Simon, your last post makes me think of two questions.
Approx when would the KM have started using that version of DF loop? I'm wondering of course if I should try to make that for my model or leave it the round one it started as.
And the other one to do with torpedoes is, how close would the nose of a torpedo come to the inside of the torpedo door? Or perhaps, how long is a torpedo and how long is the entire torpedo tube (assuming the torpedo is as far back in the tube as possible when ready to fire).