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#20
by
UltraViolet9
on 01 Mar, 2018 21:41
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I see the internal volume on the charts. So even to compete with Orion, the other companies would have to have multiple launches for living modules, service modules, food and fuel, either assembled in orbit or at say L1. Orion could still be cramped for 4 without a living module at a cis-lunar region and a toilet, especially for a long duration mission.
Orion's mass is driven by both questionable design choices and questionable requirements choices.
You could probably revisit some of Orion's design choices (like its diameter, toilet, etc.) and reduce mass. Maybe that alone would get it down to D2 mass, but my gut doubts it. (Maybe close.)
I think you'd have to fundamentally revisit the requirements from the ESAS study (mission duration, crew size, etc.) and rethink the mission architecture to get down to D2 mass.
D2 can do lunar missions. It just can't do the large, long lunar missions as dictated by Griffin's requirements to ESAS.
[soapbox on]
Requirements are everything. Stick to the minimum necessary for the mission as defined by your stakeholders. Or, if you're going to add requirements, understand very well their incremental costs to your program's budget, schedule, and risk.
Unfortunately for Orion, Griffin and ESAS did neither.
[/soapbox off]
AFAIK, it was later rejected, so back to plastic bags.
Articles just last week on the waste disposal system in the emergency suits state that Orion still has a toilet:
Like the space shuttle before it, Orion will be equipped with a toilet, but NASA is making contingency plans in case of emergencies, including the possibility that the Orion capsule depressurizes and the astronauts have to remain in their suits to survive. In fact, the agency wants astronauts to be able to survive in their suits for up to six days — meaning the men and women would have to be able to do things like eat, urinate and defecate without taking them off.
https://www.space.com/39710-orion-spacesuit-waste-disposal-system.html But someone working the program may know better.
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#21
by
joek
on 01 Mar, 2018 22:12
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All things considered, the Orion crew + service module mass is not too bad given its intended purpose.
The real porker is the LAS, which accounts for ~22% of Orion's launch mass (7463kg of 35384kg). A few other odds-and-ends consume an additional ~4% of non-injected mass.
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#22
by
Steven Pietrobon
on 02 Mar, 2018 05:22
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The reason Orion is so much heaver is simple its huge size. For a pressure vessel, the mass is proportional to its volume. The Apollo CM mass was 5.84 t with a 3.91 m diameter. Orion is 5.0 m diameter, so directly scaling gives 5.84*(5/3.91)³ = 5.84*2.09 = 12.21 t. Orion CM mass is 19% less less at 9.89 t, probably due to using lighter materials, such as aluminium instead of steel for the pressure vessel, lithium-ion batteries and modern electronics. Orion was originally going to carry six crew so that it could be used for ISS and Mars missions. Had Orion been sized for four crew, its diameter would have been 3.91*(4/3)^{1/3} = 4.3 m. That would have reduced its mass to between 9.89*(4.3/5)³ = 6.29 t (Orion model) and 5.84*(4.3/3.91)³ = 7.77 t (Apollo model). Lets use the average of 7.03 t, which is a 29% reduction in mass. So instead of a 25.85 t Orion, it would now be a 18.37 t Orion, which would allow it to be launched by Atlas V and Falcon 9, instead of the only option being the very expensive Delta-IV Heavy.
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#23
by
envy887
on 02 Mar, 2018 14:04
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The reason Orion is so much heaver is simple its huge size. For a pressure vessel, the mass is proportional to its volume. The Apollo CM mass was 5.84 t with a 3.91 m diameter. Orion is 5.0 m diameter, so directly scaling gives 5.84*(5/3.91)³ = 5.84*2.09 = 12.21 t. Orion CM mass is 19% less less at 9.89 t, probably due to using lighter materials, such as aluminium instead of steel for the pressure vessel, lithium-ion batteries and modern electronics. Orion was originally going to carry six crew so that it could be used for ISS and Mars missions. Had Orion been sized for four crew, its diameter would have been 3.91*(4/3)^{1/3} = 4.3 m. That would have reduced its mass to between 9.89*(4.3/5)³ = 6.29 t (Orion model) and 5.84*(4.3/3.91)³ = 7.77 t (Apollo model). Lets use the average of 7.03 t, which is a 29% reduction in mass. So instead of a 25.85 t Orion, it would now be a 18.37 t Orion, which would allow it to be launched by Atlas V and Falcon 9, instead of the only option being the very expensive Delta-IV Heavy.
