To my complete surprise, I received last Friday the last 2 books I ordered from Amazon ... which was in fact pretty good, as I put the book from Asif Siddiqi to good use the following day .. in search for some Soyuz's details (btw both books from that author are again available in 24h). Castorp and I were trying to figure out the purpose and whereabout of the torus shaped compartment located at the aft of the service module (to which the Igla antenna is attached to):
According to the Wikipedia article on Soyuz 6, it is a housing for docking electronics equipment, to be jettisoned following docking in order to lower the mass of the spacecraft. That is pretty much the description that I found in Siddiqi's book:
"The jettisonable compartment was a remnant of the original 7K vehicle's mission: circumlunar flight. It was originaly a toroidal section at the base of the vehicle that would carry electrical systems for rendezvous and docking and be discarded following translunar injection. In redesigning the 7K to the 7K-OK, early models of the Soyuz evidently retained this compartment for chimical batteries, with all rendezvouz and docking instrumentation was moved to the spheroid living compartment at the forward end of the vehicle"
According to a schematic on the PAO which can be found in the book, Soyuz 1 to 9 where the only Soyuz 7K-OK equiped with such compartment. Instead some mysterious boxes made their apparitions:
Now, the question is ... what are those boxes?