you drill and train them. Gaining experience and becoming better at their jobs. Thereby improving the ships performance. :ahoy:

I know it will never happen, but at least I can dream.

[sonar732]

I might suggest putting the link in Orion Warrior's Hints and Tips website! Lord knows that everyone needs as much help as they can get with manual TMA! :rock: :rotfl:

[Bill Nichols]

I've posted the links at my site, under 'Downloads'. There's also another link there I haven't mentioned above :sunny:

[PeriscopeDepth]

Could someone possibly post what the procedure is for Ekelund ranging? I can't make sense of that web site and my local library doesn't have the book Bill mentioned.

Sorry for being dense. :oops:

[MarkShot]

I think TMA must be some kind of magical topic.

The other day I was waiting with my wife at a doctor's office and rereading some TMA stuff I had printed. She asked me what I was reading. Normally, I tell her about the various principles of different war games I play, but, for the most part, she just humors me and has no interest.

Surprisingly, when listening to the basic principle and procedures of TMA, she actually seemed curious and for the first time I could see that she felt perhaps one of my various gaming hobbies wasn't a total waste of time.

[Bellman]

Mark,
The 'fairer' can actualy interpret knitting patterns - so I guess they can unravel TMA ? :lol:

Another thing they muti-task in a way no guy can. Once behind a barbi or a Wok - notice all those things
we overlook that just get done by........ :up:

Hopefully though joint action stops at the study door - the dust in here is my responsibility alone. :rock:

[compressioncut]

Could someone possibly post what the procedure is for Ekelund ranging? I can't make sense of that web site and my local library doesn't have the book Bill mentioned.

Sorry for being dense. :oops:

single leg Ekelund

Range in nautical miles = (RSA x 0.955)/B*

where RSA is the resultant speed across the line of sound, and B* is the bearing rate.

Since you need to have a very good idea as to what the target's speed and course are to find RSA, the single leg Ekelund is pretty much useless, except as a training tool to confirm your understanding of the LOS relationships.

In other words even though it's pretty simple, I wouldn't really worry about it.

A double leg Ekelund is more useful.

Range in nautical miles = (change in OSA x 0.955)/change in B*

OSA being ownship speed across the line of sound, which is sin(OAA) x OS. OAA is ownship aspect angle, which is own course +/- the line of sound (i.e. target bearing).

The caveats with that ranging method are that each leg can't exceed 20 minutes, nor can the bearing rate change more than 15*.

Also, if one of your change in B* ends up at exactly 1*/min, it will not work.

http://img278.imageshack.us/img278/632/forms9pq.th.jpg (http://img278.imageshack.us/my.php?image=forms9pq.jpg)

That image has a LOS diagram, which should help a lot.

I'm not sure if the frequency rate Ekelund would work in game, it's been a while since I took a look at the Doppler effects. I think it would if you log the bearings and frequencies carefully, although that would be very tedious.

[PeriscopeDepth]

Thanks compressioncut, that was perfect! :up: