SpaceX First Stage Propulsive landing Discussion

Roundaboutdan

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Rumour I heard was they were planning on flipping the first stage round after separation, performing a powered reentry and attempting to 'land' on the ocean surface a la Grasshopper (minus legs etc. of course, so just a low speed splash!). That would be rather cool......
 

PhantomCruiser

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That would be rather cool. And it'd be in the middle of nowhere so no harm done if it doesn't work as planned. If nothing else it would make for good data gathering outside of what the computer models predict.
 

Urwumpe

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Rumour I heard was they were planning on flipping the first stage round after separation, performing a powered reentry and attempting to 'land' on the ocean surface a la Grasshopper (minus legs etc. of course, so just a low speed splash!). That would be rather cool......

Would be pretty doubtful to happen - how much value would have such a test, if nobody could receive the telemetry (Unless you are lucky enough to place a ship within ~24 km of the splash site, which would be a rather big ellipse after lots of tumbling and shutdown inaccuracy)? Additionally, such modifications to the flight control software on a maiden flight would be extremely risky. What if the rocket decides right after launch, that it should turn around and land?
 

Galactic Penguin SST

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Would be pretty doubtful to happen - how much value would have such a test, if nobody could receive the telemetry (Unless you are lucky enough to place a ship within ~24 km of the splash site, which would be a rather big ellipse after lots of tumbling and shutdown inaccuracy)? Additionally, such modifications to the flight control software on a maiden flight would be extremely risky. What if the rocket decides right after launch, that it should turn around and land?

This is the source of the "rumor" (not quite actually, seeing that it's from a presentation from a SpaceX employee): http://forum.nasaspaceflight.com/index.php?topic=30385.msg1023706#msg1023706

I agree that it has its own risks - there are many software code changes that could bring the rocket down. Then again, given that this is half a new rocket, the risk is already there anyway (see the first launches of Ariane 5 and Delta III to see how slapping old systems to a new rocket configuration can make things go all wrong). Being the first flight of v1.1 (actually should be 1.5.....) with a less costly payload (than a Dragon CRS flight or a big communication satellite or a NASA mission), this is already the best chance to test such a thing. And I guess even another failure wouldn't hurt too much at this stage, seeing that it's still the poster child of NewSpace (TM) ..... :chainsaw:
 

Urwumpe

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Only because you already have high risks, this does NOT mean, you can not have higher risks. ;)

Also, if it fails, you would have so much stuff in the failure path, that you can't draw many conclusions from it for other 1.1 launches. It would be a big expensive firework if it fails, and a pretty useless test for telling much about the other 1.1 launches.

You can only do so, if you recover the first stage in every flight.
 

Urwumpe

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What if rocket decides it is time to separate second stage?

What if rocket is told during desperate launch processing that it is time to ignite the second stage engine... :facepalm:

Its already 52 years in the past, but still a big red warning sign of the importance of safety procedures...
 

Kyle

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Well, there's nothing to loose either way whether they decide to crash it into the ocean at terminal velocity or at a much lower speed. Looks like SpaceX is going to do it, they've been putting a lot of time and have been making a lot of progress with that Grasshopper.
 
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Urwumpe

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Well, there's nothing to loose either way whether they decide to crash it into the ocean at terminal velocity or at a much lower speed. Looks like SpaceX is going to do it, they've been putting a lot of time and have been making a lot of progress with that Grasshopper.

Nothing aside of the launch... again, even a software modification is not less of an modification, as if they would install a tenth engine somewhere.
 

Kyle

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Nothing aside of the launch... again, even a software modification is not less of an modification, as if they would install a tenth engine somewhere.

It's all part of the game, you've got to take the risk sometime. Eventually it will be crewed.

