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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!
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#20
by
USFdon
on 18 May, 2014 18:34
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Interesting that the Delta IV User's Guide shows what appears to be a dual RL-10 upper stage under future enhancements (though doesn't go into detail about it).
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#21
by
Rocket Science
on 18 May, 2014 21:27
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#22
by
PahTo
on 19 May, 2014 00:10
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Good stuff--thanks! Over the years I've seen references and inferences [EDIT: in NSF] to info contained therein, but I don't think I've read that report before (and I need to re-read a few times). The citations/profiles of the contributors at the end are great.
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#23
by
Lee Jay
on 19 May, 2014 00:28
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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
What makes it "nonsense"? I'm imagining an answer like "if it can be trusted with billion dollar payloads...." or "as long as the vehicles have abort capability...." but I'm curious as to your thoughts, Jim.
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#24
by
Jim
on 19 May, 2014 00:46
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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
What makes it "nonsense"? I'm imagining an answer like "if it can be trusted with billion dollar payloads...." or "as long as the vehicles have abort capability...." but I'm curious as to your thoughts, Jim.
Have you ever heard of a vehicle failure due to a component that was overloaded?
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#25
by
Lee Jay
on 19 May, 2014 00:47
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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
What makes it "nonsense"? I'm imagining an answer like "if it can be trusted with billion dollar payloads...." or "as long as the vehicles have abort capability...." but I'm curious as to your thoughts, Jim.
Have you ever heard of a vehicle failure due to a component that was overloaded?
No, but I have probably 1% of the historical knowledge you do. Is that your argument? That historical data seems to indicate that 1.25 is sufficient? If so, that would seem to have statistical merit if the history supports it.
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#26
by
Jim
on 19 May, 2014 01:04
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Have you ever heard of a vehicle failure due to a component that was overloaded?
No, but I have probably 1% of the historical knowledge you do. Is that your argument? That historical data seems to indicate that 1.25 is sufficient? If so, that would seem to have statistical merit if the history supports it.
[/quote]
1.4 vs 1.25 is really an emotional issue
This is a good read
http://www.amazon.com/Space-Systems-Failures-Satellites-Exploration/dp/0387215190
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#27
by
Lee Jay
on 19 May, 2014 01:10
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Okay, from a conceptual/emotional point of view...
There are two general ways to deal with failure - safe life, and fail safe.
Safe life is about making it so it won't fail.
Fail safe is about making it safe even when it fails.
Airliners are exceptionally safe, mostly because of the later (fail safe). A whole bunch of things have to go wrong for an airliner to fail, because most failures are fail-safe.
If the vehicles have a proven, well-designed, high reliability abort system (a system in the fail safe category), I'd be happy with less safe life type margin.
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#28
by
sdsds
on 19 May, 2014 04:00
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Have you ever heard of a vehicle failure due to a component that was overloaded?
While it didn't lead to a mission failure, the attached photo is of a booster that was nominally supposed to be reusable. That's a structural component that "failed" during a mission. Sure, it was exposed to off-nominal stresses. But that's why we leave the extra structural margin in the designs even when it is proven to be unnecessary in the nominal case.
(I know. You weren't asking me!
)
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#29
by
Lee Jay
on 19 May, 2014 13:08
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Have you ever heard of a vehicle failure due to a component that was overloaded?
While it didn't lead to a mission failure, the attached photo is of a booster that was nominally supposed to be reusable. That's a structural component that "failed" during a mission. Sure, it was exposed to off-nominal stresses. But that's why we leave the extra structural margin in the designs even when it is proven to be unnecessary in the nominal case.
(I know. You weren't asking me! )
It didn't fail during ascent, it failed impacting the water after chute failure. This would not have endangered any crew being carried.
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#30
by
Joel
on 19 May, 2014 14:35
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Is there an educated guess on how long a Delta IV human-rating could take? Assuming silly rules such as 1.25 vs. 1.4 are waivered.
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#31
by
savuporo
on 19 May, 2014 18:54
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If we have this thread, lets have it from the horses mouth.
http://enu.kz/repository/2009/AIAA-2009-6729.pdfThe Delta IV has ample performance to support the existing Orion vehicle, without Black Zones. The Delta IV can support a mid-2014 Crewed IOC, which is superior to Orion launch alternatives. The proposed 37A pad is a look-alike counterpart to the existing 37B pad with low development risk. Human rating the Delta is a relatively modest activity, with the addition of an Emergency Detection System, an array of relatively small redundancy and safety upgrades, both in the vehicle and the engines that are minor compared to the original development of the Delta IV.