Interestingly, a 5-meter diameter aluminum sphere capable of holding 1.25 atmospheres would weigh about 105 kg and have 3.5x the pressurized volume of Orion.
A truncated cone is not an efficient pressure vessel design, and most of the structural mass is not related to containing internal pressure but more likely external loads, puncture resistance, MMOD, etc.
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#24
by
the_other_Doug
on 02 Mar, 2018 15:49
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All things considered, the Orion crew + service module mass is not too bad given its intended purpose.
The real porker is the LAS, which accounts for ~22% of Orion's launch mass (7463kg of 35384kg). A few other odds-and-ends consume an additional ~4% of non-injected mass.
NASA's Orion system is mass-starved, as have been almost all spacecraft systems to date -- certainly all American spacecraft, anyway. The mantra has always been to make flight hardware as light as possible, allowing more performance from your propulsion stages. (Shuttle's airframe was an exception, but other Shuttle systems were built as light as possible, to gain performance edges.)
In such a mass-starved system design, who in the world came up with Enormo the Fairing? Granted, it is dropped early enough in the launch that it has less impact than it would if, say, it was retained to orbit. But, in a mass-starved system, why increase the mass of the fairing so ridiculously high? Why not just fly a reasonably light boost protective cover, a la Apollo? As originally designed?
Are they trying to make an SRB field joint failure survivable from a flying debris perspective, or something?
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#25
by
whitelancer64
on 02 Mar, 2018 16:19
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One of the big things that Orion has that Starliner and Dragon v2 do not is a toilet. So keep that in mind for long-duration mission planning.
AFAIK, it was later rejected, so back to plastic bags.
I haven't heard about it being deleted from the Orion design.
Last I heard there will be a demonstration toilet flown to the ISS for testing.
"Universal Waste Management System: Demonstration of common compact toilet for ISS and Orion (Oct. 2018)"
www.nasa.gov/sites/default/files/atoms/files/moore_aes_tagged.pdfCan anyone dig up a notification or report where that was cancelled?
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#26
by
whitelancer64
on 02 Mar, 2018 16:19
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One of the big things that Orion has that Starliner and Dragon v2 do not is a toilet. So keep that in mind for long-duration mission planning.
I don't think Orion has a toilet. Can you provide a reference?
"The crew module contains four seats that the astronauts will fold and stow after launch. “Orion won’t be a roomy ship, but it does have 150 percent more elbow room than Apollo,” says Rick Mastracchio, the astronaut office’s representative to the Orion program. The galley is spartan, with just a water dispenser and food warming case. Nearby is a small, resistive exercise machine.
Tucked into the lower deck will be a very compact toilet compartment, rigged with pop-up curtains to preserve a modicum of privacy."
https://aerospaceamerica.aiaa.org/departments/building-orion/
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#27
by
whitelancer64
on 02 Mar, 2018 17:02
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All things considered, the Orion crew + service module mass is not too bad given its intended purpose.
The real porker is the LAS, which accounts for ~22% of Orion's launch mass (7463kg of 35384kg). A few other odds-and-ends consume an additional ~4% of non-injected mass.
NASA's Orion system is mass-starved, as have been almost all spacecraft systems to date -- certainly all American spacecraft, anyway. The mantra has always been to make flight hardware as light as possible, allowing more performance from your propulsion stages. (Shuttle's airframe was an exception, but other Shuttle systems were built as light as possible, to gain performance edges.)
