Author Topic: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION  (Read 1087856 times)

Offline Kabloona

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #220 on: 12/28/2015 06:49 pm »
DSCOVR was the fast and hot one way downrange...  ;)

Can you confirm or deny my recollections of no boostback burn and 8x kinetic energy at atmospheric interface for DSCOVR?  Looking back I see that DSCOVR was the one that was headed to the ASDS but the ASDS was not in position due to a severe storm out there.  It did have a landing on the water surface that was within 10M, which is IIRC, the first to do so.

Interesting discussion but very OT, so I'll just throw this in "SES-9".

You may be remembering this tweet from Elon.

Quote
Elon Musk – Verified account ‏@elonmusk

Rocket reentry will be much tougher this time around due to deep space mission. Almost 2X force and 4X heat. Plenty of hydraulic fluid tho.
11:43 AM - 8 Feb 2015
« Last Edit: 12/28/2015 06:50 pm by Kabloona »

Offline Dante80

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #221 on: 01/04/2016 03:10 pm »
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000

Barging may occur after all. That's interesting (GTO-1800? sub-synchronous flight?)

NET 23-JAN-2016

Barge location (its far away this time, about 660km out)...
« Last Edit: 01/04/2016 03:28 pm by Dante80 »

Offline Comga

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #222 on: 01/04/2016 03:32 pm »
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000

Barging may occur after all. That's interesting (GTO-1800? sub-synchronous flight?)

NET 23-JAN-2016

Barge location (its far away this time, about 660km out)...
mapped

(Isn't 1800 m/sec the velocity change needed to circularize at Geo? Doesn't 1800 m/sec reflect a lower perigee than the somewhat standard 1500 m/sec?)
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline ugordan

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #223 on: 01/04/2016 03:36 pm »
Doesn't 1800 m/sec reflect a lower perigee than the somewhat standard 1500 m/sec?

Higher inclination of the GTO orbit, usually.

Offline Dante80

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #224 on: 01/04/2016 03:40 pm »
(Isn't 1800 m/sec the velocity change needed to circularize at Geo? Doesn't 1800 m/sec reflect a lower perigee than the somewhat standard 1500 m/sec?)

We use to call Cape GTO missions as GTO-1800. The reason is that a launch from the Cape will leave a 20+ degree inclination in a standard GTO mission. GTO-1500 is for a mission that gets to 0 inclination (and you only have to circularize from that). That's what Ariane 5 does (which launches from Kuru).

Yes, both -1800 and -1500 means m/s needed to circularize to GEO/0 inclination.

« Last Edit: 01/04/2016 03:41 pm by Dante80 »

Offline The Amazing Catstronaut

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #225 on: 01/04/2016 03:43 pm »
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000

Barging may occur after all. That's interesting (GTO-1800? sub-synchronous flight?)

NET 23-JAN-2016

Barge location (its far away this time, about 660km out)...

It always startles me how (deceptively) easy those applications look to fill out, although it's a lot more complex than they appear. What's the point of paperwork if it's not frightening?

May occur, but didn't they make similar applications practically every other time? Still holding out for an RTLS.

Edit: derp, wrong thread.
« Last Edit: 01/04/2016 03:58 pm by The Amazing Catstronaut »
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Offline ugordan

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #226 on: 01/04/2016 03:45 pm »
Still holding out for an RTLS.

I'd be very impressed if SES-9 flight had the performance to do a RTLS...

Offline The Amazing Catstronaut

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #227 on: 01/04/2016 03:58 pm »
Still holding out for an RTLS.

I'd be very impressed if SES-9 flight had the performance to do a RTLS...

And then there's me thinking this is the Jason 3 thread...  ::)
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Offline Dante80

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #228 on: 01/04/2016 03:59 pm »
Still holding out for an RTLS.

I'd be very impressed if SES-9 flight had the performance to do a RTLS...

If F9 FT S1 could RTLS after dispensing a 5,330kg GTO sat, then FH would probably be heavily delayed/cancelled and SpaceX would service the whole commercial market with the single stick.

Maybe in 10 years and with M1-Fs..XD
« Last Edit: 01/04/2016 03:59 pm by Dante80 »

Offline edkyle99

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #229 on: 01/04/2016 04:06 pm »
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000

Barging may occur after all. That's interesting (GTO-1800? sub-synchronous flight?)

