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SpaceX fully reusable launcher



 
 
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  #1  
Old October 1st 11, 01:17 PM posted to sci.space.tech
byblow
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Posts: 9
Default SpaceX fully reusable launcher

I would love to hear opinions about Elon Musk's announcement a
fully reusable, two-stage launcher. In this SpaceX animated video --
http://www.youtube.com/watch?v=p176UpWQOs4 -- the launcher reminds me
of the Falcon 9; it looks like the first stage has nine engines.

I would think SpaceX would need a much more capable launcher, perhaps
something more like the Falcon X or Falcon XX (sans its NERVA-based
NTR, for political reasons) to get a decent payload and have enough
fuel for a tail-first, soft landing.

Would a LOX-kerosene first stage provide enough capability for such a
launcher, or would SpaceX have to switch to a LOX-LH2 first stage?

Musk made a comment about reusing such a launcher 1,000 times. Was he
just stirring up interest, or could a tail-first, soft landing make it
possible to reuse a launcher 1,000 times?

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  #2  
Old October 2nd 11, 03:13 AM posted to sci.space.tech
Robert Heller
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Posts: 17
Default SpaceX fully reusable launcher

At Sat, 1 Oct 2011 08:17:56 EDT byblow wrote:


I would love to hear opinions about Elon Musk's announcement a
fully reusable, two-stage launcher. In this SpaceX animated video --
http://www.youtube.com/watch?v=p176UpWQOs4 -- the launcher reminds me
of the Falcon 9; it looks like the first stage has nine engines.

I would think SpaceX would need a much more capable launcher, perhaps
something more like the Falcon X or Falcon XX (sans its NERVA-based
NTR, for political reasons) to get a decent payload and have enough
fuel for a tail-first, soft landing.

Would a LOX-kerosene first stage provide enough capability for such a
launcher, or would SpaceX have to switch to a LOX-LH2 first stage?


You do know that the Saturn 5 first stage was LOX-kerosene, and it was
able to send the Applo missions to the moon...


Musk made a comment about reusing such a launcher 1,000 times. Was he
just stirring up interest, or could a tail-first, soft landing make it
possible to reuse a launcher 1,000 times?



--
Robert Heller -- 978-544-6933 /
Deepwoods Software --
http://www.deepsoft.com/
() ascii ribbon campaign -- against html e-mail
/\ www.asciiribbon.org -- against proprietary attachments




  #3  
Old October 3rd 11, 06:33 AM posted to sci.space.tech
Jorge R. Frank
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Posts: 2,089
Default SpaceX fully reusable launcher

On 10/01/2011 09:13 PM, Robert Heller wrote:
At Sat, 1 Oct 2011 08:17:56 EDT wrote:


I would love to hear opinions about Elon Musk's announcement a
fully reusable, two-stage launcher. In this SpaceX animated video --
http://www.youtube.com/watch?v=p176UpWQOs4 -- the launcher reminds me
of the Falcon 9; it looks like the first stage has nine engines.

I would think SpaceX would need a much more capable launcher, perhaps
something more like the Falcon X or Falcon XX (sans its NERVA-based
NTR, for political reasons) to get a decent payload and have enough
fuel for a tail-first, soft landing.

Would a LOX-kerosene first stage provide enough capability for such a
launcher, or would SpaceX have to switch to a LOX-LH2 first stage?


You do know that the Saturn 5 first stage was LOX-kerosene, and it was
able to send the Applo missions to the moon...


The S-IC didn't attempt to fly back to the launch site, either.

  #4  
Old October 3rd 11, 06:33 AM posted to sci.space.tech
Dr J R Stockton[_130_]
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Posts: 8
Default SpaceX fully reusable launcher

In sci.space.tech message [email protected]
qe.googlegroups.com, Sat, 1 Oct 2011 08:17:56, byblow
posted:

I would love to hear opinions about Elon Musk's announcement a
fully reusable, two-stage launcher. In this SpaceX animated video --
http://www.youtube.com/watch?v=p176UpWQOs4 -- the launcher reminds me
of the Falcon 9; it looks like the first stage has nine engines.

