Soviet/Russian space programs Q&A

• #100 by tnphysics on 15 Oct, 2007 00:48
• How much delta-V will the KVRB (cryo stage) provide?
  
  If it is optimised correctly then it will provide the majority.
  
  This assumes that it is only for Angara-5.
• #101 by Citabria on 16 Oct, 2007 16:26
• About the two-day Soyuz or Shuttle approach to ISS: Why does it take two days? Is there a technical reason or is it for space-adaptation time for the crew? I doubt that it is for fuel efficiency - the total delta vee is about the same for a two-burn Hohmann transfer as for multiple intermediate transfers, is it not?
• #102 by Citabria on 16 Oct, 2007 16:33
• A question that Korolev's team answered more than fifty years ago, but I have not seen a satisfactory answer: How do the R-7/Soyuz strap-on boosters separate in flight? Do they simply slip backward out of their forward sockets when thrust is cut off? (I saw a film once of a failed launch where one of the boosters lost thrust and slid downward and the rest of the rocket flew for some time before failing!) Does the release of LOX tank pressure push the boosters' noses away from the core? Are there pyrotechnics involved?
• #103 by Jorge on 16 Oct, 2007 17:12
• Quote

  Citabria - 16/10/2007  11:26 AM
  
  About the two-day Soyuz or Shuttle approach to ISS: Why does it take two days? Is there a technical reason or is it for space-adaptation time for the crew? I doubt that it is for fuel efficiency - the total delta vee is about the same for a two-burn Hohmann transfer as for multiple intermediate transfers, is it not?

  
  Maximize launch window and standardize the terminal part of the rendezvous.
• #104 by Citabria on 16 Oct, 2007 17:38
• Quote

  Jorge - 16/10/2007  1:12 PM
  
  Maximize launch window and standardize the terminal part of the rendezvous.

  
  So you're saying that a launch delay would cost little extra fuel and cause no docking delay if the error is spread over two days? I guess that makes sense. Thanks.
• #105 by DarthVader on 16 Oct, 2007 18:54
• I believe one of the reason is that it also help the cosmonaut to get used to "living" in 0g. Which is apparently much easier to get used to if you are in a small area such as the Soyuz.
• #106 by Satori on 18 Oct, 2007 16:23
• Hello!
  
  I'm searching for the launch time of a 11K77 Zenit-2 launch vehicle that failled to launch a Tselina-2 sat on February 5, 1992. Any help?
• #107 by William Graham on 18 Oct, 2007 20:14
• Hi, I'm interested about carrier rockets which are currently in service, but out of production, and specifically how many of each are left. As I see it:
  
  Tsyklon-3: 1-2 launches remaining
  Molniya-M: 3 launches remaining
  Proton-K: 5 launches remaining
  
  Could somebody please check the accuarcy of the above, and give me information on the numbers of launches believed to be remaining for any other types approaching the end, particuarly the following:
  
  Tsyklon-2
  Kosmos-3M
  Soyuz-U (if it is on the way out)
  
  Thanks.
• #108 by sammie on 18 Oct, 2007 22:20
• I believe Kosmos 3M production has restarted. During the mid-nineties only 14 remained in stock, and I'm pretty sure that at their current launch rate, they would have run out of stockpiled rockets long ago.
  
  I'm not so sure whether there is a big difference between the Tsyklon 3 and 2, other then the upper stage. I think it's safe to say that only a few remain in stock and that there is the option to launch to as a either a 2 or a 3.
• #109 by Skyrocket on 19 Oct, 2007 13:24
• Quote

  sammie - 19/10/2007  12:20 AM
  I'm not so sure whether there is a big difference between the Tsyklon 3 and 2, other then the upper stage. I think it's safe to say that only a few remain in stock and that there is the option to launch to as a either a 2 or a 3.

  
  No, these are not interchangeable.
  
  Tsiklon-2 uses RD-251 (= 3 x RD-250) engine on the first stage, while Tsiklon-3 uses RD-261 (= 3 x RD-260)  - don't ask me for the differences.
  
  
• #110 by darkenfast on 22 Oct, 2007 15:38
• I noticed that no one has answered this question, so I'll give it a shot from memory (and I may be wrong).  The strap-ons (Blocks B, V, G and D), are attached by a ball and socket at the forward tip, and straps at the base.  The straps are blown when there is still some residual thrust, and the boosters rotate up and out, causing the ball to come out of the socket.  There is also some venting of residual oxygen to aid in separation.  This discription was from a history that was referring to the original R-7 rocket, and I'm assuming that the method is still used.  Others, with better information may correct me.
  
  Edited: this is in reply to a previous question about strap-on separation on the Soyuz launcher.
• #111 by Nicolas PILLET on 22 Oct, 2007 17:22
• Quote

  Satori - 18/10/2007  6:23 PM
  
  Hello!
  
  I'm searching for the launch time of a 11K77 Zenit-2 launch vehicle that failled to launch a Tselina-2 sat on February 5, 1992. Any help?

