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Capacity of Delta IV growth options? Delta 4 medium+ 5,8?
by
Robotbeat
on 14 Mar, 2014 05:39
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I thought I remember hearing talking of a Delta IV Medium+ with 8 GEMs on it, bringing its capacity closer to the heaviest Atlas V configuration. What is the capacity of that option, and where's the source? My google-fu has failed me. I guess I was thinking about it because Delta IV supposedly was originally built with a capacity of 40 cores per year, and if you wanted to use ALL the cores, you'd maximize your performance if you had them flying with GEMs attached.
...Actually, here it is, page 264:
http://www.ulalaunch.com/site/docs/product_cards/guides/DeltaIVPayloadPlannersGuide2007.pdfEDIT:Or here p.246-247:
http://www.ulalaunch.com/site/docs/product_cards/guides/Delta%20IV%20Users%20Guide%20June%202013.pdfIt's about 17 tons to LEO (407km, 52deg), but probably more like 20 tons with upgraded RS-68A and lower altitude and lower inclination.
That's about 800 tons to LEO per year, assuming you can launch every 9 days (!).
Supposedly, the 8-GEM version of Delta IV Medium+ is available within 48 months of order.
...and add in an ACES upper stage and Al-Li, and you're probably in the 20-25 ton to LEO range.
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#1
by
MATTBLAK
on 14 Mar, 2014 06:29
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Sounds credible and sensible - and probably cheaper than Delta IV-Heavy. Although D-4H these days is supposed to lift about 27 tons to LEO. And it could lift a lot more with an upper stage upgrade (slight stretch, MB-60 engine) and switching to aluminium/lithium structures. Not to mention adding up to 6x GEMs...
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#2
by
baldusi
on 14 Mar, 2014 13:35
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The 2013 Paylaod Planner's Guide already has RS-68A performance included. M+(4,4) is not an issue and almost a given, because now they have a true Common Core from M to M+(5,4). So, doing (4,4) shouldn't be an issue. But doing M+(5,6) and specially M+(5,8) might require reinforcements that would mean a different core. That would significantly increase costs. Regrettably the Delta IV Common Core isn't. Heavy require three custom cores. And until the RS-68A so did each version.
And they got horizontal integration wrong. vehicle checkout is done on the pad vertical, instead of on the HIF. Thus, they get the cost of a VIF and a HIF with long pad times. Atlas V got it right for wholly vertical. We have to see, but I suspect SpaceX will get it right for mostly horizontal with vertical just for integration. The Soyuz at ELS seems a bit expensive with the mobile tower, but from an ops POV is done right.
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#3
by
Lobo
on 20 May, 2014 23:20
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This, along with some uncertainty in Atlas's future, and various discussions about if ULA could/would every down select to just Delta IV, as -supposedly- the two EELV's are redundant, made me think about this a little bit.
So, if we make a few assumptions (very big assumptions) that SLS survives long enough for NASA to fund RS-25E devepment. And -if- Atlas looses access to Russian RD-180's. And -if- a domestic replacement engine is not funded because USAF/DoD decides Delta IV and FH provide sufficient assured access to space.
If we were in such a scenario in say 2019, I was wonder if Delta IV could be streamlined a little to get it's costs down. A few thoughts.
1) Retire D4H. It's very expensive and doesn't fly much. And it needs 3 unique cores.
2) Modify the D4M+ core, to mount more than four GEM-60's, and to replace the RS-68A with one RS-25E, who's development would already be paid for by NASA, and annuals costs of it would then be shared.
Make Delta IV a single core only, with a true sustainer core. With perhaps 4-8 GEM-60's, and a long burning higher impulse core, the GTO and escape performance should be pretty good on the top end. (design to mount enough GEM-60's to replicate D4H's performance, however many that might be. Delta II seemed to work pretty good with 9 GEM's. Maybe 8, 9, or 10 would bee needed to replicate D4H performance?)
