Soyuz

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Eric Mc

Original Poster:

122,101 posts

266 months

Friday 12th October 2018
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View of the abort taken from the space station.


Eric Mc

Original Poster:

122,101 posts

266 months

Friday 12th October 2018
quotequote all
They could - although without knowing what caused this failure they may not want to risk that.

Eric Mc

Original Poster:

122,101 posts

266 months

Saturday 13th October 2018
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I have to say, the presenter on RT said this a few hours after the event. I also thought that this was a possibility and mentioned it too although I can't remember which thread as we had four threads running on this topic at one point..

Manley has uncovered a different view of the incident which seems to back up this hypothesis. Unfortunately, the broadcast live view cut to a shot of the interior of the Soyuz spacecraft just at the moment the strap-ons were discarded. By the time they cut back to an exterior shot, the incident was already in progress.

I'd like to see that original external view of the launch all the way through to booster separation.


Eric Mc

Original Poster:

122,101 posts

266 months

Saturday 13th October 2018
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I am absolutely sure we will - and in a few weeks, if not months.

Because this was carrying a NASA astronaut, NASA will insist on a full and detailed technical report on what went wrong. NASA insisted on similar reports on the 1971 Soyuz fatal depressurisation event and also on the 1975 Soyuz launch abort.

We therefore found out exactly what happened in those two accidents.

Eric Mc

Original Poster:

122,101 posts

266 months

Saturday 13th October 2018
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From an interview with Russian TV -

Former Russian Cosmonaut and current current Executive Director of Roscosmos Sergei Krikalev spoke about the possible reasons for the Soyuz MS-10 booster failure while speaking to the press in Moscow on Friday.

“There are no final versions, but the immediate cause is clear, it is due to the collision of one of the side elements,” Krikalev said.

“In the separation of the first and second stages, contact occurred. There was a deviation from the nominal trajectory and, it seems, there was a destruction of the lower part of the second stage. The rocket stopped normal flight, then the automatics worked out regularly,” he added.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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The R7 family of rockets lifts off the ground with five sets of rocket motor firing - a central core stage to which is attached four strap-on boosters.



After 2 minutes of flight, the four strap-ons fall away.

The four strap-ons and core stage all firing together is sometimes referred to as the "1st stage" and the core stage firing on its own is sometimes referred to as the "2nd stage". This is not strictly speaking accurate as with the core stage firing continuously it is really part of the 1st stage for a bit and then only becomes the 2nd stage when the boosters fall away.

There is also a 3rd stage with sits above the core and is separated by the open strut system shown here -



The reason why the interstage section is open like this is because the 3rd stage engines fires before it separates from the core stage. The open structure allows exhaust gases to be dissipated sideways and outwards. Once the 3rd stage is firing at the correct thrust, the core stage falls away.

When the original version of this booster (the R7) was designed by Korolev in the early/mid 1950s, the engineers were not confident that they could separate and ignite different stages in sequence in a reliable manner. They were concerned that the shock of separating and discarding separate stages could cause problems with the ignition of the next stage in the sequence.

The Americans had a similar set of concerns which is why the original Atlas rocket also had side mounted boosters which fired alongside a central core stage during the first few minutes of flight. These boosters slid away when expended whilst the core stage continued firing. You can see the layout in this scale model (The old but nice Revell kit which dates from 1959).



The Saturn V is a good example of a rocket where each stage separates initially before being ignited and indicated the confidence Von Braun and his team had in thinking that they would be able to separate and ignite the various stages in sequence without any issues.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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It's increasingly looking like that all rocket motors were firing correctly at thrust levels within the required parameters. The problem seems to be at the moment of separation of the side boosters.

Funnily enough, it could be very similar to what happened with Challenger. The Orbiter was destroyed when one of the side boosters pivoted into the external tank which, of course, ruptured and caused the break up of the entire stack.

The big difference between the two incidents is that the Soyuz has a viable and reliable abort system which saved the crew.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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4x4Tyke said:
Challenger was the O ring failure, sending a jet of flame onto the main tank and a near immediate explosion.