  
  Encyclopedia Astronautica has no information.
  United Nations have no information.
  Jonathan McDowell has no information.
  Novosti Kosmonavtiki has no information.
  
  Sorry... :frown:
• #112 by Satori on 22 Oct, 2007 17:32
• Quote

  Nicolas PILLET - 22/10/2007  12:22 PM
  
  

  Quote

  Satori - 18/10/2007  6:23 PM
  
  Hello!
  
  I'm searching for the launch time of a 11K77 Zenit-2 launch vehicle that failled to launch a Tselina-2 sat on February 5, 1992. Any help?

  
  Encyclopedia Astronautica has no information.
  United Nations have no information.
  Jonathan McDowell has no information.
  Novosti Kosmonavtiki has no information.
  
  Sorry... :frown:

  
  Yes, that's strange I have also look for it there but no info there... humm, a mistery to be resolved!!!!
• #113 by mark147 on 22 Oct, 2007 18:11
• Can someone explain the difference between a normal Suyuz re-entry and a ballistic re-entry?
  
• #114 by Jim on 22 Oct, 2007 18:19
• Ballistic entry means aerodynamics are not involved with the flight path.  Soyuz, Apollo and Gemini use a lift entry to modify the flight path with the lift generated by an offset CG.
  
   A guidance system is a requirement to manipulate the lift vector.  A way of canceling the lift force is to roll the vehicle.
• #115 by Citabria on 23 Oct, 2007 17:11
• Quote

  darkenfast - 22/10/2007  11:38 AM
  
  The straps are blown when there is still some residual thrust, and the boosters rotate up and out, causing the ball to come out of the socket.  There is also some venting of residual oxygen to aid in separation.  This discription was from a history that was referring to the original R-7 rocket...
  
  

  
  Thank you for replying to my question. I read that same explanation in Asif Siddiqi's history but I don't believe it (his history is not very technically oriented). If they rotate up and out with some residual thrust, the boosters would likely have different levels of thrust and different angles of rotation and the nose of the core would get pushed to one side. That seems like it would interfere too much with stability of the core.
  
  Also, I saw a close-up photo of a booster nose and socket on a museum R-7 and it is definitely not ball-shaped, although there was not enough detail visible to fully explain the mechanism.
  
  It seems more likely that cutting booster thrust and blowing the aft-end straps would cause the nose to depart the socket rearward, but I'm not sure. No one else has replied, so maybe it's still a Soviet secret. Just kidding! Is this kind of info available on L2? Or anywhere in English?
  
• #116 by NotGncDude on 23 Oct, 2007 18:28
• Also, in ballistic entry you have little control of where you land, and higher G's.
• #117 by darkenfast on 24 Oct, 2007 04:14
• Oh, well...I was remembering the same source!  I quite enjoyed Siddiqi's book, but I wouldn't mind a better explanation either.
  [/QUOTE]
  
  Thank you for replying to my question. I read that same explanation in Asif Siddiqi's history but I don't believe it (his history is not very technically oriented). If they rotate up and out with some residual thrust, the boosters would likely have different levels of thrust and different angles of rotation and the nose of the core would get pushed to one side. That seems like it would interfere too much with stability of the core.
  
  Also, I saw a close-up photo of a booster nose and socket on a museum R-7 and it is definitely not ball-shaped, although there was not enough detail visible to fully explain the mechanism.
  
  It seems more likely that cutting booster thrust and blowing the aft-end straps would cause the nose to depart the socket rearward, but I'm not sure. No one else has replied, so maybe it's still a Soviet secret. Just kidding! Is this kind of info available on L2? Or anywhere in English?
  [/QUOTE]
• #118 by DarthVader on 02 Nov, 2007 22:17
• AFAIK there's no clear and definitive description of how the strap-ons detach. Personally, I think that your are correct darkenfast since there is some video evidence which show clearly how a strap-on simply fell away during a launch (in the 60s I'll said). So what I think happen is that once the thrust in the booster start to decline and that it's time to let them go, the straps that hold them at the bottom is blown, allowing them to simply fall down from the core, all the while some venting at the top of each strap-on push them gently away of the core .. so they rotate  head first away from the core. The bottom line is that it's not like the SRB on the shuttle that are bolted to the tank. On a Soyuz rocket, the strap-ons are only hold in place because they push the core and that the strap at the bottom avoid them from rotating up-wards while pushing the core .... also I seem to recall that the strap-ons reach full thruste before the core ... If that is correct, that'll could confirm this theory since you will not want the core to start building thrust before the strap-on ... anyhow .. I'm no rocket scientist so I could be (very) wrong ...
  
  I wish we could have some definitive explanation on the subject.
• #119 by tnphysics on 05 Nov, 2007 01:04
• Why does the Breeze-M have such a low thrust/weight ratio?
  
  I assume that it is almost in orbit prior to engine start.