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#20 by mmeijeri on 03 May, 2010 04:58
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Doing this would allow NASA to focus for the next few years on constructing payloads, principally a "deep space" Orion.
Better yet, a deep-space Altair precursor which could also serve as a makeshift hypergolics depot. To go to the moon, we need a lander. We already have launch vehicles. An uprated commercial capsule could then serve as the return vehicle. The Altair work could even start now, instead of the CRV Orion, using the same workforce, but doing it a few years from now using CRV Orion as a basis for the lander would also be a good idea. -
#21 by A_M_Swallow on 03 May, 2010 05:10
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On the performance calculations: I'm getting about 17.5mT through TLI. You also have to take the mass of a docking mechanism and an extended duration mission kit into account. That might be enough to do L1/L2 insertion as well, even without the capacity of a Delta upper stage. I'd be uneasy with not having return propellant. A smaller capsule sounds like a better idea to me.
It sounds like you will need the return propellant waiting at EML. -
#22 by mmeijeri on 03 May, 2010 05:13
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Yeah, and I'm a bit uneasy with that. That's why I'd rather use an uprated smaller commercial capsule than Orion. Once at L1/L2 you could dock with a mission module, say an Altair precursor or a Bigelow style hab, or both. Orion could still serve as a CRV if necessary.
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#23 by FinalFrontier on 03 May, 2010 05:14
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On the performance calculations: I'm getting about 17.5mT through TLI. You also have to take the mass of a docking mechanism and an extended duration mission kit into account. That might be enough to do L1/L2 insertion as well, even without the capacity of a Delta upper stage. I'd be uneasy with not having return propellant. A smaller capsule sounds like a better idea to me.
It sounds like you will need the return propellant waiting at EML.
Centaur (modified i.e. mini aces based) Depot
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#24 by FinalFrontier on 03 May, 2010 05:16
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Yeah, and I'm a bit uneasy with that. That's why I'd rather use an uprated smaller commercial capsule than Orion. Once at L1/L2 you could dock with a mission module, say an Altair precursor or a Bigelow style hab, or both. Orion could still serve as a CRV if necessary.
I was under the impression that bigelow habs are better for stations or for surface bases, not deep space mission modules........... -
#25 by mmeijeri on 03 May, 2010 05:17
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The Bigelow modules started their life as NASA's Mars TransHab.
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#26 by sdsds on 03 May, 2010 14:49
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Suppose the Centaur were launched as a passive payload on a Delta-IV Heavy. [...] Is this concept a "no brainer," or is it somehow "brain dead"?
Oh. I don't suppose the propellant tanks at SLC-47 already have the capacity to fill a Centaur after having filled the three CBCs and the 5 m Delta upper stage? -
#27 by tnphysics on 04 May, 2010 00:02
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If not, then just offload the CBCs slightly.
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#28 by FinalFrontier on 04 May, 2010 18:23
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It looks like there is a really good idea here for a future upper stage/EDS. Great job SDSDS and all.
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#29 by meiza on 05 May, 2010 00:12
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You can launch A Delta IV Heavy without an upper stage too...
Of course modified
http://gravityloss.wordpress.com/2009/08/13/delta-iv-manrating/ -
#30 by sdsds on 09 May, 2010 23:30
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An obvious aspect of this approach is that it requires some sort of interstage between the Delta vehicle and the Centaur. Estimating a mass for that should be easy, i.e. it should be about the mass of the interstage used on Atlas between the booster and the Centaur.
Looking at spacelaunchreport.com, though, makes this a bit confusing. The 400-series interstage is reported as 0.8 t, but the 500 series interstage is reported as 1.57 t. What do those interstages look like? Is one more appropriate than the other for supporting a Centaur?
On a related question, for an EELV Heavy vehicle there was at one point a bolt pattern specified for the "Standard Interface Plane" at the top of the launch vehicle that was a circle 173 inches in diameter. Did this match the interface to a pre-existing Titan payload adapter? Has this interface actually been implemented for Delta IV-Heavy launches? -
#31 by Jim on 10 May, 2010 00:18
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1. Looking at spacelaunchreport.com, though, makes this a bit confusing. The 400-series interstage is reported as 0.8 t, but the 500 series interstage is reported as 1.57 t. What do those interstages look like? Is one more appropriate than the other for supporting a Centaur?
2. On a related question, for an EELV Heavy vehicle there was at one point a bolt pattern specified for the "Standard Interface Plane" at the top of the launch vehicle that was a circle 173 inches in diameter. Did this match the interface to a pre-existing Titan payload adapter? Has this interface actually been implemented for Delta IV-Heavy launches?
1. The 400 series interstage is visible. It the truncated cone between the Centaur and Atlas. . The 500 series interstage is inside the fairing and it also supports the fairing. There are pics in the planner's guide.
2. The 173" bolt circle was from the outer Centaur G' forward adapter bolt circle on the Titan IV. Delta IV can provide a payload attach fitting that has the same dimensions. -
#32 by Jim on 10 May, 2010 00:19
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Why is it a Centaur in the first place? Why not a D-IV upperstage?
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#33 by mmeijeri on 10 May, 2010 00:22
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So it will fit on a Delta Heavy. Would a Delta upper stage fit on a Delta Heavy with RS-68A? Or else on an Atlas Heavy? You could always offload some propellant of course.
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#34 by Jim on 10 May, 2010 00:27
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there are two D-IV upperstages and adapters can be made
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#35 by mmeijeri on 10 May, 2010 00:34
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Doh, of course! It even has better Isp than Centaur. On the other hand, I thought Centaur was considered to be the best upper stage in the world. Is it?
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#36 by sdsds on 10 May, 2010 01:29
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Why is it a Centaur in the first place? Why not a D-IV upperstage?
