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#100
by
psloss
on 29 May, 2017 14:46
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#101
by
Lars-J
on 29 May, 2017 18:27
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Any update on when ULA will fly the first dual engine Centaur on Atlas V?
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#102
by
russianhalo117
on 29 May, 2017 19:56
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Any update on when ULA will fly the first dual engine Centaur on Atlas V?
A potential TBD LEO flight next year is last I've heard. No word if its an NROL, NASA or Commercial payload and which range it fly from. If another Cygnus flight on Atlas occurs it would be a great test method as OA have said CRS-2 can fly in all 4-metre configs and a launch would be to ISS on same trajectory.
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#103
by
ethan829
on 30 May, 2017 00:17
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Right, I got the picture. However, according to ULA the first digit refers to the fairing diameter, not if the Centaur is encapsulated or not (which is a natural byproduct of the fairing variant used of course). So if they use no fairing at all it's kind of misleading to designate the variant 422 imho.
"N22" is also used.
https://twitter.com/barbegan13/status/787351995078152192
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#104
by
brickmack
on 30 May, 2017 04:21
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5XX means fairing that encapsulates the whole centaur, 4XX means fairing on top centaur, exposing Centaur.
In the Starliner configurtion, the Centaur is not inside a failring, so 4XX.
Nope. There used to be an Atlas V 300 configuration as well (would've been used both for narrow payloads on Atlas V-Centaur, and all payloads for Atlas V Lite (Atlas V-Agena 2000). 400/500 just means the fairing diameter
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#105
by
russianhalo117
on 30 May, 2017 15:53
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5XX means fairing that encapsulates the whole centaur, 4XX means fairing on top centaur, exposing Centaur.
In the Starliner configurtion, the Centaur is not inside a failring, so 4XX.
Nope. There used to be an Atlas V 300 configuration as well (would've been used both for narrow payloads on Atlas V-Centaur, and all payloads for Atlas V Lite (Atlas V-Agena 2000). 400/500 just means the fairing diameter
and there was also early option that would have been called AV-200 for DII class payloads, but was dropped in favor of would have been called AV-300 config that ended up being named AV-401 config.
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#106
by
Newton_V
on 30 May, 2017 16:20
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Some clarification:
There was never a AV-200 or AV-300.
The names during EELV development were:
MLV-D: The Common Core Booster with SUS (Storable Upper Stage with Athena-based engine), 11 ft PLF. The "D" was for Delta-class payloads.
MLV-A: The Common Core Booster with Centaur (Stretched Centaur II with RL10A-4), LPF, EPF, and maybe the 11 ft PLF if needed.
HLV-D: CCB Heavy with SUS for LEO missions
HLV-G: CCB Heavy with Centaur for GSO missions
When SUS went away, MLV-G appeared. This was the additional of solids and the 5-meter PLF.
Then the Atlas V name was chosen.
MLV-A became 401 with only LPF, EPF, and eventually an XPF. The 11 ft PLF was already off the table.
Then 4xx came to be.
MLV-G became the 5xx series
HLV-G just became Atlas HLV or Atlas HVY
Edit: Thinking a little more about this, HLV-D might have actually been called HLV-L (L for LEO).
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#107
by
brickmack
on 31 May, 2017 05:30
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#108
by
Newton_V
on 31 May, 2017 12:51
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There definitely WAS an Atlas V 300. Specific reference to it exists in several regulatory and development documents. It wasn't abandoned until sometime after 2000, the last document I can find that mentions it is https://www.faa.gov/about/office_org/headquarters_offices/ast/licenses_permits/media/eelvSEis.pdf and thats after the Atlas V name was finalized. As best as I can tell, CUS was still planned to use RL10E-1 up until very shortly before the name change to Atlas V as well.
That's interesting, because when Lockheed ceded the small payload market to Delta II (mostly NASA missions segment) the plan was to just use the 401 for the GPS, DMSP, and DSCS, and other MLV-II class payloads. It was cheaper to just use the 401 than have another smaller/cheaper upper stage. At that same time, the decision was made to eliminate the 3-m PLF as well, because it's expensive to produce another diameter PLF, but not to add plugs or remove plugs form the 4-m PLF if need be.
Now I'm wondering if Lockheed ever used the 300 naming convention, or just the government.