While that would require a new modified core to mount more than four GEM's and an RS-25E instead of an RS-68A, but then that could be the -only- core ULA produces. A truely "common core". With a downselect to just the 5m DCSS as the only upper stage. RAC-3 looked at EELV configurations with a D4 sustainer core with RS-25, so while it wouldn't be without effort, I don't think it's unfeasible.
The drawback would be that this would need some GEM's to even get off the ground. I thought an original requirement of the EELV program was that the base EELV could launch without SRB's? But even if so, today's EELV's have been changed from the original requirements anyway, so I don't know if that would be much of a problem. And the Delta 4M+ (5,2) already needs two GEM's to get off the ground anyway with the 5m DCSS, and likey would with any sort of 5m Common Upper Stage like WBC or ACES. Also, looking back at the launch record, the last time a truely slick Delta 4M core was launched was 2006. So USAF/DoD apparently doesn't have much use for that configuration anyway.
Would this be a feasible evolution option to let ULA to lower costs and save money, and retain Delta IV as their only EELV? Seems like it could be.
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#4
by
Jim
on 21 May, 2014 01:56
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1) Retire D4H. It's very expensive and doesn't fly much. And it needs 3 unique cores.
There are payloads that need the Heavy
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#5
by
Jim
on 21 May, 2014 01:59
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2) Modify the D4M+ core, to mount more than four GEM-60's, and to replace the RS-68A with one RS-25E
Not feasible. Too low of thrust, no roll control. Too low performance for mission capture
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#6
by
edkyle99
on 21 May, 2014 03:07
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Rather than mess with the core or add more boosters, why not simply upgrade the boosters themselves? Atlas V already uses beefier solids than Delta IV. Wouldn't it be nifty if a common booster could be used to boost these common cores?
- Ed Kyle
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#7
by
Lobo
on 21 May, 2014 06:41
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2) Modify the D4M+ core, to mount more than four GEM-60's, and to replace the RS-68A with one RS-25E
Not feasible. Too low of thrust, no roll control. Too low performance for mission capture
Wouldn't the RS-25 provide the roll control, as the RS-68 does?
Also, 10 GEM-60's plus one RS-25E would have more thrust at lift off than three RS-68A's. There will be less thrust after SRB separation as the GEM's don't burn for nearly as long as the outboard D4H cores. Is that what you are referring to?
But the RS-25 would have significantly more ISP (over 40s more), and as they don't consume propellant as fast as the RS-68, they'd have a much longer burn time. Would the gravity losses be too great, or could that RS-25 core make up the performance with it's better efficiency and longer burn?
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#8
by
Lobo
on 21 May, 2014 06:47
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Rather than mess with the core or add more boosters, why not simply upgrade the boosters themselves? Atlas V already uses beefier solids than Delta IV. Wouldn't it be nifty if a common booster could be used to boost these common cores?
- Ed Kyle
Certainly. But I think the Delta IV cores would need to be messed with to mount the Atlas V SRB's. So a new core anyway. Perhaps Take my RS-25E core, and add 6-8 Atlas V SRB's? Each would produce about 100klbs more thrust per booster than GEM-60's. Eight of them along with the RS-25 would produce 2.7Mlbs of thrust.
As Jim says, it may not be feasible. Just trying to think of a way that Delta IV could be made cheaper and more competitive for ULA, especially if it were to be the only remaining EELV (hypothetically). Going from 4 cores to 1 in the production line would seem like a good place to start.
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#9
by
MATTBLAK
on 21 May, 2014 06:48
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While we are sort of playing rocket Legos (I love doing that) - RS-25E powered corestage, 4x Aerojet solids from Atlas V (modifying for 6x worth the cost?), 5 meter upper stage powered by MB-60 or RL-60 - what sort of performance are we talking about? Is J-2X feasible for a stretched 5 meter upper stage? An all-new Ares 1 type upper stage?
