Chrom I don't know a lot about armor vehicles I'm learning but wouldn't a door or hatch not be as strong a solid wall? So in theory wouldn't the side of BTR-? be weaker or at least at the door/hatch? I guess if they come under attack the driver could turn to let out troops but wouldn't expose more of the vehicle to further attack? I thought giving an enemy less of a target in combat is better. Unless you can explain the benefits I would have to agree with the poster who mentioned this flaw. Watching the military channel the convoy in Iraq seem to get hit from the side more. I do see one good point you mention that of course is if your attacked from one the other having a way out the other side isn't a bad thing. But on the flip side if the driver turns toward the attack exposing a smaller target and assume a little thicker armor maybe it would provide cover for troops exiting out the back. I guess like the glass of water is half full or half empty.
Can I assume the 30mm auto cannon and other weapons used on a BMP-3 can be mounted on a BRT-90?
Does one vehicle (BTR-90/BMP-3)have more armor protection against mines then the other?
Thanks
BTR-90 carry 30mm cannon by default. In fact, BTR-90 carry BMP-2 turret and FCS. There is also BTR-90 version with BMP-3 turret and 100/30 mm cannons. As for sides... no, doors are not less armored than the rest. The sides of BTR-90 is not as thick as frontal tank armor - so there is no problem making doors exactly as protected as normal armor..
As for drivers turning towards attack - sometimes they can, sometimes they cant. Either way in the case of wider enemy distribution it is almost impossible to provide protection for troops exiting rear, while it is much easer in case of sides exit.
As i said, it is probably disadvantage in more cases than advantage - just not always disadvantage, and not nearly to some deree as sometimes portrayed.
Do not mistake BTR-90 and BTR-80. Despite they similar name and look, they are completely different vehicles. One is APC, other is true wheeled IFV.
P.S. Believe me, USSR designers werent complete idiots, they last experience was Afganistan war. So there were a good reasons why they gone with sides exits, and there were a good reasons why army accepted that.