I would think SpaceX would need a much more capable launcher, perhaps
something more like the Falcon X or Falcon XX (sans its NERVA-based
NTR, for political reasons) to get a decent payload and have enough
fuel for a tail-first, soft landing.


The current Falcon 9 will do about 10 tonnes to LEO, 5 tonnes to GTO,
and the LEO price is of the order of $30M. Wikipedia figures.

If they get just 10 flights per F9, but 1/2 the payload, the cost per go
should be well under $10M (allowing for fuel, servicing, staff costs,
etc.). That looks a price worth designing payloads for. Figures are
pure guesses.

BTW, the Video did not, as far as I recall, say that the second stage
would flu back; the obvious route is once around Earth. And I think EM
said that the video was not faithful to all planned detail.

--
(c) John Stockton, nr London, UK. Turnpike v6.05 MIME.
Web http://www.merlyn.demon.co.uk/ - FAQqish topics, acronyms and links;
Astro stuff via astron-1.htm, gravity0.htm ; quotings.htm, pascal.htm, etc.
No Encoding. Quotes before replies. Snip well. Write clearly. Don't Mail News.

  #5  
Old October 3rd 11, 08:00 AM
dglow dglow is offline
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First recorded activity by SpaceBanter: Oct 2011
Posts: 2
Default

Quote:
Originally Posted by byblow View Post
I would love to hear opinions about Elon Musk's announcement a
fully reusable, two-stage launcher. In this SpaceX animated video --
http://www.youtube.com/watch?v=p176UpWQOs4 -- the launcher reminds me
of the Falcon 9; it looks like the first stage has nine engines.
How can anyone fail to admire SpaceX for attempting this? The video is awe-inspiring. I'm sure many rocket experts have already dissected it frame-by-frame, but I've found no such discussions online. Perhaps that can begin here...

For my part, a few layman's observations and questions:

First Stage:

- Yes, it looks a lot like Falcon 9, byblow. SpaceX says they're all about economies of scale, so I guess it's no surprise this appears to be an evolutionary design.
- It's nice how the landing gear fold into aerodynamic nacelles and tuck against the body for launch.
- Is there an ablative surface on the front of the first stage? The video doesn't show this clearly. However, after separation the second stage appears to fire against the first stage as it departs. A clever way of conserving energy and saving fuel?
- What happens to the black interstage element between separation and landing? Does it retract into the body somehow?

Second stage:

- Look at how the rocket nozzle both emerges from and contracts into the body, with the landing gear rocking in and out to provide clearance - very clever.
- The ablative surface is asymmetrical, with more of it on one side. That means there's only one good orientation for re-entry, yes?
- Will the ablative surface pose any difficulties for mating the payload atop it?
- After the re-entry burn we don't see the main rocket firing again; as the stage touches down we only see small, side-rockets firing. Any thoughts as to what's going on here?

Dragon:

- Do we see anything which hasn't been shown in previous videos? It doesn't appear so, but perhaps I'm missing something.
- What is the small surface, shown at the 'top' of Dragon, which folds down prior to ISS docking?

Wow, so much going on here. Somebody please help me out: for SpaceX to pull this off, are they banking on using atmospheric oxygen for the propulsive landings? It seems doing so could save a great deal of weight, but... is such an approach readily possible? Do there exist rocket engines with the ability to switch from LOX to air-derived O2?

Last edited by dglow : October 3rd 11 at 08:19 AM.
  #6  
Old October 3rd 11, 03:58 PM posted to sci.space.tech
Keith Henson
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Posts: 34
Default SpaceX fully reusable launcher

On Oct 3, 6:41 am, dglow wrote:

snip

Do there exist
rocket engines with the ability to switch from LOX to air-derived O2?


The proposed SABRE engines for the Skylon make the switch from air to
LOX so I suppose they could do the opposite.

Musk isn't a fan of space based solar power, but he does seem to be
trying to get the lift cost down into the range where SBSP makes sense
(100/kg to GEO).

Some years ago I came to the conclusion that even LOX/LH2 isn't good
enough and think it will take the exhaust velocity you can get from
beamed energy to get the cost down.

NASA does have a small project starting up that will investigate
hydrogen skin heaters to around 10 MW/m^2.