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#10
by
hkultala
on 21 May, 2014 09:02
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2) Modify the D4M+ core, to mount more than four GEM-60's, and to replace the RS-68A with one RS-25E
Not feasible. Too low of thrust, no roll control. Too low performance for mission capture
Wouldn't the RS-25 provide the roll control, as the RS-68 does?
No. RS-68 can do roll control because it has separate roll control nozzle which is fed from the exhaust of the gas generator.
In RS-25 everything is coming out of the one main nozzle, because it's staged cycle engine. There is no roll control nozzle, and no possibility to add that roll control nozzle.
Some russian rocket stages have small dedicated multi-hamber control thruster engine to allow roll control with single-chamber closed cycle main engine.
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#11
by
Jim
on 21 May, 2014 11:03
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Also, 10 GEM-60's plus one RS-25E would have more thrust at lift off than three RS-68A's.
10 GEM's won't fit on the vehicle. The TSM's would get in the way
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#12
by
clongton
on 21 May, 2014 11:27
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Have you thought about the TR-106? That LOX/LH2 engine was actually completed, built and tested at Stennis in 2000 thru its full range from max 108% to throttle down to 65%. The TR-106 has about 650,000 lbsf/sl thrust and was designed to be inexpensive. It is a sweet engine and would easily fit under the existing Delta core. The RS-25e will have about 520,000 lbsf/sl thrust and be an expensive engine.
Tom Mueller was a lead engineer for development of the TR-106 and became TRW vice president of propulsion. In 2002, Elon Musk asked Mueller to join him as a founding member of SpaceX becoming its head of propulsion, along with other TRW staffers. Technology lessons from the Low Cost Pintle Engine project were used in the development of the SpaceX Merlin engine.
If you're looking to upgrade the Delta-IV with an engine change, forget the expensive RS-25e and the RS-68A. Do something real and go to the TR-106. More powerful, less expensive, better throttle range, potentially reusable should ULA want to consider that route.
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#13
by
MATTBLAK
on 21 May, 2014 12:03
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What Chuck said! And about those 4x Aerojet solids and the MB-60...
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#14
by
baldusi
on 21 May, 2014 14:15
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What you are talking about would be a Delta V. Why not go all the way and use the 5.5m composite tooling on a new core. You could put 2 RS-25E and design to take upto 8 Atlas SRB. You'd of course be talking about a new vehicle, anyways. Same technology for the Upper Stage, while still using the RL-10C-2, with option of dual RL-10C-1 for LEO.
Regarding any TRW engine, I understand the engineering team was disbanded. And many are working for the competition. In fact, it would be easier for TRW to license the technology of the TR-106 to AeroJet.
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#15
by
TrueGrit
on 21 May, 2014 16:35
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Once again from my real world experience... The logic of the expendable SSME (RS25E) has always escaped me. The RS25 has ~5x the number of parts and ~2x the amount of labor hours to build compared to an RS68. For NASA to say the RS25E is going to be cheaper just doesn't pass the smell test... When has NASA ever been right on program costs? But let’s just say they do the impossible... For the RS25E to work on a Delta IV you would need 2 of them, to get the thrust or you can get off the ground. This solves the roll control issue, but do any of you believe the RS25E will be half the cost of an RS68? And I haven't begun to talk about the costs of a completely new aft structural section and new propellant feedsystem that has to be designed, built, and qualified.
As for the Atlas solids... The differences have some hidden integration costs and don't provide that much of a performance improvement. The Delta solid thrust profile was tuned specifically to manage the Delta loads, while the same was done for Atlas. There is a great potential of problems mixing and matching, which means a full up development loads cycle for the whole "mission box". This potentially could result in a need to pour the solid differently, or cause major redesign in the interstage or other structural areas. And I haven't begun to address the other integration problems: the Atlas solids are longer which results in major changes to the Delta tank and manufacturing tooling, the Atlas solids electrical connection and attach configuration is different and has some incompatibilities, the Atlas solids need to gain and be qualified for gimbal capability, the Atlas solids would impact liftoff acoustics and IOP, and more.
