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Delta IV for Commercial Crew
by
Rocket Science
on 17 May, 2014 12:38
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After watching the beautiful sight of the Delta IV launching into the evening sky, I began to wonder if we should revisit human certification of this vehicle in light of the political issues regarding the RD-180’s on the Atlas V... It is expensive, but when we are dealing with space autonomy in light of current events it might be worth the expense and a quicker solution than producing a new domestic liquid engine for Atlas V.
Report on HR of the Heavy for some background:
http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdf
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#1
by
EE Scott
on 17 May, 2014 15:03
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Since the DIV is less powerful than Atlas V, it would need more solids than Atlas V to lift the capsule/spaceplane. How many solids would be unacceptable from a man-rating point of view I wonder. I don't believe the number of solids needed was ever nailed down for the Atlas V - was it one or two? If Atlas V needed two let's say, then Delta IV would need four? I'm just thinking out loud here, haven't even finished my coffee yet.
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#2
by
Rocket Science
on 17 May, 2014 15:23
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Since the DIV is less powerful than Atlas V, it would need more solids than Atlas V to lift the capsule/spaceplane. How many solids would be unacceptable from a man-rating point of view I wonder. I don't believe the number of solids needed was ever nailed down for the Atlas V - was it one or two? If Atlas V needed two let's say, then Delta IV would need four? I'm just thinking out loud here, haven't even finished my coffee yet.
Enjoy the coffee!
4GEM60's should do it...
http://www.spacelaunchreport.com/delta4.html
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#3
by
PahTo
on 17 May, 2014 16:12
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Thanks for starting this, Rocket Science. With SLS decision to NOT human rate the iCPS (effectively the 5 meter DCSS), it seems things are going the wrong way for human-rating the D-IV(M or H). I believe it is time to consider human rating one or more forms of the D-IV, as that seems more expeditious than getting a new hydro-lox engine/core designed, built and flying (Falcon 9 notwithstanding).
Having said that, it seems there are two different DCSS--a 4 meter and a 5 meter. I have to believe only one of these would be human rated, but how different are they? Would rating one effectively result in both being rated?
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#4
by
Rocket Science
on 17 May, 2014 16:35
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Thanks for starting this, Rocket Science. With SLS decision to NOT human rate the iCPS (effectively the 5 meter DCSS), it seems things are going the wrong way for human-rating the D-IV(M or H). I believe it is time to consider human rating one or more forms of the D-IV, as that seems more expeditious than getting a new hydro-lox engine/core designed, built and flying (Falcon 9 notwithstanding).
Having said that, it seems there are two different DCSS--a 4 meter and a 5 meter. I have to believe only one of these would be human rated, but how different are they? Would rating one effectively result in both being rated?
I would believe so, but I would defer to Jim and his expertise in this area...
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#5
by
DGH
on 17 May, 2014 17:03
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In 3rd quarter of 2015 a new common avionics suite is expected to fly on the Atlas V. ULA is planning on replacing the current 4 meter upper stage on the Delta IV with Atlas upper stages after testing a new common avionics suite.
These two upper stages are already being man rated for use on the Atlas V.
Also these upper stages will increase Delta IV performance to ISS.
A Delta 4,2,2 would have the same performance as an Atlas 422 to ISS.
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#6
by
Star One
on 17 May, 2014 17:53
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In 3rd quarter of 2015 a new common avionics suite is expected to fly on the Atlas V. ULA is planning on replacing the current 4 meter upper stage on the Delta IV with Atlas upper stages after testing a new common avionics suite.
These two upper stages are already being man rated for use on the Atlas V.
Also these upper stages will increase Delta IV performance to ISS.
A Delta 4,2,2 would have the same performance as an Atlas 422 to ISS.
How easy would it be to move Dream Chaser & CST-100 to the Delta IV, would it incur much in the way of additional costs?
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#7
by
sdsds
on 17 May, 2014 18:07
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How easy would it be to move Dream Chaser & CST-100 to the Delta IV, would it incur much in the way of additional costs?
Wind tunnel testing of the DC/Atlas stack cost ~20 million dollars. I am not making this up, but more precisely that was the award amount for the corresponding Commercial Crew milestone. Presumably they would need to repeat much of that work to demonstrate the safety of an integrated DC/Delta stack.
(The milestone task description was, "Wind Tunnel Testing. The purpose of this testing is to reduce risk on both the DC vehicle and the DC/Atlas stack by maturing the DC and DCiAtias aerodynamic databases, providing improved fidelity in Reynolds number effects and control surface interactions, and will help determine pre-CDR required updates to the OML or control surface geometry if required." - See more at e.g.:
http://www.parabolicarc.com/2014/02/28/sierra-nevada-completes-dream-chaser-flight-profile-data-review, or elsewhere.)
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#8
by
edkyle99
on 17 May, 2014 19:04
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The 2009 Aerospace Corp. study included the following discussion about RL10.
"The RL10B-2 and RL10A-4-2 have substantial component commonality, with the primary exceptions being
the ignition system, chamber design, and nozzle extension. Given that the second-stage engine must meet human-rated reliability requirements, the RL10B-2 was eliminated from consideration based on its requirement to extend a large nozzle extension following stage separation using a single-string belt drive system. It may be possible to develop redundancy for this hardware, but such a system would likely be difficult and expensive to develop and also to verify that it meets reliability requirements under flight-like conditions."
