This may belong somewhere else - but it's building off of the Otorten. Right now, it isn't near a complete theory, but food for thought:
1) Tourist sledge - was this an actual object, or imaginary?
a) they mentioned possibly bringing it with them on the train, or dragging it via horse - but maybe they were saying "that's all it
would have been good for" - I don't see it in any pics, or mentioned in diaries until the Otorten.
b) they say it is useless...seems like they tried it? maybe after they noticed the "sledge-deer trail" on January 30, they thought it
would be a good method? they were obviously struggling and trying new things to get through the snow - Dyatlov writes about
trying to send a guy forward without a backpack to create a track, but it still was clearly slow-going. Maybe that's why they
took the route with less trees and obstacles, hoping that being able to drag the gear would make it worth it?
c) "chief constructor com.Kolevatov" (or maybe they found one discarded near the Mansi storage and Kol. repaired it for their
purposes) - definitely seems like it was something real, and that they tried but didn't like - but it wasn't mentioned in any
inventory? I'm suggesting Kol. made it for their Feb1 hike while the others built their storage
2) Many times, the chest injuries are compared to an automobile accident - high speed with a brutal and immediate stop.
So...the tent was set up, and while some folks wrote "Evening Otorten", the others (we know that many in the group liked to laugh and have fun and goof around a little bit) thought they would ride the sledge down the hill before eating dinner. The first trip didn't go far - maybe 400m, but it packed some snow. The second trip was Semyon in back, for weight (camera around his neck, but on his back, since he was leaning forward against Lyuda), Lyuda in the middle, and Rustik steering up front. They found better snow and ended up sliding faster and farther than expected. They lost control and crashed into the Ravine that they didn't realize was there. Rustik saw the danger first and tried to jump clear, but struck his head. Lyuda took the full brunt, partially shielding Semyon, but not enough to save him.
Semyon and Lyuda were immobilized, but Rustik in a state of shock was able to hike/crawl a ways towards the tent before succumbing to his head injury.
Some of the crew watched from the top of the hill, and realized something was wrong. They called to whoever else was in the tent, and went downhill to help (quickly but not running, because they were cautious of unknown ledges at various spots of the hill). They found their friends in worse shape than expected. They tried to save them, then tried to comfort them, and decided too late to return to the tent. They may not have known exactly where the tent was, hence climbing the tree to try to spot it.
Maybe it's worth thinking about? I'm sure a few of you will have some quick evidence to tear into the theory right away...I'll start:
1) everybody we see in pics of the final hike still is wearing a backpack - did they give up on the sledge already, but dragged it along anyway?
2) how did the Yuris still apparently die early enough that the others borrowed their clothes?