I doubt that the rudders would bend or flutter as I called it very much at all ,but is not better to have some support top and bottom ? I thought about them being used with the net cutter set up ,but when the cutter was deleted in 1941 and u-boat loses shot up sky I would think that if this was now useless that it would be dropped like a sack of bricks inorder to conserve on steel and quicken the building time.
Yes I build R/C u-boats,I have 4 of them.I myself do not have the ROBBE u-47 but many of my friends have it and they love it.I was going to by this kit but instead I am building my 1/32nd scale type 7D minelayer. For this support piece I use brass rod material,the plastic will break in no time! As for it being a dynamic diver this is no problem ,I like them alot and you have less problems with this system . The robbe kit is a great starter boat and is alot of fun to sail and there is plenty of vroom for detailing it to suit whatever particularu-boat you want to sail.