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#120
by
Galactic Penguin SST
on 29 Sep, 2013 01:16
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SFN now also has the press kit:
http://www.spaceflightnow.com/falcon9/006/UpgradedF9DemoMission_PressKit.pdf
"Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration."
Vs. another quote further down:
"The first stage engines are gradually throttled near the end of first-stage flight to limit launch vehicle acceleration as the rocket’s mass decreases with the burning of fuel."
Also, inconsistent durations of the 2nd stage burn in different places in the kit - 5m57s vs. 6m17s ?
In fact, the whole "Flight" section is suspiciously similar to the CRS-1 press kit.
No target orbital parameters or other juicy stuff. The highlight seems to be a couple of unseen pictures, one also showing the individual engine RP-1 feedlines coming directly off the tank bottom as opposed to the "octopus" on v1.0.
I wonder if the flight plan includes any throttling down for transsonic flight? Judging from the stated max Q timing, this thing is likely to have the same liftoff acceleration as v1.0. Which, given the vehicle is taller, should make it look slower.
The "flight" section looks suspect, but I think the launch timeline seems to be correct.
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#121
by
benson125
on 29 Sep, 2013 02:20
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American Islander is heading toward recovery zone.
That's certainly interesting. But what can that ship do? It is not big enough to salvage the stage, I think. Maybe it can anchor and stabilize it until a bigger salvage ship arrives?
Why not? Just have to tow it!
It's this big:
http://spacexlaunch.zenfolio.com/p278054961/h499c29de#h499c29de
you can track American Islander position on marinetraffic.com
American Spirit is also headed at the same speed and direction as American Islander, but about 100 km to the south.
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#122
by
darkenfast
on 29 Sep, 2013 02:44
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If one of the American Marine vessels was towing a barge, would it show up on the tracking resource?
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#123
by
cro-magnon gramps
on 29 Sep, 2013 03:00
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If one of the American Marine vessels was towing a barge, would it show up on the tracking resource?
Doesn't show up on the graphic map, don't see any links to details of ship purpose; American Spirit is going 8 Knots
American Islander is doing 8.6 Knots, heading 206 degrees both of them...
ok, changed: now American Islander is doing 8.4 Knots and heading 207 degrees, American Spirit unchanged. looks like American Islander has headed onto a converging heading with American Spirit.
well, back to 206 degrees for both ;( but American Islander is maintaining a speed difference over American Spirit.
Could be either American Islander is towing something or hitting rough seas compared to the other ship...
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#124
by
cro-magnon gramps
on 29 Sep, 2013 03:42
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I am going to take a wild guess that American Islander is towing something, as her heading varies by 1-2 degrees either side of 206 degrees and speed varies from 8.2 to 8.6 knots, While on the other hand, American Spirit, is doing consistent 8 knots on a very consistent 206 degree heading...
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#125
by
Wetmelon
on 29 Sep, 2013 05:30
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Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
That was the v1.0 method, I was sure that one of the benefits of M1D was the 70% throttle capability eliminates the need to shut down engines.
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#126
by
Robotbeat
on 29 Sep, 2013 05:37
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Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
That was the v1.0 method, I was sure that one of the benefits of M1D was the 70% throttle capability eliminates the need to shut down engines.
I think it's actually technically more efficient to shut-off engines, because throttling down means a lowering of the chamber pressure which means a worsening of the pressure ratio which means lower Isp.
...If you did want to shut down some engines early, it may make sense to shut down some of the three engines that have restart capability since theoretically they could be restarted in case of engine-out.
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#127
by
Garrett
on 29 Sep, 2013 06:29
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Around two and a half minutes into the flight, two of the first-stage engines will shut down to reduce the rocket’s acceleration.
That was the v1.0 method, I was sure that one of the benefits of M1D was the 70% throttle capability eliminates the need to shut down engines.
Being able to throttle does not imply that they HAVE to throttle. I presume it will all depend on the mission profile, i.e. on a case by case basis. Also, since the v1.1 is a hefty upgrade, they might be replicating the v1.0 flight profile as much as possible to avoid adding unnessary unknowns to the test flight.
Finally, maybe the throttle capability is geared more for the Falcon Heavy configuration than the single F9 config?
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#128
by
Zaran
on 29 Sep, 2013 06:33
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The ability to throttle may also be needed for the Human/crewed Dragon flights to keep the G loads on the passengers to a safe level.
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#129
by
Helodriver
on 29 Sep, 2013 06:46
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#130
by
Lars_J
on 29 Sep, 2013 07:06
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Thanks for those links... Some of the IMO best ones:
- lots of detail of the new pad release mechanism, plus stage one umbilicals on the right side
- interstage looks simpler and more aerodynamic
- close-up of payload stickers, plus big US flag on opposite side
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#131
by
Jcc
on 29 Sep, 2013 12:11
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Looking for cold gas thrusters, is that one above the US flag on the interstage?
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#132
by
subzero788
on 29 Sep, 2013 12:28
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Bit strange that there's no special banner or mention of this launch on the SpaceX website
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#133
by
Kasponaut
on 29 Sep, 2013 12:33
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Bit strange that there's no special banner or mention of this launch on the SpaceX website
YES! VERY strange!!!
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#134
by
Chris Bergin
on 29 Sep, 2013 13:32
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#135
by
yg1968
on 29 Sep, 2013 13:34
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Do we know, when the webcast starts?
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#136
by
ugordan
on 29 Sep, 2013 13:36
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40 minutes before opening of launch window. 10 minutes before NASA's Cygnus presser...
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#137
by
corrodedNut
on 29 Sep, 2013 13:39
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#138
by
belegor
on 29 Sep, 2013 13:43
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40 minutes before opening of launch window. 10 minutes before NASA's Cygnus presser...
And when is that? Or in other words, is the 12pm EDT mentioned on the webcast page the beginning of the launch window or the beginning of the webcast?
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#139
by
ugordan
on 29 Sep, 2013 13:44
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40 minutes before opening of launch window. 10 minutes before NASA's Cygnus presser...
And when is that? Or in other words, is the 12pm EDT mentioned on the webcast page the beginning of the launch window or the beginning of the webcast?
Launch window.