Maybe they were optimistic.
Same quote in here :
https://info.aiaa.org/tac/SMG/STTC/White%20Papers/ULA-Innovation-March-2010.pdf?origin=publication_detail
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#32
by
simonbp
on 19 May, 2014 23:10
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Is there an educated guess on how long a Delta IV human-rating could take? Assuming silly rules such as 1.25 vs. 1.4 are waivered.
This Aerospace Corp. report (which was posted above) covers the important issues:
http://www.nasa.gov/pdf/377875main_081109%20Human%20Rated%20Delta%20IV.pdfUsing the Ares I standards for human-rating, neither the first stage nor second stage engine are ready for human flights. They assumed the first stage would need "RS-68B HR", which was the version being developed for Ares V, while the second stage would need either J-2X or a cluster of RL-10As. Either way, these are things that would take nearly as long to develop as the new hydrocarbon engine that Congress wants...
Rather interestingly, that report also mentions the possibility of a Delta IV H with
no upper stage. They claim this is sufficient to get an Orion to ISS (but not if it had a lunar SM). If human-rating the RS-68A is not difficult, then a Delta IV H with no upper stage could the quickest route to launching CST-100 or DreamChaser (but not exactly cheap per flight).
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#33
by
jongoff
on 19 May, 2014 23:34
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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
Especially seeing as how the Shuttle ETs had margins of only 1.15 in some areas...
~Jon
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#34
by
the_roche_lobe
on 19 May, 2014 23:52
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Rather interestingly, that report also mentions the possibility of a Delta IV H with no upper stage. They claim this is sufficient to get an Orion to ISS (but not if it had a lunar SM).
I wonder if that would allow the core stage to be used in partial thrust all the way - making it a real sustainer stage?
Anyway, as you say, still sounds expensive! And whats the mission again?
P
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#35
by
edkyle99
on 19 May, 2014 23:55
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
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#36
by
Joel
on 20 May, 2014 11:18
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Rather interestingly, that report also mentions the possibility of a Delta IV H with no upper stage. They claim this is sufficient to get an Orion to ISS (but not if it had a lunar SM). If human-rating the RS-68A is not difficult, then a Delta IV H with no upper stage could the quickest route to launching CST-100 or DreamChaser (but not exactly cheap per flight).
Maybe combine this with booster flyback? A core will fly exactly three times, twice as side booster and once as center core. Combined with no upper stage, that might make it more affordable per flight.
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#37
by
rpapo
on 20 May, 2014 13:02
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Rather interestingly, that report also mentions the possibility of a Delta IV H with no upper stage. They claim this is sufficient to get an Orion to ISS (but not if it had a lunar SM). If human-rating the RS-68A is not difficult, then a Delta IV H with no upper stage could the quickest route to launching CST-100 or DreamChaser (but not exactly cheap per flight).
Maybe combine this with booster flyback? A core will fly exactly three times, twice as side booster and once as center core. Combined with no upper stage, that might make it more affordable per flight.
Are you confusing Delta Heavy with Falcon Heavy?
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#38
by
Zed_Noir
on 20 May, 2014 13:30
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
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#39
by
baldusi
on 20 May, 2014 13:40
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
It's a performance issue. Single RL10 is puny for LEO. If you look at the presentation, dual engine Centaur has by far the worst risk profile. It needs the two engines and any failure would mean LOM, thus, worst performance. A 4 engine US would only need two, and thus could tolerate a lot of propulsion failures. BTW, the Aerospace Corp paper was done assuming Ares I human rating process. Which has been (luckily) deprecated. As Jim said, is not about inflating specs to say "thus it is safer". It's about looking into actual failure modes and probabilities and minimizing overall risk. And let the contractor make their decisions as long as they hit the risk probabilities!
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#40
by
Prober
on 20 May, 2014 14:01
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
define: unflown duo Centaur do you know the history?
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#41
by
edkyle99
on 20 May, 2014 14:02
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
I'm talking about the engine itself, not the stage.
