have this perfect way to estimate speed ever existed? [Archive]

View Full Version : have this perfect way to estimate speed ever existed?

lockon

08-10-07, 11:28 AM

cali03boss

08-10-07, 11:33 AM

I doubt it since there are certain .wavs for certain RPM ranges.

tater

08-10-07, 11:37 AM

In RL (in the PTO anyway) this would have been very dicey. The amount of information ONI had on japanese shipping, particularly merchants was abysmally low. Many of the ships listed in ONI 208-J are rated B and C (very little known about them, only trust the shape, not the data). Few if any have turn counts. That is also true of warships.

tater

SteamWake

08-10-07, 11:43 AM

http://www.subsim.com/radioroom/showthread.php?t=108454&highlight=COUNTING+TURNS

:up:

raduz

08-10-07, 11:51 AM

While using hydrophone can we count the REV per minute of fans so as to aquire speed of the ship???:hmm:

We may get speed for caculating intercept point from very long range , what a wonderful way!:rock:

yes... cool:huh: try to use the search function before admitting a new topic...

take a look here
http://www.subsim.com/radioroom/showthread.php?t=112919&highlight=turn+count
this is
why the turn count method cannot be used in SH4 because of technical reasons

and here
http://www.subsim.com/radioroom/showthread.php?t=119531&highlight=turn+count
this is why the players dont want it - they think it is not real

lockon

08-10-07, 12:21 PM

raduz

08-10-07, 12:26 PM

i m sorry .
i will utilize search function next time.

no problem:) I didnt meant to be peevish

greyrider

08-12-07, 07:24 AM

seems like any question about hydrophones will draw a post from me,
it seems that rpm's and speed are closely related in sea going vessels,
there are terms used such as," makings turns for 6 knots",
theres a propcalc in the JP sonar, some members have reported some skippers using tachnometers
to count rpm's, from novels or movies that they have read or seen.
if you saw the movie the enemy below, how does the german commander destroy the american tin can?
by sound he did, not by a well aimed shot, he killed it and he wasnt even observing it.
how many shots were taking like that in ww2?, probably alot, whether they hit or not.
one thing about playing this game, is not so much what was, but also what if,
some skippers felt comfortable, and had some skill with turn counts, others did not.
lockon, you do what works for you, and what your happy with.
if people have a hard time believing that turn counts were used, theres an even more chart that would really blow their minds.
but it had to do with air search radar.
a radar operator would get a bogie, fast movers incoming on his scope, he could see the bogie on his CRT. then suddenly, it disappears, and then in a few seconds
it reappears on the CRT again.
they finally figured out that it was a perculiar thing in radar, and they figured out that when the pip on the CRT disappeared, they could determine the altitude and range of
the incoming plane or planes were flying at.
no one here has posted anything here about this matter, of RADAR FADE CHARTS. this is the first post about radar fade charts.
no one here can say, with any kind of authority including myself, what went on in ww2. we dont have the whole picture, we dont have all the answers.
everyone helps out here, with little tib bits of information, and we get alot of collective knowlwdge about naval warfare in ww2, sometimes, we lack the specifics,
but does that mean you cant imagine and think about it, and try to work it out?
if you have the imagination, and the skill, use it! thats basically what the u-boat commanders handbook says in the preliminary observations, on page 17.
preliminary observations
in war, only submarine commanders who possess distinctive tactical knowledge and ability will be successful in the long run. In order, however,
to understand and master the tactics, (i.e., of submarine warfare) it is necessary to BE thoroughly FAMILIAR with the WEAPON, and its CHARACTERISTICS
and PECULIARITIES, for it is ON THESE that the tactics depend.
In addition, complete success as a RESULT of a thorough EXPLOTATION of the POSSIBILITIES of the WEAPON can only be achieved if all the officers in charge
of it are trained to think along the same tactical lines.
from u-boat commanders handbook

once i read those two little paragraphs, i threw the book away, it could not tell me anymore, it was just me and the weapon.
i like to imagine that im an RA, or SO, IN WW2, and that im learning about sonar and radar like they did, from square one.
its kinda fun to retrace thier steps of learning

Sailor Steve

08-12-07, 02:23 PM

it seems that rpm's and speed are closely related in sea going vessels,
there are terms used such as," makings turns for 6 knots",
theres a propcalc in the JP sonar, some members have reported some skippers using tachnometers
to count rpm's, from novels or movies that they have read or seen.
I can't really argue for or against using turns, but I have a couple of possible problems, at least for me to understand.

1) "Making turns for six knots" is fine for your own ship, but different ships have different sized props, so different revs for each class of ship to make the same speed. Do they know all the different possibilities for each enemy ship? If so, how do you tell which ship it is without having looked at it?

2) Even if you can tell the speed from the revs, what about the Doppler effect: if he's heading toward you the pitch changes, but so does the apparent speed. Likewise if he's heading away, and without looking you can't know the direction he's heading.

That said, I've heard claims that some could do it; I just don't understand how.

Fearless

08-12-07, 10:01 PM

Welcome to the forum Lockon. Unlike Dangerous Waters, I kinda believe there weren't any data tables available that would provide estimated speed based on revs per minute for different ship types.

tater

08-12-07, 11:57 PM

The WW2 information I DO have, are the ONI recognition manuals that were aboard US submarines for... IDing and targeting shipping.

The information is very sketchy, and they admit it. They rate the information quality A, B or C for each ship. Many are "C." Of the As, only a tiny fraction have any rpm information at all.

The japanese didn't mass produce shipping like the US Liberty and Victory types, so any rpm data gotten would apply to only a couple ships. The only way to get the data is to count the turns, and accurately get the speed by another method. At that point you can write it down, and when you RTB it can be published (the rec manuals were looseleaf for easy addition/removal of pages). I have the 44/45 revised edition. There is squat for RPM data. Maybe 15% have 1 rpm at 1 speed listed.

Once surface radar was common, that was how the range was determined quickly. with accurate range and bearing, speed---actual speed, not a rpm guestimate---falls out.

tater

WernerSobe

08-13-07, 09:11 AM

ive ran tests on it earlier.

it doesnt work.

The sound seem to be shifted from 0-6 knots, after that it sounds the same no matter if its going 6 knots or 16. Also all merchants sound the same.

SteamWake

08-13-07, 10:44 AM

ive ran tests on it earlier.

it doesnt work.

The sound seem to be shifted from 0-6 knots, after that it sounds the same no matter if its going 6 knots or 16. Also all merchants sound the same.

Exatcly, while counting turns in real life would be possible it is not possible in this game.

raduz

08-13-07, 03:20 PM

ive ran tests on it earlier.

it doesnt work.

The sound seem to be shifted from 0-6 knots, after that it sounds the same no matter if its going 6 knots or 16. Also all merchants sound the same.
Exatcly, while counting turns in real life would be possible it is not possible in this game.

It could work, although within some limits.

SteamWake

08-13-07, 03:26 PM

ive ran tests on it earlier.

it doesnt work.

The sound seem to be shifted from 0-6 knots, after that it sounds the same no matter if its going 6 knots or 16. Also all merchants sound the same.
Exatcly, while counting turns in real life would be possible it is not possible in this game.

It could work, although within some limits.

Maybe you can tell fast vs slow but (shrug) thats not a hella lot of help.