[TorpX]

OK, what I don't understand is why would anyone expect the german U-boats to work right when using RFB, or the 3d TDC mods which were intended for USN boats?

I'll admit I've noticed some odd behavior with the TDC (US), but I haven't really tried to pin it down.

I noticed in SH4 you have to re-calculate the distance at least AND send it to the computer, or the gyro-angle will not update with the periscope movement.

This is because the gyro angle is not supposed to update with PS movement. The TDC uses inputs you manually give it, (along with own ship course and speed-automatically), but if the gyro angles chased after the PS every time you moved it to check around and look for escorts/aircraft/secondary targets, your firing solution would be scrambled.