Wasn't the Shuttle supposed to complete separate in some scenarios, and they added the bailout guide rail thing later.
Not quite

The O ring failure allowed hot exhaust gas to play on the lower attachment strut where the booster was linked to the External Tank. As a result, the lower strut burned through allowing the booster to swivel around the upper attachment point. The tip of the booster then punctured the top of the External Tank. The tank therefore lost its structural integrity and aerodynamic forces caused the tank to collapse - a bit like bursting a paper bag. Once the tank had collapsed, the Orbiter was pushed away due to the expansion of the gases contained in the tank. As the Orbiter was now being pushed outwards into a very high speed airflow, it too broke up due to excessive aerodynamic loads.

There was no "massive explosion" in the true sense of the word. The break up was due to aerodynamic air flow. Once the Orbiter broke up, some of the hypergolic fuel tanks and fuel lines which operate the smaller manouevering thrusters and the OMS system did rupture and caused smaller explosions. You see the hypergolic explosions as they added a reddish-brown tinge to the white vapour cloud caused by the mingling of the oxygen and hydrogen from the External Tank.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
quotequote all
4x4Tyke said:
Yes; I get there was a struts failure but from reading the wiki, that was an element of the complete structural failure rather than its cause which seems might be the case with Soyuz. I accept I'm nitpicking over cause and effect, but it is I think an important part of the sort of analysis they will be doing. The wiki uses the word fireball from the LH2 and LOX tanks' failure, though I accept they also say the shuttle broke from aerodynamic stress not the fireball.

I'd also forgotten until reading it, the Challenger crew were probably alive until the cabin hit the Ocean and the escape rails thing was more of a proposal than actual system. It seems a lot of other escape systems were ruled out over cost, weight and time to implement.



Edited by 4x4Tyke on Sunday 14th October 11:36
There was no "fireball" in the true sense of the word. The large cloud you see in the aftermath of the Challenger is actually steam from the mixing of the oxygen and hydrogen in the tank. As I said earlier, there were smaller explosions from hypergolic reactants mixing when those smaller tanks burst.

The tank really was "squashed" by aerodynamic pressure. It collapsed from the top downwards. If you watch frame by frame analysis of the accident, you can actually see the initial gas release at the top of the tank as the booster pivots and punctures it. A couple of frames later, there is another gas release from the bottom of the tank when the rear pressure bulkhead fails under aerodynamic loads because the top of the tank has already gone.

The gas released at the base of the tank is ignited by the still running Shuttle Main Engines but by then the Orbiter is already beginning to break up because it has been forced outwards by the bursting of the tank. As the Orbiter moves out, it encounters aerodynamic loads it cannot withstand and breaks up into its constituent parts. In fact, you can see major components of the Orbiter coming out of the steam cloud, namely, the port wing, the crew cabin and the rear thrust assembly to which the main engines are attached. These engines continue to fire for a few seconds even though they are now no longer attached to the orbiter due to residual propellants in the feed pipes.

The Orbiter was a lot less robust compared to , say, an airliner. It did not have a single wing spar of the type you get in virtually all aircraft. The wings were essentially bolted on to the side of the fuselage. That's why both wings broke away cleanly when the Orbiter broke up.
There were two reasons why the Orbiter was designed without a single spar system. Firstly it saved weight and secondly it ensured the cargo bay was unobstructed.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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I've read that the normal structural limit for a modern airliner is five times the structural loading. The Orbiter was stressed to twice its nominal structural limit.

If the Shuttle was an airliner it would not have been given a Certificate of Airworthiness.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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Forget Ground Control, I held my breath every time the Shuttle took off.

I followed the programme from before it was even sanctioned (1972) and the whole argument for its design was routine, reliable and affordable access to low earth orbit.

I remember watching the first ever launch in April 1981 live on TV and my immediate reaction was "That will NEVER be routine". It actually frightened me a bit because it was altogether more dramatic and violent than a Saturn V launch - which what we all had been used to from watching the Apollo missions.

Of course, as the missions progressed we became more used to what a Shuttle lift off looked like but Challenger brought home to me that my initial reaction to that 1st launch wasn't wrong.

