Author Topic: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon  (Read 976589 times)

Offline mlorrey

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2700 on: 02/28/2009 01:50 AM »
Of course, you'll have to pick your crewmates from among your very best friends...

Can I have a list of super models to chose from?

Much too tall. As long as we're on Fantasy Island, I bet Tattoo can recommend some more compact models...

Legs are really useless in low-g/zero-g environments. Recruit some amputees to save mass, increase dV.
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Offline A_M_Swallow

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2701 on: 02/28/2009 04:11 AM »

I look at that picture and have to ask myself.... why is the Dragon backwards?

I suspect the Dragon is backwards because the docking hatch is built into its roof.  If the other module is providing the thrust then the Dragon ends up flying backwards.  Connecting to the bottom of the service module would require a very different sort of docking system.

Online Ben the Space Brit

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2702 on: 02/28/2009 02:14 PM »
Connecting to the bottom of the service module would require a very different sort of docking system.

The basic requirement would seem to be putting a standard common berthing ring mechanism on the base of the trunk plus rendezvous sensors.  Put another ring on top of the EDS and you're there. 

Oh... there would also have to be a fairing between the F9US and the Dragon to protect the rear docking ring from contact with the booster.
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Offline Lars_J

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2703 on: 03/01/2009 12:35 AM »
Connecting to the bottom of the service module would require a very different sort of docking system.

The basic requirement would seem to be putting a standard common berthing ring mechanism on the base of the trunk plus rendezvous sensors.  Put another ring on top of the EDS and you're there. 

Oh... there would also have to be a fairing between the F9US and the Dragon to protect the rear docking ring from contact with the booster.

But... WHY? Why is it so important to travel to the moon facing forward???

Offline NUAETIUS

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2704 on: 03/01/2009 03:04 AM »
But... WHY? Why is it so important to travel to the moon facing forward???

Partially because vehicles are designed to take the stresses they are under in very specific manners.  Launching it in that different a way would take requalification of even redesigning of the vehicle.

Partially because negative G forces are very much more nasty that positive G forces.  You would have to have the seating arraignments accept 2 different orientations (with 4 crew, it would be way harder to fit them in the other direction). 

More than anything else, a capsule is the KISS form of manned space transport.  It's simple because it works, and it works because it is simple(relatively). The TPS system gives a tiny bit of protection to the capsule from an explosion of the 2st stage, the capsule doesn't need a fairing beyond the LAS, the LAS can attach to the capsule without interfering with the TPS system, the shape works well for the seating arrangement....

It just works better the way EVERY capsule manned or unmanned has ever been launched, TPS down.
« Last Edit: 03/01/2009 03:05 AM by NUAETIUS »
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Offline stexer

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2705 on: 03/01/2009 03:33 AM »
Connecting to the bottom of the service module would require a very different sort of docking system.

The basic requirement would seem to be putting a standard common berthing ring mechanism on the base of the trunk plus rendezvous sensors.  Put another ring on top of the EDS and you're there. 

Oh... there would also have to be a fairing between the F9US and the Dragon to protect the rear docking ring from contact with the booster.

But... WHY? Why is it so important to travel to the moon facing forward???

In a real mission such as this, I am sure that a new service module would be built and designed directly for the mission.
As for the simulator, it's good enough.  ;D
There is also a BFR launcher available now, based on a prediction of the future Merlin-2's. Fun stuff.

Offline A_M_Swallow

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2706 on: 03/01/2009 06:29 AM »

I look at that picture and have to ask myself.... why is the Dragon backwards?

I suspect the Dragon is backwards because the docking hatch is built into its roof.  If the other module is providing the thrust then the Dragon ends up flying backwards.  Connecting to the bottom of the service module would require a very different sort of docking system.

There is an existing rocket that connects to the bottom of the service module - the Upper Stage of the Falcon 9 (or Falcon 9 Heavy).  If that can be refuelled simply do not separate the two machines.

Offline NUAETIUS

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2707 on: 03/01/2009 02:06 PM »
I suspect the Dragon is backwards because the docking hatch is built into its roof.  If the other module is providing the thrust then the Dragon ends up flying backwards.  Connecting to the bottom of the service module would require a very different sort of docking system.

There is an existing rocket that connects to the bottom of the service module - the Upper Stage of the Falcon 9 (or Falcon 9 Heavy).  If that can be refuelled simply do not separate the two machines.

I have searched but can not find the quote, but it has been stated multipule times that the Merlin Vac can only be started twice.  Once at 2nd stage ignition, one for circularization.

