Delta IV Q&A

• #80 by Skyrocket on 21 Sep, 2007 08:06
• At least the Delta-4M+(4,4) could be implemented rather quickly, as no pad modification would be necessary.
• #81 by Jim on 21 Sep, 2007 11:12
• Quote

  TrueGrit - 21/9/2007  3:50 AM
  
    Quite simply there isn’t a costumer need for a better Medium.  But there’s enough work to feel confident that everything from a 4/4 to a 5/8 could be quickly brought on-line if a costumer indicates a need.

  
  The real issue is that the need can be satisified by an Atlas  4XX or 5XX more cheaply and thus that is why we won't see any 4/4 or 5/8
• #82 by tnphysics on 21 Sep, 2007 11:41
• What would be the 5/8's payload?
  
  How much would it cost to stretch the CBC's tanks and increase the payload of such a configuration?
  
  TrueGrit, are you stating that ULA could provide a 5/8 to a customer for less than they would charge for a Heavy?
  
  This includes pad mods, to whatever extent ULA would decide to charge its first 5/8 customer for them as opposed to amortizing them over many 5/8 missions.
• #83 by tnphysics on 21 Sep, 2007 11:53
• Could the CBC be modified for parachute recovery and reuse?
• #84 by Jim on 21 Sep, 2007 13:33
• Quote

  tnphysics - 21/9/2007  7:41 AM
  
  What would be the 5/8's payload?
  
  How much would it cost to stretch the CBC's tanks and increase the payload of such a configuration?
  
  TrueGrit, are you stating that ULA could provide a 5/8 to a customer for less than they would charge for a Heavy?
  
  This includes pad mods, to whatever extent ULA would decide to charge its first 5/8 customer for them as opposed to amortizing them over many 5/8 missions.

  
  You figure it out.  You would get just as good of answer
• #85 by Jim on 21 Sep, 2007 13:35
• Quote

  tnphysics - 21/9/2007  7:53 AM
  
  Could the CBC be modified for parachute recovery and reuse?

  
  It just takes time, money and some  performance.  which all would be a waste
• #86 by tnphysics on 22 Sep, 2007 01:58
• Shouldn't a Delta IV Heavy with a multi-engine upper stage be able to put about 35 metric tons in LEO?
  
  This assumes that the additional engines are staged after they are no longer needed.
  
  And couldn't the three common booster cores be able to put about 19 metric tons in LEO?
• #87 by MKremer on 22 Sep, 2007 02:08
• Quote

  tnphysics - 21/9/2007  8:58 PM
  
  Shouldn't a Delta IV Heavy with a multi-engine upper stage be able to put about 35 metric tons in LEO?

  Define "multi-engine upper stage", please.
  
  

  Quote

  This assumes that the additional engines are staged after they are no longer needed.

  Say what??
  
• #88 by tnphysics on 22 Sep, 2007 02:28
• Multi-engine upper stage means more than one upper stage engine.
  
  I was going to jettison each engine once its thrust was less important than its mass.
• #89 by Nick L. on 22 Sep, 2007 04:06
• Quote

  tnphysics - 21/9/2007  10:28 PM
  
  Multi-engine upper stage means more than one upper stage engine.
  
  I was going to jettison each engine once its thrust was less important than its mass.

  
  Yeah, we know. The question is, what kind of multi-engine stage? 2 engines? 4? How big? How much fuel? How long of a burn time? How much would it cost?
  
  1.5 staging (like you are proposing) is very complex, and to be able to do such a thing successfully would probably not be cost effective considering the lack of payloads in the weight range.
  
  Developing a new upper stage would be too expensive and would not be worth it; there are not enough payloads out there to absorb the cost of development. This is why the Advanced Upper Stage was canceled in the first place. There are cheaper ways to improve the Delta IV's performance. RS-68 upgrades and GEMs are some of these.
  
  
• #90 by MKremer on 22 Sep, 2007 04:10
• Quote

  tnphysics - 21/9/2007  9:28 PM
  
  Multi-engine upper stage means more than one upper stage engine.
  
  I was going to jettison each engine once its thrust was less important than its mass.

  
  Both D-IV and Centaur have pretty efficient upper stage engines now (and with Centaur you can choose either one or two engines based on payload mass and type of orbit injection requirements).
  
  You do realize how much extra hardware would be required to do an Atlas-1-type jettison of upper stage engines, right?
  (And that they -upper stage engine(s)- have to be balanced both thrusting and stopping and jettisoning so the CoP and CoG and overall thrust vector are balanced and designed/programmed to place the payload in its contracted orbit.)
  
