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#880
by
maitri982
on 08 Jan, 2018 15:44
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Planning a long distance trip for this one might require some quick reflexes. You can't really count on a launch date until they conduct a good static fire, and after conducting a good static fire it might not be that long (a couple/few weeks) before the launch attempt. Late January seems to be the current target, let's see what happens with testing in the next week.
HA!!! No need to tell me. I have tried twice to make launches (I live in Central PA...so not a short trip) and have been foiled over and over again. Once by damn air force radar not working on what would have been beautiful day for launch.
I have scheduled trip for January 27-Feb 4th. So may the launch gods have some mercy on me for once.
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#881
by
oiorionsbelt
on 08 Jan, 2018 16:00
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Even the hold down firing test will be pretty exciting. If27 engines are starting up with 0.2secs between each pair that alone will last close to 3 secs between the first and the last pair igniting.
Is it certain that it's two engines at a time or two engines per core at a time?
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#882
by
oiorionsbelt
on 08 Jan, 2018 16:21
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To follow up on that question, what single engine will fire last? 27 and 9 are odd numbers.
I assumed two per core with the center engine last.
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#883
by
AncientU
on 08 Jan, 2018 16:34
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Even the hold down firing test will be pretty exciting. If27 engines are starting up with 0.2secs between each pair that alone will last close to 3 secs between the first and the last pair igniting.
Is it certain that it's two engines at a time or two engines per core at a time?
My understanding was one per core at a time, separated by 120ms. -- whole start about one second in duration, which we won't see except in slo-mo replay.
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#884
by
wannamoonbase
on 08 Jan, 2018 17:09
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Even the hold down firing test will be pretty exciting. If27 engines are starting up with 0.2secs between each pair that alone will last close to 3 secs between the first and the last pair igniting.
Is it certain that it's two engines at a time or two engines per core at a time?
My understanding was one per core at a time, separated by 120ms. -- whole start about one second in duration, which we won't see except in slo-mo replay.
I recall it being pairs, 2 at a time, not 1 per core.
Edit: This is likely one, as well as staging are areas where they expect to tune (shorten) this once they get operational data and experience.
Edit-Edit: I like that SpaceX takes this approach. NASA would spent billions and years modeling and testing. SpaceX builds, assemblies, flies, gets paid, changes and fly again. I really like this iterative approach, it has huge advantages for companies that have to pay their own way.
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#885
by
BeamRider
on 08 Jan, 2018 17:30
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In reference to “launching straight up”, my understanding would be that this would NOT be a valid test of the vehicle. I am under the impression that when launching into orbit, LEO or GTO, the rocket stack experiences some non-trivial amount of aerodynamic “lift” force after it has assumed a horizontal trajectory. If this is true, launching straight up would not be a real test of the flight or booster sep characteristics.
If I am wrong I would appreciate correction. I think I heard EM make reference to the lift characteristics of a cylinder in this regard, and without some lift, I fail to see how the whole thing would not fall into a ballistic trajectory that terminated into the ocean. I appreciate that at exo-atmospheric altitudes there would be no aerodynamic forces, but at the altitudes up to and including side-booster sep, there could certainly be some.
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#886
by
Paul_G
on 08 Jan, 2018 17:42
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In reference to “launching straight up”, my understanding would be that this would NOT be a valid test of the vehicle. I am under the impression that when launching into orbit, LEO or GTO, the rocket stack experiences some non-trivial amount of aerodynamic “lift” force after it has assumed a horizontal trajectory. If this is true, launching straight up would not be a real test of the flight or booster sep characteristics.
If I am wrong I would appreciate correction. I think I heard EM make reference to the lift characteristics of a cylinder in this regard, and without some lift, I fail to see how the whole thing would not fall into a ballistic trajectory that terminated into the ocean. I appreciate that at exo-atmospheric altitudes there would be no aerodynamic forces, but at the altitudes up to and including side-booster sep, there could certainly be some.
Launching straight up will not get you to orbit. To go to orbit, you need to be moving very fast sideways, not so much up ways. On ascent, I don't think the lift of the stage (the cylinder) is a hugely meaningful part of the force needed to get into orbit, however on its way down, the lift does come in to play. My understanding is that SpaceX use the gridfins to position the stage so that it can use that lift to control where the stage comes down.