I do not know the reason for this, but my layman's guess is that once it cools down all the way it feezes up.
« Last Edit: 03/01/2009 02:07 PM by NUAETIUS »
“It has long been recognized that the formation of a committee is a powerful technique for avoiding responsibility, deferring difficult decisions and averting blame….while at the same time maintaining a semblance of action.” Augustine's Law - Norm Augustine

Offline Jim

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2708 on: 03/01/2009 02:23 PM »

I do not know the reason for this, but my layman's guess is that once it cools down all the way it feezes up.

Probably only two start charges

Offline kevin-rf

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2709 on: 03/01/2009 06:27 PM »

Probably only two start charges

Not to second guess SpaceX, Assuming that is correct, why didn't they scar it for three. I think a bunch of people here can think of several profiles that will require three burns ( if you plan on getting the stage back ).
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Offline ugordan

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2710 on: 03/01/2009 06:51 PM »
Not to second guess SpaceX, Assuming that is correct, why didn't they scar it for three. I think a bunch of people here can think of several profiles that will require three burns ( if you plan on getting the stage back ).

Deorbit burns would apparently be done by RCS thrusters.

Offline jabe

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2711 on: 03/01/2009 08:24 PM »
Probably only two start charges
Now i need to ask... I guess I'm missing a key point on how rocket engines are started..is there a summary some where on how they start up rocket engines..I didn't realize a charge is needed to start the engine..
jb

Offline Jim

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2712 on: 03/01/2009 08:31 PM »
This only applies to turbopump engines.  Some engines use head pressure (SSME, RL-10) to start the turbine.  Others use start cartridges (Bell 8086), start tanks (J-2) or even high pressure gas (RS-68) to spin up the turbine.  I believe the Merlin for the booster stages uses high pressure gas, don't recall what the upper stage version does

Offline William Barton

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2713 on: 03/01/2009 09:10 PM »
But... WHY? Why is it so important to travel to the moon facing forward???

Partially because vehicles are designed to take the stresses they are under in very specific manners.  Launching it in that different a way would take requalification of even redesigning of the vehicle.

Partially because negative G forces are very much more nasty that positive G forces.  You would have to have the seating arraignments accept 2 different orientations (with 4 crew, it would be way harder to fit them in the other direction). 

More than anything else, a capsule is the KISS form of manned space transport.  It's simple because it works, and it works because it is simple(relatively). The TPS system gives a tiny bit of protection to the capsule from an explosion of the 2st stage, the capsule doesn't need a fairing beyond the LAS, the LAS can attach to the capsule without interfering with the TPS system, the shape works well for the seating arrangement....

It just works better the way EVERY capsule manned or unmanned has ever been launched, TPS down.

Isn't Orion going to be flying "bottoms up" for TLI and LOI? Also, wasn't Discoverer/Corona launched TPS up? And, of course, that was the plan for CXV (neither built, nor launched, so only a hypothetical).

Offline William Barton

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2714 on: 03/01/2009 09:12 PM »
Of course, you'll have to pick your crewmates from among your very best friends...

Can I have a list of super models to chose from?

Much too tall. As long as we're on Fantasy Island, I bet Tattoo can recommend some more compact models...
Naa they'll fit just fine I believe Dragon can accommodate crew members up to  6'4".

It's the benchmark all crewed space vehicles are designed by today even Soyuz TMA can carry crew members from 4'11" to 6'3".

Sure the vehicle is small but it's no Gemini or Soyuz.

The real issue is can they pass the physical some of the more waifish ones like Kate Moss might not pass the 4g centrifuge test.

Though if Kate Moss  survives the test the good news is she won't eat very much but baggage she would probably want to bring would probably exceed the payload of an F9-H .


But you can probablyfit more compact models in the same volume...

Offline iamlucky13

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2715 on: 03/02/2009 04:16 AM »
Isn't Orion going to be flying "bottoms up" for TLI and LOI? Also, wasn't Discoverer/Corona launched TPS up? And, of course, that was the plan for CXV (neither built, nor launched, so only a hypothetical).

TLI, LOI, and TEI will all be relatively low accelerations. Around 1/3 to 1/2 G if I remember right.

I don't know how the Corona satellites were launched, but obviously they had no human occupants, and it's not impossible to launch in that configuration. It's just generally not the best. They might have had other reasons for it.

FYI, the human body doesn't hold up particularly well to negative g's. They force blood to the head, and "redout" occurs at around 2-3 g's. A little bit higher can cause permanent vision damage, or even a fatal stroke.