In such a mass-starved system design, who in the world came up with Enormo the Fairing? Granted, it is dropped early enough in the launch that it has less impact than it would if, say, it was retained to orbit. But, in a mass-starved system, why increase the mass of the fairing so ridiculously high? Why not just fly a reasonably light boost protective cover, a la Apollo? As originally designed?
Are they trying to make an SRB field joint failure survivable from a flying debris perspective, or something?
It's Enormo, the LAS. Yep, the LAS has to be very beefy to pull the Orion away from chunks of an exploding SRB.
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#28
by
Zed_Noir
on 02 Mar, 2018 23:04
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The reason Orion is so much heaver is simple its huge size. For a pressure vessel, the mass is proportional to its volume. The Apollo CM mass was 5.84 t with a 3.91 m diameter. Orion is 5.0 m diameter, so directly scaling gives 5.84*(5/3.91)³ = 5.84*2.09 = 12.21 t. Orion CM mass is 19% less less at 9.89 t, probably due to using lighter materials, such as aluminium instead of steel for the pressure vessel, lithium-ion batteries and modern electronics. Orion was originally going to carry six crew so that it could be used for ISS and Mars missions. Had Orion been sized for four crew, its diameter would have been 3.91*(4/3)^{1/3} = 4.3 m. That would have reduced its mass to between 9.89*(4.3/5)³ = 6.29 t (Orion model) and 5.84*(4.3/3.91)³ = 7.77 t (Apollo model). Lets use the average of 7.03 t, which is a 29% reduction in mass. So instead of a 25.85 t Orion, it would now be a 18.37 t Orion, which would allow it to be launched by Atlas V and Falcon 9, instead of the only option being the very expensive Delta-IV Heavy.
That is contrary to the wishes of Mike Griffin to make the Orion large enough to be unable to be lofted up with any EELV, including the Delta IV Heavy. So he can foisted
the stick into the mix.
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#29
by
MATTBLAK
on 02 Mar, 2018 23:12
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Yes - I'm with Steven Pietrobon on this. Orion is too large! 4.3 or 4.4 meters should have been it's diameter. And at about 12 tons, it's a real boomsticks.
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#30
by
joek
on 03 Mar, 2018 03:53
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Jeepers... "Orion should have been..." It should have been a lot of things. So now you want to re-engineer it given 20-20 hindsight. Reduce it's size to reduce it's mass. Sure, why not. You want to pony up the $$$ to do that today? Where were all you experts way-back-when? No where. So please spare us the retrospective what-should-have-been. Your 20-20 hindsight is not constructive and your harping on it is annoying.
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#31
by
MATTBLAK
on 03 Mar, 2018 05:46
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Jeepers... "Orion should have been..." It should have been a lot of things. So now you want to re-engineer it given 20-20 hindsight. Reduce it's size to reduce it's mass. Sure, why not. You want to pony up the $$$ to do that today? Where were all you experts way-back-when? No where. So please spare us the retrospective what-should-have-been. Your 20-20 hindsight is not constructive and your harping on it is annoying.
You're obviously new around here, or are you just feigning ignorance?! We
HAVE been saying and doing what you suggest - since 2005...
And so have some of the senior members of NSF who have worked for or are still working for NASA and it's contractors. Also; Nasaspaceflight.com is and was regularly viewed by those who conceived and designed Orion, the Ares rockets and most other elements of 'Project Constellation'. Research the 'Direct' project. The reservations and arguments against poor design choices and architecture problems were
presented directly to the concerned NASA, Senatorial and Congressional personnel,
years ago.
Did it have any effect? Somewhere between nil and negligible...
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#32
by
MATTBLAK
on 03 Mar, 2018 06:01
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... And many of the experts here are
not 'so-called'
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#33
by
UltraViolet9
on 03 Mar, 2018 12:27
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#34
by
spacenut
on 03 Mar, 2018 13:22
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I think Orions size and mass was originally for 6 or 7 astronauts and was 5.5 meters in diameter. Also to carry enough supplies and water for a long duration deep space mission. Then they realized it was too big. They cut it back to 5 meters, but I guess that still isn't enough.
