Questions concerning Russian Submarine

What I've got maybe wrong, but according to books I read
1) Akula was designed based on Sierra. If this is right, why the profile of Akula more resemble to Alfa not Sierra?

2) Information indicated there are four disposes of torpedo launchers on Akula class
a) 4 533mm with 4 650mm
b) 8 533mm
c) 4 533mm and 2 650mm
d) 6 533mm, 2 650mm
which one is correct?

the only torpedo tube variant that I know of is 4 650 and 4 533, that gives the CO a great deal of weapons versatility. The weapons load is always an issue with submarines, as they can carry only a few "rounds". The design of the Akula and Sierra are different, but mechanically similar, as I understand it. The major difference was the material used for the hull, titanium vs steel. The Akula was optimized for smooth water flow, the blockier Sierra, tho lighter because of the use of titanium, is slightly faster and noisier when moving at higher speeds. And noise is the bane of the silent service. The Akula and Akula 2 are very good boats, and limited only by the crews.

it is better if you can post any picture to prove that torpedo luancher number
thanks for your reply.

I have no pictures of them to prove or disprove the number and size of the torpedo tubes. I looked in another naval guide, an older Jane's, which gives the 2 x 650, 6 x 533, that you cited as a possibility. The one that I cited was a later reference, from Russian sources. I believe the source using Russian sources, as accurate, having said that Jane's is also considered as very reliable.