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#40
by
HailColumbia
on 23 Jul, 2006 22:23
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mr.columbus - 23/7/2006 3:11 AM
There is enough space in a 4.5m diameter CEV to accomodate a crew of 4 for Moon missions (or ISS missions, if any).
L2 has 3D drawings of the crew seated in the CEV, filled with ony minimal equipment. It is EXTREMELY cramped. If anything, NASA should try to build the biggest capsule it reasonably can.
mr.columbus - 23/7/2006 3:11 AM
The 23t effective mass in LEO mentioned above is the CEV mass after the new design changes, is it?
Yes, after changes.
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#41
by
imfan
on 23 Jul, 2006 22:50
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deltaV remains same? it would be shame to give up the capability to land everywhere on surface
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#42
by
hyper_snyper
on 23 Jul, 2006 22:55
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imfan - 23/7/2006 6:37 PM
deltaV remains same? it would be shame to give up the capability to land everywhere on surface
The LSAM does plane changes for landing anywhere on the moon, not the CEV. All the deltaV the CEV is responsible for is orbit circul. and TEI.
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#43
by
nacnud
on 23 Jul, 2006 22:57
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The land everywhere capability is a function of the LSAM not the CEV.
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#44
by
imfan
on 23 Jul, 2006 23:51
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I know that landing and arive are jobs for LSAM but landing the crew without return has no point. and thats the part for CEV. LSAM+CEV arive in a plane that is suitable for desired landing site, but during 14day stay it is possible that CEVs orbit plane will be out of reach af ascending module which implies that CEV has to have some plane change capability. and to ensure anytime return there is a need to make up to 90 degrees plane change and that is a quite demanding maneuver requiring even more dV than TEI(from idelal inclination) itself
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#45
by
edkyle99
on 23 Jul, 2006 23:54
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Jim - 23/7/2006 3:43 PM
Neither. Define bloated. Lift off mass is 27.6t, injected mass is 22.0t, effect mass 23t
By bloated I meant "had it grown heavier than the original spec" or "had it grown too heavy for the launcher", etc. In other words, is this reduction making it lighter than originally planned, or is it merely shaving excess that accumulated during the initial design phase to get it back down to where it was originally supposed to be? The numbers you list make me think that the latter may be the answer.
- Ed Kyle
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#46
by
Jim
on 23 Jul, 2006 23:54
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mr.columbus - 23/7/2006 6:01 PM
There is enough space in a 4.5m diameter CEV to accomodate a crew of 4 for Moon missions (or ISS missions, if any). If there is CM equipment that would fit only into a 5m CEV and not in a 4.5m CEV, I would like to know what that is. A CEV with a mass under 20t would be a major improvement to NASA's plans in my opinion, as I said earlier it helps a lot on the development of the CLV and also gives more leeway on the CaLV and LSAM.
How do you know the 4.5 m is enough. 6 man requirement is also a ISS requirement.
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#47
by
simonbp
on 24 Jul, 2006 00:36
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edkyle99 - 23/7/2006 4:41 PM
Jim - 23/7/2006 3:43 PM
Neither. Define bloated. Lift off mass is 27.6t, injected mass is 22.0t, effect mass 23t
By bloated I meant "had it grown heavier than the original spec" or "had it grown too heavy for the launcher", etc. In other words, is this reduction making it lighter than originally planned, or is it merely shaving excess that accumulated during the initial design phase to get it back down to where it was originally supposed to be? The numbers you list make me think that the latter may be the answer.
- Ed Kyle
ESAS launch mass: 27.3 tonnes
ESAS on orbit mass: 23.1 tonnes
ESAS SPS net delta v: 1.7 km/s
DAC2 launch mass: 27.0 tonnes
DAC2 on orbit mass: 22.0 tonnes
DAC2 SPS net delta v: 1.8 km/s
And there you have it: the difference between a 90-day "rough draft" and nearly a year of real engineering...
