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#120
by
OneSpeed
on 12 Nov, 2019 20:13
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There's no useful aerodynamic lift at that point, it's purely for trajectory optimizing purposes.
SpaceSim calculates the maximum lift for Starlink 0.9 after the gravity turn was complete was about 126kN, or 12t of force. That is small compared to the mass of the vehicle (234t at that point), but still useful. The difference between inertial and orbital acceleration at that point is 0.33g, so there are still some gravity losses occurring.
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#121
by
Lars-J
on 13 Nov, 2019 00:37
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There's no useful aerodynamic lift at that point, it's purely for trajectory optimizing purposes.
Then why not just point in the direction you want to go?
The nice thing about being outside the sensible atmosphere is that you can point your thrust in the direction you want to go, but you can point the rocket itself in other directions.
For instance, if you want to thrust purely horizontally without gravity pulling the nose of the rocket down below the horizon, you point the thrust horizontal and the nose slightly up, offsetting the thrust vector from the CG by the exact amount that gravity is pulling down on the CG. This eliminates gravity losses for that part of the trajectory, since all the the thrust is going to horizontal acceleration and none of ti is fighting gravity directly.
There isn't a lot of atmosphere there, but it is still below 60km, and there is a reason why they don't open the fairing until 100+ km altitude.
OneSpeed is probably right - it is a combination of fighting gravity losses and lift effect.
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#122
by
Danderman
on 13 Nov, 2019 11:56
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These satellites were injected into a 280 km parking orbit, compared to 350 km for the previous mission, or is my memory failing me?
The slightly lower injection orbit might account for additional payload capability.
Yep.
This launch was to a 280 km injection orbit, but the first went to 440 km.
Not only does the lower orbit support greater payload capacity, but if the plan is to deploy to 3 planes, it's much quicker from this lower orbit.
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#123
by
ChrisC
on 13 Nov, 2019 12:21
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Can someone point me to a post here that tells us the fate of the fairings? I've searched this Discussions thread, the Updates thread, and the fairing catchers thread, and can't find anything.
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#124
by
HiHatWhenItsClosed
on 13 Nov, 2019 12:53
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The fairings were not caught, both Ms. Tree and Ms. Chief left the LZ before the launch.
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#125
by
Mandella
on 13 Nov, 2019 17:24
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There were comments from SpaceX that they would fish the fairings out, but obviously they need a ship to do that with. Do they have anything else out there aside from the two catchers?
If they don't I guess these are gone, unless of course they've got a deployable outboard and are going to motor back to harbor themselves.
That last was a joke -- I think.
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#126
by
SteveU
on 13 Nov, 2019 19:18
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...If they don't I guess these are gone, unless of course they've got a deployable outboard and are going to motor back to harbor themselves.
Don't give SpaceX any crazy ideas - they come up with enough on their own!
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#127
by
rsdavis9
on 13 Nov, 2019 19:50
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There were comments from SpaceX that they would fish the fairings out, but obviously they need a ship to do that with. Do they have anything else out there aside from the two catchers?
If they don't I guess these are gone, unless of course they've got a deployable outboard and are going to motor back to harbor themselves.
That last was a joke -- I think.
Don't they usually have 2 tugs minding OCISLY?
One towing and another to assist.
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#128
by
Joffan
on 13 Nov, 2019 20:07
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There were comments from SpaceX that they would fish the fairings out, but obviously they need a ship to do that with. Do they have anything else out there aside from the two catchers?
If they don't I guess these are gone, unless of course they've got a deployable outboard and are going to motor back to harbor themselves.
That last was a joke -- I think.
Don't they usually have 2 tugs minding OCISLY?
One towing and another to assist.
Go Quest was out there. Can they haul fairings aboard?
https://twitter.com/SpaceXFleet/status/1193580421247713284
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#129
by
CyndyC
on 13 Nov, 2019 20:42
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#130
by
Brovane
on 13 Nov, 2019 21:13
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These satellites were injected into a 280 km parking orbit, compared to 350 km for the previous mission, or is my memory failing me?
The slightly lower injection orbit might account for additional payload capability.
Yep.
This launch was to a 280 km injection orbit, but the first went to 440 km.
Not only does the lower orbit support greater payload capacity, but if the plan is to deploy to 3 planes, it's much quicker from this lower orbit.
