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#1360
by
Jim
on 24 Jan, 2018 16:45
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Does someone have a comparison between Delta IV Heavy and FH first launch preparations? My search skills couldn'the locate anything yet.
Delta IV Heavy first went vertical Dec. 10th 2003 and launched Dec. 21st 2004. So Delta IV Heavy preparations took over a year. And the payload did not deploy to the correct orbit.
That's a fair comparison. Two cases of a three-barrel where the individual barrels are already known.
Clearly not a trivial issue.
Actually not. Delta IV Heavy used three unique cores than are not used on any other versions. Their early trade studies and design decisions, along with under performance really f'ed up the "common" core concept. Atlas V Heavy would have avoided many of these issues. The Boeing EELV scandal and Air Force wrongfully award of the majority of the missions to Boeing really messed up the EELV program and what it could have achieved.
Good to know, thx.
However, in the grand scheme of things, how far off are the individual DIV barrels from the single stick one?
It's the same engine, similar (at least) tanks, similar (at least) avionics, no?
Just sounds like as with SpaceX they found out that the heavy is more complex then they thought, and ended up not where they thought they would.
Atlas may have worked out better - I don't have the information to judge.
SpaceX ended up with dissimilar cores too, right? Plus the added interactions, (which I'm sure are more significant after release) and there it is, getting debugged on the pad.
At least they have two pads...
The side boosters are mirror images of each other and the core is heavily reinforced, since the basic core was lighten to meet performance goals for single stick missing
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#1361
by
abaddon
on 24 Jan, 2018 16:54
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Video from Dennis Kapatos on YouTube
In this one, it might be my imagination, but it seems like you can pick out waves in the exhaust cloud from the staggered engine start.
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#1362
by
ugordan
on 24 Jan, 2018 16:56
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In this one, it might be my imagination, but it seems like you can pick out waves in the exhaust cloud from the staggered engine start.
Nah, I think that was already over by the time the recording started. What we're seeing there is probably interaction with the leftover water in the flame trench.
What *can* definitely be seen is that the 2nd stage vents at 7 seconds into the video so that marks the end of the burn. Give it a second or so before the clip started and it roughly matches my earlier 8-ish second estimate.
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#1363
by
Flying Beaver
on 24 Jan, 2018 16:57
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Video from Dennis Kapatos on YouTube
Only 8 seconds shown here, plus at most a 2 second lead before it started recording.
Also the plume picks up in energy maybe 2 seconds into the video. Could the ignition staggering have been increased? It would almost seem so going off of the audio from Chris G.'s stream, where it seemed like staggered ignitions could be heard.
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#1364
by
JonathanD
on 24 Jan, 2018 17:04
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#1365
by
Rocket Science
on 24 Jan, 2018 17:04
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Now, let's analyze the data stream...
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#1366
by
kking
on 24 Jan, 2018 17:07
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WOW!! about time. Beautiful site! Way to go Spacex! Wonder if we will have a launch date soon.
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#1367
by
mfck
on 24 Jan, 2018 17:10
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THAT SOUND. I am wet
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#1368
by
DrRobin
on 24 Jan, 2018 17:11
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And the rocket is still there! Yay!
Kind of a inverse Star Spangled Banner, where not the Flag but the Rocket's still there! (and thank goodness,
nothing bursting in air!)
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#1369
by
Lars-J
on 24 Jan, 2018 17:12
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#1370
by
ugordan
on 24 Jan, 2018 17:14
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#1371
by
Lars-J
on 24 Jan, 2018 17:16
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Looks like about 8 seconds, assuming the video caught the start.
No, I would guess 10+... This is the best view, and it doesn't even show the beginning. (probably started 1-2 secs before video)
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#1372
by
Kabloona
on 24 Jan, 2018 17:19
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...cutoff is clearly at about the 8 second point in the video.
Hawk-eyed ugordan noted upthread that S2 vents 7 seconds into the video, ie end of burn.
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#1373
by
mme
on 24 Jan, 2018 17:20
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THAT SOUND. I am wet
So is my keyboard. (I was sipping my coffee when I read your comment.)
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#1374
by
Alpha Control
on 24 Jan, 2018 17:20
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Great day in Florida! Fire & smoke from a new rocket!
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#1375
by
abaddon
on 24 Jan, 2018 17:21
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Wonder how long we will have to wait for official word from SpaceX, hopefully including whether the burn was as long as they intended, and if they plan to do another.
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#1376
by
ugordan
on 24 Jan, 2018 17:22
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I'm with Ed, looked like around 8, maybe 9 seconds to me, but that's beside the point. They ignited it right off the start and it burned long enough for steady state to kick in so maybe it was some conservative limit that triggered an early abort so, all in all, it looked like a very useful test. I was skeptical they'd even manage to ignite it today.
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#1377
by
abaddon
on 24 Jan, 2018 17:24
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#1378
by
Ademptis
on 24 Jan, 2018 17:25
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From the sound alone:
There's the initial boom, then ~4s pause before the main rumbling of the engines. The main firing seems to only be 6 seconds from listening to it.
I attached the sound file I used.
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#1379
by
meekGee
on 24 Jan, 2018 17:26
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Does someone have a comparison between Delta IV Heavy and FH first launch preparations? My search skills couldn'the locate anything yet.
Delta IV Heavy first went vertical Dec. 10th 2003 and launched Dec. 21st 2004. So Delta IV Heavy preparations took over a year. And the payload did not deploy to the correct orbit.
That's a fair comparison. Two cases of a three-barrel where the individual barrels are already known.
Clearly not a trivial issue.
Actually not. Delta IV Heavy used three unique cores than are not used on any other versions. Their early trade studies and design decisions, along with under performance really f'ed up the "common" core concept. Atlas V Heavy would have avoided many of these issues. The Boeing EELV scandal and Air Force wrongfully award of the majority of the missions to Boeing really messed up the EELV program and what it could have achieved.
Good to know, thx.
However, in the grand scheme of things, how far off are the individual DIV barrels from the single stick one?
It's the same engine, similar (at least) tanks, similar (at least) avionics, no?
Just sounds like as with SpaceX they found out that the heavy is more complex then they thought, and ended up not where they thought they would.
Atlas may have worked out better - I don't have the information to judge.
SpaceX ended up with dissimilar cores too, right? Plus the added interactions, (which I'm sure are more significant after release) and there it is, getting debugged on the pad.
At least they have two pads...
The side boosters are mirror images of each other and the core is heavily reinforced, since the basic core was lighten to meet performance goals for single stick missing
FWIW, I hate mirrored assemblies with a passion, since they never really are.