• #91 by tnphysics on 22 Sep, 2007 12:29
• You need more than 2 to fight the gravity losses.
  
  4 RL-10 engines is more like it.
  
  This will improve payload even if the switch must be made to less efficient RL-10-A-4 engines (instead of RL-10-B-2).
  
  I did not realize how much extra hardware was required for jettisoning upper stage engines.
• #92 by Jim on 22 Sep, 2007 13:27
• Quote

  tnphysics - 21/9/2007  10:28 PM
  
  Multi-engine upper stage means more than one upper stage engine.
  
  I was going to jettison each engine once its thrust was less important than its mass.

  
  why??
  
  And drop an engine on some people
  
  This is the real world  Theorical solutions are not always practical nor cost effective.  Delta IV and Atlas V were designed to meet specific requirements, which they do.  Any other "requirements" would have to paid for by the org that needs the change.  
  
  Right now, the only upgrade to the EELV's, is the Delta IV Heavy enhancements. Any others don't exist until a paying user is found
• #93 by TrueGrit on 22 Sep, 2007 15:05
• Why would you need to strech the CBC to incorporate more solids?  Any studies certianlly didn't involved development a new GEM (big $$), but utilize the existing 40, 46, or 60 designs (first two from Delta II and III).  Any additional GEMs would be placed radially around the CBC.  But I think it's safe to say that the M+4/4 and M+5/8 along with WBC and Atlas Heavy are all a question marks at the least with ULA around.  That doesn't mean the advanced product development teams are sitting on their hands.  But the focus has changed from "beating the other guy" to "working with the other guy".
• #94 by TrueGrit on 22 Sep, 2007 15:16
• So Delta spends countless hours keeping the CBC internal enviornment "dry" and you want it to be dropped in the ocean to soak in sea water for hours.  No one has conviced me you can keep the propellant systems from getting contaminated in that process.  And once contaiminated how do you clean a 15000+ cuft tank with isogrid cutouts without disassembling the entire structure.  The disassembly, cleaning, and reassembly process would be more expensive than simply making another tank.  And that doesn't begin to talk about the 1000+ lbm weight hit for parachutes, costs to incorporate it, or costs to support the recovery boat/team.
• #95 by meiza on 22 Sep, 2007 17:05
• Isn't the tank cleaned after welding too? Are the segments cleaned (washed) after machining before welding? It seems to be a small part of the manufacturing process.
• #96 by TrueGrit on 22 Sep, 2007 21:34
• All cleaning is done while the tank is still in subassembly...  There is no forward or aft covers, or small/electrical equipement installed.  As such you have great access through the top and bottom and don't have to worry about small/electircal parts.  With the vehicle all assembled removing the covers means removing the feedlines, electrical equipment, and small lines/valves.  Nothing short of a compelte disassembly of the tank.  And this doesn't being to address the composite structure...  All of which degrades when exposed to a high moistore enviornment.  My guess would be that the composite structure structure would be a loss.  So now your talking about disassembling the stage into subsections, diassembling the tank for cleaning, and completely replacing the Centerbody/Instage...  Building the tank and engine section structure is actually quite cheep.  Particuarly now that the tooling is built and the processes arer developed.
• #97 by tnphysics on 22 Sep, 2007 21:41
• Okay, you've presuaded me. It's not cost effective.
• #98 by meiza on 22 Sep, 2007 22:56
• Quote

  TrueGrit - 22/9/2007  10:34 PM
  
  All cleaning is done while the tank is still in subassembly...  There is no forward or aft covers, or small/electrical equipement installed.  As such you have great access through the top and bottom and don't have to worry about small/electircal parts.  With the vehicle all assembled removing the covers means removing the feedlines, electrical equipment, and small lines/valves.  Nothing short of a compelte disassembly of the tank.  And this doesn't being to address the composite structure...  All of which degrades when exposed to a high moistore enviornment.  My guess would be that the composite structure structure would be a loss.  So now your talking about disassembling the stage into subsections, diassembling the tank for cleaning, and completely replacing the Centerbody/Instage...  Building the tank and engine section structure is actually quite cheep.  Particuarly now that the tooling is built and the processes arer developed.

  
  Thanks, this is good info! I for one didn't have this good insight into the whole process. That makes the arguments powerful and justified - reuse would be costly.
• #99 by tnphysics on 23 Sep, 2007 02:38
• What about scrapping the tankage and focusing on reusing the engines?
  
  Or making a flyback CBC?