I never learned 3D canvas type programs, but after 40 years of screwing around with computer games I'm a pretty fair hacker. So after reading this, I made a backup copy of the PORPOISE folder, fired up S3D;
http://www.subsim.com/radioroom/down...o=file&id=4489
Then opened the NSS_Porpoise.sim file.
At the bottom is the wpn_SubTorpedoSys datablock, select Tubes, right click, select Add Array Item. Then go to one of the existing tubes, copy and paste the data from that, paste into the new tube;
door = NSS_P1_Door02_FRU_anim01
ext_door = NSS_P1_Door01_FRU_anim
Somebody who can use a 3D model editing program would have to add the actual graphics and animation, but yes, it is possible - I now have a Porpoise with 8 working forward tubes. Looks funky but it's operational, this was just 10 minutes of screwing around by an old fossil so I'm sure it could be improved on.