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#109
by
Jim
on 31 May, 2017 13:28
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That's interesting, because when Lockheed ceded the small payload market to Delta II (mostly NASA missions segment) the plan was to just use the 401 for the GPS, DMSP, and DSCS, and other MLV-II class payloads.
That wasn't a Lockheed call. The USAF eliminated both EELV-S configurations from both contractors.
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#110
by
russianhalo117
on 31 May, 2017 15:27
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Now I'm wondering if Lockheed ever used the 300 naming convention, or just the government.
Both did for about 2 years until EELV-S was officially dropped by USAF. AV-200 was mere proposal before merged into AV-300 as a new configuration and then abandoned with EELV-S.
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#111
by
FutureSpaceTourist
on 12 Oct, 2017 10:34
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#112
by
intrepidpursuit
on 10 May, 2018 23:57
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I asked this in the ULA thread, but perhaps it is more applicable here. Are there flight requirements for the DEC before they will put people on the rocket? And do we know when the DEC will first fly?
These requirements and difference across manufacturers are interesting. SpaceX is allowed their single 10x more powerful upper stage engine, but they seem to be required to do more testing of the final configuration than ULA despite ULA adding a whole engine to the design. Any input into the reasoning behind these requirements would be appreciated.
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#113
by
Lars-J
on 11 May, 2018 00:24
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I asked this in the ULA thread, but perhaps it is more applicable here. Are there flight requirements for the DEC before they will put people on the rocket? And do we know when the DEC will first fly?
These requirements and difference across manufacturers are interesting. SpaceX is allowed their single 10x more powerful upper stage engine, but they seem to be required to do more testing of the final configuration than ULA despite ULA adding a whole engine to the design. Any input into the reasoning behind these requirements would be appreciated.
The DEC doesn't use two engines for safety - Two engines are needed for the required thrust. CST-100's will be heavy payloads for Atlas V, and they will also fly a different trajectory that requires more thrust.
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#114
by
intrepidpursuit
on 11 May, 2018 04:19
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I asked this in the ULA thread, but perhaps it is more applicable here. Are there flight requirements for the DEC before they will put people on the rocket? And do we know when the DEC will first fly?
These requirements and difference across manufacturers are interesting. SpaceX is allowed their single 10x more powerful upper stage engine, but they seem to be required to do more testing of the final configuration than ULA despite ULA adding a whole engine to the design. Any input into the reasoning behind these requirements would be appreciated.
The DEC doesn't use two engines for safety - Two engines are needed for the required thrust. CST-100's will be heavy payloads for Atlas V, and they will also fly a different trajectory that requires more thrust.
That makes a lot of sense. We saw how under powered the SEC is for LEO on OA-6. Still though, does Atlas V require testing with the DEC? Seems like a huge change.
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#115
by
Lars-J
on 11 May, 2018 05:39
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DEC will first fly on the orbital flight test of the CST-100. Now it will be the first flight for this configuration on an Atlas V, but the DEC has flown on previous Atlas models, so they would argue that it has flight experience.
Still, Centaurs has gone through several upgrades and minor changes in the last 12(?) years since DEC last flew, so it won't be completely risk free. But they consider the OFT a sufficient demonstration, I guess.
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#116
by
LouScheffer
on 12 May, 2018 22:00
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The DEC is not the only change for human-rating. There is also the EDS system for detecting emergencies, and likely other smaller changes as well. Do we know if these have already been rolled into the standard Atlas production? Unlike a DEC, an EDS would be new, and I'd assume they (and NASA) would want more than one flight's worth of experience with it before launching a CST-100.
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#117
by
brickmack
on 13 May, 2018 22:11
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EDS has been present on all Atlas launches for a while now.
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#118
by
erioladastra
on 22 May, 2018 17:28
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EDS has been present on all Atlas launches for a while now.
Incorrect. I suspect you may be confusing this with the Fault Termination System (FTS) that destructs the stack if a problem. EDS is not complete and will fly on OFT for the first time, but disabled.
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#119
by
russianhalo117
on 22 May, 2018 17:52
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EDS has been present on all Atlas launches for a while now.
Incorrect. I suspect you may be confusing this with the Fault Termination System (FTS) that destructs the stack if a problem. EDS is not complete and will fly on OFT for the first time, but disabled.
No the poster is likely confusing the fault detection system on RD-180 which dates back to both the never completed human rated versions of the Zenit and Energia launcher families.