[ikalugin]

We have borrowed a number of solutions from existing subs.

Titanium hull is expensive to build, the idea behind our projects is to create a line up of "cheap" yet capable submarines both for domestic use and export. To this end we have sacrificed the buoyancy reserve, speed and dive depth.

WoT is World of Tanks. Images show to me, but they are very large.

p.s. about buoyancy reserves and displacement. The overall displacement was selected to accommodate the required depth (and thus hull structure), speed (and thus the powerplant mass/power output) and equipment (sonar, weapons ect) requirements. The buoyancy reserve is given for when the submarine is surfaced, when the submarine is submerged it is basically the part of displacement taken up by water. While it does help with upgrading the submarine (there is a room for growth) or when hit (you could do an emergency blow), it is still displacement wasted when going under water. Increasing the reserve to 30 percent level (ie to the level of Akula class) would create futher need to increase power output for the powerplant, which would lead to further displacement increase and so on (making the sub bigger).