No TDC on Suger Boats
 

Just sank a 19k ton escorted Euro Liner NW of PI. As we know, Sugar boats didn't have a TDC so I used the horizontal reticules on the objective lens of the scope.

In high power, each small mark = 15' MOA; each large mark = 1°.Top to bottom and side to side, lens face = 8°.
In Low power, each small mark = 1°; each large mark = 4°. Top to bottom and side to side, lens face = 32°.

Acquired first range and bearing, down scope...made plot, 3 min. later, acquired second range and bearing, down scope...made plot. Dist. travelled converted to 13 kn.

Computed OAC via ASIN (( 13 tgt speed / 31 torp speed ) x SIN 80 aob ) = 24°. Therefore, I fired a spread of 4 at the liner as she passed in front of 336° travelling left to right. All hit and she sank within 1 min. leaving 4 liferafts (RB-15's) braving the sea.

edit: btw, I might add that the escorts paid little attention to the proximity of the liferafts as they attempted to do me in. Interesting.

Most are not as hardcore and skilled as yourself, though to get firing solutions without a TDC. Good job!

PD

WTG Don,

:up:

Hey, hey...its the, Frank Kulick, method from SH1:D .

That works well, nice information. But in WWII they did not have a calculator to compute those fun conversions, arcsin, sin, even divide? I thought that is what they use the TDC for (as a calculator).

Though I do admit, I also make the same manual calculation without the TDC...except I stick into the TDC just for fun.

I think they would have had to use that nomograph, wizwheels and stuff (no TDC ). How did they do it without the power of a modern calculator, or a TDC? BTY what is a Sugar boat? the S-class?

I assume they had spread-sheets for the trig computations. I have one. They also had a another guy or two doing the computations and map plotting other then the guy looking through the scope to make it efficient time wise considering they couldnt pause real life:D

Absolutely, there would be someone to make the calculations while the captain made the observations. Slide rules and charts would have to suffice to make the calculations. I have a copy of the Submarine Torpedo Fire Control Manual, circa 1950, and it does have quite a few "plates" in the back which contain angles, slopes, etc. It also provides things such as "lead angle for target beyond critical range" and SINa = target speed/torpedo speed. I haven't had a chance to read through it entirely, but I have a lot of respect for someone who can do that and hit a target. BZ!

I believe they had a circular slide rule called an "Is/Was" or "Banjo".

JCC

Thanks for the info. You know, it maybe cool to try to reproduce those tables and banjo thingy to do it the old fasion way, no modern calculator. :cool:

One other question, in SH3 someone did have a way to determine speed by listing to the number of revolution of the screws via hydrophone. It was bit hard to use depending on what ship you were listening too. iRL you did not know this ship's ID.

If the hydrophone does not work at PD, you can still get range via an active sonar ping to the target. I am surprised that a warship's passive sonar guy did not hear that. Is that realistic> pinging the target to get range via active sonar at PD? without spooking the warship.

Modern ships/subs would hear that immediately. I guess in the old days, it was hard to hear that one or two pings unless they got real lucky.

I have the files. They may not reproduce very well, but I can try and post it to my personal webpage and let people look at it and take what they will.

Aw, man, I read the title and thought "Really? They don't have them in the game? COOL!"

It isn't even April first anymore; it wasn't even a joke...but it got me anyway!:damn: :rotfl:

Sure. It would be neat for a reference, a real life mod sort of.

It would be nice to reproduce what they really used, if it can be used in game. As the one poster said, they use to count screws to get speed. We cannot do that in game, reliabley.

The equation above, for a specific torpedo type (let say Mark 14 slow at 31 knots) could have a circle wheel were one turns it to the calculated target speed, to match up the calculated AOB, then read off toward the center the given degree offset you would need to fire from your present given target bearing you are observing. OP method.

This does not need the range...it is taken into account when determining the speed/plot method, which I like to do.

I believe "War in the Boats" by Ruhe mentions using the "banjo" (S-class). Will check in the local library tomorrow...

Yours, Mike

Doubting Thomas' :D

I posted this in June 2006 on the SHIII forum:

http://www.subsim.com/radioroom/showthread.php?t=94608


Yes, those WWII sub/uboat skippers (all nationalities, btw) were smarter than we give them credit for. Some of those guys became scientists, architects, & engineers after the war, I'm told :)

...and would you believe, the entire USA Lunar project of placing men on the moon (1969) was completed before the era of pocket calculators...hmmmm.

...someone must have been using a sliderule.:|\\

Cheers,

Here is how the Arcsin (( 13/31 ) sin 80° ) is completed using a dimestore sliderule.

http://img58.imageshack.us/img58/9359/picket1jz0.th.jpg
http://img64.imageshack.us/img64/8248/picket2ev6.th.jpg
http://img64.imageshack.us/img64/7688/picket3xe1.th.jpg