And before you talk about what Delta got wrong about horizontal integration… Get some historical perspective and bother to do some research. The HIF was designed from the start to be capable of doing stage integration testing. But the launch rate collapsed before they ever got to fitting it all out. Delta abandoned it in place, unfinished because there is no need with a launch rate of 6 week centers or longer. The biggest difference between Delta processing and Atlas processing is that Atlas has eliminated WDRs. If Delta did the same it would eliminate 2+ weeks from the processing schedule, prep for and recovery from the WDR, putting it on par with Atlas. That also was in the inital Delta planning aswell, but hasn't been done... At least not yet.
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#16
by
Jim
on 21 May, 2014 17:34
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Delta abandoned it in place, unfinished because there is no need with a launch rate of 6 week centers or longer.
The pad ops are still longer than Atlas VIF ops with removing the WDR (which is only a week hit for Atlas). Atlas reduces some time with ASOC testing.
There are no get ahead tasks available in the HIF after the vehicle is assembled.
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#17
by
Lobo
on 21 May, 2014 19:40
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2) Modify the D4M+ core, to mount more than four GEM-60's, and to replace the RS-68A with one RS-25E
Not feasible. Too low of thrust, no roll control. Too low performance for mission capture
Wouldn't the RS-25 provide the roll control, as the RS-68 does?
No. RS-68 can do roll control because it has separate roll control nozzle which is fed from the exhaust of the gas generator.
In RS-25 everything is coming out of the one main nozzle, because it's staged cycle engine. There is no roll control nozzle, and no possibility to add that roll control nozzle.
Some russian rocket stages have small dedicated multi-hamber control thruster engine to allow roll control with single-chamber closed cycle main engine.
Ok, thanks for that.
Then how did STS provide roll control? How will SLS? How could Jupiter 130 have done it? The SRB nozzles?
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#18
by
Lobo
on 21 May, 2014 19:50
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Have you thought about the TR-106? That LOX/LH2 engine was actually completed, built and tested at Stennis in 2000 thru its full range from max 108% to throttle down to 65%. The TR-106 has about 650,000 lbsf/sl thrust and was designed to be inexpensive. It is a sweet engine and would easily fit under the existing Delta core. The RS-25e will have about 520,000 lbsf/sl thrust and be an expensive engine.
Tom Mueller was a lead engineer for development of the TR-106 and became TRW vice president of propulsion. In 2002, Elon Musk asked Mueller to join him as a founding member of SpaceX becoming its head of propulsion, along with other TRW staffers. Technology lessons from the Low Cost Pintle Engine project were used in the development of the SpaceX Merlin engine.
If you're looking to upgrade the Delta-IV with an engine change, forget the expensive RS-25e and the RS-68A. Do something real and go to the TR-106. More powerful, less expensive, better throttle range, potentially reusable should ULA want to consider that route.
TR-106 was a pretty cool engine from what I've read on it. Just like it's cousin, the TR-107. But my main reason for even bringing this up was not so much to play legos with Rockets (although I do love to do that), but for two reasons.
1) Eliminate the D4H but replicate it's capability with a cheaper variant.
2) Use an engine that will already be developed and paid for by NASA.
3) Keep modifications down as much as possible.
TR-106 Would work, but it'd have a ways to go to bring it back at this point I think. Not as much as a new engine from scratch, but enough that it might be hard to justify over RS-25e which would already be rolling off the assembly line for SLS. Now, if NASA were developing TR-106 for SLS, then that would be the way to go. Too bad things didn't work out that way. So reason #2 goes away.
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#19
by
Jim
on 21 May, 2014 19:53
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Then how did STS provide roll control? How will SLS? How could Jupiter 130 have done it?
They had more than one engine.