Paul
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#887
by
Greg Hullender
on 08 Jan, 2018 17:46
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My impression was that there's enough lift that you have to take it into account, but not enough that it's worth trying to exploit. Someone probably has precise figures.
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#888
by
ChrisGebhardt
on 08 Jan, 2018 18:42
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#889
by
maitri982
on 08 Jan, 2018 19:10
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#890
by
Formica
on 08 Jan, 2018 19:25
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Pure speculation: might we see a second static fire? Much and more has been made of the complexity of lighting twenty seven engines. It would seem logical to analyze the first static fire and then, based on that, optimize and test again before launching.
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#891
by
envy887
on 08 Jan, 2018 19:52
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Pure speculation: might we see a second static fire? Much and more has been made of the complexity of lighting twenty seven engines. It would seem logical to analyze the first static fire and then, based on that, optimize and test again before launching.
Unless the first one goes perfectly, there will probably be a second.
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#892
by
spacetraveler
on 08 Jan, 2018 19:59
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Launch date is end of January per Elon's instagram:
Falcon Heavy now vertical on the former Apollo 11 moon rocket launchpad. At 2500 tons of thrust, equal to 18 Boeing 747 aircraft at full throttle, it will be the most powerful rocket in the world by a factor of two. Excitement on launch day guaranteed, one way or another.
Hold-down test fire next week. Launch end of the month.
Even the hold down firing test will be pretty exciting. If27 engines are starting up with 0.2secs between each pair that alone will last close to 3 secs between the first and the last pair igniting.
Anyone. Any idea how long for a Merlin to get to steady state on these tests? will they have all of them run together, or will they shut down each pair as it reaches steady state?
I have to believe they want to get at least some data for all engines burning concurrently.
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#893
by
FutureMartian97
on 08 Jan, 2018 20:43
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If we see FH go back into the hanger we'll know the Zuma mishap was a vehicle issue.
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#894
by
GeneBelcher
on 08 Jan, 2018 20:45
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#895
by
AncientU
on 08 Jan, 2018 20:46
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If we see FH go back into the hanger we'll know the Zuma mishap was a vehicle issue.
Don't get out ahead of the headlights... 'the Zuma mishap' is TBD, and FH
is on the pad morning after launch.
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#896
by
deruch
on 08 Jan, 2018 21:09
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And now on the pad!
Note: Payload is attached
Great view of the reaction frame as well.
https://twitter.com/SkeerRacing/status/950406990387433473
What's the red/ping ring around the boosters? Looks like something wrapped around and over the attach points of the grid fins.
"Plastic wrap" for moisture protection. It is over the joints between stages. They do it for F9 launches too.
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#897
by
Inoeth
on 08 Jan, 2018 21:39
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If we see FH go back into the hanger we'll know the Zuma mishap was a vehicle issue.
Perhaps you're right... I entirely missed the info about the possible Zuma issue... tho the fact that they rolled out the FH this morning many, many hours after the launch makes me guess that whatever issue Zuma is having, it's not SpaceX's fault.
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#898
by
moralec
on 08 Jan, 2018 21:50
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I never really understood why the Tropics of Cancer and Capricorn were special.
On the day of the equinox at the equator at noon, a vertical pole casts no shadow and you can see to the bottom of your well. Every day after that equinox, the sun will be off-vertical more and more at noon on the equator and will cast a longer and longer shadow each day until the solstice, where shadows would then get shorter until the next equinox.
If you’re a little above the equator, the day the sun casts no shadow at noon is a few days after the equinox, this day gets further and further from the equinox the more north or south you go (depending on the season). On the summer solstice, the place where the sun casts no shadow is along the Tropic of Cancer. It is the most northerly circle of latitude on Earth at which the Sun can be directly overhead. The same happens along the Tropic of Capricorn on the day of the winter solstice.
This is one of my favourite posts ever. Totally offtopic but amazing nonetheless.
Sent from my iPhone using Tapatalk
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#899
by
russianhalo117
on 08 Jan, 2018 21:50
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If we see FH go back into the hanger we'll know the Zuma mishap was a vehicle issue.
Perhaps you're right... I entirely missed the info about the possible Zuma issue... tho the fact that they rolled out the FH this morning many, many hours after the launch makes me guess that whatever issue Zuma is having, it's not SpaceX's fault.
Chris G already said in the updates thread that SpaceX said the Falcon 9 performed and completed it's flight nominally.