Author Topic: SpaceX Falcon 9 : Iridium NEXT Flight 3 : Oct 9, 2017: DISCUSSION  (Read 37363 times)

Offline edkyle99

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Block 4 stages, presumably.  Hope we learn more about post-landing situation (mention of post-landing fire upthread).

 - Ed Kyle
There was no such as a post-landing fire. What was seen in the post-landing footage was the usual burning-off of residual propellant from the center engine. It stopped less than 15 seconds after touch-down. No fire after that. This burning-off of residual propellants happens on all landings. It is completely nominal. The only reason it was seen this clearly is because of the night-time conditions. Had this landing been witnessed in bright daylight the burning-off would have hardly been visible.
Yes, I saw that initial brightness as normal.  I'm wondering about what happened after the view cut away.  There was a flicker or two at the base of the propulsion section just before the view ended.

 - Ed Kyle
« Last Edit: 10/09/2017 07:08 PM by edkyle99 »

Offline ChrisC

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Here's another video I stumbled across zoomed in on stage separation and boostback:



Going to quote this closeup video into here for further discussion.  Absolutely astonishing! 
NASA TV in HD:  history, FAQ and latest status

Online ZachS09

I've said this before after the SpaceX CRS-9 launch: that phenomenon during which both the first and second stage plumes collided with each other made me think the rocket exploded until I checked the webcast to make sure everything was fine.
"Liftoff of Falcon 9: the world's first reflight of an orbital-class rocket."

Online acsawdey

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Going to quote this closeup video into here for further discussion.  Absolutely astonishing!

Yes ... this reminds me of images of the Crab Nebula and other similar things, it's just many orders of magnitude closer and smaller, supersonic shock waves of low density gas interacting in space.

Offline woods170

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I've said this before after the SpaceX CRS-9 launch: that phenomenon during which both the first and second stage plumes collided with each other made me think the rocket exploded until I checked the webcast to make sure everything was fine.
Only seen because of the nighttime conditions of this launch. The same interactions take place in daylight launches but are not seen as sunlight is much brighter than light effects coming off the interaction of the plumes.

Offline woods170

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Block 4 stages, presumably.  Hope we learn more about post-landing situation (mention of post-landing fire upthread).

 - Ed Kyle
There was no such as a post-landing fire. What was seen in the post-landing footage was the usual burning-off of residual propellant from the center engine. It stopped less than 15 seconds after touch-down. No fire after that. This burning-off of residual propellants happens on all landings. It is completely nominal. The only reason it was seen this clearly is because of the night-time conditions. Had this landing been witnessed in bright daylight the burning-off would have hardly been visible.
Yes, I saw that initial brightness as normal.  I'm wondering about what happened after the view cut away.  There was a flicker or two at the base of the propulsion section just before the view ended.

 - Ed Kyle
Yes. Completely normal for Falcon 9. When Falcon 9 lands there is massive interaction of fuel-rich center-engine exhaust with both the deck of the ASDS as well as the business end of Falcon 9 itself. There will be burning stuff on the outside of the aft end and it will burn for some time after touch-down. On previous landings this localized burning stuff has also been spotted on the legs, and the ASDS deck.
You have to remember that prior to Falcon 9 there was no reference in what is "normal" for a propulsively landed rocket stage. Falcon 9 is now writing the initial "handbook" for this, including all the phenomena observed after touch-down.
« Last Edit: 10/10/2017 07:07 AM by woods170 »

Offline octavo

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You have to remember that prior to Falcon 9 there was no reference in what is "normal" for a propulsively landed rocket stage. Falcon 9 is now writing the initial "handbook" for this, including all the phenomena observed after touch-down.

I might be well off-base here, but that sort of sounds like the thinking that lead to the loss of Columbia? I don't think post-landing fires are quite the same as heat-shield damage, but imo "normal" should only be decided once Block V has proven at least 5 or 6 unrefurbished reflights.

Offline woods170

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You have to remember that prior to Falcon 9 there was no reference in what is "normal" for a propulsively landed rocket stage. Falcon 9 is now writing the initial "handbook" for this, including all the phenomena observed after touch-down.

I might be well off-base here, but that sort of sounds like the thinking that lead to the loss of Columbia? I don't think post-landing fires are quite the same as heat-shield damage, but imo "normal" should only be decided once Block V has proven at least 5 or 6 unrefurbished reflights.
Incorrect. Post-landing fires are a problem if they are of the type that does unexpected damage. Like having an extended fire INSIDE the octoweb when there is not supposed to be one.
They have had those on early landings, but not anymore, courtesy of progressive improvements to prevent fires inside the octoweb. Short duration fires on the outside of the stage are now effectively remedied by the stage TPS and are expected. You don't do propulsive landings - of the type SpaceX does - and expect flaming stuff to NOT hit the legs or bounce back up against the stage itself.
Trouble was that SpaceX initially did not quite know what kind of a local environment a landing Falcon 9 would create. So, during the first several landings they ran into some surprises. Things they hadn't expected yet happened anyway. That's "writing the book" on this stuff. The way SpaceX operates they learned from their observations quickly AND next began to "harden" Falcon 9 to better withstand the landing-environment and subsequent results. One of the best observable effects was that eventually the post-landing fires INSIDE the octoweb went away. A substantial part of the effort being put into Block 5 is taking protection from the landing-environment to the ultimate level. So, SpaceX has been busy fixing the problem, and they are succeeding.