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#20
by
Lobo
on 21 May, 2014 19:54
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For the RS25E to work on a Delta IV you would need 2 of them, to get the thrust or you can get off the ground. This solves the roll control issue, but do any of you believe the RS25E will be half the cost of an RS68? And I haven't begun to talk about the costs of a completely new aft structural section and new propellant feedsystem that has to be designed, built, and qualified.
No, I don't think going to two RS-25E's would be feasible, for the reason you mentioned. Going form one single engine to another single engine I think could be done without needing too radical of an MPS redesign, but going one engien to two would.
Myself I was advocating looking at more GEM-60's, rather than switching to Atlas SRB's, for the reasons you mentioned.
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#21
by
TrueGrit
on 21 May, 2014 21:58
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Delta HIF was originally designed to do electrical powerup and testing after stage mate. Concept was to be do all integrated stage and box level testing in the Decatur and HIF prior to roll out. After roll out the only thing was to be done was an umbilical integrety check, and flight computer final alignment and quick sequences. As I said the rate collapsed prior to activation and as such it was never activated, but this would be a way to get ahead.
In the end nearly everything aft of the LH2 tank will be redesigned and requalified for Delta to accomidate the RS25. Just for starters the RS25 gimbals at the pump inlet, while RS68 (like RS27) gimbals aft of the pump inlet. The primary load bearing structure of the vehicle aft section is a box for Delta which picks up the engine upside down piramid thrust frame. This is signficantly different than center load pickup of the RS25, which will impact the entire load pickup structure of the compartment. Additionally the location of the two primary feedlines are different, which will result in a need for a new feedline design (which has its own load pickup structure). And this doesn't mention the secondary equirement and thermal shield closeout which are completely redesigned.
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#22
by
Sotar
on 23 May, 2014 17:38
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This has been a really helpful topic for me. I had been contemplating potential up grades of D4M+ in order to fill the gap that Atlas V currently covers between D4M and D4H. My thoughts were to change out the solids. I refrained from asking about it as I don’t know much about rockets but know enough that they are not Lego’s. Though I agree Lego rockets are a lot of fun.
Per TrueGrit my ideas seem impractical and I can now answer the questions pretty much myself. So thank you.
My 2 ideas
1)Replace the GEM 60s with Castor 120s.
- 120s are fat so maybe hard to fit, need new attachment points, electrical etc. Higher total impulse but shorter burn time, per ATK catalog can be used as strap on boosters.
2) Potential to use the Titan IV RSRM to replace the outer Cores on the DIV-H, I don’t have the knowledge to figure out if these would be a benefit or not.
- Out of production, would require modifications to the core, modifications to transporter, acoustics, etc. Unknown if RS-68A could survive the heat.
Would like to hear your thoughts on these.
Ego sum non a erucae scientiae,
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#23
by
Jim
on 23 May, 2014 18:15
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1)Replace the GEM 60s with Castor 120s.
- 120s are fat so maybe hard to fit, need new attachment points, electrical etc. Higher total impulse but shorter burn time, per ATK catalog can be used as strap on boosters.
2) Potential to use the Titan IV RSRM to replace the outer Cores on the DIV-H, I don’t have the knowledge to figure out if these would be a benefit or not.
1. You nailed most of it. The pad can't take it nor the vehicle
2. They wouldn't be a benefit. The outer cores have more impulse.
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#24
by
Helodriver
on 23 May, 2014 18:56
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Pros:
High payload;segments on hand, possibly shared with SLS; Corporate knowledge is fresh; "Reusable"; simpler man rating; fly from LC-39B on a modified shuttle MLP.
Cons:
High acceleration; payload access; expense; rocketsarenotLEGOs
It would look interesting though. Sort of like the LH2 son of SRB-X
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#25
by
gospacex
on 23 May, 2014 19:00
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I want to rip my eyes out looking at this contraption.
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#26
by
bubbagret
on 23 May, 2014 19:10
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Pros:
High payload;segments on hand, possibly shared with SLS; Corporate knowledge is fresh; "Reusable"; simpler man rating; fly from LC-39B on a modified shuttle MLP.