Again, from the report:
"
Both RL10 variants (Delta 4 and Atlas 5 versions) 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."
- Ed Kyle
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#42
by
PahTo
on 20 May, 2014 14:14
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Does the RL-10C-1 offer the noted modifications to make the engine more palatable, or are they simply stream-lined manufacturing processes to reduce overall cost?
Which is more likely: two engine Centaur (or perhaps more accurately, two engine 4 meter upper stage) or the 5 meter 1/2/4 engine upper stage posited by ULA per ACES? To read the 2009 ULA report, they make it sound like human rating is relatively easily attainable...
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#43
by
kevin-rf
on 20 May, 2014 14:30
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
define: unflown duo Centaur do you know the history?
I believe the history is only the single engine Centaur transitioned from hydraulic steering to electric steering. The work to transition Dual Engine Centaur (DEC) from hydraulic to electric has not yet been completed. Thus while hydraulic DEC's have been flying since the start of the program, the electric DEC has not yet flown.
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#44
by
Prober
on 20 May, 2014 14:32
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
define: unflown duo Centaur do you know the history?
I believe the history is only the single engine Centaur transitioned from hydraulic steering to electric steering. The work to transition Dual Engine Centaur (DEC) from hydraulic to electric has not yet been completed. Thus while hydraulic DEC's have been flying since the start of the program, the electric DEC has not yet flown.
that's a fair point.
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#45
by
baldusi
on 20 May, 2014 14:50
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Note that the 2009 Aerospace Corp report also said that the current Atlas 5 Centaur RL10 engine was not human rated. Nonetheless, two commercial crew entrants are proposing its use.
- Ed Kyle
Both of the commercial crew entries are using the unflown duo Centaur version for their missions, not the single Centaur version currently use with the Atlas V.
define: unflown duo Centaur do you know the history?
I believe the history is only the single engine Centaur transitioned from hydraulic steering to electric steering. The work to transition Dual Engine Centaur (DEC) from hydraulic to electric has not yet been completed. Thus while hydraulic DEC's have been flying since the start of the program, the electric DEC has not yet flown.
that's a fair point.
Yes, but sort of a technicality. The electromecanical TVC has been proven time and again on the Atlas V, and the hydraulic dual Centaur flew a lot. In fact, the human rated Centaur will fly with Common Avionics that, while having a lot of Atlas V inheritance, will be a new development. But it will include the EDS and thus get a lot of flight history.
Thus, for whoever it needs to, the Common Avionics and RL10C-1/2 seem to be human rated. RS-68A is almost there. And the Common Booster Core is based on the (5,4), thus, it should have good margins for a (4,2). If SLS had human rated the DIVUS, then Crewed Delta IV would have been a very easy task.
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#46
by
Antares
on 20 May, 2014 14:55
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"Fixing" that can be changing the nonsense of 1.4 to 1.25
What makes it "nonsense"? I'm imagining an answer like "if it can be trusted with billion dollar payloads...." or "as long as the vehicles have abort capability...." but I'm curious as to your thoughts, Jim.
Have you ever heard of a vehicle failure due to a component that was overloaded?
No, but I have probably 1% of the historical knowledge you do. Is that your argument? That historical data seems to indicate that 1.25 is sufficient? If so, that would seem to have statistical merit if the history supports it.
1.4 vs 1.25 is really an emotional issue
This is a good read
http://www.amazon.com/Space-Systems-Failures-Satellites-Exploration/dp/0387215190
But isn't everything really a structural failure (unless, obviously, it's software or electrical)? That additional 15% protects for the random defects that aren't caught by normal QA. I'm not saying a perfectly good, existing vehicle at 1.25 needs to be 1.4; but a clean-sheet vehicle designed to 1.4 will be more robust to escapes, at the expense of weight, cost and performance.
*Possible* failures that could have been stopped with 15% more margin: Delta 269, Delta 241, AC-62, K-11, and the 3 Titan failures in the 80s.
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#47
by
Antares
on 20 May, 2014 15:05
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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.
NASA reliability predictions are crap. They are not absolute (1 in X) and yet they are treated as such. They are a relative measure of perceived design simplicity and perceived QA practices. NASA has never published its statistical inputs to these methods. Perfectly good vehicles are held as less reliable by methods not subject to public scrutiny. They are at best a Pareto tool to suggest where the weak points in a design are, yet the answers are entirely subject to the perceived risk values arbitrarily assigned to the components. There's no validation of those risk values.