NET 23-JAN-2016

Barge location (its far away this time, about 660km out)...

I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 

 - Ed Kyle

Offline AncientU

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #230 on: 01/04/2016 04:08 pm »
https://apps.fcc.gov/oetcf/els/reports/STA_Print.cfm?mode=initial&application_seq=69076&RequestTimeout=1000

Barging may occur after all. That's interesting (GTO-1800? sub-synchronous flight?)

NET 23-JAN-2016

Barge location (its far away this time, about 660km out)...

I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 

 - Ed Kyle

*** only??? ***
How quickly things change.  ;)
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Online abaddon

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #231 on: 01/04/2016 04:09 pm »
I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 
I would assume so, this has to be right at the margins of a recoverable flight even for F9FT.

Offline Semmel

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #232 on: 01/04/2016 06:49 pm »
I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 

My understanding is that they need the boost-back to target the landing site even when its the barge down range. My understanding can be wrong of course.

Offline Lars-J

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #233 on: 01/04/2016 07:13 pm »
I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 

My understanding is that they need the boost-back to target the landing site even when its the barge down range. My understanding can be wrong of course.

Yep, that is my understanding as well. A more proper term for the burn may simply be "aiming burn", since it doesn't always result in a boost-back. But it is there to aim the stage to the landing point.
« Last Edit: 01/04/2016 07:13 pm by Lars-J »

Offline joek

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #234 on: 01/04/2016 10:53 pm »
I wonder if there will be a "boost back" burn at all on this flight.  Perhaps reentry and landing only? 
My understanding is that they need the boost-back to target the landing site even when its the barge down range. My understanding can be wrong of course.
Yep, that is my understanding as well. A more proper term for the burn may simply be "aiming burn", since it doesn't always result in a boost-back. But it is there to aim the stage to the landing point.

The CASSIOPE flight did only two burns: reentry and landing.  The first stage survived reentry but not landing.

All ASDS recovery attempts since have also done a third boostback-aiming-whatever burn.  However, that may have been because SpaceX wanted to test and refine the three-burns required for RTLS--not necessarily because it was absolutely required for ASDS-based recovery.

For downrange ASDS landing, it may be that two burns are sufficient and that the grid fins provide sufficient cross- and down-range control and precision.  That might explain why ASDS for this attempt appears to be farther down-range than previously(?): less propellant spent for recovery means more for payload.

Offline ugordan

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #235 on: 01/04/2016 10:59 pm »
All ASDS recovery attempts since have also done a third boostback-aiming-whatever burn.  However, that may have been because SpaceX wanted to test and refine the three-burns required for RTLS--not necessarily because it was absolutely required for ASDS-based recovery.

I'm not sure letting the stage coast for such a long time after MECO (when its state vector can only be *so* close to preflight predict) is a good idea. There's only so much crossrange capability available during reentry phase (both powered and unpowered) once you realize you may be way off track. The 3rd burn may well be desirable, even if it's only a couple-of-second trim.
« Last Edit: 01/04/2016 11:01 pm by ugordan »

Offline Johnnyhinbos

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #236 on: 01/04/2016 11:10 pm »
Ullage issues would cause me to lose sleep...
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Offline Lars-J

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #237 on: 01/04/2016 11:16 pm »
Ullage issues would cause me to lose sleep...

Why? They don't seem to have had any problems settling the propellant for those boost back/aiming burns, since the engines have started properly.
« Last Edit: 01/04/2016 11:17 pm by Lars-J »

Offline Dante80

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Re: SpaceX Falcon 9 FT - SES-9 - March 4, 2016 - DISCUSSION
« Reply #238 on: 01/04/2016 11:18 pm »
Ullage issues would cause me to lose sleep...

Not when you have cold nitrogen thrusters and a good time margin to re-light.

Offline Herb Schaltegger

Ullage issues would cause me to lose sleep...

In addition to what Lars-J and Dante80 said, there's also the fact that even if the first burn in the sequence is the re-entry burn, there would probably already be sufficient aerodynamic drag acting on the stage to settle the prop by deceleration.
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