Author Topic: SpaceX Falcon 9 : Koreasat 5A : October 30 : DISCUSSION THREAD  (Read 67935 times)

Online Jakusb

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The roomba is optional for landing, but that broken thruster pod is not...
How much time do they need before they need to sail off again for KoreaSat booster?
Can they fix it in time?
What are consequences for that booster if it cannot be fixed in time?
Expend it or postpone launch?
So many questions...

Offline macpacheco

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The roomba is optional for landing, but that broken thruster pod is not...
How much time do they need before they need to sail off again for KoreaSat booster?
Can they fix it in time?
What are consequences for that booster if it cannot be fixed in time?
Expend it or postpone launch?
So many questions...
One of the reasons for choosing this Marmac platform for ASDS is its easy to fix. Its NOT rocket science. There's very very low probability it won't be fixed in time. And I'm pretty certain the launch will proceed regardless of ASDS being ready or not. Recoveries from LEO are important cause those boosters are likely to be reflown. From GTO, not so much (until its a full Block V).
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Offline ClayJar

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The roomba is optional for landing, but that broken thruster pod is not...

Are four fully operational thrusters actually necessary for landing?  With four independently powered thrusters, I don't imagine the stationkeeping algorithm would be rendered unable to function by having one less.  I could certainly see the loss of one thruster reducing the available margins when it comes to control authority, putting tighter constraints on acceptable weather.

It would be interesting to know what the minimum equipment list for an ASDS would be.  Is one thruster offline acceptable?  How about two diagonal? same side? same end?  And how does a set of three current thrusters compare to the original four thrusters back before they were upgraded?

Offline vanoord

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The roomba is optional for landing, but that broken thruster pod is not...

Are four fully operational thrusters actually necessary for landing?  With four independently powered thrusters, I don't imagine the stationkeeping algorithm would be rendered unable to function by having one less.  I could certainly see the loss of one thruster reducing the available margins when it comes to control authority, putting tighter constraints on acceptable weather.

It would be interesting to know what the minimum equipment list for an ASDS would be.  Is one thruster offline acceptable?  How about two diagonal? same side? same end?  And how does a set of three current thrusters compare to the original four thrusters back before they were upgraded?

Probably not the place to discuss it at length, but I'd suspect that the positioning system would be able to hold station adequately on three thrusters - as long as the control system knew that it only had those three thrusters.  If it believed it had four but only three were operating, the results might not be so great.

Offline JasonAW3

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The roomba is optional for landing, but that broken thruster pod is not...

Are four fully operational thrusters actually necessary for landing?  With four independently powered thrusters, I don't imagine the stationkeeping algorithm would be rendered unable to function by having one less.  I could certainly see the loss of one thruster reducing the available margins when it comes to control authority, putting tighter constraints on acceptable weather.

It would be interesting to know what the minimum equipment list for an ASDS would be.  Is one thruster offline acceptable?  How about two diagonal? same side? same end?  And how does a set of three current thrusters compare to the original four thrusters back before they were upgraded?

Probably not the place to discuss it at length, but I'd suspect that the positioning system would be able to hold station adequately on three thrusters - as long as the control system knew that it only had those three thrusters.  If it believed it had four but only three were operating, the results might not be so great.

Properly programmed, it would know if it had a non-functioning pod or two.  (might require some additional sensors to check if the pod were producing thrust and how much, as blades could be damaged on the pod and it would still act as if it were functioning normally).

     In fact, with proper programming and a relatively calm sea, (outside of a current) I suspect that the ASDS could maintain station keeping with only two pods.

     Regardless; would they be able to reprogram this flight to a Cape landing, if the ASDS isn't available?
« Last Edit: 10/17/2017 07:59 PM by JasonAW3 »
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Online EspenU

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This is probably starting to get off topic, but just to put the discussion to rest.

Yes, a DP system would be able to hold position with 3 azi pods (unless the weather was really bad of course).
2 pods might work, but it will depend on the rotation time of the thrusters, weather, and how important it is to maintain a specific heading. Heading is often prioritized over position, but I'm guessing that's not the case for the ASDS.

Interesting fact: when working with few thruster, perfectly still weather is much harder to work with than if there is a little bit of wind or current. With no weather the thrusters have to keep turning 180 (or reversing) to compensate for its own forces. With a little wind/current the system can use the weather as a counter force and just use the thrusters in one direction.

A good DP system will often have an internal model that shows it what to expect when a given force is applied. That is then compared to refsys data like GPS.
If a  thruster is damaged, giving less thrust,  the system will see it as an unexpected force (like current) and can often compensate by adjusting its model (within limits of course).