See Jeff Greason's retort to Joe Fragola's testimony during the Augustine Committee.
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#48
by
PahTo
on 20 May, 2014 16:03
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...
Thus, for whoever it needs to, the Common Avionics and RL10C-1/2 seem to be human rated. RS-68A is almost there. And the Common Booster Core is based on the (5,4), thus, it should have good margins for a (4,2). If SLS had human rated the DIVUS, then Crewed Delta IV would have been a very easy task.
I was under the impression the RL-10C-2 is out of consideration for human rating due to the extensible nozzle.
And wasn't SLS looking to HR the iCPS (based on the 5 meter DCSS)? I guess what I'm trying to pin down (and per thread topic) aren't we really talking about the Delta-IV M 4 (+x) here--the 4 meter cryo upper stage? No need for D-IV H (thus 5 meter upper stage) for commercial crew.
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#49
by
baldusi
on 20 May, 2014 16:22
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...
Thus, for whoever it needs to, the Common Avionics and RL10C-1/2 seem to be human rated. RS-68A is almost there. And the Common Booster Core is based on the (5,4), thus, it should have good margins for a (4,2). If SLS had human rated the DIVUS, then Crewed Delta IV would have been a very easy task.
I was under the impression the RL-10C-2 is out of consideration for human rating due to the extensible nozzle.
And wasn't SLS looking to HR the iCPS (based on the 5 meter DCSS)? I guess what I'm trying to pin down (and per thread topic) aren't we really talking about the Delta-IV M 4 (+x) here--the 4 meter cryo upper stage? No need for D-IV H (thus 5 meter upper stage) for commercial crew.
You are right that RL10C-2 isn't human ratable without some significant nozzle redesign. But you can always put an RL10C-1 and eat the performance difference. I understand that ULA will try to move to Common Centaur, which would solve the upper stage issue for Delta IV.
But while SLS was paying for iCPS human rating, it would have made more sense to human rate the (5,2) than the (4,2). Since they have dropped that requirement (for now), I would go with Common Centaur for the upper stage.
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#50
by
notsorandom
on 20 May, 2014 17:27
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...
Thus, for whoever it needs to, the Common Avionics and RL10C-1/2 seem to be human rated. RS-68A is almost there. And the Common Booster Core is based on the (5,4), thus, it should have good margins for a (4,2). If SLS had human rated the DIVUS, then Crewed Delta IV would have been a very easy task.
I was under the impression the RL-10C-2 is out of consideration for human rating due to the extensible nozzle.
And wasn't SLS looking to HR the iCPS (based on the 5 meter DCSS)? I guess what I'm trying to pin down (and per thread topic) aren't we really talking about the Delta-IV M 4 (+x) here--the 4 meter cryo upper stage? No need for D-IV H (thus 5 meter upper stage) for commercial crew.
You are right that RL10C-2 isn't human ratable without some significant nozzle redesign. But you can always put an RL10C-1 and eat the performance difference. I understand that ULA will try to move to Common Centaur, which would solve the upper stage issue for Delta IV.
But while SLS was paying for iCPS human rating, it would have made more sense to human rate the (5,2) than the (4,2). Since they have dropped that requirement (for now), I would go with Common Centaur for the upper stage.
Is using the Centaur on the Delta IV something that has ever been talked about by ULA?
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#51
by
Jim
on 20 May, 2014 17:39
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Is using the Centaur on the Delta IV something that has ever been talked about by ULA?
common upperstage
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#52
by
PahTo
on 20 May, 2014 17:50
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Is using the Centaur on the Delta IV something that has ever been talked about by ULA?
common upperstage
Not to be confused with ACES, which is notionally a common 5 meter upper stage...
Right?
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#53
by
Lars_J
on 20 May, 2014 18:12
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Is using the Centaur on the Delta IV something that has ever been talked about by ULA?
common upperstage
Will this common upper stage retain the current Centaur tank diameter, or will it be scaled up to 4m or at least Atlas V booster diameter?
