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#540
by
Antares
on 16 Oct, 2013 15:13
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#541
by
mr. mark
on 16 Oct, 2013 15:28
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Have to say I'm really excited that the first stage was able to successfully execute the first retro propulsion maneuver and well as getting so close on secondary burn despite impact. This deserves a follow up article...Chris?
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#542
by
Norm38
on 16 Oct, 2013 15:31
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http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.pngI'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
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#543
by
Lars_J
on 16 Oct, 2013 15:34
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If that is indeed a second (or less) before impact, then yes the engine must have just starved - it is still producing some thrust to create the cloud ring(?) over the water surface. This means that this restart must have been attempted VERY close to the surface...
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#544
by
notsorandom
on 16 Oct, 2013 15:38
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http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.png
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
It has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
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#545
by
guckyfan
on 16 Oct, 2013 15:42
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http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.png
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
It has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
I am certain it was spinning before the engine started. But the engine must start a fair distance from the surface to have time for braking. So if this is immediately before impact the engine cannot be running unless it was started way too late.
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#546
by
Lars_J
on 16 Oct, 2013 15:50
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The final braking burn NEEDS to start very late - there isn't enough propellant to do a nice slow descent. (at least once operational - this flight probably had more margin) But until the video is released, I guess we won't see exactly how late it was started.
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#547
by
LegendCJS
on 16 Oct, 2013 15:51
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http://www.spacex.com/sites/spacex/files/11_c439042b-ee14-45c7-aa50-6f0f6396b0db.png
I'm confused about what we're seeing in this shot. Is the engine firing or not? It looks like it, but then some things don't add up.
If this image literally is 1 second before impact, as Padrat said, and the engine is firing, that means the rocket spun up and flamed out in less than a second, immediately after this shot. But in that case it must have already decelerated significantly and couldn't have had much braking left to do, and thus didn't hit *that* hard.
Anyone have a guess how fast it might have been going at impact? Is it already spinning significantly in this shot?
It has been postulated by other more knowledge posters than I that there was enough propellant in the feed lines for the engine to start and burn for a little while. It might have been spinning already when the engines started.
I am certain it was spinning before the engine started. But the engine must start a fair distance from the surface to have time for braking. So if this is immediately before impact the engine cannot be running unless it was started way too late.
Sure, but an engine flaming out and starving for fuel isn't going to be a clean shutdown step function. Imagine it sputtering and coughing all the way into the drink? Especially as the turbo pumps are driven by a pre-burner that needs fuel as well to turn- the pumps would have slowed, forcing the last spurts of fuel through much more slowly than full blast to empty.
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#548
by
kevin-rf
on 16 Oct, 2013 15:52
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I am certain it was spinning before the engine started. But the engine must start a fair distance from the surface to have time for braking. So if this is immediately before impact the engine cannot be running unless it was started way too late.
Remember SpaceX said the pumps came uncovered during the attempted water landing due to the spin caused by the control system not being able to compensate. Meaning the second restart worked, it was working it's way down towards the water, then the engine shut down at some point above the water. Judging by the photo, it is at some point after this picture...
If I was a POA I would release the image as close to the water as possible, so we could most likely assume that the next frame or two has engine shutdown.
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#549
by
Lars_J
on 16 Oct, 2013 15:54
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Here is a tweet:
https://twitter.com/jeff_foust/status/390503333561401344Jeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Presumably this is the picture we have been discussing.
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#550
by
mr. mark
on 16 Oct, 2013 15:59
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OMG that's only 10 feet off the water! Fully intact Yowza!
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#551
by
Kasponaut
on 16 Oct, 2013 16:07
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Here is a tweet: https://twitter.com/jeff_foust/status/390503333561401344
Jeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Presumably this is the picture we have been discussing.
Where can we see that picture?
Kasper
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#552
by
Silmfeanor
on 16 Oct, 2013 16:16
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Here is a tweet: https://twitter.com/jeff_foust/status/390503333561401344
Jeff Foust
@jeff_foust
Shotwell shows a picture of the F9 1st stage from the previous launch just 3 meters above the ocean before splashdown, "fully intact" #ispcs
Presumably this is the picture we have been discussing.
Where can we see that picture?
Kasper
Really?
.....8 posts above your reply. And earlier in this thread, before that.
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#553
by
Antares
on 16 Oct, 2013 16:22
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that's only 10 feet off the water. Fully intact
Why is that surprising? If the stage had been torn up by aero, it would have happened at higher q (or q-alpha) when it was traveling much faster. Impact would have been much more destructive than low q aero.
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#554
by
Jim_LAX
on 16 Oct, 2013 16:25
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Just 10 feet away from complete success! No wonder Elon is saying that all the pieces are in place.
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#555
by
AnjaZoe
on 16 Oct, 2013 16:25
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The final braking burn NEEDS to start very late - there isn't enough propellant to do a nice slow descent. (at least once operational - this flight probably had more margin) But until the video is released, I guess we won't see exactly how late it was started.
What's the thrust to weight ration of 1 throttled 1D engine and the nearly empty stage? I can imagine that firing the engine too long will eventually result in the stage taking off again.
Zoe
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#556
by
Antares
on 16 Oct, 2013 16:32
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Why do people keep asking questions that are proprietary to SpaceX?
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#557
by
Lars_J
on 16 Oct, 2013 16:36
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Why do people keep asking questions that are proprietary to SpaceX?
Since the dawn of this forum?
Why get annoyed over it now? Asking is one thing... getting an answer is another.
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#558
by
AnjaZoe
on 16 Oct, 2013 16:42
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Why do people keep asking questions that are proprietary to SpaceX?
if you refer to my question, methinks the thrust of the 1D was published mutliple times (with multiple values varying over time
) on the Space-X page; the mass of the stage should be able to be derived from the total mass of the stage (should also have been mentioned somewhere on the F9 fact sheet) and the amount of fuel.
So what's so proprietary about it? Next thing I will hear is that the name of the company founder is a piece of classified information subject to ITAR...
Zoe
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#559
by
mlindner
on 16 Oct, 2013 16:58
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Jeff Foust
@jeff_foust
This is the photo Shotwell showed of the F9 1st stage just before splashdown (h/t @kkairq): http://bit.ly/1byP9S3
It's the same image, so thats 3m above the ocean, confirmed.
Why get annoyed over it now? Asking is one thing... getting an answer is another.
) on the Space-X page; the mass of the stage should be able to be derived from the total mass of the stage (should also have been mentioned somewhere on the F9 fact sheet) and the amount of fuel.