[FPSPACE] Soyuz LV question

Sat Sep 26 16:10:11 EDT 2009

Dave:

As Sergey explained, boosters actually need thrust exceeding that of the
core stage in order to rotate around the front (top) attachment AFTER
severing of lower connections. However, again, a disconnect between the core
stage and tips of boosters happens as a result of that rotation. No
pyrotechnics involved on the tips. I want to emphasize again, lower
connections are cut first.

Anatoly Zak
http://www.russianspaceweb.com

On 9/26/09 9:55 PM, "David R. Woods" <drwoods at stny.rr.com> wrote:

> Guys,
> 
> I had an opportunity to watch a Soyuz launch out of Complex-1 at Baikonur an
> number of years ago.  I videotaped the whole thing and when I watched it later
> at home, I could see the strap-on separations: four white dots against the
> blue sky drifting away from a fifth center dot core stage.  I have also been
> to MAI Lab-601 to see the  R-7 there and another one in Orevo, and examine the
> top attachment mechanism for each strap-on against the core stage.  It is my
> impression that the RD-107s on the strap-ons continue to burn whatever
> residual propellant is left after separation (as I witnessed in my video), so
> they do not simply fall away due to lack of thrust.  If you look as pictures
> of a Soyuz booster rolling out to the pad, you can see a small umbilical
> running down the outside of the core stage to the top of the upper attachment
> mechanisms.  The only reason for something like that is for wiring or a cable
> to initiate the release.  Therefore, release is a commanded rather than lack
> of thrust process.  Releasing the bottom attachment first may be correct, but
> it sounds a little dangerous, because the strap-ons could rotate inward and
> crunch into the core stage.  It has always been my impression that the release
> sequence starts with detachment at the top, followed by venting of the
> pressurized LOX tank that is nearly empty.  That starts the strap-ons rotating
> away (pivoting at the base) from the core.  The bottom attachments then
> release the whole assembly and they go their separate ways.
> 
> Dave
> 
> -------- Original Message --------
>  Subject:  Re: [FPSPACE] Soyuz LV question
>  Date:  Sat, 26 Sep 2009 19:13:02 +0200
>  From:  Anatoly Zak <agzak at optonline.net> <mailto:agzak at optonline.net>
>  To:  Untitled <fpspace at friends-partners.org>
> <mailto:fpspace at friends-partners.org>
> 
> Re: [FPSPACE] Soyuz LV question Jim, it is the same answer, just in different
> words. But obviously, the opening of the pressurization valve  would not lead
> to physical separation of the booster, but just give it some downward thrust.
> It is the rotation of the booster around horizontal axis at the top connection
> point, what really leads them to physical disengagement from the core stage.
> 
> Anatoly Zak
> http://www.russianspaceweb.com
> 
> 
> On 9/26/09 5:36 PM, "James Oberg" <jeoberg at comcast.net>
> <mailto:jeoberg at comcast.net>  wrote:
> 
>> Anatoliy, this is significantly different from Sergey's answer.
>>   
>>  I never knew for sure, but I had always believed that the
>> strap-on nose was held in locked position by its own thrust,
>> and then when that stopped, it slid backwards slightly,
>> then hinged outwards top first, the bottom held on a hinge
>> through a certain angle before falling free.
>>   
>>  This is a good chance to clear up a lot of misconceptions.
>>   
>>  By the way -- it's got to be said:   WELL DONE on
>> your Fobos-Grunt coverage in IEEE and for BBC and
>> elsewhere, you were definitely the man on top of --
>> and ahead of -- the story. Molodets!!
>>   
>>  Jim
>>   
>>  
>>   
>>>  
>>> ----- Original Message -----
>>>  
>>>  From:  Anatoly Zak <mailto:agzak at optonline.net>
>>>  
>>>  To: Untitled <mailto:fpspace at friends-partners.org>
>>>  
>>>  Sent: Saturday, September 26, 2009 9:39  AM
>>>  
>>>  Subject: Re: [FPSPACE] Soyuz LV  question
>>>  
>>>  
>>> Nicolas:
>>>  
>>> During a nominal separation, bottom  connections of strap-on boosters are
>>> severed first, which causes boosters to  start rotating around the forward
>>> (top) attachments, which are in turn  designed to disengage, when a certain
>>> angle of rotation is  reached.
>>>  
>>> Hope it helps,
>>>  
>>> Anatoly Zak
>>>  http://www.russianspaceweb.com
>>>  
>>>  
>>> On 9/26/09 3:38 PM, "Nicolas PILLET" <nikolai39 at hotmail.fr>
>>> <mailto:nikolai39 at hotmail.fr>  wrote:
>>>  
>>>  
>>>   
>>>> Dear FPspacers,
>>>>  
>>>> I have a question regarding  the Blocks B/V/G/D/ attachment to the central
>>>> core (Block A).
>>>>  
>>>> Lateral  blocks litterally bear the central core. During the ascent, they
>>>> litterally  PUSH the launcher, so if their RD-107 engines shut down, they
>>>> simply fall  down on the pad, like it was the case during Foton-M n°1
>>>> launch, in october  2002.
>>>>  
>>>> I am writing an article on the lateral blocks for my website,
>>>> Kosmonavtika, and you can see the draft here :
>>>>  http://www.kosmonavtika.com/lanceurs/soyouz/tech/2/2.html
>>>>  
>>>> My  question is : do you know how the separation occur after the completion
>>>> of  the lateral blocks' burn ? Do they NATURALLY fall down, or is there a
>>>> separation device to ensure they separate exactly at the good time  ?
>>>>  
>>>> Other question : how are the lateral blocks linked to the pad's  "arms" ?
>>>> And how are the "arms" separated at the moment of the launch  ?
>>>>  
>>>> Thank you very much for sharing information  !
>>>>  
>>>> Regards,
>>>>  
>>>> Nicolas
>>>>  
>>>>  
>>>> 
>>>> 
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