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#35
by
Proponent
on 03 Mar, 2018 14:30
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Where were all you experts way-back-when?
There were voices in the wilderness:
http://rocketsandsuch.blogspot.com/2007/09/launch-abort.html....
Very interesting. I wish I had been reading that blog at the time.
I believe, though, that the first-linked of Rocket Man's blog posts contains one small historical error:
Soyuz T-10-1 and Soyuz 18a both employed a launch abort system similar to (based directly on Max Faget's design for which Max received an award acknowledging that fact from the Russians many years later) the American design.Although Soyuz 18A did abort short of orbit, I believe the maneuver was performed after the escape tower had been jettisoned.
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#36
by
kevinof
on 03 Mar, 2018 15:02
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Interesting to read through those blogs (and then bang head repeatedly off desk in frustration!). I always felt that SLS (and what came before it) was trying to do too much. I know it's been hashed out before but I would have liked Orion to launch without crew and therefore no fairing and no LAS. Would have saved a ton of money, time and importantly weight. Send the crew up in CST or Dragon, dock and go.
Yes it's extra expense, but I think it would have solved a lot of problems and also given more flights to commercial crew which always helps.
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#37
by
Proponent
on 03 Mar, 2018 15:19
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I like your thinking, but I'd take it a step further: skip Orion altogether. Having clearly defined the objectives (wishful thinking here, of course) let NASA contract for in-space modules as needed. Use commercial crew, as you suggest to get the crew to LEO. If the optimal mission architecture calls for the crew making a direct return to earth at the end of the mission, ask the commercial-crew contractors to bid on re-entry modules, which would no doubt be variations on their commercial-crew vehicles.
Obviously, this is impossible, because it neglects poor old Lockheed Martin... unless maybe it could get contracts for in-space modules?
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#38
by
joek
on 03 Mar, 2018 19:47
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You're obviously new around here, or are you just feigning ignorance?! We HAVE been saying and doing what you suggest - since 2005... And so have some of the senior members of NSF who have worked for or are still working for NASA and it's contractors. Also; Nasaspaceflight.com is and was regularly viewed by those who conceived and designed Orion, the Ares rockets and most other elements of 'Project Constellation'. Research the 'Direct' project. The reservations and arguments against poor design choices and architecture problems were presented directly to the concerned NASA, Senatorial and Congressional personnel, years ago.
Did it have any effect? Somewhere between nil and negligible...
I certainly appear to have put my foot in it, and apologies to anyone who feels diss'd by my comment.
The point is that attempting to re-design or -engineer Orion at this point is a lost cause. There are no good outcomes other than likely...
I like your thinking, but I'd take it a step further: skip Orion altogether.
...
Debates which focus on its weight appear to assume that solving that problem will address more fundamental problems. It will not. Orion and the architecture it is based on are fundamentally flawed; its weight is a quibble in the greater debate.
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#39
by
Proponent
on 04 Mar, 2018 15:47
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There were voices in the wilderness and warnings galore: ....
On the official side, there was also the Booz Allen Hamilton study in 2011 (attached
here), according to the publicly released summary of which (we peasants weren't allowed to see the whole thing), costs estimates for Orion/SLS beyond a 3-5-year horizon (i.e., after 2014-16) were based on unjustified optimism.
The report produced howls of criticism and allegations of bias and "slow-rolling" in this forum, but it has proved
eerily prophetic.
And so have some of the senior members of NSF who have worked for or are still working for NASA and it's contractors. Also; Nasaspaceflight.com is and was regularly viewed by those who conceived and designed Orion, the Ares rockets and most other elements of 'Project Constellation'. Research the 'Direct' project. The reservations and arguments against poor design choices and architecture problems were