Author Topic: SpaceX Q&A  (Read 123851 times)

Offline manboy

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Re: SpaceX Q&A
« Reply #20 on: 05/26/2012 01:05 pm »
Russia, ESA, China (borrowed tech) have automated docking.
Is Space X and Orbital and NASA ever going to adopt this tech too?

Not for cargo. CRS will continue to use berthing.

Commercial Crew Program will use docking. SpaceX, Boeing, SNC, Blue Origin, and Excalibur Almaz are involved in CCP. Orbital is not, at the moment.
Some additional info. The Russian/Chinese/European vehicles use a radar based system that require antennas to be located on both the Visiting Vehicle (VV) and the target vehicle. I believe the CCP vehicle proposals that have discussed how they will autodock have said they plan to use a LIDAR based system.
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Offline CitabriaFlyer

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Re: SpaceX Q&A
« Reply #21 on: 05/31/2012 10:52 am »
Does anyone know if a Falcon 9 Heavy has the performance to send a Dragon to SEL-2? 

Can Dragon support a crew of 3 for the journey to SEL-2 and back with about a week on station?

Offline cro-magnon gramps

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Re: SpaceX Q&A
« Reply #22 on: 05/31/2012 01:09 pm »
Does anyone know if a Falcon 9 Heavy has the performance to send a Dragon to SEL-2? 

Can Dragon support a crew of 3 for the journey to SEL-2 and back with about a week on station?

I asked a similar question, regarding an Apollo 8 style mission using the new FH using the first stages of the F9 v1.1 with a core of the same;

the rocket guys were hesitant to say yes, straight out; they did say that it would likely require a new upper stage engine, mvac or a raptor with vac capabilities; as well, they pointed out that a Service Module, likely utilizing the trunk space, with it's own in space engine, would be required; and does not exist at this time; whether in power point, it is unknown; the Dragon that is going to the ISS, even with upgrades to crew taxi, for LEO, would need beefing up for a BEO mission, with supply space, and improved radiation protection for going through and outside the Van Allen Belts;
     for a simple Apollo 4 or 8 mission without landing on the Moon this is going to be complicated enough; to do what you are asking,  like going to an NEO / A, will probably require  larger living quarters, such as a Deep Space Habitat; either designed from scratch in house by SpaceX or perhaps utilize a Bigelow Inflatable Module, with the Dragon+SM serving as propulsive and manoeuvring module;
     hope this has helped some;
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Offline DavidH

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Re: SpaceX Q&A
« Reply #23 on: 05/31/2012 03:12 pm »
100% useful. Berthing is harder than docking.
More detail please.

How is it harder to "sit and stay" than to autonomously formation fly, rendezvous with, and dock (even with a cooperative target)?
TL;DR
Keep your posts short if you want them to be read.

Offline joertexas

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Re: SpaceX Q&A
« Reply #24 on: 06/07/2012 08:38 pm »
Would the Falcon 9 shroud be flyable if it were lengthened by 3 meters?

Thanks!

JR

Offline baldusi

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Re: SpaceX Q&A
« Reply #25 on: 06/08/2012 12:29 pm »
Would the Falcon 9 shroud be flyable if it were lengthened by 3 meters?

Thanks!

JR
You mean lengthening the fairing by 3 meters? It would need lots of calculation on the aerodynamics, but much bigger fairings have flew. In fact, the Payload's User Guide does states that bigger fairings are possible, but would require analysis. The Atlas V states that they think fairings as wide as 7.2m are possible, and they currently offer a 5.4m x 26.5m fairing (though, it has never actually fly). Granted, Atlas V is a shorter vehicle than Falcon 9 v1.1, but there doesn't seems to be a problem.

Offline Danderman

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Re: SpaceX Q&A
« Reply #26 on: 06/08/2012 01:18 pm »
100% useful. Berthing is harder than docking.
More detail please.

How is it harder to "sit and stay" than to autonomously formation fly, rendezvous with, and dock (even with a cooperative target)?

Loose formation flying and rendezvous in general represent a subset of the control required for arriving at and holding in the berthing box.

Berthing requires that the spacecraft proceed from a flyaround point towards the target spacecraft, with a stop at a point in space, and then holding position with high accuracy.

Docking requires that the spacecraft proceed from a flyaround point and then move in one dimension towards the target vehicle, while maintaining position in two other dimensions. While moving towards the target vehicle, maintaining velocity is important, but the docking system can tolerate minor misalignments and errors in velocity that the ISS RMS cannot.
« Last Edit: 06/09/2012 05:45 am by Danderman »

Offline joertexas

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Re: SpaceX Q&A
« Reply #27 on: 06/09/2012 04:56 am »
You mean lengthening the fairing by 3 meters? It would need lots of calculation on the aerodynamics, but much bigger fairings have flew. In fact, the Payload's User Guide does states that bigger fairings are possible, but would require analysis. The Atlas V states that they think fairings as wide as 7.2m are possible, and they currently offer a 5.4m x 26.5m fairing (though, it has never actually fly). Granted, Atlas V is a shorter vehicle than Falcon 9 v1.1, but there doesn't seems to be a problem.

Thank you  :)

JR

Offline ARD

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Re: SpaceX Q&A
« Reply #28 on: 08/07/2012 08:20 pm »
I'm not sure if the answer to this has been posted elsewhere on the forum, but here goes:

How long can a Falcon 9 or FH second stage last on-orbit before either electrical power runs out or the LOX boils away?  What might be the LOX boil-off rate on FH's upper stage?

