Engine RPMs and hydrophone speed calculation question
 

Hello skippers!

Today, I decided to convert to the much acclaimed, old-styled, sonar only attack. Now, in order to get speed for the target, with contacts on, I'd start a 10 minute monitor over the PPI and divide the range covered from start time to stop time, then do the regular maths distance/time to get his speed. Now comes the submerged problem as an arbitrary estimate is usually the case, and you end up with off the chart calculations and many misses...

Now, I wanted to ask if there was a RPM guide around here, much like RPM over speed in kts?, for trained ears to use.. I kinda like the idea of staying low and not exposing myself at all, and this is what I also hope to get your advice on.

To be exact, is there a chart or not necessarily a chart, but a rule for rpms vs speed (kts) here? And, if I put my hydrophone operator on monitor, he leaves all the targets and focuses on the warships which are naturally ahead of the convoy, so is there a way to let him monitor that specific screw on the telegraph? I guess there aint, but I'm just spitballing here..

Another thing, if he were to monitor a sole merchant, should I set the TDCPK to this bearing or do a fan spread ahead of the target?

Does anyone know the actual grading on scope, corresponding to the spread dial, meaning which periscope mark on the horizontal line corresponds to say, 5 clicks left spread?


And if someone could help me with this periscope? I cant find the markings anywhere here, and certainly its not websters mod.

Here, I want these extra periscope bearing marks:


http://i1218.photobucket.com/albums/...6/3668079a.jpg

So, do you guys know this?
Thanks

Yes there is a rule. Shaft RPM heard through the hydrophones does not correlate to an exact speed of target. The best you can get is a slow, medium, or fast speed report from the operator. Besides if you could accurately count the shaft rpm you would need to classify the contact in order to determine the turns per knot ratio.

but but..:oops: ...

Well here is the thing, I think most merchants do in between 5 to 12 knots, unless its a hospital ship (aka modern passenger liner), regularly doing 17 kts....


But I think its possible to count rpms either through the actual turn or the cavitation although I think you focus on a portion of the sound you hear and count how many per minute... But you're right, wish I had an answer:damn::damn:, what about the periscope thing?

If you are asking about how to use a prop turns to estimate speed in the game, it is not possible. The game is modeled too simply; only a small number of sound files are used to create the screw sounds. Someone asked this before. In RL, O'Kane used this, but I don't think it was ever considered a substitute for the usual methods; more of a supplementry method.

About the periscope index ring. I don't know where you get that. It looks like a definate improvement.

On a few things. I remember listening to saft rpms. The slowest chug-chug sound that you get usually means between 5-7knts. Once they've sped up means about 11-13 knts.

Now. I forget where, but in the downloads section for Sh4 there is a Hydrophone plotter utility. What you do, take 3 hydrophone readings, spaced out say 5-10 minutes apart. Take these values and enter them into the program. Now, take the same amount of time you used for your previous bearing checks and set that as your time limit to spring to another location (you need to be stationary for your original plots). Now, once you have your new position, take a bearing check, and measure distance between the two points you had.

You know have distance, speed AOB and bearing to target. d

find speed
 

[QUOTE=commandosolo2009;1589099]Hello skippers!

Today, I decided to convert to the much acclaimed, old-styled, sonar only attack. Now, in order to get speed for the target, with contacts on, I'd start a 10 minute monitor over the PPI and divide the range covered from start time to stop time, then do the regular maths distance/time to get his speed. Now comes the submerged problem as an arbitrary estimate is usually the case, and you end up with off the chart calculations and many misses...

Now, I wanted to ask if there was a RPM guide around here, much like RPM over speed in kts?, for trained ears to use.. I kinda like the idea of staying low and not exposing myself at all, and this is what I also hope to get your advice on.

To be exact, is there a chart or not necessarily a chart, but a rule for rpms vs speed (kts) here? And, if I put my hydrophone operator on monitor, he leaves all the targets and focuses on the warships which are naturally ahead of the convoy, so is there a way to let him monitor that specific screw on the telegraph? I guess there aint, but I'm just spitballing here..

I was looking for this ,,rev/chart'' on the net but i did not find it and if i will find i can not use in game (i play sh5) because i do not have a mod to make proper sounds file for that.

But i think the methode the krauter spoked to you is the best ever to find cource, speed and distance of a target using the hydrofone: it is the ,,4 bearings methode,,

You can download a very well made video about how you can use this methode (very well explained the ,,4 bearing methode'') and a tool that you can use to aplie this methode (the tool take away 90% from the work that you must do:D)

I uploaded a file, for a friend of mine, with this 2 things -

http://www.subsim.com/radioroom/showthread.php?t=179490

see post#46

Salute!:salute:

Grazie mille buddies!!

:up:

About rpms speed calculation i found this thread (very interesting):

http://www.subsim.com/radioroom/show...=107303&page=4

see post #1, but it works only in sh3

Salute!:salute:

You find that picture file at .../data/menu/gui/bearing.dds
You'll find references to it in .../data/menu/menu_1024_768.ini file under sections TBT/Periscope/OBSScope.. as 'compass' IIRC
:)

Isn't that the Periscope Lens Kollmorgen Graphics mod by CaptainCox?, if it is you can find it Here

no it isnt, I'm not looking for the gasket, I'm looking for more bearing marks, like BG 120,121,122,123,124,125,....... on the upper caret

I sure like the looks of this too however I'm wondering how it looks at night, since I prefer night periscope attacks mostly because I'm harder to spot and evading the ASW is easier.

Happy Hunting!

Art

If you do it like that, you'll have 'number-overload' in that you cannot make out what the bearing is. 5 degree intervals are about the best, and it's easy to work out the bearing at a glance.

There's an alternative bearing indicator mod in the download section somewhere
:)

Found the Mod = Capt Scurvy's MaxOptics.. There are different versions fo GFO, TM, and RFB AFAIK

Thanks dude! Well, I've just finished the American career.. Been quite a ride, and I'm heading to SH5... Been an honor serving on USS Balao. Cheers everybody.

SH5? See you back here in a couple weeks..... LMAO

Thanks for the name of the graphics mod vanjast.

edit - Wow, at first dial up would have been faster but after several attempts it finally downloaded in MB/sec. Patience pays! Very nice mod !!

Happy Hunting!

Art