Keith Henson

  #7  
Old October 4th 11, 03:22 AM posted to sci.space.tech
byblow
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Posts: 9
Default SpaceX fully reusable launcher

I'm curious about the first-stage landing technique. The video doesn't
show a a nose-first reentry for the first-stage, but as dglow astutely
noticed, the front of the first-stage appears to have a heat shield
that can handle the second-stage exhaust at separation.

After separation, the first stage flips over and fires three of its
nine engines to begin reentry (I wonder what altitude the stage will
reach?). It's next shown descending tail first, possibly with just the
center engine firing. The landing struts begin to deploy, rotating
downward from a 12 o'clock position, to roughly 5 o'clock and 7
o'clock positions by touchdown. The landing struts appear rather wide,
perhaps for extra drag during final descent. I wonder if they're
thinking about using aerodynamic flaps as well?

My guess is the first-stage does a nose-first reentry like the second-
stage, flips over and goes into free fall during most of its descent
through the atmosphere, perhaps using the RCS at the top of the stage
to control its attitude. I'm curious about what altitude SpaceX
envisions firing the center engine for final descent and landing. I
assume only one engine is needed because most of its fuel is spent,
and the second-stage and Dragon are absent.

The Wiki article about the DC-X notes that if it could reach orbit, it
would make an ideal craft for landing on the moon or Mars, the latter
of which is Musk's ultimate goal. Perhaps he has visions of using the
second stage as a Mars cargo lander to complement the Dragon-derived
Mars people lander. He might need a fuel depot in earth orbit for
such a scheme.

Wiki: "Had a DC-type craft been developed that operated as an SSTO in
Earth's gravity well, even if with only a minimum 4-6 crew capacity,
variants of it might prove extremely capable for both Mars and Moon
missions. Such a variant's basic operation would have to be
"reversed"; from taking off and then landing, to landing first then
taking off. Yet, if this could be accomplished on Earth, the weaker
gravity found at both Mars and the Moon would make for dramatically
greater payload capabilities, particularly at the latter destination."

  #8  
Old October 5th 11, 02:02 AM posted to sci.space.tech
ed kyle
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Posts: 276
Default SpaceX fully reusable launcher

On Oct 3, 9:22 pm, byblow wrote:
My guess is the first-stage does a nose-first reentry like the second-
stage, flips over and goes into free fall during most of its descent
through the atmosphere, perhaps using the RCS at the top of the stage
to control its attitude. I'm curious about what altitude SpaceX
envisions firing the center engine for final descent and landing. I
assume only one engine is needed because most of its fuel is spent,
and the second-stage and Dragon are absent.


I suspect that the key to this method is the reduction of reentry
velocity, which would have to occur *before reentry*. The intent
would be to reduce reentry heating, which has destroyed all of the
Falcon stages launched to date, by reducing velocity at the "entry
interface" (or whatever they call it). This requires the engines to
fire well before reentry, probably even before apogee, which would
mean starting them not long after staging. I'm just guessing
though ....

- Ed Kyle

www.spacelaunchreport.com

  #9  
Old October 6th 11, 10:22 PM posted to sci.space.tech
byblow
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Posts: 9
Default SpaceX fully reusable launcher


Would anyone care to venture a guess as to how much a fully reusable
launcher -- based on a Falcon 9 -- could place in LEO?

How about a fully reusable launcher with fully reusable side boosters?
If cross-feed were used, would that result in the first-stage core
booster going too high for the heat shield currently envisioned to
protect it during descent?


  #10  
Old October 7th 11, 08:15 AM
dglow dglow is offline
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Posts: 2
Default

Quote:
Originally Posted by byblow View Post
Would anyone care to venture a guess as to how much a fully reusable
launcher -- based on a Falcon 9 -- could place in LEO?

How about a fully reusable launcher with fully reusable side boosters?
If cross-feed were used, would that result in the first-stage core
booster going too high for the heat shield currently envisioned to
protect it during descent?
I presume you're referring to the Falcon Heavy, of course. What leads you to believe its first-stage core achieves a greater altitude than the standard Falcon 9?
 




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