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Elon Musk's SpaceX to build 'Grasshopper' hover-rocket



 
 
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  #1  
Old September 27th 11, 06:47 PM posted to sci.space.policy
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Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

"SpaceX, the upstart start-up rocket company founded
by famous techwealth kingpin Elon Musk, is to build
and test-fly a "Grasshopper" hover rocket based on
the massive first-stage fuel tank of the company's
Falcon 9 vehicle, capable of carrying ten tonnes of
cargo or seven people into orbit.

As yet SpaceX is not discussing the Grasshopper
publicly, but we learn some interesting details of the
new craft from an environmental impact statement
covering planned test flights filed with the Federal
Aviation Administration (65-page PDF/1.4MB).

According to the filing, the Grasshopper is seen as a
"Reusable Launch Vehicle" (RLV). It will be 106ft tall,
and built around the first-stage fuel tank of the existing
Falcon 9 rocket stack:"

See:

http://www.theregister.co.uk/2011/09...hopper_spacex/
  #5  
Old September 28th 11, 03:28 PM posted to sci.space.policy
Niels Jørgen Kruse
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Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

Jochem Huhmann wrote:

It's still curious. Landing a first stage or a booster would mean having
some ground to land it on, which would mean having to launch over land.
Which SpaceX doesn't. Or they mean to land the thing on a ship or barge
out there....


Go straight up until first stage separation?

You would have to transport the stage back otherwise.

--
Mvh./Regards, Niels Jørgen Kruse, Vanløse, Denmark
  #6  
Old September 28th 11, 07:13 PM posted to sci.space.policy
Jeff Findley[_2_]
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Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

In article , nospam@ab-
katrinedal.dk says...

Jochem Huhmann wrote:

It's still curious. Landing a first stage or a booster would mean having
some ground to land it on, which would mean having to launch over land.
Which SpaceX doesn't. Or they mean to land the thing on a ship or barge
out there....


Go straight up until first stage separation?

You would have to transport the stage back otherwise.


I've suggested this before. Launching straight up until booster
separation would recovery easier if the chosen approach is a powered
vertical landing. One of the criticisms of this approach is that's not
an "optimal" trajectory, so the launch vehicle pays a payload penalty
for this approach. The launch vehicle also pays a penalty for the
increased mass of the recovery hardware and/or propellant.

That said, throwing away your first stage on each an every launch
doesn't strike me as "optimal". ;-)

That's why I'm wondering about Falcon Heavy. Due to the cross-feeding
of propellants to the core, those two outer boosters will burn out
earlier than Falcon 9's first stage. Because of this, staging will
happen at a lower altitude and speed. This means that recovering Falcon
Heavy boosters ought to be easier than recovering a Falcon 9 first
stage.

Yes, reusability will cost some payload mass, but if any launcher can
afford this sacrifice, you'd think that Falcon Heavy would be the one.
If SpaceX goes this route with Falcon Heavy, at least they'll be
recovering 1/2 of the stages used.

To quiet the "performance uber alles" crowd, SpaceX could always offer
the same launch vehicle with expendable boosters. For launches that
can't sacrifice that payload, SpaceX would just charge the customer a
higher price for expendable boosters.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker
  #7  
Old September 29th 11, 09:08 AM posted to sci.space.policy
Jochem Huhmann
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Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

Jeff Findley writes:

That's why I'm wondering about Falcon Heavy. Due to the cross-feeding
of propellants to the core, those two outer boosters will burn out
earlier than Falcon 9's first stage. Because of this, staging will
happen at a lower altitude and speed. This means that recovering Falcon
Heavy boosters ought to be easier than recovering a Falcon 9 first
stage.


Yes, for the Heavy boosters this could make sense. For the normal Falcon
9, not so much. You'd need the second stage then to provide all the
delta-v to orbital speed which is a bit too much for the poor thing.

If they indeed can manage to land the boosters at the launch site after
burn-out this could mean major cost savings.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery
  #9  
Old September 29th 11, 04:13 PM posted to sci.space.policy
Jeff Findley[_2_]
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Posts: 1,388
Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

In article om,
says...

On 28/09/2011 11:12 PM, Jeff Findley wrote:
In gpond.com,
says...

That's a bloody big lander they're developing!

thinking I wonder what Musk has in mind.....thinking


We all know he wants to reuse his launch vehicles. It's quite possible
that he's using this as a testbed to gather data on the feasibility of
recovering Falcon 9 first stages. Even easier ought to be Falcon Heavy
boosters, which are similar but expend their fuel/oxidizer earlier due
to cross-feeding of propellants to the core.


I don't think this is about a booster recovery system. I think it's
more 'planetary' than Earth-based.


Possibly, but the technology could also be applied to landing Dragon
under rocket power, which I'd consider "Earth-based". Splashing down in
the ocean isn't such a great idea for a capsule you want to reuse.
Dunking aluminum and electronics in salt water isn't a good thing. For
disposable capsules, this really doesn't matter, except to museum
curators who are interested in preserving history.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker
  #10  
Old September 29th 11, 08:26 PM posted to sci.space.policy
Dr J R Stockton[_130_]
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Posts: 8
Default Elon Musk's SpaceX to build 'Grasshopper' hover-rocket

In sci.space.policy message , Wed, 28 Sep
2011 15:46:37, Jochem Huhmann posted:

Jeff Findley writes:

In article om,
says...

That's a bloody big lander they're developing!

thinking I wonder what Musk has in mind..... thinking


We all know he wants to reuse his launch vehicles. It's quite possible
that he's using this as a testbed to gather data on the feasibility of
recovering Falcon 9 first stages. Even easier ought to be Falcon Heavy
boosters, which are similar but expend their fuel/oxidizer earlier due
to cross-feeding of propellants to the core.


It's still curious. Landing a first stage or a booster would mean having
some ground to land it on, which would mean having to launch over land.
Which SpaceX doesn't. Or they mean to land the thing on a ship or barge
out there....


Get the first stage range right, launch from south Texas, over the Gulf
of Mexico to Florida. Refuel, and, with no second stage or payload, fly
it back to Texas.

--
(c) John Stockton, nr London, UK. Turnpike v6.05.
Website http://www.merlyn.demon.co.uk/ - w. FAQish topics, links, acronyms
PAS EXE etc. : http://www.merlyn.demon.co.uk/programs/ - see in 00index.htm
Dates - miscdate.htm estrdate.htm js-dates.htm pas-time.htm critdate.htm etc.
 




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