Note that I don't know the details of the thrustmaster system on the ASDS. But I work with DP systems on a daily basis.


Online gongora

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Further ASDS discussion should probably move to the ASDS threads.

Edit/lar: https://forum.nasaspaceflight.com/index.php?topic=39766 seems well suited.
« Last Edit: 10/17/2017 09:20 PM by Lar »

Offline Formica

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Regardless; would they be able to reprogram this flight to a Cape landing, if the ASDS isn't available?

Negative. Koreasat 5A weighs an estimated 3500kg and is traveling to GTO. That's too heavy and too far for a Block 4 RTLS landing. If the ASDS is not available, they'd have to expend the booster.
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Offline Ronsmytheiii

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work being performed on the TEL/Launch mount in preparations for launch

taken yesterday, Note the small cane

(wonder if they are adding more equipment for Falcon Heavy as well)

https://www.instagram.com/p/BaZm5UXAUuS/

https://www.instagram.com/p/BaZn_67HXnJ/
« Last Edit: 10/19/2017 05:15 PM by Ronsmytheiii »
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Offline foragefarmer

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Do they have a couple JLG boom lifts hoisted up on the RSS in that first pic?

Offline kdhilliard

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Do they have a couple JLG boom lifts hoisted up on the RSS in that first pic?

They were both up there during the Oct. 11 SES 11 launch.  See https://twitter.com/flatoday_jdean/status/918096757329932288

And clegg78 took a good photo of them when he toured KSC on Sept. 29.  See: https://forum.nasaspaceflight.com/index.php?topic=41015.msg1730172#msg1730172
« Last Edit: 10/22/2017 05:33 PM by kdhilliard »

Offline russianhalo117

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Do they have a couple JLG boom lifts hoisted up on the RSS in that first pic?
yes and there were 3 and they have been up there since before the beginning of the year. It is becoming very hard for them to hide.

Offline su27k

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TEL is now back in the HIF. There are also reports that all three FH cores are in there as well, I'm sure it's nice and cozy!

Is it actually possible to fit 3 cores plus TEL in HIF at the same time? I thought HIF is only 5 cores wide, and TEL is 3 cores wide.

Offline vaporcobra

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TEL is now back in the HIF. There are also reports that all three FH cores are in there as well, I'm sure it's nice and cozy!

Is it actually possible to fit 3 cores plus TEL in HIF at the same time? I thought HIF is only 5 cores wide, and TEL is 3 cores wide.

Hehe some of us already spent way too long discussing this, but we concluded from our armchairs that it's at least possible to fit 4 cores and the TEL simultaneously. Not optimal, but possible.

Offline deruch

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I believe the additional cores can be shifted some toward the "upper end" of the HIF floor so that the wider base of the T/E isn't an issue when it is also inside.  This may not be a possibility when there are additional second stages inside (besides the one going on the T/E for the next launch), but should be fine if they only have the first stages in.
« Last Edit: 10/26/2017 01:15 PM by deruch »
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Offline StuffOfInterest

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I believe the additional cores can be shifted some toward the "upper end" of the HIF floor so that the wider base of the T/E isn't an issue when it is also inside.  This may not be a possibility when there are additional second stages inside (besides the one going on the T/E for the next launch), but should be fine if they only have the first stages in.

If I remember correctly, one of the photos from inside the HIF when several returned cores were in residence showed enough space for about five cores side-by-side.  This makes sense if you think about stacking operations for a Heavy.  Before the T/E is rolled in, the center core can be lifted up on the crane and the side boosters will sit off to the sides.  Once the T/E is inside, the center core can be put in place and then the crane has to pick up each side core and move it to the correct position.

There shouldn't be an issue with having the side cores inside when a single stick launch is being prepared.  They just never pick up the sides for mounting.

Online Chris Bergin

SFN have paywalled the livestream of the test and all future tests I would assume (so while I'd encourage anyone to support a space site they use, it would rule out screenshots from members of their site on here as accreditation only works when it's a public link, which this stream no longer is). So unless Florida Today or someone else streams, the next "image" will be from the SpaceX tweet of confirmation.

Doubt this will be a problem for FH's tests and CRS etc...as it's going to be a full table of Facebook live etc. We'll have reporters there too and have it set up. But I am desperately trying to avoid any "oh, let's find a way around". Perfect world is everyone supports every space site they like.

Offline dedead

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Do you know if the ASDS is on it's way today for the launch of K5A ? I saw one on the sea 30 minutes from the pier of cocoa but i'm not sure.

Offline Michael Baylor

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They are still in port.

Offline Lar

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They are still in port.
That's potentially sad news, splashing a new one, rather than a block 3...

If true though, while sad, it is the right thing to do for the customer
"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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