Cons:
High acceleration; payload access; expense; rocketsarenotLEGOs
It would look interesting though. Sort of like the LH2 son of SRB-X
I think you would have to rename it Titan V... Both look and cost would be similar.
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#27
by
Jim
on 23 May, 2014 19:14
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
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#28
by
Helodriver
on 23 May, 2014 19:24
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
There's a solution for that.
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#29
by
Targeteer
on 23 May, 2014 19:27
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
There's a solution for that.
Classic
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#30
by
russianhalo117
on 23 May, 2014 19:32
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
There's a solution for that.
That will only work if you plan on ramming it into the ground first.
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#31
by
Excession
on 23 May, 2014 20:12
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
There's a solution for that.
That will only work if you plan on ramming it into the ground first.
No no no, launch it upside-down using only the SRBs. Then airstart the core when they burn out and use thrust-vectoring to flip it around in the right direction. It works in kerbal space program!
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#32
by
Will
on 23 May, 2014 20:55
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Seriously, how about a pair of monolithic 100 t solids?
Will
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#33
by
Lobo
on 24 May, 2014 04:38
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Delta HIF was originally designed to do electrical powerup and testing after stage mate. Concept was to be do all integrated stage and box level testing in the Decatur and HIF prior to roll out. After roll out the only thing was to be done was an umbilical integrety check, and flight computer final alignment and quick sequences. As I said the rate collapsed prior to activation and as such it was never activated, but this would be a way to get ahead.
In the end nearly everything aft of the LH2 tank will be redesigned and requalified for Delta to accomidate the RS25. Just for starters the RS25 gimbals at the pump inlet, while RS68 (like RS27) gimbals aft of the pump inlet. The primary load bearing structure of the vehicle aft section is a box for Delta which picks up the engine upside down piramid thrust frame. This is signficantly different than center load pickup of the RS25, which will impact the entire load pickup structure of the compartment. Additionally the location of the two primary feedlines are different, which will result in a need for a new feedline design (which has its own load pickup structure). And this doesn't mention the secondary equirement and thermal shield closeout which are completely redesigned.
TrueGrit, Jim,
Thanks for the info. Learning lots of new things. :-)
Doesn't really sound like there's anything that could really be done to "streamline" the number of Delta cores or really improve it's cost structure much from a hardware standpoint anyway. Can't blame a guy for trying.
By the time you are into it for that, you are about into it for a whole new LV.
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#34
by
Lobo
on 24 May, 2014 04:39
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Pros:
High payload;segments on hand, possibly shared with SLS; Corporate knowledge is fresh; "Reusable"; simpler man rating; fly from LC-39B on a modified shuttle MLP.
Cons:
High acceleration; payload access; expense; rocketsarenotLEGOs
It would look interesting though. Sort of like the LH2 son of SRB-X
You'd probably burn up your RS-68...
Cool graphic though.
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#35
by
Lobo
on 24 May, 2014 04:40
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Since we're looking at upgrading of solids, how about integrating a CBC with a pair of 4 segment SRBs?
Not viable. Shuttle SRB's lift from the top. They don't have the structure at the aft (without a major design) to lift from the bottom
There's a solution for that.
Classic
Heheheheh....nice!
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#36
by
MATTBLAK
on 25 May, 2014 06:04
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So for future Delta IV upgrade options; we're back to talking about aluminium/lithium and composite tanks and structures, upper stage engine upgrades and the future possibility of a regenerative version of the RS-68A? A couple tons mass shaved from the core and upper stages, an MB-60 or RL-60 for the 5 meter upper stage, add 4x GEM-60 solids and a regenerative RS-68 and would we be talking about 20+tons to L.E.O. for a 'single stick' Delta IV? Even more if the propellants are densified with slush-liquid hydrogen? This would give more options to the ULA 'launch fleet of one' if Atlas dies: Single stick Deltas with 2x solids or none, the smaller 4 meter upper stage and only using Delta IV-H when really needed. The D-IV-H with all the upgrades, even without propellant cross feed would be a formidable booster.
