Author Topic: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 1)  (Read 316504 times)

Offline R.Simko

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Re: SpaceX Falcon 9 v1.1
« Reply #1230 on: 03/09/2013 04:56 PM »
Any chance they can do the water landing in shallow water, in case the rocket breaks up or sinks?  Makes it a lot easier to retrieve.

Offline Jason1701

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Re: SpaceX Falcon 9 v1.1
« Reply #1231 on: 03/09/2013 05:04 PM »
So if the center engine creates a bowl wider than 3.3 m, the rocket could descend into the bowl, which would then get deeper. I wonder how deep it could descend before the top of the bowl collapses and swallows the booster!

Sounds like an xkcd what-if topic.

Offline joek

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Re: SpaceX Falcon 9 v1.1
« Reply #1232 on: 03/09/2013 05:10 PM »
Right now, SpaceX views their manifest is basically a self-funding technology development program (not something that customers love, I'm sure) but so far it seems to have a good chance of working out for both sides.

Unless the development is seen as beneficial by customers, especially if they see that the costs and risks are spread across many.

edit: To clarify... Agree; I think that's something that most customers find attractive and will work to the benefit of both SpaceX and their customers.
« Last Edit: 03/09/2013 05:51 PM by joek »

Offline go4mars

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Re: SpaceX Falcon 9 v1.1
« Reply #1233 on: 03/09/2013 05:32 PM »
So if the center engine creates a bowl wider than 3.3 m, the rocket could descend into the bowl, which would then get deeper. I wonder how deep it could descend before the top of the bowl collapses and swallows the booster!
Interesting question.  Old footage of Sea Bee and Sea Horse implies to me, not very deep, but if I'm wrong, and if the stage could handle it, a "brown pants ocean landing" would be interesting. 

If needed, to make a big enough "bowl", perhaps a 5 engine (9 is probably not survivable for the stage at that point) very high-g puddle dimpler maneuver would save fuel and allow them to arrive at the ocean surface with a fair bit of speed (actually landing in a highly agitated water tube filled with a steam cushion).   Thrust transient could be the denouement.

The difference in fuel use between that, and doing a dry land brown pants landing might be negligible, now that I think about it a little more. 

A new name for brown pants landing:  Shedoudami Landing. 
As in "That scared the shedoudami!"        Say it out loud...
« Last Edit: 03/11/2013 11:38 AM by go4mars »
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Offline kch

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Re: SpaceX Falcon 9 v1.1
« Reply #1234 on: 03/09/2013 07:56 PM »
So if the center engine creates a bowl wider than 3.3 m, the rocket could descend into the bowl, which would then get deeper. I wonder how deep it could descend before the top of the bowl collapses and swallows the booster!

Sounds like an xkcd what-if topic.

Well, the exhaust gases would flow up the sides of the booster, possibly keeping the water away.  It might just keep right on going, descending into the "bowls" of the Earth ... :D

Online Prober

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Re: SpaceX Falcon 9 v1.1
« Reply #1235 on: 03/11/2013 11:32 AM »
It will displace some water - proportionally to the engine thrust, but not 100%. So, just before "touchdown" there should be a bowl of about several dozens cubic meters volume, I'd love to see that :)

Hmmm, maybe they will try to "touchdown" at a negative altitude of a couple of meters for this test then, depending on how deep the "bowl" is, the effects of the bowl collapsing on engine shutdown, and the floating stability of the stage. Falling over and buckling can't be good for recovery prospects.

@everyone
don't focus on the water landing or miss the real test.
I have not failed. I've just found 10,000 ways that won't work. ~ by Thomas Alva Edison

Offline Okie_Steve

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Re: SpaceX Falcon 9 v1.1
« Reply #1236 on: 03/11/2013 08:35 PM »
don't focus on the water landing or miss the real test.
Yep, totally agree. It's just that Spacex seems to like to have a long string of possible tests if everything works, or until something goes wrong so they get the most for their testing $$. Think of COT2+ for example. It would not surprise me if the much discussed rotation of the 1st stage after separation was preliminary testing for the V1.1 flip maneuver for example. So for the V1.1 flight there are a bunch of probably objectives as I see it.

1 - Does it fly norminally
2 - Can the 1st stage be flipped and stabilized with cg thrusters to orient for reentry.
3 - Can the 1st stage avionics settle fuel and restart the engine properly
4 - Can they maintain stable attitude and trajectory down to subsonic speeds
5 - Can they do a hoverslam to the ocean surface
6 - Can they recover the stage and engines
7 - What does forensic analysis tell them about their design assumptions
8 - etc.

Obviously number 1 is the biggie for the V1.1 vehicle and launching for paying customers, but the further down the list they get on any given flight the more they learn towards F9R and future projects. I was just curious about the water landing and recovery since I'd not really thought in those terms before but it's certainly not "that important" in the near term compared to things higher up the list. Feel free to add or reorder as you see fit.

Offline modemeagle

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Re: SpaceX Falcon 9 v1.1
« Reply #1237 on: 03/11/2013 11:03 PM »
I did some simulations and came up with a preliminary figure with the following:
If SI is shut down with ~ 3km/s delta-v residual prop (this is with the upper stage mass removed) then the vehicle could be 24km down range, 85 km altitude and with a apogee of 168km. This could land ~100km down range after removing all horizontal velocity at apogee (~523m/s).  This is just one simulation run I ran and it still gave just over 700 m/s residual prop on SII at MECO.  I am not saying this is what they are doing, just that the payload for CASSIOPE is small enough that they should have a lot of room for reserve propellant.

Online oiorionsbelt

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Re: SpaceX Falcon 9 v1.1
« Reply #1238 on: 03/12/2013 03:46 PM »
That's interesting modemeagle.
Did anyone figure out how SpaceX will resolve the over the horizon telemetry acquisition for this flight?

Offline Jim

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Re: SpaceX Falcon 9 v1.1
« Reply #1239 on: 03/12/2013 04:30 PM »
TDRSS

Online oiorionsbelt

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Re: SpaceX Falcon 9 v1.1
« Reply #1240 on: 03/12/2013 04:35 PM »
Thanks. Any idea as to the expected landing/impact zone.

Offline Lar

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Re: SpaceX Falcon 9 v1.1
« Reply #1241 on: 03/12/2013 05:23 PM »
TDRSS

Does NASA charge for use of TDRSS (bandwidth, time, bytes transferred ???) or is access to the network provided as a public utility?

I found this doc but I could not tell

http://sbir.gsfc.nasa.gov/SBIR/sbirsttr2010/solicitation/sbirsttr2010.rtf

(from http://sbir.nasa.gov )
"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

Offline Jim

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Re: SpaceX Falcon 9 v1.1
« Reply #1242 on: 03/12/2013 05:26 PM »

Does NASA charge for use of TDRSS


Yes

Offline mr. mark

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Re: SpaceX Falcon 9 v1.1
« Reply #1243 on: 03/12/2013 07:31 PM »
Thanks. Any idea as to the expected landing/impact zone.

I asked this same question about where the first stage impact (water landing) would be for the first Vandenburg flight. Hope someone can give us a possible answer.

Offline Lars_J

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Re: SpaceX Falcon 9 v1.1
« Reply #1244 on: 03/12/2013 07:56 PM »
Thanks. Any idea as to the expected landing/impact zone.

I asked this same question about where the first stage impact (water landing) would be for the first Vandenburg flight. Hope someone can give us a possible answer.

We don't know - it all depends on how much forward momentum they will try to kill before re-entry.

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