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#340
by
Zed_Noir
on 17 Oct, 2015 12:30
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This could simply be to reassure that the Vac still operates as expected.
Could someone please summarize the changes between the RTF MVac and the MVac that most recently performed in space? Are there any?
AIUI the major change from previous F9 upper stage is that SpaceX is using a new pneumatic mechanism to separate the stages sited within the Merlin Vac engine nozzle bell.
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#341
by
The Roadie
on 17 Oct, 2015 15:26
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Larger bell extension, longer stage for additional propellant, running with densified propellants, presumably full thrust increased injector pressure.
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#342
by
Chris Bergin
on 17 Oct, 2015 17:29
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Converted this into the discussion thread for the ORBCOMM-2 mission, as it covers both RTF and what is now the RTF mission.
Update only thread is live.
Party thread will be later.
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#343
by
cro-magnon gramps
on 17 Oct, 2015 21:33
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#344
by
Space Ghost 1962
on 18 Oct, 2015 20:06
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I wonder about that restart test. Even if it is on the extremely cautious side. Maybe there are larger changes than we knew about in the restarting tech? Maybe it is only the new upper stage that is capable of loiter time long enough to do direct GEO insertion? Both Elon Musk and Gwynne Shotwell emphasized Falcon 9 can do it but maybe the ability is there only now? It would be still in time for any Airforce launch.
It's not possible for SpaceX to do a vacuum test on Merlin at McGregor.
Yes. How do you "stress" a US, in the environment?
This could simply be to reassure that the Vac still operates as expected.
Like an earlier US test they did with F9 v1.0, you'll get from US:
* max performance (iSP, thrust, burn duration, restart)
* residual and/or depletion
* thermal environment
* max acceleration/fatigue on components
Won't perfectly match the results as on post staging full duration burn to depletion, but then you're not risking it all on the roulette wheel
Clearly they are still stung badly by the US failure. Two ways to come back from this: they either are cautious, or overly "bada$$" following a successful RTF. Predict the latter.
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#345
by
Barrie
on 18 Oct, 2015 20:32
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I wonder about that restart test. Even if it is on the extremely cautious side. Maybe there are larger changes than we knew about in the restarting tech? Maybe it is only the new upper stage that is capable of loiter time long enough to do direct GEO insertion? Both Elon Musk and Gwynne Shotwell emphasized Falcon 9 can do it but maybe the ability is there only now? It would be still in time for any Airforce launch.
I see the test of the US as what they call 'regression testing' in IT - not just making sure changes have the desired effect, but that they don't have any undesired effects. So you run the full test suite, not just the parts that seem relevant to the changes made.
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#346
by
Ben the Space Brit
on 22 Oct, 2015 08:28
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From the Update Thread:
Preps for the Full Duration Static Fire are now taking place. Upcoming potentially later this week.
Does that mean that we're into the pad flow for OG-2? Have the payloads arrived at the Cape?
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#347
by
rpapo
on 22 Oct, 2015 10:19
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From the Update Thread:
Preps for the Full Duration Static Fire are now taking place. Upcoming potentially later this week.
Does that mean that we're into the pad flow for OG-2? Have the payloads arrived at the Cape?
The Full Duration Static Fire spoken of is the one at McGregor...
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#348
by
Jarnis
on 22 Oct, 2015 10:42
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From the Update Thread:
Preps for the Full Duration Static Fire are now taking place. Upcoming potentially later this week.
Does that mean that we're into the pad flow for OG-2? Have the payloads arrived at the Cape?
The Full Duration Static Fire spoken of is the one at McGregor...
...and since this is a the first full duration firing of a 9-engine F9 FT ("v1.2") config, there is obviously a considerable chance that they may have to try this a couple of times if problems show up. Individual engines they of course have already tested a lot, but not with a full 9-engine flight stage config.
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#349
by
TOG
on 22 Oct, 2015 15:11
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From the Update Thread:
Preps for the Full Duration Static Fire are now taking place. Upcoming potentially later this week.