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#37
by
TrueGrit
on 27 May, 2014 16:10
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I have confidence the M+6 and M+8 are reasonable updates, and wouldn't be in ULA's published payload guide if it wasn't fairly well understood. It would result in a major structural change to the LH2 tank and aft section, to add new solid attach points, along with bringing the rocket back to the wind tunnel to prove out the loads. But these seem technically reasonable things to accomplish, assuming the other structure can manage the peak loads. Don't be surprised if items like air lighting, i.e. Delta II, and RS68 load relief throttling might be needed to mitigate some of the impacts. This reduces the benifit a bit, but the hinted at impacts (i.e. pad accustics and in-flight loads) could be quite costly to mitigate.
Weight to performance trade on first stages says any major strcutural change difficult to justify. Major material change would require significant costs which would have to have a return in said investment. For example a change in the tank to AL-LI would result in a manfuacturing development program to "tune" the tooling used to cut, bend, and weld the tanks together. And there are technical reasons why cryogenic propellant composite tanks are still a concept and not used in prodruction. The so called techical readiness level was missed badly on X-33 and I seems there han't been much progress on large scale tanks since then.
Slush hydrogen and other desified propellants would introduce a large number of problems. It would add a signficant number of new systems to mantain the propellant at a super dense state for the a multiple hour launch window. Secondly the RS68 has never run with super dense propellant... In my memory no large sale engine has ever been tested with super dense propellants. The test stands used to hot fire the engines would have to be updated, don't think they run that cold, and a certification process would have to be pursued. What seems a "small change" to some would be considered a "major chagne" to many as it would be ground breaking technically... And that always comes with surprises.
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#38
by
MATTBLAK
on 28 May, 2014 06:47
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Then if it's all as hard as you're portraying it to be - probably more than a grain of truth - then upper stage upgrades are about all that's left... And RS-68 improvements.
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#39
by
TrueGrit
on 29 May, 2014 15:28
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I personally think super dense propellants and composite tank structures are "not ready for prime time"... And even if they were would introduce significant enough changes that one would probably want to start with a semi-clean state.
To me the preferred evolutionary routes would be:
- Examine different SRM configurations... 6 & 8 as advertised in the ULA payload users guide
- Replace the current Delta upper stages with Centaur based upper stages (would need two sizes)
- Additional RS68 upgrades including a regen nozzle and pump seal changes to reduce helium consumption
- Cross-feed on the Heavy vehicle
The upper stage change seem much more plausible in the near future with talk of ULA moving to a Common Avionics system for both Delta and Atlas. After which Centaur electronics and flight control will be compatible with the Delta first stage and ground systems. This would seem to have the biggest "bang for your buck".
I've already discussed my belief that the SRM configuration changes seem reasonable. While cross-feed has always been a reasonable option on the Delta IV upgrade list... But has a limited need in the market (Heavy isn't in demand).
Latestly the RS68 upgrades are all known, and some have gone to the point of PDR. They would all seem to be a far less risky approach to the than an entirely new development program. I know the industry is clamoring for the R&D funds, and there is an open disdain for a hydrogen booster. But to me the question is... Is it better to go down the route of a RS68 upgrade for 1/3 the quoted cost of a whole new technology development. If past performance is an indicator of the future... That new technology development will end of being 2x the costs and 4x the schedule of what the Air Force and NASA are saying now. That says one could have an improved RS68 and Delta IV for 1/6th the cost and 4x faster than anything to do with a new technology development. But that ship seems to have sailed...
