Author Topic: SpaceX Falcon 9 : Merah Putih (Telkom 4) : August 7, 2018 - DISCUSSION  (Read 68156 times)

Offline John Alan

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Two newly cataloged objects:

2018-064A   2018-08-07 06:57 UTC - 193/29503km/27.06°
2018-064B   2018-08-07 06:59 UTC - 181/29527km/27.04°

I get a delta-V of 1923.3 m/s to reach GEO.

Enter initial perigee height (km): 193
Enter initial apogee height (km): 29503
Enter required inclination change (deg): 27.06

theta1 =  0.08 deg, dv1 =  119.7 m/s
theta2 = 26.98 deg, dv2 = 1803.6 m/s
dv = 1923.3 m/s

I get almost identical numbers
::)
I'll put in a GTO-1925 subsync guess as to where this one ends up in orbit...  ;)

SSL has got this - build it to fit ASDS F9 for lowest cost to orbit - thing down...  8)

And SpaceX is not going to push the landing margin too tight, in my opinion...  :)
8)

Offline envy887

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Two newly cataloged objects:

2018-064A   2018-08-07 06:57 UTC - 193/29503km/27.06°
2018-064B   2018-08-07 06:59 UTC - 181/29527km/27.04°

I get a delta-V of 1923.3 m/s to reach GEO.

Enter initial perigee height (km): 193
Enter initial apogee height (km): 29503
Enter required inclination change (deg): 27.06

theta1 =  0.08 deg, dv1 =  119.7 m/s
theta2 = 26.98 deg, dv2 = 1803.6 m/s
dv = 1923.3 m/s

I get almost identical numbers
::)
I'll put in a GTO-1925 subsync guess as to where this one ends up in orbit...  ;)

SSL has got this - build it to fit ASDS F9 for lowest cost to orbit - thing down...  8)

And SpaceX is not going to push the landing margin too tight, in my opinion...  :)
8)

Sorry, you have to guess exactly to win the prize. You were off by more than 1 m/s!

:D

Offline DeanG1967

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Offline Jakusb

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Last time they tested folding one leg and gained valuable new info on what to improve to make it really work.
They then lowered that leg and removed them all. Since they removed them from 2 later launches.
Clearly the improvements have not found their way to an launched core yet.

a little more patients is required... ;)

Offline Prettz

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Last time they tested folding one leg and gained valuable new info on what to improve to make it really work.
They then lowered that leg and removed them all. Since they removed them from 2 later launches.
Clearly the improvements have not found their way to an launched core yet.

a little more patients is required... ;)
Let's be honest, that's what all the previous block versions were for.

Offline Jakusb

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Last time they tested folding one leg and gained valuable new info on what to improve to make it really work.
They then lowered that leg and removed them all. Since they removed them from 2 later launches.
Clearly the improvements have not found their way to an launched core yet.

a little more patients is required... ;)
Let's be honest, that's what all the previous block versions were for.
How so?
Nobody claimed Block-5 would be totally final... SpaceX will always improve the smaller things if that helps improve processes...
Every flight gives extra experience and every flight is used to test new things.
Every piece of hardware that is new or adjusted or is used under new conditions will be reviewed for performance. If need be it will be adjusted to perform better, if the change is significant enough.

Some stuff will be frozen now, but the first few Block 5 cores don’t even have the latest COPV design... pretty significant detail.

Fairings are still being worked on, as is the second stage for potential recovery later...

Offline Semmel

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Last time they tested folding one leg and gained valuable new info on what to improve to make it really work.
They then lowered that leg and removed them all. Since they removed them from 2 later launches.
Clearly the improvements have not found their way to an launched core yet.

a little more patients is required... ;)

Maybe. Or maybe their stage transporter is not designed to handle the legs still attached.

Offline deruch

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Anyone know why they took the legs off?  Block 5 was supposed to be a "stow and go" landing leg configuration?

Last time they tested folding one leg and gained valuable new info on what to improve to make it really work.
They then lowered that leg and removed them all. Since they removed them from 2 later launches.
Clearly the improvements have not found their way to an launched core yet.

a little more patients is required... ;)
Let's be honest, that's what all the previous block versions were for.
 

This is the first time they've ever attempted to fold the legs up post flight and landing.  How do you imagine they were going to be testing that on previous blocks which didn't include the new leg design?  I'm sure they'd already practiced with mock-ups and test articles, but none of those had actually experienced flight yet.  So, if they've found out that reality doesn't quite match their predictions, it shouldn't come as a surprise that there may yet be minor modifications needed to fully implement the change.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline CorvusCorax

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This is the first time they've ever attempted to fold the legs up post flight and landing.  How do you imagine they were going to be testing that on previous blocks which didn't include the new leg design?  I'm sure they'd already practiced with mock-ups and test articles, but none of those had actually experienced flight yet.  So, if they've found out that reality doesn't quite match their predictions, it shouldn't come as a surprise that there may yet be minor modifications needed to fully implement the change.

Another factor is, leg removal ( and supposedly reinstallation ) isn't really all that work intensive. They need to switch to foldup to get to their famed 24h turnaround, but unless theres a payload waiting for a booster already, which currently isn't the case, they don't need that. Removing the leg is completely marginal workload, but it allows easier post flight inspection of the leg ( not necessarily repairs, just looking at it in detail how it held up ) which would make sense to do for the first couple of flights to have a meaningful sample size ( soft landings, hard landings, high speed reentry, ... )
So as long as the benefits of in-detail inspection outweigh the tiny bit iof extra work of leg removal, why shouldn't they do it?

Once Block 5 has been flyong by the douzends and barely any tweaks to the design are made anymore, you learn less and less by inspection. At some point it willno longer be worth it to remove the legs every flight. Or scrape the paint to do tests on the metal every flight. Just like with an airlplane, individual parts will get a maintenance schefule. Like "every five flights or if landing was over x g, remove leg, replace crush core, oil hinge A  and check bolt y for wear."
But they are a few flights away from that kind of practical experience.

Offline vanoord

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Maybe. Or maybe their stage transporter is not designed to handle the legs still attached.

It looks as if it can handle a stage with folded legs.

Offline stcks

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Maybe. Or maybe their stage transporter is not designed to handle the legs still attached.

It looks as if it can handle a stage with folded legs.

It can and has already.

Offline Semmel

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Maybe. Or maybe their stage transporter is not designed to handle the legs still attached.

It looks as if it can handle a stage with folded legs.

It can and has already.

Can you point me to a picture where it shows the transport of a F9 first stage with legs attached? I am not aware of any such case. And I dont mean the TEL.

Offline stcks

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Maybe. Or maybe their stage transporter is not designed to handle the legs still attached.

It looks as if it can handle a stage with folded legs.

It can and has already.

Can you point me to a picture where it shows the transport of a F9 first stage with legs attached? I am not aware of any such case. And I dont mean the TEL.

No can do sorry. You'll just have trust me. It was the transporter and there was a leg attached.

Offline Semmel

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Can you point me to a picture where it shows the transport of a F9 first stage with legs attached? I am not aware of any such case. And I dont mean the TEL.

No can do sorry. You'll just have trust me. It was the transporter and there was a leg attached.

OK, I'll take insider knowledge over pictures any day :) Thanks!

Offline Lar

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They mount two hoops on the stage.... These mate to the transporter. The lower hoop pretty clearly have clearance for legs, you can see this in just about any transporter photo that has that hoop present.

(the name they use for this mounting fixture may not be "hoop")
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

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