Simon
(Note: my "launch mass" doesn't count the adapter b/c ESAS doesn't have it)
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#48
by
Mark Max Q
on 24 Jul, 2006 05:54
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#49
by
mr.columbus
on 24 Jul, 2006 07:42
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Jim - 23/7/2006 7:41 PM
mr.columbus - 23/7/2006 6:01 PM
There is enough space in a 4.5m diameter CEV to accomodate a crew of 4 for Moon missions (or ISS missions, if any). If there is CM equipment that would fit only into a 5m CEV and not in a 4.5m CEV, I would like to know what that is. A CEV with a mass under 20t would be a major improvement to NASA's plans in my opinion, as I said earlier it helps a lot on the development of the CLV and also gives more leeway on the CaLV and LSAM.
How do you know the 4.5 m is enough. 6 man requirement is also a ISS requirement.
I don't know if 4.5 m is enough, I assume that (i) if 5m is a comfortable size for a crew of 6 and (ii) 3.7 m was comfortable for a crew of 3 with Apollo then 4.5 m is comfortable for a crew of 4. A 6-man ISS requirement is strange anyway, (i) we might see as few as 2-3 ISS flights by a CEV between 2014 and 2016 and (ii) it is not contemplated that Soyuz will go out of service before the ISS project end, so no need to carry 6 people to the ISS or have a lifeboat capability of 6 (+ I always thought that the CEV will carry only 3 astronauts to the ISS anyway).
What I am saying is, the more the mass of the CEV gets reduced the better. You open up new launcher possibilities with a mass well under 20t and can shift the same mass to the LSAM which in turn can sustain longer sortie-missions on the Moon.
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#50
by
Jim
on 24 Jul, 2006 11:48
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5m isn't comfortable for the crew, it doesn't quite meet the requirements
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#51
by
BogoMIPS
on 24 Jul, 2006 14:41
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I have to agree that I think a 5m CEV is going to be a bit stuffy for a 4-person crew to the moon, but they will have the LSAM docked for extra "living space" while en route back and forth. It it probably the bare minimum size that can do the job for 4 people.
5m doesn't seem scalable to a 6-person ISS transfer vehicle, though. I'm guessing that requirement will have to be revised for the 5m sizing.
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#52
by
nacnud
on 24 Jul, 2006 15:22
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I don't know for sure but I think that the LSAM assent module is to be ditched before departing the Moon.
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#53
by
Marcus
on 24 Jul, 2006 15:35
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Was the Delta II second-stage engine (AJ10-118K) "always" intended as the CEV's injection engine? I thought they were trying to steer clear of NTO/MMH. So the stack-up of engines is:
1st stage: 4/5-segment SRB
2nd Stage: J-2x (restart capable)
Injection Motor: AJ10? (restart capable)
Has that list changed since the switch from RS-25x?
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#54
by
BogoMIPS
on 24 Jul, 2006 17:22
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nacnud - 24/7/2006 10:09 AM
I don't know for sure but I think that the LSAM assent module is to be ditched before departing the Moon.
I think you're right, now that you mention that. It'll be like a road trip in a Ford Festiva on the way back.
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#55
by
imfan
on 24 Jul, 2006 17:27
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"2nd Stage: J-2x (restart capable)"
what is this good for?
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#56
by
nacnud
on 24 Jul, 2006 18:06
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Which bit, the restart bit? The restart is needed as I think the Earth departure stage is used as a kick stage for the LSAM + EDS to get into a stable LEO. It is then restarted once the CEV has docked for the Earth departure burn.
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#57
by
dmc6960
on 24 Jul, 2006 19:26
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imfan - 24/7/2006 12:14 PM
"2nd Stage: J-2x (restart capable)"
what is this good for?
The J-2x for the CLV will likely not have any restart hardware installed in it, not necessary since for the CLV it needs to burn only once. (The J2's on the Saturn V second stage also did not have restart hardware installed). The J-2x for the CaLV on the other hand needs restart. First burn will but the LSAM and EDS into proper orbit, the second burn will send it off to the moon.
-Jim
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#58
by
imfan
on 24 Jul, 2006 22:32
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yeah... need for restart is obvious for CaLV. I only thought we were discussing CLV
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#59
by
David AF
on 24 Jul, 2006 22:41
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Might be worth nothing this is an ongoing process, and given the savings they've been able to make some other changes on top, with one just now.
what is this good for?