Author Topic: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION  (Read 1087700 times)

Offline matthewkantar

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #760 on: 02/23/2016 06:29 pm »
Wiring for heaters to keep the leg locks dry?

Matthew

Offline Joffan

Over from the updates thread, I just wanted to observe from the static firing that this pad does a great job of directing all the smoke/flame sideways (which seemed to catch the camera operator off-guard), leaving the vehicle visible throughout. That has to be regarded as a positive step (and not just for us spectators). Of course at launch, there will still be some exhaust after lift-off that stays local to the pad.

Video of the test from US Launch Report.




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Offline Space Ghost 1962

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #762 on: 02/23/2016 07:25 pm »
Mission press kit: http://www.spacex.com/sites/spacex/files/spacex_ses9_press_kit_final.pdf

"Following stage separation, the first stage of the Falcon 9 will attempt an experimental landing on the “Of Course I Still Love You” droneship. Given this mission’s unique GTO profile, a successful landing is not expected."

No timeline for first-stage landing included this time.

At the same time James Dean tweets the following:

"SES has clarified that profile adjustment made to upcoming launch had no bearing on F9 booster recovery; only impacts upper stage burn."
https://twitter.com/flatoday_jdean/status/702182942458642432

A little confusing.

All a booster can do is get US+payload to staging. US is responsible for orbital velocity and margin for stage shortfall (you can't minimize this margin). 3 burns can improve this, more props e.g. more densified can get you this.

In truth a higher/faster staging still, in theory, has no bearing on stage recovery, because it could still make it to a landing. It would however have bearing on stage reuse, in yielding a stage that has its integrity compromised.

This might explain how both statements are still true and consistent.

Offline LastStarFighter

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #763 on: 02/23/2016 07:34 pm »
Over from the updates thread, I just wanted to observe from the static firing that this pad does a great job of directing all the smoke/flame sideways (which seemed to catch the camera operator off-guard), leaving the vehicle visible throughout. That has to be regarded as a positive step (and not just for us spectators). Of course at launch, there will still be some exhaust after lift-off that stays local to the pad.

Video of the test from US Launch Report.





What do you mean by a positive step? It looks the same as all other launchers out there.

Offline MarekCyzio

In other words, odds of successful stage recovery were low even before SpaceX offered SES extra delta V. But seems to me you could argue they're even lower now. I guess maybe "low" and "lower" are still in the same semantic ballpark.

Anyway, that statement is coming from the payload, not SpaceX, so perhaps we should take it with a grain of salt.

I guess this explains why SpaceX needs Falcon Heavy - F-9 is not capable of delivering heavy loads to GTO and landing.

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #765 on: 02/23/2016 08:03 pm »
Mission press kit: http://www.spacex.com/sites/spacex/files/spacex_ses9_press_kit_final.pdf

"Following stage separation, the first stage of the Falcon 9 will attempt an experimental landing on the “Of Course I Still Love You” droneship. Given this mission’s unique GTO profile, a successful landing is not expected."

No timeline for first-stage landing included this time.

At the same time James Dean tweets the following:

"SES has clarified that profile adjustment made to upcoming launch had no bearing on F9 booster recovery; only impacts upper stage burn."
https://twitter.com/flatoday_jdean/status/702182942458642432

A little confusing.

All a booster can do is get US+payload to staging. US is responsible for orbital velocity and margin for stage shortfall (you can't minimize this margin). 3 burns can improve this, more props e.g. more densified can get you this.

In truth a higher/faster staging still, in theory, has no bearing on stage recovery, because it could still make it to a landing. It would however have bearing on stage reuse, in yielding a stage that has its integrity compromised.

This might explain how both statements are still true and consistent.

Wait, doesn't the statement that the adjusted trajectory "only impacts upper stage burn" imply that the extra delta V is coming from the upper stage, not S1, and therefore S1 will stage at the same velocity/altitude as previously planned, and thus have the same amount of residual props for the recovery attempt? That's how I read it.

In which case, the adjustment has "no bearing" on S1 recovery odds, and the statements are consistent.
« Last Edit: 02/23/2016 08:08 pm by Kabloona »

Offline LastStarFighter

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #766 on: 02/23/2016 08:07 pm »
Mission press kit: http://www.spacex.com/sites/spacex/files/spacex_ses9_press_kit_final.pdf

"Following stage separation, the first stage of the Falcon 9 will attempt an experimental landing on the “Of Course I Still Love You” droneship. Given this mission’s unique GTO profile, a successful landing is not expected."

