[FPSPACE] Soyuz LV question

Sat Sep 26 18:26:48 EDT 2009

That is correct Dave as Sergey says as you will find on the Molniya launch
vehicle flight sequence picture I took at Oreva that was clearly displayed
on the wall there

-----Original Message-----
From: fpspace-bounces at friends-partners.org
[mailto:fpspace-bounces at friends-partners.org] On Behalf Of Anatoly Zak
Sent: Saturday, September 26, 2009 4:10 PM
To: David R. Woods; Untitled
Subject: Re: [FPSPACE] Soyuz LV question

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>
<mailto:agzak at optonline.net>   
 To:  Untitled <fpspace at friends-partners.org>
<mailto: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> <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>
<mailto:agzak at optonline.net>   

 To: Untitled  <mailto:fpspace at friends-partners.org>
<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> <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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