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#100
by
LouScheffer
on 09 May, 2017 17:47
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That does not seem like enough. 6100-2437 = 3663 kg. So burning all propellant at an ISP of 320 implies a total delta-V of 320*9.8*ln(6100/3663) = 1600 m/s. Assuming the same F9 performance as EchoStar, that's not enough to get into GEO (the lighter Echostar 23 had more than this to go to reach GEO), much less do any stationkeeping.
So either this is a more powerful F9, or they will need to do final orbit raising electrically.
Well if they are doing a Super-Synchronous GTO and or reducing inclination they could possibly get it down to 1600, right? Also I think the total mass is actually more like 6070kg.
To get to a GEO-1600 orbit from the cape, you need about +350 m/s over a minimal transfer orbit. The EchoStar 23, about 500 kg lighter, only made it to +200 m/s over minimal GTO. Raising the mass to 6070 kg would only leave about +20 m/s over minimal GTO.
On the other hand, one of the advantages of the SSTO, compared to inclination reduction, is that it lends itself to minimum residual shutdown. This is because for SSTO you just blast as much as you can in the direction of the orbit, whereas inclination reduction wants a burn of specific direction and delta-V. This can be a big deal since the last bit of propellant gives a lot of delta-V. If we assume the residual fuel is on the order of 1%, or about 1,150 kg, and the stage 4500 kg, and the satellite 6070 kg, then this last percent of fuel would give about 348*9.8*ln((1150+4500+6070)/(4500+6070)) or about 350 m/s more - just about what is needed.
So that's my new prediction - a super-synchronous transfer orbit, with a minimum residual shutdown, and a final deficit of 1600 m/s. So an inclination of 25-28 degrees, and an apogee of at least 65000 km.
Edit: add apogee and inclination predictions.
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#101
by
BabaORileyUSA
on 09 May, 2017 18:12
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That does not seem like enough. 6100-2437 = 3663 kg. So burning all propellant at an ISP of 320 implies a total delta-V of 320*9.8*ln(6100/3663) = 1600 m/s. Assuming the same F9 performance as EchoStar, that's not enough to get into GEO (the lighter Echostar 23 had more than this to go to reach GEO), much less do any stationkeeping.
So either this is a more powerful F9, or they will need to do final orbit raising electrically.
Well if they are doing a Super-Synchronous GTO and or reducing inclination they could possibly get it down to 1600, right? Also I think the total mass is actually more like 6070kg.
To get to a GEO-1600 orbit from the cape, you need about +350 m/s over a minimal transfer orbit. The EchoStar 23, about 500 kg lighter, only made it to +200 m/s over minimal GTO. Raising the mass to 6070 kg would only leave about +20 m/s over minimal GTO.
On the other hand, one of the advantages of the SSTO, compared to inclination reduction, is that it lends itself to minimum residual shutdown. This is because for SSTO you just blast as much as you can in the direction of the orbit, whereas inclination reduction wants a burn of specific direction and delta-V. This can be a big deal since the last bit of propellant gives a lot of delta-V. If we assume the residual fuel is on the order of 1%, or about 1,150 kg, and the stage 4500 kg, and the satellite 6070 kg, then this last percent of fuel would give about 348*9.8*ln((1150+4500+6070)/(4500+6070)) or about 350 m/s more - just about what is needed.
So that's my new prediction - a super-synchronous transfer orbit, with a minimum residual shutdown, and a final deficit of 1600 m/s. So an inclination of 25-28 degrees, and an apogee of at least 65000 km.
Edit: add apogee and inclination predictions.
Apogee Height: 63,520 km; Inclination = 24.6 degrees.
That's not a guess, and not a calculation (that *I* did, anyways!)
Kudos to LouSheffer - you Devil, you!
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#102
by
abaddon
on 09 May, 2017 18:45
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I had guessed it would be a burn-to-depletion scenario... but wow, well done @LouScheffer!
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#103
by
FutureSpaceTourist
on 11 May, 2017 10:51
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#104
by
Chris Bergin
on 11 May, 2017 10:58
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Article for the firing and forward manifest, by Chris Gebhardt:
https://www.nasaspaceflight.com/2017/05/falcon-9-static-fire-1-inmarsat5f4/
Great article as always, thank you.
One possible omission? SpaceX did a 14 day turnaround at LC-40 in Sep 2014 (AsiaSat 6 on the 7th and CRS-4 on the 21st).
I just pictured you typing that with one hand whilst holding a very long spreadsheet printout was in the other hand.
(as a compliment). Let me see if I can add that without messing up his article
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#105
by
ChrisGebhardt
on 11 May, 2017 15:10
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#106
by
getitdoneinspace
on 11 May, 2017 16:50
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STATIC FIRE! SpaceX Falcon 9 (Inmarsat 5 F4) has fired up at 39A. Wait for SpaceX tweet (after test data review).
RIGHT ON TIME. I like that. Hopefully a consistent trend while progressing through the increasing launch cadence.
