Author Topic: SpaceX COTS Demo 1 Updates  (Read 605750 times)

Offline Antares

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Re: COTS Demo 1
« Reply #120 on: 09/04/2010 01:34 pm »
Yes, another virtue of hydrocarbon engines.
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline ugordan

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Re: COTS Demo 1
« Reply #121 on: 09/04/2010 02:04 pm »
“The second-stage roll is being fixed by changing the location of the [liquid oxygen] pump drain outlet to avoid chilling the hydraulic lines of the roll control actuator,”

This would be part of the Merlin turbopump, not the tank fill/drain valve seen in the video, right? Is that what was responsible for the gas efflux seen spraying the engine *above* the nozzle exit?

Offline corrodedNut

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Re: COTS Demo 1
« Reply #122 on: 09/04/2010 03:54 pm »
This would be part of the Merlin turbopump, not the tank fill/drain valve seen in the video, right? Is that what was responsible for the gas efflux seen spraying the engine *above* the nozzle exit?

Are you referring to the T-shaped valve or vent by the GG exhaust nozzle, seen venting white gases to the left and right at MVac [EDIT: stage sep]? I wondered what that was, I thought it was something to do with the start-up sequence, as it seems to stop soon afterwards. Considering that the actuator doesn't 'freeze up' until later, maybe it (drain outlet) keeps venting and it's just hard to see because of the recirculating exhaust gases?
« Last Edit: 09/04/2010 04:07 pm by corrodedNut »

Offline ugordan

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Re: COTS Demo 1
« Reply #123 on: 09/04/2010 04:38 pm »
No, I'm not referring to that. If you look closely after ignition, there's another source of GOX coming from somewhere in the lower left corner of the frame, behind the umbilical connectors. This venting persisted for the entire duration of the burn.

Offline corrodedNut

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Re: COTS Demo 1
« Reply #124 on: 09/04/2010 04:59 pm »
Well...I see whitish gasses swirling around, coming from the direction you describe, but I really have no idea what or why this is.

Do you think this "drain outlet" vents to the outside of the vehicle through the interstage during 1st stage flight, and after stage sep is free to impinge on these hydraulic lines?
« Last Edit: 09/04/2010 05:06 pm by corrodedNut »

Offline cuddihy

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Re: COTS Demo 1
« Reply #125 on: 09/07/2010 11:54 am »

Yeah, the Merlin engines use pressurized RP-1 tapped off the turbopump outlet as the hydraulic fluid.  My understanding is that this is a unique innovation.  Most launch vehicles use a separate APU and pump system for hydraulics.  Kestrel is pressure-fed and therefore uses a different system for actuation.


No, the F-1 did it the same way. 

Don't some of the big russians (RD-170-and-friends) also use fuel-as-hydraulic fluid?

I think confusion on separate hydraulic pump could come from the small electric circulation pumps to keep fluid temperature under control (older Centaurs before they went electromechanical, for example).

Cheers,

  --Nick

I would bet most of the confusion lies with the wider public understanding of how Shuttle works (i.e., MMH powered APUs).

People who only follow space occasionally have still likely read or seen a detailed shuttle launch description.

* edited to correct "NTO" in the APU
« Last Edit: 09/07/2010 03:02 pm by cuddihy »

Offline Jim

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Re: COTS Demo 1
« Reply #126 on: 09/07/2010 12:50 pm »

I would bet most of the confusion lies with the wider public understanding of how Shuttle works (i.e., MMH/NTO powered APUs).


The shuttle APU's are hydrazine powered.  They have dedicated tanks separate from the OMS/RCS.

Offline cuddihy

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Re: COTS Demo 1
« Reply #127 on: 09/07/2010 02:58 pm »

I would bet most of the confusion lies with the wider public understanding of how Shuttle works (i.e., MMH/NTO powered APUs).


The shuttle APU's are hydrazine powered.  They have dedicated tanks separate from the OMS/RCS.

yep, oops.

Goes to show...

Offline beancounter

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Re: COTS Demo 1
« Reply #128 on: 09/10/2010 02:32 am »
A few comments lately seem to indicate that NASA is more seriously considering combining COTS-C Demo's 2&3 if 1 goes well.  Would love to see that and even better, the first actual CRS delivery and return.
Beancounter from DownUnder

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Re: COTS Demo 1
« Reply #129 on: 09/10/2010 01:07 pm »
Per SpaceX coverage on L2, they have officially got the range for that October 23 launch date.
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Offline corrodedNut

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Re: COTS Demo 1
« Reply #130 on: 09/12/2010 04:34 pm »
In an interview with the BBC last week, at the World Summit for Satellite Financing, Gwynne Shotwell says:

"...[COTS 1] is sitting on the range on October 23 and we'll launch it hopefully, actually before then, we're hoping to move to the left."

http://www.bbc.co.uk/blogs/thereporters/jonathanamos/2010/09/the-big-rockets-jostle-for-mar.shtml

See the audio player halfway down the page, at about 0:50 in the recording.

Mark your calendars! (in pencil)
« Last Edit: 09/12/2010 07:19 pm by corrodedNut »

Offline Ronsmytheiii

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Re: COTS Demo 1
« Reply #131 on: 09/14/2010 06:43 pm »
hmm, looks like Falcon IX 2 is on the pad:
« Last Edit: 09/14/2010 06:43 pm by Ronsmytheiii »

Offline ugordan

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Re: COTS Demo 1
« Reply #132 on: 09/14/2010 06:45 pm »
Not only that, it looks like the arm of the erector is open which could mean a tanking test is in progress.

EDIT: Yup, strongback retracting now. Could also mean an RF test with the range I suppose - remember the FTS signal problem.
« Last Edit: 09/14/2010 06:53 pm by ugordan »

Online Robotbeat

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Re: COTS Demo 1
« Reply #133 on: 09/14/2010 07:11 pm »
hmm, looks like Falcon IX 2 is on the pad:
Woah! Didn't see that coming.
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Offline corrodedNut

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Re: COTS Demo 1
« Reply #134 on: 09/14/2010 07:40 pm »
Woah! Didn't see that coming.

That's what you get for not reading my posts! (kidding)

So, are the cameras on for good this time?

Offline ugordan

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Re: COTS Demo 1
« Reply #135 on: 09/14/2010 08:01 pm »
Well, whatever test that was, it's over. The vehicle's coming down.

Offline corrodedNut

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Re: COTS Demo 1
« Reply #136 on: 09/14/2010 08:08 pm »
I'm thinking that there might be some new umbilicals for Dragon, at least A/C anyway. Would they erect and lower the strongback to check these?
« Last Edit: 09/14/2010 09:39 pm by corrodedNut »

Offline Lars_J

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Re: COTS Demo 1
« Reply #137 on: 09/14/2010 09:35 pm »
It's nice to see the whole stack at least! Now if we could only get some up-close shots. :D

Offline Ronsmytheiii

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Re: COTS Demo 1
« Reply #138 on: 09/14/2010 09:44 pm »
going up again
« Last Edit: 09/14/2010 09:55 pm by Ronsmytheiii »

Offline TheFallen

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Re: COTS Demo 1
« Reply #139 on: 09/15/2010 12:37 am »
Falcon 9 at night

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