Online edkyle99

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Re: SpaceX Q&A
« Reply #29 on: 08/10/2012 03:26 pm »
I'm not sure if the answer to this has been posted elsewhere on the forum, but here goes:

How long can a Falcon 9 or FH second stage last on-orbit before either electrical power runs out or the LOX boils away?  What might be the LOX boil-off rate on FH's upper stage?

In its users guide, now several years old, SpaceX talked about adding a mission kit to allow the stage to perform a geosynchronous transfer orbit apogee burn.  That would require an ability to perform a six hour mission.  Otherwise, a standard GTO mission would only last less than an hour or thereabouts.

 - Ed Kyle 

Offline MP99

Re: SpaceX Q&A
« Reply #30 on: 08/10/2012 05:37 pm »
That raises another question - is there any value for FH to perform both GTI and apogee burn for a single satellite rather than GTI-only for a dual-manifest?

Or would that just leave a large sat with more prop than it needs over it's operational lifetime? Could the prop be contingency in case it gets left short of full GSO, eg by FHUS failing to perform the apogee burn?

cheers, Martin

Offline mgfitter

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Re: SpaceX Q&A
« Reply #31 on: 09/26/2012 05:24 pm »
Something has been puzzling me ever since the first Falcon-1 wet dress rehearsal: How are Space-X insulating the LOX tank from the Kerosene tank?

For the first F1 they had a few problems with freezing the Kerosene, so they apparently added some insulation. I would like to know how. Was it was some sort of polyurethane foam stuck inside the Kerosene side of the common bulkhead?

Also, the LOX feedline runs straight through the center of the Kerosene tank too, which raises the question of how they insulate that too. Do they use the S-1C method and just have two tubes and an N2 purge between them, or are they using an insulation material layer of some kind?

Anyone know?

-MG.
« Last Edit: 09/26/2012 05:25 pm by mgfitter »

Offline 2552

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Re: SpaceX Q&A
« Reply #32 on: 10/02/2012 02:12 am »
How much does Dragon's PICA-X heatshield weigh? I'm wondering how much of a weight penalty it would be for a reusable upper stage.

Offline IRobot

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Re: SpaceX Q&A
« Reply #33 on: 10/02/2012 12:47 pm »
How much does Dragon's PICA-X heatshield weigh? I'm wondering how much of a weight penalty it would be for a reusable upper stage.
AFAIK, it is mostly cork. Cork is a very lightweight material.

Offline guckyfan

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Re: SpaceX Q&A
« Reply #34 on: 10/02/2012 02:05 pm »
How much does Dragon's PICA-X heatshield weigh? I'm wondering how much of a weight penalty it would be for a reusable upper stage.
AFAIK, it is mostly cork. Cork is a very lightweight material.

Phenolic Impregnated Carbon Ablator (PICA)

If cork is involved in any way it would be a carbon matrix derived from cork by heating.

http://www.nasa.gov/offices/oce/appel/ask/issues/40/40s_space-x.html

About weight the article I linked only mentions "lightweight".


Offline IRobot

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Re: SpaceX Q&A
« Reply #35 on: 10/02/2012 02:37 pm »
I live close to the Portuguese company (Corticeira Amorim) that developed, with NASA, the Apollo and post Apollo heat shields and vibration pads made with cork. AFAIK, the ablative material is mostly cork.

It is also used in Titan, Delta IV and Ariane 5. And on the ISS too, for vibrations and insulation.
http://www.development.amorimcorkcomposites.com/client/documentos/english/tps%20pp_04_07_2008ac.pdf

I'm trying to find more documentation about PICA, but for now I've found that the SLA-561 TPS from Lockheed was developed with Amorim.

http://www.development.amorimcorkcomposites.com/client/skins/english/page.asp?id=10
« Last Edit: 10/02/2012 02:39 pm by IRobot »

Offline Danderman

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Re: SpaceX Q&A
« Reply #36 on: 10/05/2012 06:08 pm »
That raises another question - is there any value for FH to perform both GTI and apogee burn for a single satellite rather than GTI-only for a dual-manifest?

Or would that just leave a large sat with more prop than it needs over it's operational lifetime? Could the prop be contingency in case it gets left short of full GSO, eg by FHUS failing to perform the apogee burn?

cheers, Martin

There is never "too much prop" for a commercial communications satellite.

Offline mgfitter

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Re: SpaceX Q&A
« Reply #37 on: 10/13/2012 07:14 pm »
Why does the Dragon capsule approach the station in that particular orientation?

Would I be right in guessing that it is a combination of optimal LOS between the station and Dragon's communicaiton antenae, together with a minimum exposure to the station from Dragon's RCS?

Just curious.

-MG.

Offline mgfitter

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Re: SpaceX Q&A
« Reply #38 on: 10/14/2012 08:29 pm »
No, it's because the DragonEye LIDARs in the Dragon GNC bay need a clear line-of-sight to ISS.

Ahhh, that makes sense. Thanks for clearing that one up Jorge.

-MG.

Offline go4mars

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Re: SpaceX Q&A
« Reply #39 on: 10/14/2012 09:02 pm »
How much does Dragon's PICA-X heatshield weigh? I'm wondering how much of a weight penalty it would be for a reusable upper stage.
"slightly denser than balsa wood"

http://www.nasa.gov/exploration/commercial/cargo/spacex_heatshield_prt.htm



« Last Edit: 10/14/2012 09:04 pm by go4mars »
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

 

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