What is the expected passive time it would take for a dead satellite to de-orbit from the 280 km injection orbit?
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#131
by
gongora
on 13 Nov, 2019 21:23
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These satellites were injected into a 280 km parking orbit, compared to 350 km for the previous mission, or is my memory failing me?
The slightly lower injection orbit might account for additional payload capability.
Yep.
This launch was to a 280 km injection orbit, but the first went to 440 km.
Not only does the lower orbit support greater payload capacity, but if the plan is to deploy to 3 planes, it's much quicker from this lower orbit.
What is the expected passive time it would take for a dead satellite to de-orbit from the 280 km injection orbit?
For 350km they said a couple weeks to 8 months depending on the solar cycle. I don't think they've said numbers for 280km.
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#132
by
CyndyC
on 13 Nov, 2019 22:45
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A lower de-orbit was probably the only reason they lowered the insertion orbit.
I did a little searching on the subject because the Falcon 9 FT max payload to LEO is 22,800kg/50265lbs, much greater than even this record payload
at ~20.7 tons (including the adaptor & dispenser hardware). Maybe they saved a little on fuel, but the 2nd & final 2nd stage firing was what, 2-3 seconds? So another 160km/99mi would have cost another second or two of fuel, or probably not very much, and we all saw how much fuel the 1st stage came back with.
Turns out Thomas Burghardt of NSF and Stephen Clark of SFN both reported the lower insertion was to check out and de-orbit improperly functioning satellites from a lower altitude. They'll actually be drifting to their respective planes farther up if they check out, at 350km/217mi, but still lower than the previous insertion at 440km/273mi. Operational orbit will remain the same at 550km/342mi, although previously lowered right before the test launch with FCC approval in April.
From Thomas Burghardt's article at
https://www.nasaspaceflight.com/2019/11/spacex-cape-return-first-operational-starlink-mission/:
After launch, SpaceX will establish contact with each satellite and confirm each spacecraft’s health before maneuvering them to 350 kilometer orbits. Any satellites not functioning properly after launch will be left in the initial 280 kilometer orbit to naturally deorbit. Satellites that pass their health checks will use the 350 kilometer orbit to drift to their orbit planes, where they will then maneuver up to their operational altitude of 550 kilometers.
From SFN in the next to last paragraph at
https://spaceflightnow.com/2019/11/10/spacex-readies-upgraded-starlink-satellites-for-launch/:
SpaceX says injecting the satellites into a lower orbit at an altitude of 174 miles will allow time for checkouts before orbit-raising. The Starlink satellites launched in May were deployed in a higher orbit at an altitude of around 273 miles (440 kilometers).
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#133
by
Alexphysics
on 13 Nov, 2019 22:48
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A lower de-orbit was probably the only reason they lowered the insertion orbit.
I did a little searching on the subject because the Falcon 9 FT max payload to LEO is 22,800kg/50265lbs, much greater than even this record payload at ~20.7 tons (including the adaptor & dispenser hardware). Maybe they saved a little on fuel, but the 2nd & final 2nd stage firing was what, 2-3 seconds? So another 160km/99mi would have cost another second or two of fuel, or probably not very much, and we all saw how much fuel the 1st stage came back with.
Turns out Thomas Burghardt of NSF and Stephen Clark of SFN both reported the lower insertion was to check out and de-orbit improperly functioning satellites from a lower altitude. They'll actually be drifting to their respective planes farther up if they check out, at 350km/217mi, but still lower than the previous insertion at 440km/273mi. Operational orbit will remain the same at 550km/342mi, although previously lowered right before the test launch with FCC approval in April.
From Thomas Bruhardt's article at https://www.nasaspaceflight.com/2019/11/spacex-cape-return-first-operational-starlink-mission/:
After launch, SpaceX will establish contact with each satellite and confirm each spacecraft’s health before maneuvering them to 350 kilometer orbits. Any satellites not functioning properly after launch will be left in the initial 280 kilometer orbit to naturally deorbit. Satellites that pass their health checks will use the 350 kilometer orbit to drift to their orbit planes, where they will then maneuver up to their operational altitude of 550 kilometers.
From SFN in the next to last paragraph at https://spaceflightnow.com/2019/11/10/spacex-readies-upgraded-starlink-satellites-for-launch/:
SpaceX says injecting the satellites into a lower orbit at an altitude of 174 miles will allow time for checkouts before orbit-raising. The Starlink satellites launched in May were deployed in a higher orbit at an altitude of around 273 miles (440 kilometers).
