Target speed calculation made easy
 

Hi mates,

I received my deluxe version yesterday and tried it for 3 hours (with 1.1 patch installed) : it's very nice IMO! Then I came to this forum and discovered that many simers were complaining about the speed calculation broken in the TDC... Even if it is a bug as it is written to work in the manual, I believe that it is fairly more realistic that way. I were always asking myself in SHIII who was the guy in my uboat who was calculating the speed estimation while I was pushing "the little button on the chronometer"... So now in SH4 with manual TDC on, we can use the chronometer but the guy who was calculating like crazy in SHIII is gone. Not a big deal IMO. We will just have to work our trigonometry again ;) .

There are several ways to do estimation of speed but I would like to present you the way I use. It's limited because it's only exact at an AOB of 90° and with the sub travelling slow. However, it is a very good estimation between 75° and 105° AOB. The interest of this method is that you do not need a calculator which would kill the immersion and that it is fast (no map drawing). You just need a "target speed estimation Table" that you can find below.

I find it to be immersive and far more realistic than the always accurate magic speed that you obtain in SHIII...

Hope it will helps some simers.

http://img115.imageshack.us/img115/3977/sh4tableoc2.jpg

lms_oid

Edited : Table modified - 30 seconds for range from 1750 to 2000 yards.

This is debatable depending on what is your impression of what are the tasks that you as a captain must do. I hope they fix this issue with chronometer for people who want to keep it simpler.

But this table is quite useful regardless, thanks.

It would be cool if you could make a few tables for different common AOBs. Like one for 45 and like 25 or something. You could have a few charts. Hell you could just give us the equation involved in that chart and we could all make our own custom ones.

Me personally I'd make one for every say 10 or 15 degrees. Probably need fewer too as you get closer to 90.

I'd think map plotting would be easier. Take a range and bearing of the target, start clock and mark it on the map. Wait a minute and repeat. Use the ruler to measure the distance travelled. Now you have time and distance, calculating speed is easy after that...granted it requires we have bearing info as a map plotting tool. I have yet to play the game so thats something im not sure we have. But if it is, its accurate under all conditions.

I missed the Nagato battleship I was aiming at and instead hit a carrier far behind.

Sorry, It seems that none of us newbies can elaborate exactly how much we need the Auto Speed Determination of the chronometre to even get started using a manual tdc. Because the issue is this simple: We cannot hit anything of what we are aiming at. As in, nothing, maybe by luck, if I crazily enough manage to determine the speed, by a wild guess, then maybe I hit once or twice.

Right now, It would be easier for me to put everything on Zero on the TDC, and just aim ahead of the enemy ship I`m shooting at, and simply develop a feel for how many clicks in the periscope, ahead, of the enemy ship, I have to shoot, to get a hit.
But for real.. Who had time and resources enough to practice that.. that person would not be a sub captain for long..


S! to all


SK

Don't get me wrong, I totally understand that people want this bug to be solved. I just find that it's very realistic as this and I love it.

Yes, this way is good too. You only have to multiply the distance travelled in one minute by 60 to have the actual speed. Depending on the speed you may have to wait a little longer though. By waiting 3 minutes between the two checks, you only have to multiply by 20... And it is a lot of fun to draw that on the map (very immersive IMO).

The formula I use is only true at an AOB of 90 because it use trigonometry. The exact formula is :

1 yard = 3 feet
1 nm = 6080 feet
1 hour = 3600 seconds

BC = Bearing Change in degrees
S = Speed in knots
R = Range in yards (given by the stadimeter)
T = Time between the to bearing checks in seconds

S = (tan BC x 3 x R x 3600)/(T x 6080)

However, the more your AOB is far from 90° (more or less), the more the speed is underestimated by this table so you can guess that adding x knots to the estimated speed would be a good idea.

lms_oid

After thinking it through and recalling all the old ways of getting target info in SH3, I still dig the functionality of the nomograph.

In SH3 if I needed speed I could take the range, mark it on the map, run the stopwatch for any period of time (longer the better) and then apply those numbers to the nomograph and get a solid speed out of it. And it works at any AOB.

If the stadimeter in SH4 is better than the one in SH3 then range shouldn't be an issue. That means that all you need is time, and thats a number that you can generate yourself.:up:

But I dig the charts anyway. I want to work out a chart system that can spare me the need of a nomograph under as many circumstances as I can avoid.

Thanks for the table! :up:

Nomograph?? what the heck is that? :P (yes, i'm green but wanna learn) ;)

Why would the good old 3min 15sec method not work in US subs ?

I want the nomograph in SH4 asap. Is there any way to get it in?

Loved it in SH3..

This is Wazoo's nomograph mod for SH3

http://i4.photobucket.com/albums/y13.../findknots.jpg


The 3 lines at the bottom is the nomograph. If you know any 2 values of the 3, you can discover the 3rd unknown value. If you know time travelled, and distance travelled, you can find speed. If you know speed and time travelled, you can find distance. All you need to do is make a line between the 2 known points, and the line will cross the 3rd line where you will find the value you were looking for.
Quite ingenious.

Imperial metrics? However, if you have more than one minute, drawing the all thing on map should be the better way. The table I made is more intended for fast solution building when you have to fire quickly.

lms_oid

Right ! but then if now distances on the map are in nautical miles like it should be, it makes things even easier as you don't need the nm/km conversion anymore... Distance travelled in 3mns x 20 = speed in knots.

Exactly what I said :D !

lms_oid

i try again and again but the numbers are just way off. Cant hit anything.

S!

RH