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#40
by
baldusi
on 29 May, 2014 16:25
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Ordering one of each Delta IV (4,4), (5,6) and (5,8) right now would be the best cover strategy. Together with Heavy they can cover everything that Atlas V does at a not so higher cost. Those actions should have a relatively small incremental cost (wrt an AV431, AV531 and an AV551 that would otherwise use the missions). And I would seriously consider reading an activation plan for finishing as much possible in Decantur and doing full integration testing in the HIF. That should enable 6 to 8 missions per year and assure availability of (4,4) for 2016 and (5,6) and (5,8) for 2017.
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#41
by
DGH
on 29 May, 2014 21:33
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Ordering one of each Delta IV (4,4), (5,6) and (5,8) right now would be the best cover strategy. Together with Heavy they can cover everything that Atlas V does at a not so higher cost. Those actions should have a relatively small incremental cost (wrt an AV431, AV531 and an AV551 that would otherwise use the missions). And I would seriously consider reading an activation plan for finishing as much possible in Decantur and doing full integration testing in the HIF. That should enable 6 to 8 missions per year and assure availability of (4,4) for 2016 and (5,6) and (5,8) for 2017.
Sounds like a plan to me.
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#42
by
PahTo
on 29 May, 2014 22:39
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Ordering one of each Delta IV (4,4), (5,6) and (5,8) right now would be the best cover strategy. Together with Heavy they can cover everything that Atlas V does at a not so higher cost. Those actions should have a relatively small incremental cost (wrt an AV431, AV531 and an AV551 that would otherwise use the missions). And I would seriously consider reading an activation plan for finishing as much possible in Decantur and doing full integration testing in the HIF. That should enable 6 to 8 missions per year and assure availability of (4,4) for 2016 and (5,6) and (5,8) for 2017.
Don't forget the all-important upper stages (likely the most immediate upgrade path) :: common 4m (Centaur) upper stage, two engine Centaur, and ACES (common 5m upper stage).
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#43
by
baldusi
on 29 May, 2014 22:54
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Ordering one of each Delta IV (4,4), (5,6) and (5,8) right now would be the best cover strategy. Together with Heavy they can cover everything that Atlas V does at a not so higher cost. Those actions should have a relatively small incremental cost (wrt an AV431, AV531 and an AV551 that would otherwise use the missions). And I would seriously consider reading an activation plan for finishing as much possible in Decantur and doing full integration testing in the HIF. That should enable 6 to 8 missions per year and assure availability of (4,4) for 2016 and (5,6) and (5,8) for 2017.
Don't forget the all-important upper stages (likely the most immediate upgrade path) :: common 4m (Centaur) upper stage, two engine Centaur, and ACES (common 5m upper stage).
Common Centaur and ACES have their own timelines and critical path. In particular, can only be done after Common Avionics. Delta IV (4,4) can be done today. The new true Common Core is based on the old (5,4). So is actually reinforced for the 4 boosters. It's just certifying the combo. The (5,6) and (5,8) would require new reinforced cores. Obviously would bring back the problem that a (5,4) mission can't upgrade by simply adding boosters to the (5,6), because the core itself would need mods. And a (5,8) whose payload got delayed can't be easily reassigned to a (5,4) mission. But you'd get coverage for a worse case scenario for relatively little money.
It might happen, that ULA's schedule for Common Centaur is such that they would rather debut Common Centaur on a (4,4) or (5,6), but that would only be a potential synergy. In any case most people might not be worried about the Rd-180 availability at all and rather wait for the word war to pass.
I still believe it would be a cautious plan to execute.
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#44
by
sdsds
on 29 May, 2014 23:12
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Delta IV (4,4) can be done today. The new true Common Core is based on the old (5,4). So is actually reinforced for the 4 boosters. It's just certifying the combo.
Could a high value payload fly on the maiden (4,4) launch, or would a qualifying flight (with a lower value demonstration payload) be required for certification?
The (5,6) and (5,8) would require new reinforced cores.
Two different core designs for (5,6) and (5,8), or could those two share a core between them? (Essentially, what is the performance penalty for (5,6) if it flies with a core structurally capable of flying in the (5,8) configuration? Does it still offer improvement over (5,4)?)