If it blows up, figure out what happened and try again - all part of R&D. :cheers:
 

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Well, why we heavy discus already how there gonna soft splashdown the Falcon 1.1 first stage when there is only one unknown source who noted this? Don't forget also if there will do it that you need more then landing. You need a good software code for the AP to doing this steps, add parachutes to it, and to send a recovering ship (All of this three things cost money) to get the first stage back home. Without parachutes, you need more fuel and a strict correct AP to doing this sucessful.

But we must first see that the first launch of the Falcon-9 1.1 become successful or not, and if it is a success, then there can look to the next step.
 
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MaverickSawyer

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Agreed. Fly it first, and prove that it works in the new configuration. THEN try for the semi-Grasshopper approach and see if you can do it. I would suggest doing it on the strapons of the Falcon Heavy, not the core stage.
 

Kyle

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Just an update, they are indeed going to flip the 1st stage around and re-ignite it in a "first stage water landing."
Musk: SpaceX to Attempt Falcon 9 First Stage Water Landing

During the initial test, the first stage will continue on a ballistic arc and execute a velocity reduction burn to cushion its re-entry into the atmosphere, the SpaceX chief said. Just before splashdown, the rocket will light up its engines again.
 

Urwumpe

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What is there left to say other than: Don't fail this launch, SpaceX. :shifty:

If the main objectives of the flight are achieved, its good enough. If all test objectives are achieved, it would be a badly heroic flight. If it fails to achieve any of them, it would be a PR and an engineering disaster at once.
 

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What this discussion is basically saying is "business vs safety". Since the launch is unmanned, there's really no safety issue either, just the potential loss of the payload. SpaceX doesn't insure launches, so they don't stand to loose if the launch goes bad. The way I see it, the more they can test per launch, the better. I'm sure in a few years when crewed launches begin, Elon will be far more conservative considering most launches will be crewed, and SpaceX will have less opportunity to push the envelope and so the big risk taking should be done now. With that said, I think there's not much chance of anything going south with this landing attempt. I think the same software that has been working great so far will be the same until post staging when the newer code will take over, by which time the upper stage will have ignited and left the first stage behind.
 

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What this discussion is basically saying is "business vs safety". Since the launch is unmanned, there's really no safety issue either, just the potential loss of the payload. SpaceX doesn't insure launches, so they don't stand to loose if the launch goes bad. The way I see it, the more they can test per launch, the better. I'm sure in a few years when crewed launches begin, Elon will be far more conservative considering most launches will be crewed, and SpaceX will have less opportunity to push the envelope and so the big risk taking should be done now. With that said, I think there's not much chance of anything going south with this landing attempt. I think the same software that has been working great so far will be the same until post staging when the newer code will take over, by which time the upper stage will have ignited and left the first stage behind.

Well, because there use a new type of the Merlin-1 engine for the first stage, and because SpaceX needs more good PR then any government space agency because SpaceX is a "Private" (Yes, in parentheses) spaceflight company. There almost must have a good first launch for the Falcon-1.1, or else much future customers begin to be nervous. And then even NASA begins to be nervous, especially when there comes a next failed launch in less then a year. And then we not even talk about the R&D what must go almost be back to the drawing table if something bad happens about this launch.

And, there is no landing of the first stage planned in this mission.
 

MaverickSawyer

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Right, it's just checking some of their concepts and control systems. It would be stupid to try a landing right off the bat.
 

Urwumpe

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Right, it's just checking some of their concepts and control systems. It would be stupid to try a landing right off the bat.

It is already now no really wise decision, it is pretty rushed. But if it works, nobody has a right to complain. If it does not work out... well, everybody said it before, right? ;)
 

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White knuckle is always fun !!
 

Mader Levap

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I dont understand why some folks have problems with it.

Some other launches have very complex flight plan with multiple burns, at least three stages, hours of coasting etc. You can as well ask "what if during 5-th second of launch computer will think it is time to execute second orbital burn of thrid stage?".

I don't hear Urwumpe or anyone else complaining about these other launches. I hear only that somehow SpaceX risks so horribly with this re-ignite post-separation.
 
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