SUBSIM Radio Room Forums - Need expert on torpedo data

I will assume you are interested in the USN Mk III TDC, and not other KM or UK mechanisms.

Quote:

Originally Posted by drEaPer (Post 1871983)

Hi,

I am looking for very specific information and maybe someone here can help me out, this would be great:

In a WW2 setting when firing a torpedo:

1. The TDC is being set up with data and calculates a target solution
2. The TDC constantly updates the forward torpedo (and has a 2nd independent channel for the aft, as far as I know).

Questions:

A) Does the TDC update only one tube? Or does it update all tubes?

It updates all tubes. The whole reason for it's development was to facilitate the rapid engagement of a target or targets with multiple torpedos. If it could only be used with one torpedo at a time, it would have been of little use.

B) Is it possible for the TDC to update and program torpedo #1, after which the torpedo is set up and ready, whereafter the TDC can be switched to another tube with an entirely new solution?
Or will this overwrite the programming for torpedo #1? Is it all just one channel?

Only one solution at a time can be calculated. Simultainous solutions for two targets would have required another TDC. It was quite a feat to get it all to work reliably in a compact machine, with the technology of the day. There were a lot of gears, rods, and such just for the one channel.

3. When the torpedo is set with a gyro angle, and is fired, it will travel a straight forward distance called "reach" until it passes the point called "arm" at which it starts changing the heading towards it's set gyro angle.

C) How long is the distance "reach" for WW2 torpedos?

IIRC, it was about 20 yds., but I'm not sure. It might be different for different torpedos.

D) Is the spot "arm" also the same spot where the weapon becomes
enabled?

No. The arming would depend on the exploder, and would be set according to doctrine and warhead capabilities. Safety of the boat is the criteria here. The reach is only required to clear the boat before the turn. An excessive reach would tend to increase parallax errors, and make good firing solutions more difficult to obtain. From the standpoint of firing solutions, it is best to have a quick and tight turn. Limitations of torpedo design and different circumstances, require a compromise.

E) When flooding a torpedo tube, is there a max depth for doing so, below which the submarine would take damage due to pressure?

Yes. The interior doors of the tubes are weaker than the outer doors, and might fail if subjected to too much pressure. (This could easily be fatal for all aboard.) Also, the impulse mechanism must push the torpedo out, and this requires more pressure as the depth increases. So there is a limit. However, I believe US subs could lauch up to 200 ft.

It would be great if some experts could help me out here, that would be awesome!

Greetz!

I hope this helps. I'm not really an expert, so maybe someone with further information will provide more.