No timeline for first-stage landing included this time.

At the same time James Dean tweets the following:

"SES has clarified that profile adjustment made to upcoming launch had no bearing on F9 booster recovery; only impacts upper stage burn."
https://twitter.com/flatoday_jdean/status/702182942458642432

A little confusing.

All a booster can do is get US+payload to staging. US is responsible for orbital velocity and margin for stage shortfall (you can't minimize this margin). 3 burns can improve this, more props e.g. more densified can get you this.

In truth a higher/faster staging still, in theory, has no bearing on stage recovery, because it could still make it to a landing. It would however have bearing on stage reuse, in yielding a stage that has its integrity compromised.

This might explain how both statements are still true and consistent.

Wait, doesn't the statement that the adjusted trajectory "only impacts upper stage burn" imply that the extra delta V is coming from the upper stage, not S1, and therefore S1 will have the same amount of residual props for the recovery attempt? That's how I read it.

In which case, the asjustment has "no bearing" on S1 recovery odds, and the statements are consistent.

Which doesn't make sense. Since the upper stage is expended it should have been delivering them to the best orbit possible to begin with. Something is lost in translation.

Offline starsilk

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #767 on: 02/23/2016 08:13 pm »
Mission press kit: http://www.spacex.com/sites/spacex/files/spacex_ses9_press_kit_final.pdf

"Following stage separation, the first stage of the Falcon 9 will attempt an experimental landing on the “Of Course I Still Love You” droneship. Given this mission’s unique GTO profile, a successful landing is not expected."

No timeline for first-stage landing included this time.

At the same time James Dean tweets the following:

"SES has clarified that profile adjustment made to upcoming launch had no bearing on F9 booster recovery; only impacts upper stage burn."
https://twitter.com/flatoday_jdean/status/702182942458642432

A little confusing.

All a booster can do is get US+payload to staging. US is responsible for orbital velocity and margin for stage shortfall (you can't minimize this margin). 3 burns can improve this, more props e.g. more densified can get you this.

In truth a higher/faster staging still, in theory, has no bearing on stage recovery, because it could still make it to a landing. It would however have bearing on stage reuse, in yielding a stage that has its integrity compromised.

This might explain how both statements are still true and consistent.

Wait, doesn't the statement that the adjusted trajectory "only impacts upper stage burn" imply that the extra delta V is coming from the upper stage, not S1, and therefore S1 will have the same amount of residual props for the recovery attempt? That's how I read it.

In which case, the asjustment has "no bearing" on S1 recovery odds, and the statements are consistent.

Which doesn't make sense. Since the upper stage is expended it should have been delivering them to the best orbit possible to begin with. Something is lost in translation.

except that this is a 'new' stage design (FT), and they now have one flight's worth of data - perhaps they can safely reduce their calculated margins based on the first flight and release a little more performance to the customer.

Offline Lar

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #768 on: 02/23/2016 08:17 pm »
I find all these conflicting reports very conflicting.  SES tweets say that the probability of recovery is lower suggesting that S1 is using more propellant rather than S2
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"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #769 on: 02/23/2016 08:18 pm »
Quote
except that this is a 'new' stage design (FT), and they now have one flight's worth of data - perhaps they can safely reduce their calculated margins based on the first flight and release a little more performance to the customer.

I think you just nailed it.

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #770 on: 02/23/2016 08:21 pm »
I find all these conflicting reports very conflicting.  SES tweets say that the probability of recovery is lower suggesting that S1 is using more propellant rather than S2

Well, SES apparently just told James Dean that there is "no impact" on recovery odds, so maybe starsilk's conjecture is correct, ie that SpaceX has run Monte Carlos based on previous flight performance and has now decided they have a little extra delta V to release.

SpaceX may have made that decision after the first round of statements implying a potential hit to S1 performance, hence the recent "clarification" from SES.
« Last Edit: 02/23/2016 08:23 pm by Kabloona »

Offline LastStarFighter

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #771 on: 02/23/2016 08:23 pm »
I find all these conflicting reports very conflicting.  SES tweets say that the probability of recovery is lower suggesting that S1 is using more propellant rather than S2

I agree. Weren't there specific quotes relating to SpaceX sacrificing some recovery odds to help them out. I feel like we would have heard a different message had the first flight just retired some margins on the second stage.