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#54
by
starsilk
on 20 May, 2014 20:31
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Is using the Centaur on the Delta IV something that has ever been talked about by ULA?
common upperstage
not to be a party pooper or anything, but how is this plan for 'common avionics', 'common upperstage' etc consistent with having two redundant vehicles? I was under the impression that the whole point was to have two dissimilar vehicles which can accomplish (almost) the same task, in case one (cough, cough) has some sort of problem?
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#55
by
simonbp
on 20 May, 2014 20:43
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It doesn't, but then maintaining two different RL-10 upper stages with two different versions of RL-10 doesn't make a lot of economic sense, either.
Does anyone have a performance estimate for a Delta Medium/Medium+ with a dual engine Common Centaur?
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#56
by
TrueGrit
on 20 May, 2014 22:47
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Just to give some perspective... The Aerospace report from NASA wasn't received well from the industry in general. I would caution relying upon its conclusions as solid and only us it to gain light into the challenges to be faced. One only needs to look at the lack of consistent logic of the apparent RL10 chamber pressure problem vs. that hasn't been a problem for the commercial crew program.
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#57
by
Lobo
on 20 May, 2014 22:51
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While Delta IV certainly -could- launch commercial crew, I highly doubt it every would, for a few reasons.
1) Atlas V is the mostly likely EELV to carry commercial crew. I think a domestic replacement for RD-180 is more likely than Atlas V being retired and commercial crew flying on Delta IV, if there's an inturruption in access to Russian engines. If there's not, plans will proceed as usual.
2) F9 is a very likely candidate to carry commercial crew IMO, even if Atlas stays around with Russian engines. As Dr. Sowers pointed out, F9 lags behind Atlas V in BLEO performance due to their propellant choices. However, those propellant choices make it optimized for LEO performance. Commercial crew will go to LEO, so it's really the LV of choice for such a mission, even if SpaceX does not get the commercial crew contract. DC and CST-100 are both deisgned to be LV neutral, and SpaceX will gladly take SNC or Boeing's money to provide launches. Besides, NASA seems to like launching their astroanuts from their launch complex, and F9 can do that, where EELV's cannot. (without a MLP and VAB high bay, etc.)
Not to mention F9 will likley be cheaper than Atlas or Delta, even if fully expendable. Moreso if it reuses the booster.
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#58
by
baldusi
on 20 May, 2014 22:55
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Lobo, I agree, but this is the Delta IV for Commercial Crew thread.
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#59
by
Lobo
on 20 May, 2014 23:27
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Lobo, I agree, but this is the Delta IV for Commercial Crew thread.
I know...just explaining why it's an unlikley scenario, IMO. So it's on topic when discussing if Delta IV carrying commercial crew is a possibility.
Physically? Yes. Practically? No. and expained why I felt that way.
It was physically capable of taking Orion to the ISS for CxP, but we see how that worked out. ;-)
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#60
by
Star One
on 21 May, 2014 06:33
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Lobo, I agree, but this is the Delta IV for Commercial Crew thread.
I know...just explaining why it's an unlikley scenario, IMO. So it's on topic when discussing if Delta IV carrying commercial crew is a possibility.
Physically? Yes. Practically? No. and expained why I felt that way.
It was physically capable of taking Orion to the ISS for CxP, but we see how that worked out. ;-)
It's all very well talking about developing a new engine but that it would seem would take at least four years plus a fair chunk of change. Adapting Delta IV is probably going to be at least cheaper.
http://m.aviationweek.com/space/replacing-russian-made-atlas-antares-engines-would-take-four-years
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#61
by
baldusi
on 21 May, 2014 13:41
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After all, Common avionic and Common Upper stage is part of current ULA plan. And most of the human rating effort and integration work could be reused.
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#62
by
PahTo
on 21 May, 2014 14:17
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I read more closely the 2009 ULA discussion of upgrade paths and see the common upper stage is notionally a common Centaur. ULA points out that while some high energy orbits will be negatively impacted by such a change for Delta IV (the Medium I presume) due to the lower prop load, the LEO performance will be improved with the 2-engine Centaur.
