project 1710 (NATO: Beluga)

(there is no need to try to find the reactor in the diagram below. Its a diesel submarine)

The beluga was a soviet diesel submarine designed to test and evaluate new technologies just like the USS Albacore but 35 years later and with a much shorter service life thanks to post soviet disagreements between Russia and Ukraine. Still though during the 12 years she was active, the Beluga provided important insights regarding submarine hydrodynamics as well as scaling data to improve on the accuracy of model tank testing. Among the most noteable achievements of the project were the effectiveness of polymers on hull drag and propulsion efficiency and a better understanding of submarine hull shaping (note she had a near 7:1 length to beam ratio which is the closest to the ideal in terms of hydrodynamics)

Here is a cool cutaway.

(hope you can enlarge the image)

the labels are in russian and google translate wasnt very helpful, so i just didnt list them at all.