I also read a book in 1981 called "The Cosmic Chase". It was written in 1980 and had a whole section on future Shuttle missions, One line from the book has always stuck in my mind "What happens if a solid rocket booster fails in flight? What happens is, you die".
How prescient was that.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
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carl_w said:
hirdly, it was originally designed as a lifting body without wings and the wings were added to provide crossrange ability for Soviet Union overflights.
Not strictly true. The lifting body was concept was certainly considered but only as part of a range of options. In fact, NASA favoured a winged design from the outset - although it was a very different design to what they originally ended up with.

This is the type of winged Orbiter vehicle they were looking at -



This design was championed by Max Faget who had behind the original blunt body capsule designs used in Mercury, Gemini and Apollo.
The problem with Faget's Shuttle concept was the poor cross range potential. For NASA's purposes, cross range was not that big an issue. However, for Department of Defense missions, cross range was vital as it allowed a Shuttle launched on a polar orbit from Vandenberg Air Force Base in California to do one single pass over a desired target in the Soviet Union and then land back at Vandenberg after that one single pass. Faget's stubby wing design could not do that. As a result, the Shuttle grew an enormous high lift delta wing.


Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
quotequote all
Einion Yrth said:
And having dangerously compromised the design, the USAF never flew a shuttle mission.
Not true either. There were quite a few Department of Defense missions. What they never did was fly one out of Vandenberg Air Force Base - even though they had converted a launch pad (SLC-6) to do just that.

The first Vandenberg launch was set for mid 1986 but after the Challenger accident, the DoD decided not to go ahead with any launches from Vandenberg and gradually moved away from using the Shuttle. However, they continued to use the Shuttle up until around 1990 or so.

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
quotequote all
RobDickinson said:
I'm sure there is another thread for shuttle chat Eric.
I'm sure there is.

Dragging things back to topic, full unedited versions of the video footage of the MS-10 flight are now available to see. I think we can clearly see that there is an impact between one of the boosters and the core section. The core section can be seen rotating slowly as well following the impact.

Also, I think you can see the Soyuz spacecraft floating off to the left of the tumbling core section.

https://www.youtube.com/watch?v=KF_9mVUvl3Y&li...

Eric Mc

Original Poster:

122,101 posts

266 months

Sunday 14th October 2018
quotequote all
MartG said:
Eric Mc said:
As a result, the Shuttle grew an enormous high lift delta wing.
I've read that the fin alone was twice the size and triple the weight of the original design - I wonder what the total mass penalty of the delta design was compared to the stubby straight wing one, and how much more payload could have been carried ( or higher orbits reached ).
We've been told off for chatting about the Shuttle so I won't respond - even though your point is good.

Eric Mc

Original Poster:

122,101 posts

266 months

Monday 15th October 2018
quotequote all
RobDickinson said:
Eric Mc said:
Or constantly changing priorities and directives from government.

There is a separate thread for SLS matters by the way.

This is the SpaceX thread.
You either want threads on topic or not mate. Pick one.
I'm OK. Move on.


Eric Mc

Original Poster:

122,101 posts

266 months

Monday 15th October 2018
quotequote all
Notice - I'm not arguing. Yes, discussing the Shuttle is a deviation and I've acknowledged that. Discussing me is an even bigger deviation and I won't be discussing that topic any further.

However, I did think that there were some similarities between what happened with Challenger and this recent Soyuz incident - with wildly different outcomes, of course.

Eric Mc

Original Poster:

122,101 posts

266 months

Monday 15th October 2018
quotequote all
Thanks.

No more Shuttle talk for the moment.

I'm sure NASA has little choice.

Eric Mc

Original Poster:

122,101 posts

266 months

Thursday 18th October 2018
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Let's hope they get to the bottom of what happened soon.

Eric Mc

Original Poster:

122,101 posts

266 months

Thursday 18th October 2018
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Nope - failed in that too.

The abort occurred at an altitude of 40km. I don't think that the ballistic arc carried out by the Soyuz descent module would have taken them above that arbitrary "space" marker, the 100km Karman Line.