In article ,
says...

Roscosmos released on-board video of soyuz failure.

https://youtu.be/CrzlMTRVt_I

(booster separation starts roughly 1:23 into video).

Youtube hint: use the "." and "," keys in paused video to
advance/reverse frame by frame).

Also: at roughly 1:26, there appears to be a large portion of video
skipped). And the times in video don't match actual time since launch.

The Roscosmos press release on the issuance of report:
(google translation)
https://translate.google.com/transla...%2F&edit-text=

It does confirm the damaged occiured during final assembly at Baikonour
(so not during manufacturing or transport).

But contrary to media reports that some claimed "confirmed" what
happened, it wasn't a bent pin that the crews coated with lubricant so
the booster could be slid into place, but rather a very small "push
button" pin designed to detect when separation begins in order to open
an O2 valve to act as reverse thruster at the top of booster to move it
down and out of main rocket.

And yet this shoddy workmanship *did* happen and was tested to see if it
could have caused the incident. It didn't, but that's like saying Ford
forgot to put several lug nuts on a new car, but it ended up crashing
due to an improperly installed ABS sensor. So, no need to worry about
the people installing the lug nuts, because they didn't cause this
particular accident. SMH.

It is also not clear whether the assembly workers noticed this or not.
(If not, then the assembly process itself would need to ensure such
sensors are not damaged during mating).

No, it's not clear. What is clear is that the sensor was bent during
assembly. The Russians are giving little more detail than that. And of
course NASA isn't going to give us more detail. Everything is fine! Of
course we're going to continue to launch astronauts on Soyuz. Just move
along. There is nothing to see here!

Also, in this failure, the booster, in not distancing its top portion
from core, moved down, with the top of booster ripping through the core
and causing core's propellant to be released.

Yeah, that's really bad. The release of pressure in the tank resulted
in a very large, sudden, force on the stack which caused it to
immediately tumble. IMHO, it's highly likely that the tumbling is what
caused the automatic abort system to activate. When your launch vehicle
rotation rates indicate that things are *literally* going sideways, you
have a huge problem.


(In the video one can see some long cable-like thing dragging after,
indicating more damage than simple dent in engine bell.

QUESTION: at that altitude, would releasing large amounts of kerosene
cause an explosion or would it remain unignited except for propelland
falling behind core's exhaust where there might be some lefover O2
availabls?

I swear we went over this when SpaceX lost a Falcon 9 on the pad when
the COPV let loose. It's a very similar situation. Here we go again.

To obtain an explosion, you'd have to have pre-mixing of kerosene and
LOX. That didn't happen. So there could be no explosion. But, again,
the kerosene and LOX tanks are under pressure (to maintain the required
head pressure at the pump inlets), so just releasing that pressure is
what caused the stack to immediately tumble. No "explosion" required.
If anyone calls it an explosion, they're technically wrong.

Obviously, internally, they know far more than they are releasing to the
media in terms of how/why the sensor was damaged, whether the workers
knew of it or didn't notice etc etc.

We have no idea. It's hard to tell how honest someone is being when
they know if they give the "wrong" answer, the consequences are going to
be dire. It's the Russians we're talking about. Their safety culture
is completely broken, IMHO. The floggings will continue until morale
(and reliability) improves.

So there really isn't enough information available to make
judgement on the problems that allowed this to happen.

Bull****. They have a broken safety culture. Look at their launch
record over the last 20 years. Look at all versions of the Soyuz and
Proton launch vehicles. This information is in Wikipedia, so it's dead
simple to find. Look at both "failures" and "partial failures".

Soyuz 2, their latest and "greatest" version of the R-7 family, has an
absolutely horrible reliability record. You can calculate the failure
rate yourself from the available data. And do note that Soyuz 2 is the
vehicle that they will use exclusively for crewed Soyuz capsule launches
in a scant two years. Again, look at the tables under planned launches
of Soyuz 2 and you'll see that the first crewed flight will be in 2020,
if memory serves.

So when you say "there really isn't enough information available to make
judgment on the problems that allowed this to happen", I disagree
completely. Designs that are heavily based on vehicles that have been
flying for more than half a century should *not* fail at the rate that
Soyuz 2 is failing. That is your root cause.

The Russian launch program has a failed safety culture. This is why
future Russian launches will continue to fail at an unacceptably high
rate. You can see the train wreck approaching in the Soyuz 2 tables on
Wikipedia. It's only a matter of time before a crew dies.

Jeff
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