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#480
by
sfabris
on 08 Oct, 2013 21:10
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#481
by
neoforce
on 08 Oct, 2013 21:34
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No one did notice this? https://twitter.com/Wolfram66/status/387280929514725376
If you look closely, engine bell does not seams to be in good shape...
Sfabris
Here is a Youtube link that puts the video in HD and at the right time to see what happens. (couldn't get it to embed the video and start at the right time, so using a URL instead.)
Put the video in full screen and look at the top left part of the nozzle (around 10 o'clock) and you can actually see a piece on the edge get loose and then come off.
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#482
by
bubbagret
on 08 Oct, 2013 21:44
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It appeared to occur @ T+8:53...
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#483
by
mr. mark
on 08 Oct, 2013 22:47
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No one did notice this? https://twitter.com/Wolfram66/status/387280929514725376
If you look closely, engine bell does not seams to be in good shape...
Sfabris
Welcome to the website! While you seem to be correct about the bell, we should hesitate to speculate further without having more facts. It seems the conversation on the linked post goes beyond what has been stated by SpaceX. Someone infered the engine shreded. We have no information that this is correct. At nasaspaceflight.com you will find that people will ask you for factual information sources so be prepared to back up anything you post.
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#484
by
kevin-rf
on 08 Oct, 2013 23:35
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Didn't previous Vac Merlin's use stiffing bands to protect nozzle during first stage flight then came off in flight? Might this be one?
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#485
by
Kabloona
on 08 Oct, 2013 23:59
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Didn't previous Vac Merlin's use stiffing bands to protect nozzle during first stage flight then came off in flight? Might this be one?
The stiffeners come off at ignition.
Marsman has suggested elsewhere in the forum that the piece seen coming off here is merely residual adhesive from the stiffeners, and I believe he is correct.
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#486
by
Comga
on 09 Oct, 2013 00:16
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Both shedding events are seen in the visible imagery.
Good catch, sfabris, and welcome. Excellent first post.
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#487
by
bubbagret
on 09 Oct, 2013 04:38
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Didn't previous Vac Merlin's use stiffing bands to protect nozzle during first stage flight then came off in flight? Might this be one?
The stiffeners come off at ignition.
Marsman has suggested elsewhere in the forum that the piece seen coming off here is merely residual adhesive from the stiffeners, and I believe he is correct.
That it is adhesive ablation would appear to be a very plausible explanation.
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#488
by
Hooperball
on 09 Oct, 2013 13:14
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If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?
If that was a chip coming off the engine bell late in the burn. Larger pieces could have come off during the restart attempt and this may be the debris being tracked by ground based radar....
S
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#489
by
guckyfan
on 09 Oct, 2013 13:45
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If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?
More likely the stiffener is required for ground handling and/or vibrations during first stage flight.
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#490
by
kevin-rf
on 09 Oct, 2013 14:04
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If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?
More likely the stiffener is required for ground handling and/or vibrations during first stage flight.
Bingo, the Merlin isn't the only second stage engine that uses them. They are designed to come off once they are no longer needed.
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#491
by
JBF
on 09 Oct, 2013 14:22
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If stiffeners are needed for the first MVac start wouldn't they be needed for a restart?
More likely the stiffener is required for ground handling and/or vibrations during first stage flight.
Bingo, the Merlin isn't the only second stage engine that uses them. They are designed to come off once they are no longer needed.
Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
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#492
by
cambrianera
on 09 Oct, 2013 14:41
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Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
This is an old picture of the nozzle extension (2009 press release)
The Merlin Vacuum engine expansion nozzle measures 2.7 meters (9 feet) tall, and most of it has a wall thickness of about 1/3 of a millimeter (1/64 of an inch). Photo credit: SpaceX.
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#493
by
Garrett
on 09 Oct, 2013 15:00
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Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
Would the stiffener also cause problems (e.g. mechanical stress) once the bell metal begins to thermally expand?
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#494
by
cambrianera
on 09 Oct, 2013 15:30
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Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
Would the stiffener also cause problems (e.g. mechanical stress) once the bell metal begins to thermally expand?
Don't know, but likely; I guess thermal cycle warping of the thin metal is possible.
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#495
by
Lars_J
on 09 Oct, 2013 15:34
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Is the weight penalty that bad with these that they don't design it into the bell? or is it just not possible?
On second stage 1 kg more of structure=1 kg less of payload.
This is an old picture of the nozzle extension (2009 press release)
The Merlin Vacuum engine expansion nozzle measures 2.7 meters (9 feet) tall, and most of it has a wall thickness of about 1/3 of a millimeter (1/64 of an inch). Photo credit: SpaceX.
Here is a newer (and closer to flight status) picture of a nozzle extension. The way it appears to rest on the ground probably supports the theory that the liner/stiffener is there to protect it during ground handling.
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#496
by
edkyle99
on 09 Oct, 2013 15:54
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Venting was:
Not seen before with this intensity/modality in five flights.
Quite energetic, not usual purging/venting.
It's clearly visible in frames of the movie.
From http://www.flickr.com/photos/jurvetson/10008137326/
There are a couple of videos of Merlin 1D ground tests, though not the Vacuum version. They show these engines venting immediately after shutdown in some fashion. The on board video looks like an expected type of event to me. It could be a purge.
Also, about the nozzle bit coming off, it is an external residual piece related to the stiffener, not a structural part of the nozzle itself.
- Ed Kyle
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#497
by
Nomadd
on 09 Oct, 2013 20:20
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Not to beat the "has nothing to do with Cassiope stiffener" thing to death, but didn't they have to remove the stiffener before launch on the first flight? Or did they put a shortened version back on after the nozzle was shortened?
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#498
by
corrodedNut
on 09 Oct, 2013 20:27
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Not to beat the "has nothing to do with Cassiope stiffener" thing to death, but didn't they have to remove the stiffener before launch on the first flight? Or did they put a shortened version back on after the nozzle was shortened?
The latter, IIRC.
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#499
by
ugordan
on 09 Oct, 2013 20:30
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Not to beat the "has nothing to do with Cassiope stiffener" thing to death, but didn't they have to remove the stiffener before launch on the first flight? Or did they put a shortened version back on after the nozzle was shortened?
2nd F9 flight and yes, they put
a stiffener back on. Fell off at around T+ 4 m 12 s