My thinking was motivated by two factors:
1) Duration: Centaur has a proven record of (I think) 9 hours between launch and final burn, and ULA has talked about mission kits that would extend that further. Has there been a D-IV upper stage conducting a mission of that duration? The goal is to provide a reasonably large window of time for the rendezvous and docking conducted by the departure stage's payload.
2) Workforce: The Delta upper stage workforce will be busy with activities related to the second stage. They'll be tired out once that stage has completed its mission. Some portion of the (still rested) Centaur workforce would sit in the Delta "payload" chairs; some portion would sit in their regular seats at the Atlas control center, ready to take over once Delta had done its job.
Also, from a political perspective this approach might help to "spread the wealth" and thus might garner wider support. -
#37 by Jim on 10 May, 2010 01:38
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1) Duration: Centaur has a proven record of (I think) 9 hours between launch and final burn, and ULA has talked about mission kits that would extend that further. Has there been a D-IV upper stage conducting a mission of that duration? The goal is to provide a reasonably large window of time for the rendezvous and docking conducted by the departure stage's payload.
2) Workforce: The Delta upper stage workforce will be busy with activities related to the second stage. They'll be tired out once that stage has completed its mission. Some portion of the (still rested) Centaur workforce would sit in the Delta "payload" chairs; some portion would sit in their regular seats at the Atlas control center, ready to take over once Delta had done its job.
1. The D-IV GSO mission is over 6 hours long. Also D-IV has kits.
2.
a. There is no savings there. For a mission to deliver anything to LEO, including a fully fueled upperstage, the duration is only a few minutes.
b. Anyways, the Centaur people will be on consoles during the countdown and launch, so there are no savings.
c. This is all mute. The Centaur is autonomous and there is no need for a "control" team. All ELV "flight" team only monitor telemetry and there is no uplink. The flight team is the same as the launch team.
ELV upperstages ha -
#38 by alexw on 11 May, 2010 07:26
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Doh, of course! It even has better Isp than Centaur. On the other hand, I thought Centaur was considered to be the best upper stage in the world. Is it?
Depends on your payload and your mission needs. DIVHUS has more fuel, more thrust (than DES), and higher ISP, but higher dry mass (presumably coming from both the big nozzle on RL-10-B-2 and the less efficient structural design). IIRC, running the numbers through the rocket equation for typical high-energy, lightweight space probe missions, it was about a wash. (And AV5x1 is much cheaper than DIVH). For heavy payloads, presumably DIVHUS makes a big difference.
But DIVH was never about price/performance, it was about substituting for Titan IV, some of whose payloads couldn't perform their own GSO burns. So, DIVHUS has mission packs (as Jim alludes to) to shepherd the national security payload (all?) the way.
I assume that all the same abilities were offered for Atlas V/Centaur, and indeed LockMart put up plenty of documents on upgrades they've studied (and don't seem hard to put into production), but like AVH I assume they're on hold pending a customer.
It's been said around here that Centaur's avionics are more advanced than Delta's. Is it fair to say that "ACES" as presently contemplated would look more like Centaur than DCSS?
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#39 by Bernie Roehl on 11 May, 2010 11:25
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The currently proposed budget seems to keep Orion alive as a CRV. As far as I know, the only vehicle that would be capable of lifting it would be a human-rated Delta IV Heavy. Since the existing Delta pad at LC-37 is not suitable for crewed launches, a second pad would have to be constructed for that purpose (which also means that NASA launches wouldn't interfere with DOD launches, which is a good thing).
If all this turns out to be the case, we'll have two Delta IV Heavy pads and an HR'd Delta IV Heavy capable of placing an Orion spacecraft into LEO.
Can we get from there to manned BEO missions without any new launch vehicle development? I believe the answer is yes.
One scenario would be to use the existing Delta IV Heavy to put its own mostly-fueled upper stage in orbit, launched from LC-37A. A block II Orion would be launched on a second Delta IV Heavy from LC-37B, less than 24 hours later.
The DIVUS would have a Soft Capture Module bolted to the front of it (similar to the one that was recently mounted on Hubble). The Orion would dock with the DIVUS, which would take it through TLI on a "free return" lunar trajectory or to a rendezvous at EML.
Time for some numbers...
According to http://www.astronautix.com/lvs/deltaiv.htm, the Delta IV Heavy can place 25,800 kg in LEO. With no payload, that means it can place its own upper stage in orbit with that amount of fuel remaining.
According to that same page, The upper stage has a dry mass of 3,490 kg.
According to http://en.wikipedia.org/wiki/Delta-v_budget, delta V from LEO to C3 is 3220 m/s. Let's assume the DIV upper stage has a vacuum Isp of 450 sec.
Solving the rocket equation for the dry mass we find that a DIV upper stage with 25,800 kg of fuel can put 23,990 kg through TLI. Subtracting the stage's dry weight of 3,490 leaves us with 20,500 kg of payload. That payload would be a block II Orion, placed in orbit by the second Delta IV Heavy.
According to http://astronautix.com/craft/orion.htm, Orion has a mass of 21,500 kg plus the LAS. However, a large part of that is fuel for the main propulsion system. Since our mission scenarios don't require that the Orion SM do TEI, we can reduce that mass by several thousand kg which would bring it within our budget of 20,500 kg with suitable margins.
So manned lunar flybys and round-trip missions to EML1 and EML2 are feasible with no new launch vehicle development. The only cost would be the development of the block II Orion, which would basically mean heavier heat shields and some radiation shielding.
Later on you could use the Delta IV Heavy to position a Sundancer-derived outpost at EML1 and/or EML2. Lunar landings would be harder, and would require some ACES-like technology (long-loiter cryogenics, possibly cryogenic fuel depots as well as a lander).
Of course modified