20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
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#134
by
CyndyC
on 13 Nov, 2019 22:55
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A lower de-orbit was probably the only reason they lowered the insertion orbit.
I did a little searching on the subject because the Falcon 9 FT max payload to LEO is 22,800kg/50265lbs, much greater than even this record payload at ~20.7 tons (including the adaptor & dispenser hardware). Maybe they saved a little on fuel, but the 2nd & final 2nd stage firing was what, 2-3 seconds? So another 160km/99mi would have cost another second or two of fuel, or probably not very much, and we all saw how much fuel the 1st stage came back with.
Turns out Thomas Burghardt of NSF and Stephen Clark of SFN both reported the lower insertion was to check out and de-orbit improperly functioning satellites from a lower altitude. They'll actually be drifting to their respective planes farther up if they check out, at 350km/217mi, but still lower than the previous insertion at 440km/273mi. Operational orbit will remain the same at 550km/342mi, although previously lowered right before the test launch with FCC approval in April.
From Thomas Bruhardt's article at https://www.nasaspaceflight.com/2019/11/spacex-cape-return-first-operational-starlink-mission/:
After launch, SpaceX will establish contact with each satellite and confirm each spacecraft’s health before maneuvering them to 350 kilometer orbits. Any satellites not functioning properly after launch will be left in the initial 280 kilometer orbit to naturally deorbit. Satellites that pass their health checks will use the 350 kilometer orbit to drift to their orbit planes, where they will then maneuver up to their operational altitude of 550 kilometers.
From SFN in the next to last paragraph at https://spaceflightnow.com/2019/11/10/spacex-readies-upgraded-starlink-satellites-for-launch/:
SpaceX says injecting the satellites into a lower orbit at an altitude of 174 miles will allow time for checkouts before orbit-raising. The Starlink satellites launched in May were deployed in a higher orbit at an altitude of around 273 miles (440 kilometers).
20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
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#135
by
gongora
on 13 Nov, 2019 23:07
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20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
Either the 18.5 tons or the 227kg was wrong. The 22.8 ton to LEO number is for expendable F9.
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#136
by
CyndyC
on 13 Nov, 2019 23:11
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20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
Either the 18.5 tons or the 227kg was wrong. The 22.8 ton to LEO number is for expendable F9.
Gotcha. Probably the 18.5. I'll cross out my total and just leave it blank to be safe
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#137
by
Nomadd
on 13 Nov, 2019 23:40
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20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
Either the 18.5 tons or the 227kg was wrong. The 22.8 ton to LEO number is for expendable F9.
There's no dispenser, but there is some sort of pole or structure isn't there?
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#138
by
Alexphysics
on 13 Nov, 2019 23:43
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20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
Either the 18.5 tons or the 227kg was wrong. The 22.8 ton to LEO number is for expendable F9.
There's no dispenser, but there is some sort of pole or structure isn't there?
4 tension rods. Shouldn't weigh too much, probably not even half a ton in total. The 18.5 tons figure had to be wrong one way or another, a F9 would never be able to put that mass in LEO while being reusable.
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#139
by
CyndyC
on 14 Nov, 2019 00:28
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20.7 tons? What numbers did you use? There is no dispenser for Starlink launches and the satellites alone are 15.6 tons. From where do the other 5.1 tons come from?
This was discussed earlier, now on page 5 or 6. Zach documented the test launch was 18.5 tons, and the satellite mass has increased from 227kg to 260kg per SpaceX, adding about 2.2 tons
Either the 18.5 tons or the 227kg was wrong. The 22.8 ton to LEO number is for expendable F9.
There's no dispenser, but there is some sort of pole or structure isn't there?
4 tension rods. Shouldn't weigh too much, probably not even half a ton in total. The 18.5 tons figure had to be wrong one way or another, a F9 would never be able to put that mass in LEO while being reusable.
Their strength would have to weigh enough to stabilize 4.3 tons each, or more when the stack shifts, and there would have to be adapters at both the top & bottom to in turn stabilize the tension rods, so all that can probably add up to something significant, even if not quite enough to expend a Falcon 9. How much fuel did that look like was left in the 1st stage, a lot or very little?