"Both RL10 variants currently do not meet the structural requirements outlined in NASA-STD-5012. It is possible that design modifications could achieve these requirements, but substantial modifications to the engine appear likely. One concept developed to achieve these requirements is to perform the first hot-fire at current thrust levels to cold work the engine components in question, followed by trimming the engine to a lower thrust level that would meet the standard. The drawback to this approach is the loss of available thrust to the second stage. In order to mitigate this problem, a cluster of four thrust-derated RL10s could be considered."
http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdf - Ed Kyle
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#9
by
clongton
on 17 May, 2014 19:33
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#10
by
EE Scott
on 17 May, 2014 21:04
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So both first stage and second stage engines need non-trivial modifications to be man-rated; additionally, the more robust/flexible avionics of Atlas V are slated to replace Delta IV avionics, which help with man-rating but also add an element of risk to the design as well (during implementation). That's a lot of stuff to get done, plus I'm sure it's not the only stuff that would have to be done.
That being said, it still seems like less risk than developing a new HC engine (or building RD-180 in the USA) for Atlas V.
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#11
by
Prober
on 17 May, 2014 21:17
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The drawback to this approach is the loss of available thrust to the second stage. In order to mitigate this problem, a cluster of four thrust-derated RL10s could be considered."
http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdf
- Ed Kyle
Shades of Jupiter
Don't know why, maybe its the tank color or something. But every time I see a launch it just looks like it should be launching humans.
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#12
by
AS-503
on 17 May, 2014 21:38
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IIRC there is also the issue of NASA's 1.4 structures margin.
"Fixing" that takes you back to the drawing board for a new vehicle in many ways.
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#13
by
Jim
on 17 May, 2014 21:49
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IIRC there is also the issue of NASA's 1.4 structures margin.
"Fixing" that takes you back to the drawing board for a new vehicle in many ways.
"Fixing" that can be changing the nonsense of 1.4 to 1.25
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#14
by
Star One
on 17 May, 2014 21:55
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So both first stage and second stage engines need non-trivial modifications to be man-rated; additionally, the more robust/flexible avionics of Atlas V are slated to replace Delta IV avionics, which help with man-rating but also add an element of risk to the design as well (during implementation). That's a lot of stuff to get done, plus I'm sure it's not the only stuff that would have to be done.
That being said, it still seems like less risk than developing a new HC engine (or building RD-180 in the USA) for Atlas V.
Agree neither is a desirable route but the former would seem the less risky of the two.
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#15
by
Eric Hedman
on 17 May, 2014 22:34
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IIRC there is also the issue of NASA's 1.4 structures margin.
"Fixing" that takes you back to the drawing board for a new vehicle in many ways.
"Fixing" that can be changing the nonsense of 1.4 to 1.25
Does changing to 1.25 change much in the calculations of probabilities for LOM and LOC? I've always been amazed at the odds that get calculated for something as complex as a launch vehicle. I reminds me of the odds that Mr. Spock always quoted to Kirk when he couldn't possibly have enough information to make a reasonable calculation. It seems to me that a history of performance is a better indicator.
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#16
by
sdsds
on 18 May, 2014 05:43
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It certainly seems like there could be a metric that combines flight history with the design factor of safety to reach a certification for crewed missions. For example, a 1.4 factor of safety might let a vehicle carry crew on its 2nd mission after a single successful uncrewed flight, whereas a vehicle with a 1.25 factor of safety might not be rated for crew until it had successfully flown a streak of 20 consecutive missions.
Really at its current level of mission success what astronaut would decline flying on a Delta IV M+? Surely the more likely cause of a mission contingency/abort would be a failure of the relatively immature spacecraft rather than a failure of the launch vehicle!
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#17
by
AS-503
on 18 May, 2014 13:57
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IIRC there is also the issue of NASA's 1.4 structures margin.
"Fixing" that takes you back to the drawing board for a new vehicle in many ways.
"Fixing" that can be changing the nonsense of 1.4 to 1.25
I agree, Jim. Particularly with modern methods, materials, and modeling.
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#18
by
PahTo
on 18 May, 2014 17:54
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So it sounds like the 4 meter upper stage with 2x RL-10C-1 is the ticket if this is going to happen for commercial crew/CST-100/DC. Note the NASA study edkyle99 cites is about man-rating the D-IVH (by definition a 5 meter upper stage) for lofting the Orion spacecraft.
Good stuff--let's make it happen!
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#19
by
PahTo
on 18 May, 2014 18:25
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Sorry to double-post, but I wanted to summarize that it appears to me the best option for human rating any Delta is the D-IVM 4+2 with the 2x RL-10C-1 upper stage, and that it is far less likely the D-IVH would be human rated (for any spacecraft, though notably Orion).
I pulled the following from the "Rumors that Russia may block the export of RD-180 to the US" thread because it is really OT there, but very important discussion none-the-less. Hopefully this is a more suitable thread:
Near term I wonder if it would be a good excuse to spend money on man rating the Delta IV.
This would kill two birds with one stone in that man rating the heavy also would allow a LV for LEO Orion missions.
A few problems here, considering "they" just announced they won't be man-rating the SLS iCPS (effectively the DCSS), which goes counter to man-rating it. Furthermore, there is no mission for an LEO Orion (that couldn't be done faster with a commercial solution). (snip)
Of course, now there's talk of reviving the TR-107 for Atlas, but not sure how "plug-n-play-able" that is with the Atlas core, and it still might be less expensive and faster to human rate the D-IVM!
4GEM60's should do it...