And you are taking on aircraft deliberately
why?
The U-flak concept proved to be almost worthless in real life. The gain just wasn't worth the pain. The tactical value of the few aircraft shot down was dwarfed by the loss of life amongst the gunners and damage to the boats sustained during "the great turkey shoot". There's a reason Donitz scrapped the project and returned the 4 flak boats to their regular configurations.
I've never tested it, but the drag of the increasingly larger turms (towers) with their extra weaponry had a serious negative effect on both diving times and underwater maximum speed of the boats.
Does anyone know if either SH3 or GWX models that effect?