Offline kevin-rf

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2716 on: 03/02/2009 01:55 PM »

I don't know how the Corona satellites were launched, but obviously they had no human occupants, and it's not impossible to launch in that configuration. It's just generally not the best. They might have had other reasons for it.

FYI, the human body doesn't hold up particularly well to negative g's. They force blood to the head, and "redout" occurs at around 2-3 g's. A little bit higher can cause permanent vision damage, or even a fatal stroke.

Other than T/Space was proposing using the corona shape (which I believe (someone like ed will correct me if wrong) has the most reentries of any shape). The solution they proposed was to have the couches pivot so you always had positive g's.

( http://www.transformspace.com/index.cfm?fuseaction=projects.view&workid=CCD3097A-96B6-175C-97F15F270F2B83AA )
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Offline William Barton

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2717 on: 03/02/2009 02:10 PM »
Isn't Orion going to be flying "bottoms up" for TLI and LOI? Also, wasn't Discoverer/Corona launched TPS up? And, of course, that was the plan for CXV (neither built, nor launched, so only a hypothetical).

TLI, LOI, and TEI will all be relatively low accelerations. Around 1/3 to 1/2 G if I remember right.

I don't know how the Corona satellites were launched, but obviously they had no human occupants, and it's not impossible to launch in that configuration. It's just generally not the best. They might have had other reasons for it.

FYI, the human body doesn't hold up particularly well to negative g's. They force blood to the head, and "redout" occurs at around 2-3 g's. A little bit higher can cause permanent vision damage, or even a fatal stroke.

That was my point. The imaginary SpaceX lunar mission configuration is for TLI, so it would be okay, even if real. The "lunar Dragon" depicted is just a Dragon version of the proposed lunar Soyuz that's supposed to send a couple of billionaires around the Moon (no takers so far?), also butt-first into TLI. I included the Discoverer/Corona example because your original post asserted, "It just works better the way EVERY capsule manned or unmanned has ever been launched, TPS down." There was at least the one exception. No one (including t\Space) is proposing to launch a manned capsule upside-down with the passengers facing the inertial force vector. There's actually no absolute reason to launch TPS-down, although there are good reasons to launch passengers face-up.

Offline William Barton

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2718 on: 03/02/2009 02:13 PM »

I don't know how the Corona satellites were launched, but obviously they had no human occupants, and it's not impossible to launch in that configuration. It's just generally not the best. They might have had other reasons for it.

FYI, the human body doesn't hold up particularly well to negative g's. They force blood to the head, and "redout" occurs at around 2-3 g's. A little bit higher can cause permanent vision damage, or even a fatal stroke.

Other than T/Space was proposing using the corona shape (which I believe (someone like ed will correct me if wrong) has the most reentries of any shape). The solution they proposed was to have the couches pivot so you always had positive g's.

( http://www.transformspace.com/index.cfm?fuseaction=projects.view&workid=CCD3097A-96B6-175C-97F15F270F2B83AA )


I liked the t\Space CXV very much, though I wasn't so sure about the pivoting "hammocks." I assumed the fast pivot was for abort situations, since once you're on orbit, it'd be easy enough to reorient conventional couches.

Offline HMXHMX

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Re: Elon Musk Q&A - Updates SpaceX status on Falcon and Dragon
« Reply #2719 on: 03/02/2009 06:16 PM »

I don't know how the Corona satellites were launched, but obviously they had no human occupants, and it's not impossible to launch in that configuration. It's just generally not the best. They might have had other reasons for it.

FYI, the human body doesn't hold up particularly well to negative g's. They force blood to the head, and "redout" occurs at around 2-3 g's. A little bit higher can cause permanent vision damage, or even a fatal stroke.

Other than T/Space was proposing using the corona shape (which I believe (someone like ed will correct me if wrong) has the most reentries of any shape). The solution they proposed was to have the couches pivot so you always had positive g's.

( http://www.transformspace.com/index.cfm?fuseaction=projects.view&workid=CCD3097A-96B6-175C-97F15F270F2B83AA )


I liked the t\Space CXV very much, though I wasn't so sure about the pivoting "hammocks." I assumed the fast pivot was for abort situations, since once you're on orbit, it'd be easy enough to reorient conventional couches.

It was for abort only.  We tested it and it worked very well.  Rotation takes less than 3 seconds at the altitude peak of the abort trajectory.  Weight was 13 lbs. 

The big advantage besides weight was the ability to easily dismount and store the seats when on orbit.

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