Author Topic: SpaceX Falcon 9 : GovSat-1 (SES-16) : Jan 31. 2018 - Discussion  (Read 207753 times)

Offline Oberon_Command

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Would it be possible to keep the first stage upright using the cold gas thrusters after soft splashdown for long enough to allow water to fill the RP-1 tank and act as ballast and vent the LOX tank so the stage doesn't pop?

Offline deruch

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Fairing recovery vessel, aka Mr. Steven is at LA port.

Yeah, no net or bounce house recovery attempt this time.  But they've recovered fairings or pieces that have landed in the water using GO Searcher (or Quest not sure which, but 1 of them).  So, they can track the returning fairing and hope it splashes down under its parachutes softly enough to stay intact.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline deruch

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Would it be possible to keep the first stage upright using the cold gas thrusters after soft splashdown for long enough to allow water to fill the RP-1 tank and act as ballast and vent the LOX tank so the stage doesn't pop?

No.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline CyndyC

GO Quest is the usual tracking vessel for ASDS landings. She was likely the "AOS" vessel standing by near the stage 1 splashdown zone.

GO Searcher was likely near the expected fairing splashdown zone, farther downrange.

More than likely. It sounds like Raul actually tracked the ships

Go Quest is at the position of probable booster water landing (former droneship landing position) - it means probably to receive telemetry of booster water landing here and visual check.

Go Searcher is at the position of probable fairing landing/splashdown – likely receive telemetry, try to recover the fairing or collect debris.
"Either lead, follow, or get out of the way." -- quote of debatable origin tweeted by Ted Turner and previously seen on his desk

Offline CyndyC

Yes, it appears a “toasty” landing might be successful. It seems SpaceX wishes to expend this booster. The reasons seem obvious, they are running out of room for stored boosters and have block 5s on the way. Why stick on the landing legs? Why are they cleaned? We are curious about the answer.

There are probably surplus, old model legs they don't need and it would be a good chance to test some things, like deploying the legs earlier.

And a good chance to have somewhere to dump them since the composite is not ideal for recycling ;). They might have also helped expend the RP-1 so less would pollute the ocean.
"Either lead, follow, or get out of the way." -- quote of debatable origin tweeted by Ted Turner and previously seen on his desk

Offline ValmirGP

Would it be possible to keep the first stage upright using the cold gas thrusters after soft splashdown for long enough to allow water to fill the RP-1 tank and act as ballast and vent the LOX tank so the stage doesn't pop?

Funny you asked that. Earlier I was making some back of the nap calculations to figure the booster density to find out if would float. I guess we all know the answer to that too...

No.

Offline Kabloona

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Isn't it likely the recovery ship was there to pick up the S1 after a successful splashdown. With empty tanks and a gentle touch down isn't there a good chance it is floating?

Touchdown is gentle until the stage topples over and the pressurized tanks smack the water and rupture. And even if the stage remained intact, GO Quest isn't equipped to salvage it.

And, once again, SpaceX proves us doubters wrong.

https://twitter.com/elonmusk/status/958847818583584768

Quote
This rocket was meant to test very high retrothrust landing in water so it didn’t hurt the droneship, but amazingly it has survived. We will try to tow it back to shore.

Now, let me be first to be wrong in predicting it won't survive the tow.  :)
« Last Edit: 01/31/2018 10:49 pm by Kabloona »

Offline abaddon

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Well I'll be a monkey's uncle.

To be fair, I think Elon is probably more amazed than we are.

Offline ValmirGP

Wow, update from Elon https://twitter.com/elonmusk/status/958847818583584768

Quote
This rocket was meant to test very high retrothrust landing in water so it didn’t hurt the droneship, but amazingly it has survived. We will try to tow it back to shore.

I Spoke too soon....

Wrong AND Wrong. My calculations were off the mark and it didn't pop. Amazing!

Offline ames

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9 engine landing burn? Was the mssion patch correct?

Offline Elthiryel

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9 engine landing burn? Was the mssion patch correct?

Elon confirmed on Twitter that it was actually a 3-engine landing burn.

Source: https://twitter.com/elonmusk/status/958848287628406784
GO for launch, GO for age of reflight

Offline jabe

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9 engine landing burn? Was the mssion patch correct?
Elon tweeted soon after it was only a 3 engine burn

Online docmordrid

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Nosferocket 👻
« Last Edit: 01/31/2018 11:03 pm by docmordrid »
DM

Online eriblo

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Would it be possible to keep the first stage upright using the cold gas thrusters after soft splashdown for long enough to allow water to fill the RP-1 tank and act as ballast and vent the LOX tank so the stage doesn't pop?

Funny you asked that. Earlier I was making some back of the nap calculations to figure the booster density to find out if would float. I guess we all know the answer to that too...

No.
It's very easy to estimate whether rocket boosters float, especially for RP-1 fueled ones: The propellants density is close to that of water and they are mostly tankage, so the ratio of buoyancy force to weight is more or less the mass fraction (i.e. 15-20:1).
« Last Edit: 01/31/2018 11:07 pm by eriblo »

Offline Kabloona

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Cue the GO Quest captain.

« Last Edit: 01/31/2018 11:13 pm by Kabloona »

Offline Bubbinski

So they were testing a “high retrothrust” burn? 3 engine burn at 100% thrust or something like that? How would a high retrothrust burn help future recoveries?
I'll even excitedly look forward to "flags and footprints" and suborbital missions. Just fly...somewhere.

Offline kevinof

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How far out is it?

Offline king1999

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Nosferocket 👻
SpaceX's first torpedo. :)

Offline abaddon

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So they were testing a “high retrothrust” burn? 3 engine burn at 100% thrust or something like that? How would a high retrothrust burn help future recoveries?
More fuel efficient, allowing more impulse to be used for pushing the second stage.

Offline ThePonjaX

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Maybe the can add some boat engine and the rocket can return by itself   ;)

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