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#63
by
muomega0
on 21 May, 2014 14:44
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It's all very well talking about developing a new engine but that it would seem would take at least four years plus a fair chunk of change. Adapting Delta IV is probably going to be at least cheaper.
http://m.aviationweek.com/space/replacing-russian-made-atlas-antares-engines-would-take-four-years
"I can say that the U.S. is capable of developing and fielding products similar to the capability of those that we purchase today," she said. "The country hasn’t committed to developing those products over the past several decades. We’re prepared to do that." Despite the uncertainty over the RD-180, Van Kleek said Aerojet Rocketdyne is getting ready to build an expendable version of the RS-25D Space Shuttle Main Engine for the heavy-lift Space Launch System (SLS) that NASA is developing for deep-space human exploration.
Contrast this with the
2006 AF/DOD Report on Future Propulsion NeedsThe RD-180 was developed and qualified in 42 months at a much lower cost than past U.S. booster engine developments because of the strong flight-proven RD-170 heritage.
Finding 4-2. The current family of U.S. EELV boosters does not need to be replaced for the next 15 to 20 years, nor are there plans to do so. Nevertheless several candidate designs were started under NASA’s Space Launch Initiative (SLI) program in 2001.
Recommendation 4-2. DoD should begin work relatively slowly, investing about $5 million per year in the committee’s judgment on technology development for an advanced-cycle booster engine that could provide the basis for a new far-term access-to-space vehicle.
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#64
by
baldusi
on 21 May, 2014 16:07
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I read more closely the 2009 ULA discussion of upgrade paths and see the common upper stage is notionally a common Centaur. ULA points out that while some high energy orbits will be negatively impacted by such a change for Delta IV (the Medium I presume) due to the lower prop load, the LEO performance will be improved with the 2-engine Centaur.
I believe they are referring to the DIVUS 5m stage. The 4m has practically the same same load and much worse pmf.
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#65
by
Lobo
on 21 May, 2014 20:03
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Lobo, I agree, but this is the Delta IV for Commercial Crew thread.
I know...just explaining why it's an unlikley scenario, IMO. So it's on topic when discussing if Delta IV carrying commercial crew is a possibility.
Physically? Yes. Practically? No. and expained why I felt that way.
It was physically capable of taking Orion to the ISS for CxP, but we see how that worked out. ;-)
It's all very well talking about developing a new engine but that it would seem would take at least four years plus a fair chunk of change. Adapting Delta IV is probably going to be at least cheaper.
http://m.aviationweek.com/space/replacing-russian-made-atlas-antares-engines-would-take-four-years
Since commerical crew has nothing to do with USAF and DoD, if Atlas V were to loose Russian engines, and no new US made replacement developed because it would take 4 years, then do you think adapting D4 is more likely than F9?
If SpaceX wins, it'll be F9 for sure.
If SNC wins, and Atlas is unavailable, do you think they'll pay for a modified D4? Or go with F9 which would already be basically man-rated, and launching from KSC?
If Boeing wins, maybe D4 would be in play. It wa their LV afterall and they wanted CST-100 launching on it originally, but that switched to Atlas. And now Boeing has mentioned the possibility of swithcing to F9 after maybe two initial Atlas V launches (I remember reading some where). So now if AV is no longer available, what's the most likely LV for CST-100? Or F9?
That's why I said, IMHO, D4 is pretty unlikely to ever be used for commercial crew. That will either be Atlas or Falcon.
Not to ruin everyone's fun about imagining D4 doing it, but I'm just not seeing it.
As always, I could be wrong. ;-)
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#66
by
PahTo
on 21 May, 2014 20:21
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I read more closely the 2009 ULA discussion of upgrade paths and see the common upper stage is notionally a common Centaur. ULA points out that while some high energy orbits will be negatively impacted by such a change for Delta IV (the Medium I presume) due to the lower prop load, the LEO performance will be improved with the 2-engine Centaur.
I believe they are referring to the DIVUS 5m stage. The 4m has practically the same same load and much worse pmf.
To make sure I understand, does this mean the (notional) path forward would be to fly the common Centaur upper stage on the Delta IV Heavy? That seems like a huge performance hit considering the prop load and vehicle in question.
I've been pondering all of this further, and ULA's decision to go with Centaur as the common upper stage results from the impact of using a 4m or 5m DCSS on Atlas V performance, and the fact that for pretty much any profile, at least one SRM would be needed for Atlas. Because of this, Centaur (and the performance hit on certain/fewer D-IV profiles) seemed the better choice. Now with the uncertainty of the RD-180, and considering ACES involves a 5m common upper stage, I wonder if that might change?