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#107
by
MattMason
on 11 May, 2017 17:07
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With all this successful work on 39A, you'd wonder when they'll find time to get the RSS dismantled and CC work applied. I'm sure the answer involves getting SLC 40 online by August, but their flight schedule's pretty aggressive with two active pads.
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#108
by
mme
on 11 May, 2017 17:23
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With all this successful work on 39A, you'd wonder when they'll find time to get the RSS dismantled and CC work applied. I'm sure the answer involves getting SLC 40 online by August, but their flight schedule's pretty aggressive with two active pads.
My understanding is that there is no rush to dismantle RSS and it does not interfere with CC work nor even CC missions.
I think they said they are going to mount the CC access arm while making the FH modifications later this year. But I could be misremembering and I'm not sure they even need the access arm for the first CC demo mission.
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#109
by
rockets4life97
on 11 May, 2017 17:35
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What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.
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#110
by
macpacheco
on 11 May, 2017 17:46
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What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.
Nah, my reading is a launch every two weeks is already less than they can accomplish, time to move to a launch every 10 days (when the range allows for it) and see them always be a day or two behind schedule but beating the a launch every 2 weeks current plan.
But, just perhaps, that will create problems with the range that needs to be prepared for their plans.
It will be interesting anyhow.
Maybe increase the tempo by 24 hrs at a time until they find their sustainable limits.
Or maybe this looked easy because they prepared this booster in parallel with NROL-76 during the 2 week delay.
AKA I really don't know but I would love to know the answer !
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#111
by
John Alan
on 11 May, 2017 18:06
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The RSS (I admit) is an ugly eyesore and reminder for what once was...
BUT...
I seems it's not in the way and for all practical purposes could be left as is... if need be...
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#112
by
Dante80
on 11 May, 2017 18:19
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According to
this, the payload adapter that Falcon 9 has is made by RUAG. This is talking about
the actual PAF, or a separate adapter?
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#113
by
Flying Beaver
on 11 May, 2017 18:24
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According to this, the payload adapter that Falcon 9 has is made by RUAG. This is talking about the actual PAF, or a separate adapter?
Referencing this component i'm sure.
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#114
by
Dante80
on 11 May, 2017 18:28
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That was my thought too. Here is the satellite, sitting on the heavy SpaceX PAF variant (the one that is good for ten tons).
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#115
by
AncientU
on 11 May, 2017 18:40
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What I am most impressed by is the schedule fidelity. It seems like SpaceX is coming in on time. They really need to do this regularly to get through the manifest.
Nah, my reading is a launch every two weeks is already less than they can accomplish, time to move to a launch every 10 days (when the range allows for it) and see them always be a day or two behind schedule but beating the a launch every 2 weeks current plan.
But, just perhaps, that will create problems with the range that needs to be prepared for their plans.
It will be interesting anyhow.
Maybe increase the tempo by 24 hrs at a time until they find their sustainable limits.
Or maybe this looked easy because they prepared this booster in parallel with NROL-76 during the 2 week delay.
AKA I really don't know but I would love to know the answer !
This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature. Good news is that a similar system is coming on line at LC-40 soon. TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows. Four pads with quick turn-around capability removes a key constraint on launch cadence. Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint. Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.
When launching the constellation in 2019-2020, they'll need 50-100 launches a year just for
internal payloads... plus another 25-50 for USG plus commercial customers. Doesn't seem so impossible any more.
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#116
by
AncientU
on 11 May, 2017 18:41
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That was my thought too. Here is the satellite, sitting on the heavy SpaceX PAF variant.
Is the payload adaptor carbon composite, too?
Does anyone else do that?
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#117
by
deruch
on 11 May, 2017 18:52
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This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature. Good news is that a similar system is coming on line at LC-40 soon. TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows. Four pads with quick turn-around capability removes a key constraint on launch cadence. Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint. Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.
Don't forget that they also now have a hangar (at 39A) that allows them to process multiple vehicles at a time. Unfortunately, that won't translate to SLC-40 when it is back online.
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#118
by
AncientU
on 11 May, 2017 19:31
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This bi-weekly tempo from one (relatively new) pad seems to be an achievement of the new TEL design with throwback feature. Good news is that a similar system is coming on line at LC-40 soon. TEL hardware of this design is probably also planned for Boca Chica and Vandenberg as schedule allows. Four pads with quick turn-around capability removes a key constraint on launch cadence. Likewise, reusable boosters with shorter and shorter refurb times removes the factory throughput constraint. Finally, SpaceX will remove the static fire requirement at some point which will make weekly launches from a given pad possible.
Don't forget that they also now have a hangar (at 39A) that allows them to process multiple vehicles at a time. Unfortunately, that won't translate to SLC-40 when it is back online.
Right.
There is the new refurb facility coming on line at the Port, though, which should help with the bigger rework tasks.
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#119
by
spacenut
on 12 May, 2017 01:27
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Is this launch going to be webcast? If so, when?
(as a compliment). Let me see if I can add that without messing up his article 