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #772 on: 02/23/2016 08:26 pm »
I find all these conflicting reports very conflicting.  SES tweets say that the probability of recovery is lower suggesting that S1 is using more propellant rather than S2

I agree. Weren't there specific quotes relating to SpaceX sacrificing some recovery odds to help them out. I feel like we would have heard a different message had the first flight just retired some margins on the second stage.

There were, but maybe SpaceX subsequently did more post-flight analysis and decided they had more performance margin than they thought, which they could release to SES without affecting S1.

(Credit to starsilk for that conjecture)
« Last Edit: 02/23/2016 08:29 pm by Kabloona »

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #773 on: 02/23/2016 08:34 pm »

Wait, doesn't the statement that the adjusted trajectory "only impacts upper stage burn" imply that the extra delta V is coming from the upper stage, not S1, and therefore S1 will have the same amount of residual props for the recovery attempt? That's how I read it.

In which case, the asjustment has "no bearing" on S1 recovery odds, and the statements are consistent.

Which doesn't make sense. Since the upper stage is expended it should have been delivering them to the best orbit possible to begin with. Something is lost in translation.

Apparently S2 will in fact be providing the extra delta V:

Quote
James Dean – Verified account ‏@flatoday_jdean

The Falcon 9 upper stage will burn for a few more seconds than initially was planned to lift SES-9 to higher orbit, cut days to GEO in half.

So I believe starsilk's conjecture is probably correct: after the initial round of statements implying an S1 performance hit, SpaceX did more post-flight analysis and figured they got more performance than expected from the FT upgrade, which they could release to SES in the form of a slightly longer S2 burn, without depleting S1 residuals for recovery.
« Last Edit: 02/23/2016 09:09 pm by Kabloona »

Offline eriblo

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #774 on: 02/23/2016 09:35 pm »
The 16s longer S1 burn time compared to ORBCOMM-2 means at least 28 tonnes (minimum throttle) less propellant for the recovery operations this time around...

Offline RedLineTrain

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #775 on: 02/23/2016 10:11 pm »
Reuters is reporting that SES-9 is 5,721 kg rather than ~5,300 kg, based on a pre-flight news conference.

http://www.reuters.com/article/us-space-spacex-ses-idUSKCN0VW2O7

Edit:  Looks like the Reuters article is in error.  Halliwell from SES states that it is 5,271 kg.  See the video in the Florida Today article.

http://www.floridatoday.com/story/tech/science/space/spacex/2016/02/23/spacex-falcon-9-rocket-launch-ses-9-satellite/80568980/?from=global&sessionKey=&autologin=
« Last Edit: 02/23/2016 10:21 pm by RedLineTrain »

Offline Chris_Pi

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #776 on: 02/23/2016 10:24 pm »
The timeline in the press kit has the fairing staying with S2 for 55 seconds after startup - Is this an error in the timeline? Usually it's been ~10-15 seconds. I can't think of any reason to wait so long unless unusually low staging or a really fragile payload still needs it.

Offline okan170

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #777 on: 02/23/2016 10:29 pm »
Pics of static fire on SpaceX's Instagram and Facebook.

Enjoy, Matthew

Seems like there are two rounded rectangles on either side of the leg here, a little bit inset.  Previous flights' legs had a roughly square protrusion (small fairing?) here.
It also seems they are very faintly visible on this image tweeted by the 45th Space Wing.
https://twitter.com/45thSpaceWing/status/701891806255046657

Tape. But I am noticing this string/wire first time.

Aha!  The dangers of low resolution strike again...

Offline LastStarFighter

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #778 on: 02/23/2016 10:39 pm »
The timeline in the press kit has the fairing staying with S2 for 55 seconds after startup - Is this an error in the timeline? Usually it's been ~10-15 seconds. I can't think of any reason to wait so long unless unusually low staging or a really fragile payload still needs it.

If I remember correctly most of the Falcon launches have waited this long. At least DISCOVR and Thales launches did.

Offline OxCartMark

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #779 on: 02/23/2016 11:03 pm »
What's up with SpaceX's pre-launch press conferences anymore?  I've not been aware of any since approximately CRS-7.  Am I missing them or are they not having them or did they go somewhat underground? ...Or are they only held for NASA payloaded flights?  I miss the semi-comedy of seeing Hans Koenigsman having to take the bulk of the questions related to the ASDS landing attempt which isn't really his thing.
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