Does that mean that we're into the pad flow for OG-2? Have the payloads arrived at the Cape?
The Full Duration Static Fire spoken of is the one at McGregor...
...and since this is a the first full duration firing of a 9-engine F9 FT ("v1.2") config, there is obviously a considerable chance that they may have to try this a couple of times if problems show up. Individual engines they of course have already tested a lot, but not with a full 9-engine flight stage config.
Will the full duration firing include coast and restart to simulate re-entry and landing?
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#350
by
Lars-J
on 22 Oct, 2015 15:42
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From the Update Thread:
Preps for the Full Duration Static Fire are now taking place. Upcoming potentially later this week.
Does that mean that we're into the pad flow for OG-2? Have the payloads arrived at the Cape?
The Full Duration Static Fire spoken of is the one at McGregor...
...and since this is a the first full duration firing of a 9-engine F9 FT ("v1.2") config, there is obviously a considerable chance that they may have to try this a couple of times if problems show up. Individual engines they of course have already tested a lot, but not with a full 9-engine flight stage config.
Will the full duration firing include coast and restart to simulate re-entry and landing?
No, it is usually just a test to verify that the 9 engines can function together for the duration of the 1st stage burn (~3 minutes), and that the loads/vibrations/heat can be managed by the stage structure.
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#351
by
Ronsmytheiii
on 25 Oct, 2015 14:07
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#352
by
The Roadie
on 25 Oct, 2015 16:48
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The M1-VAC is tested in McGregor without the niobium skirt extension. The longer bell and higher pressure should be giving it 180,000 lb thrust in vacuum.
The densified propellants may require some thermal changes or at least analysis, as the RP-1 is now chilled and the LOX is more chilled. Remember the Fregat upper stage failure in Aug 2014? Missing thermal insulation on a shared mounting bracket allowed cold Helium to freeze a hydrazine feed line. And it happened during the coast phase before the Fregat's second ignition. Burn profile similar to SES9.
The parallels have to be known at SpaceX.
https://en.wikipedia.org/wiki/Fregat
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#353
by
Comga
on 25 Oct, 2015 19:07
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#354
by
docmordrid
on 25 Oct, 2015 19:17
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The M1-VAC is tested in McGregor without the niobium skirt extension. The longer bell and higher pressure should be giving it 180,000 lb thrust in vacuum.
>
210,000 lbf for F9 FT
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#355
by
WHAP
on 27 Oct, 2015 11:35
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Based on typical range rules, can SpaceX target 12/1 before the Atlas launch on 12/3? Would they if it only gave them one try before having to stand down?
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#356
by
Comga
on 27 Oct, 2015 17:57
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Based on typical range rules, can SpaceX target 12/1 before the Atlas launch on 12/3? Would they if it only gave them one try before having to stand down?
https://twitter.com/pbdes/status/658913128420384768
SpaceX President Shotwell Oct 27 at CASBAA convention: Current target is early Dec for Falcon 9 v1.2 Full Thrust upgrade w/ Orbcomm sats.
Because Shotwell said "early Dec" and not specifically Dec 1, this looks like an unsurprising acknowlegement that SpaceX is getting in line behind the OA-4 Atlas launch.
Does an OA-4 thread say how many days they could keep recycling if something like weather rules out their scheduled launch day?
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#357
by
sdsds
on 27 Oct, 2015 19:37
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Because Shotwell said "early Dec" and not specifically Dec 1, this looks like an unsurprising acknowlegement that SpaceX is getting in line behind the OA-4 Atlas launch.
The other interpretation of her comment is that SpaceX has yet to decide whether to ask for Dec 1, or as you put it "get in line."
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#358
by
Jim
on 27 Oct, 2015 20:32
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Saw a fairing entering the Cape this afternoon
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#359
by
DatUser14
on 27 Oct, 2015 22:41
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nevermind, already in the updates thread.
