Author Topic: SpaceX COTS Demo 1 Updates (Read 659289 times)

Antares · « **Reply #120 on:** 09/04/2010 01:34 pm »

Yes, another virtue of hydrocarbon engines.

ugordan · « **Reply #121 on:** 09/04/2010 02:04 pm »

Quote from: corrodedNut on 09/03/2010 11:47 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?

corrodedNut · « **Reply #122 on:** 09/04/2010 03:54 pm »

Quote from: ugordan on 09/04/2010 02:04 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?

ugordan · « **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.

corrodedNut · « **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?

cuddihy · « **Reply #125 on:** 09/07/2010 11:54 am »

Quote from: just-nick on 09/04/2010 04:04 am

Quote from: Jim on 09/04/2010 02:10 am
Quote from: butters on 09/04/2010 01:55 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

Jim · « **Reply #126 on:** 09/07/2010 12:50 pm »

Quote from: cuddihy on 09/07/2010 11:54 am

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.

cuddihy · « **Reply #127 on:** 09/07/2010 02:58 pm »

Quote from: Jim on 09/07/2010 12:50 pm

Quote from: cuddihy on 09/07/2010 11:54 am

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...

beancounter · « **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.

Chris Bergin · « **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.

corrodedNut · « **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)

Ronsmytheiii · « **Reply #131 on:** 09/14/2010 06:43 pm »

hmm, looks like Falcon IX 2 is on the pad:

ugordan · « **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.