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#67
by
baldusi
on 22 May, 2014 00:05
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I read more closely the 2009 ULA discussion of upgrade paths and see the common upper stage is notionally a common Centaur. ULA points out that while some high energy orbits will be negatively impacted by such a change for Delta IV (the Medium I presume) due to the lower prop load, the LEO performance will be improved with the 2-engine Centaur.
I believe they are referring to the DIVUS 5m stage. The 4m has practically the same same load and much worse pmf.
To make sure I understand, does this mean the (notional) path forward would be to fly the common Centaur upper stage on the Delta IV Heavy? That seems like a huge performance hit considering the prop load and vehicle in question.
I've been pondering all of this further, and ULA's decision to go with Centaur as the common upper stage results from the impact of using a 4m or 5m DCSS on Atlas V performance, and the fact that for pretty much any profile, at least one SRM would be needed for Atlas. Because of this, Centaur (and the performance hit on certain/fewer D-IV profiles) seemed the better choice. Now with the uncertainty of the RD-180, and considering ACES involves a 5m common upper stage, I wonder if that might change?
What they meant was to move the Delta IV 4meters to Centaur.
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#68
by
Rocket Science
on 22 May, 2014 00:27
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Lobo, I agree, but this is the Delta IV for Commercial Crew thread.
I know...just explaining why it's an unlikley scenario, IMO. So it's on topic when discussing if Delta IV carrying commercial crew is a possibility.
Physically? Yes. Practically? No. and expained why I felt that way.
It was physically capable of taking Orion to the ISS for CxP, but we see how that worked out. ;-)
It's all very well talking about developing a new engine but that it would seem would take at least four years plus a fair chunk of change. Adapting Delta IV is probably going to be at least cheaper.
http://m.aviationweek.com/space/replacing-russian-made-atlas-antares-engines-would-take-four-years
Since commerical crew has nothing to do with USAF and DoD, if Atlas V were to loose Russian engines, and no new US made replacement developed because it would take 4 years, then do you think adapting D4 is more likely than F9?
If SpaceX wins, it'll be F9 for sure.
If SNC wins, and Atlas is unavailable, do you think they'll pay for a modified D4? Or go with F9 which would already be basically man-rated, and launching from KSC?
If Boeing wins, maybe D4 would be in play. It wa their LV afterall and they wanted CST-100 launching on it originally, but that switched to Atlas. And now Boeing has mentioned the possibility of swithcing to F9 after maybe two initial Atlas V launches (I remember reading some where). So now if AV is no longer available, what's the most likely LV for CST-100? Or F9?
That's why I said, IMHO, D4 is pretty unlikely to ever be used for commercial crew. That will either be Atlas or Falcon.
Not to ruin everyone's fun about imagining D4 doing it, but I'm just not seeing it.
As always, I could be wrong. ;-)
Or Lobo, the U.S. will still want two different launch vehicles from lessons learned for insurance...
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#69
by
Lobo
on 22 May, 2014 16:38
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Or Lobo, the U.S. will still want two different launch vehicles from lessons learned for insurance...
I think the current plan is to down select to just one spacecraft which will fly on just one LV, although at least DC and CST-100 could fly on other LV's. It wouldn't be a swap out though in case there's a problem with the primary LV. Moving DC or CST-100 from Atlas to Falcon or Delta if there were a problem with Atlas would take time I would think. Interfaces, crew access at the LV pad, etc. I woudl think a swap would be longer than 6 months, which is the time from that the next crew service would need to be done in.
So I don't think a true "backup" LV for commercial crew is in the plan. I think SLS/Orion is supposed to be that backup. Athough, given it's planned low production rate, not sure how likely that would be unless NASA keeps an Orion capsule, upper stage and SLS core/boosters stored somewhere for a contingency mission. Otherwise I doubt they could have an SLS/Orion ready to launch in the required time frame to offer a true backup.
In actual application, any problem with the primary space craft or LV would be backed up with Soyuz. NASA would just have to pay through the nose at that point if they need the Russians to provide more crew service after commercial crew takes over. But I'm sure they would for a price, and that's probably the best "backup" plan.
