I was wondering if anyone could help me with some information for a tv documentary about submarines that I am researching.

I am interested in finding out about the type IX U-boat and what innovations allowed it to carry so many torpedoes (22).

I know that it had external torpedo storage compartments, but were there any other design advances?

Also, what technology did this type have for loading/moving torpedoes? (This could have been seen on earlier types too). Any help or pointers would be much appreciated.

Many thanks,

Alex.