Columbia was completely different. That was normalization of deviance. In stead of fixing their problem (prevent foam-loss all together AND harden your heatshield to take on anything) they just comforted themselves expecting foam-loss, and other debris, to never be an issue because it had not killed in orbiter in 100 previous flights. This despite the fact that STS-27 was one heck of a wake-up call.

That's the difference: NASA failed to fix a problem despite getting warnings about the problem on almost every flight. SpaceX however got warnings of a problem and has acted (and is still acting) to fix the problem.
That doesn't go to say though that they are infallible. They had plenty of indications of a problem with their COPV's on multiple flights. They didn't begin to fix that problem however until after AMOS-6. They learned their lesson there. Unlike NASA, who knew - even before Challenger - that shuttle had several major design issues, but never bothered to fix them properly. Even the extensive improvements made after Columbia fixed only about half of the problem.
« Last Edit: 10/10/2017 12:00 PM by woods170 »

Offline Brovane

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With the barge landing, why was there a boost back burn?  I thought boost back was only for RTLS.
If you've got the fuel to spare, and don't really want to send the barge a few hundred miles further out...

Do we know if SpaceX could do an RTLS with the Iridium launches?  Assuming the Vandenberg landing site was completed and available. 
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Offline envy887

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With the barge landing, why was there a boost back burn?  I thought boost back was only for RTLS.
If you've got the fuel to spare, and don't really want to send the barge a few hundred miles further out...

Do we know if SpaceX could do an RTLS with the Iridium launches?  Assuming the Vandenberg landing site was completed and available.

Not for sure, but likely they can with Block 5.

Offline vaporcobra

I also noticed the extremely unusual lack of photos thus far. Hoping it's just a fluke or that Ben Cooper was unavailable or something ???

Offline Comga

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Some rough seas are apparently delaying crew from boarding JRTI.

Edit: I should clarify, as of ~24 hours ago.

No Roomba (as of ~28 hours ago, about 12 hours after landing)
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline vaporcobra

Some rough seas are apparently delaying crew from boarding JRTI.

Edit: I should clarify, as of ~24 hours ago.

No Roomba (as of ~28 hours ago, about 12 hours after landing)

There is only one Roomba, and that guy is on OCISLY ;)

Offline old_sellsword

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And another one. Does not get old, even if it is starting to feel routine

Edit: FWIW, the poster (an employee) said that we should "stay tuned for more pictures of the actual launch", so hopefully that means the lack of official photos is temporary!

This picture is not from Iridium-3, the caption says thatís OCISLY.

Edit: Original context of that post: https://instagram.com/p/BFMliSUl8e8/
« Last Edit: 10/11/2017 12:13 PM by old_sellsword »

Offline Comga

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Some rough seas are apparently delaying crew from boarding JRTI.

Edit: I should clarify, as of ~24 hours ago.

No Roomba (as of ~28 hours ago, about 12 hours after landing)

There is only one Roomba, and that guy is on OCISLY ;)
DUH!  Wrong coast for Roomba, wrong day of this week.
It was so much easier when launching and landing was infrequent and unknown, respectively.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline FutureSpaceTourist

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I'm confused, it was a Falcon launch but this makes it look like Dragon's breath  ;)

Quote
The SpaceX Falcon 9 Iridium NEXT III cleared the transporter erector. @SpaceX @IridiumComm @NASASpaceflight

https://twitter.com/jdeshetler/status/918122350406656000

Offline vaporcobra

And another one. Does not get old, even if it is starting to feel routine

Edit: FWIW, the poster (an employee) said that we should "stay tuned for more pictures of the actual launch", so hopefully that means the lack of official photos is temporary!

This picture is not from Iridium-3, the caption says thatís OCISLY.

Edit: Original context of that post: https://instagram.com/p/BFMliSUl8e8/

Thanks, good eye. I just went ahead and removed it, the ones above are good enough on their own :D

Offline vaporcobra

There is only one Roomba, and that guy is on OCISLY ;)
DUH!  Wrong coast for Roomba, wrong day of this week.
It was so much easier when launching and landing was infrequent and unknown, respectively.

Heh, I can't blame you ;D I am no longer able to keep a running list of cores in my head. O, what must we sacrifice in the name of progress...

Offline edkyle99

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There is only one Roomba, and that guy is on OCISLY ;)
DUH!  Wrong coast for Roomba, wrong day of this week.
It was so much easier when launching and landing was infrequent and unknown, respectively.

Heh, I can't blame you ;D I am no longer able to keep a running list of cores in my head. O, what must we sacrifice in the name of progress...
I'm trying to keep track here.  A launch log list just above this first stage list.
http://www.spacelaunchreport.com/falcon9ft.html#f9stglog

 - Ed Kyle

Offline CraigLieb

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There is only one Roomba, and that guy is on OCISLY ;)
DUH!  Wrong coast for Roomba, wrong day of this week.
It was so much easier when launching and landing was infrequent and unknown, respectively.

Heh, I can't blame you ;D I am no longer able to keep a running list of cores in my head. O, what must we sacrifice in the name of progress...

...another good reason to subscribe to L2 as there is a  great core watch thread with graphic outlining best guesses as to where the cores are, links to documentation about them and a historical listing.
(L2 link to use after you subscribe)
https://forum.nasaspaceflight.com/index.php?topic=42452.0
« Last Edit: 10/12/2017 02:08 PM by CraigLieb »
Colonize Mars!

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