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#70
by
PahTo
on 23 May, 2014 16:17
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You know, I had intended for my 1,000th post to be something really impressive and thoughtful and all that, and then boom, I missed that my 1,000th just came and went. So allow me, with my 1,001st post to volunteer my very being to be ballast on the first manned flight of DCSS (Dream Chaser Space Ship) on the DCSS (Delta-Centaur second stage) atop the first human-rated Delta IV M 4+2.
(my first shuttle launch in person came the same year NSF really took off, STS-116. Can't thank enough Chris, NSF and all of you for increasing my knowledge, excitement and involvement with everything space!)
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#71
by
Jim
on 23 May, 2014 18:06
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DCSS (Delta-Centaur second stage) atop the first human-rated Delta IV M 4+2.
Delta Cryogenic Second State. There is no relationship to the Centaur.
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#72
by
PahTo
on 23 May, 2014 18:23
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DCSS (Delta-Centaur second stage) atop the first human-rated Delta IV M 4+2.
Delta Cryogenic Second State. There is no relationship to the Centaur.
I know that DCSS = Delta Cryo Second Stage. Per the ULA document from Dec 2009 stating a goal of a common upper stage using Centaur (and eventually ACES) I thought I'd just cut to the chase and mash the names now.
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#73
by
Rocket Science
on 23 May, 2014 19:45
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Or Lobo, the U.S. will still want two different launch vehicles from lessons learned for insurance...
I think the current plan is to down select to just one spacecraft which will fly on just one LV, although at least DC and CST-100 could fly on other LV's. It wouldn't be a swap out though in case there's a problem with the primary LV. Moving DC or CST-100 from Atlas to Falcon or Delta if there were a problem with Atlas would take time I would think. Interfaces, crew access at the LV pad, etc. I woudl think a swap would be longer than 6 months, which is the time from that the next crew service would need to be done in.
So I don't think a true "backup" LV for commercial crew is in the plan. I think SLS/Orion is supposed to be that backup. Athough, given it's planned low production rate, not sure how likely that would be unless NASA keeps an Orion capsule, upper stage and SLS core/boosters stored somewhere for a contingency mission. Otherwise I doubt they could have an SLS/Orion ready to launch in the required time frame to offer a true backup.
In actual application, any problem with the primary space craft or LV would be backed up with Soyuz. NASA would just have to pay through the nose at that point if they need the Russians to provide more crew service after commercial crew takes over. But I'm sure they would for a price, and that's probably the best "backup" plan.
I think if we put all our eggs in one basket it would be silly return on investment by not getting two U.S. spacecraft on two different U.S. launch vehicles whatever they are. Then again, we have been silly before...
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#74
by
Star One
on 23 May, 2014 21:14
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Or Lobo, the U.S. will still want two different launch vehicles from lessons learned for insurance...
I think the current plan is to down select to just one spacecraft which will fly on just one LV, although at least DC and CST-100 could fly on other LV's. It wouldn't be a swap out though in case there's a problem with the primary LV. Moving DC or CST-100 from Atlas to Falcon or Delta if there were a problem with Atlas would take time I would think. Interfaces, crew access at the LV pad, etc. I woudl think a swap would be longer than 6 months, which is the time from that the next crew service would need to be done in.
So I don't think a true "backup" LV for commercial crew is in the plan. I think SLS/Orion is supposed to be that backup. Athough, given it's planned low production rate, not sure how likely that would be unless NASA keeps an Orion capsule, upper stage and SLS core/boosters stored somewhere for a contingency mission. Otherwise I doubt they could have an SLS/Orion ready to launch in the required time frame to offer a true backup.
In actual application, any problem with the primary space craft or LV would be backed up with Soyuz. NASA would just have to pay through the nose at that point if they need the Russians to provide more crew service after commercial crew takes over. But I'm sure they would for a price, and that's probably the best "backup" plan.
One would hope they would have more sense than to get into such a situation.
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#75
by
A_M_Swallow
on 27 May, 2014 17:00
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After a test flight on Atlas V all three spacecraft will end up launching on Falcon 9s. Unless the Blue Origin launch vehicle flies within 4-5 years then the Delta IV will be man rated.
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#76
by
bad_astra
on 27 May, 2014 19:16
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Russia is not going to prohibit sales of RD180 for ISS launches. There's no reason to abandon Atlas V for this. Calmer heads will prevail, eventually.
4GEM60's should do it...