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SpaceX Updates (Thread 4): F9, FH & Dragon


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#121 OP DocM

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Posted 12 January 2014 - 04:52

Methane would take less cooling & insulation to store long term than hydrogen.

FYI, until the recent move towards methane every proposed fuel depot design was for hydrogen, and the problems associated with hydrogen was why they weren't done.


#122 OP DocM

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Posted 12 January 2014 - 06:50

Regarding the proposed SpaceX Brownsville, Texas spaceport.

This launch facility would initially be very similar to their Vandenberg Air Force Bade site, launching Falcon 9, Falcon Heavy and F9-R, but Musk has made it clear the area would also get a new factory for building much larger rockets and Brownsville would be the launch site.

http://m.valleymorni...8.html?mode=jqm

Delving into SpaceX Files: Cameron County property acquisitions detailed

The proposed site of a facility for Elon Musk’s Space Exploration Technologies Corp., where the world’s first privately-owned commercial rocket-launching complex would be located, consists of 87 acres in four tracts along state Highway 4 at Boca Chica Boulevard.
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• PARCEL 4: SpaceX already has leased this tract of about 56.5 acres as its primary launch site, and purchased about 27 acres.
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The goal is to initiate unmanned launches at the site by the fourth quarter of 2015, according to public records about the proposal.
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#123 SarK0Y

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Posted 13 January 2014 - 02:02

Methane would take less cooling & insulation to store long term than hydrogen.

FYI, until the recent move towards methane every proposed fuel depot design was for hydrogen, and the problems associated with hydrogen was why they weren't done.

http://www.nasa.gov/...ities/cryo.html So far from the least valuable result.



#124 OP DocM

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Posted 13 January 2014 - 03:11

That confirms my point. Depots using deep cryo fuels like H2 suffer the most boiloff, and this is lessened with CH4. You need less cooling and insulation, and that reduces power demands.

Also note it doesn't mention any on-orbit tests of depot tech using H2. It's been tested at a very basic level in space, mainly a used Centaur stage a few years ago, but not anything really functional That is what I meant by being "done."

That said, ULA has a depot proposal - but no funding.

#125 Beittil

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Posted 17 January 2014 - 22:39

NASA released a video of last months parachute test!



#126 OP DocM

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Posted 18 January 2014 - 07:28

Note the tumble. Its intentional to test deployment under a very abnormal situation. The drogue mortar has also been moved from the service bay near the bottom to the top near the docking adapter to make more room for the SuperDraco thrusters and their tanks.

#127 SarK0Y

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Posted 19 January 2014 - 02:38

if capsule was flip-flopping that way in real flight, the would be no room to survive because initial velocity of vehicle (in real descending) to shoot drogue out is much greater. 



#128 OP DocM

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Posted 19 January 2014 - 03:28

That rotation is a few G's, which pilots and parachute deployment systems somehow regularly survive.

#129 SarK0Y

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Posted 19 January 2014 - 05:35

actually, there is rotation around longitudinal axis (in normal flight) + such rolling can & better off be stopped before *chutting.



#130 OP DocM

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Posted 19 January 2014 - 08:25

Well, then you should file consulting papers with NASA so you can inform them of the error of their ways - a similar smart release algorithm has been in the spec for the Orion spacecraft since 2009.

#131 SarK0Y

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Posted 19 January 2014 - 20:12

there isn't mistake to inform about: for initial test, such flip-flopping ain't big deal -- it's even good to stress chutes as much as possible. For re-entry phase, Yes -- such dances cannot be acceptable. By the way, that  whirling is possible in powered-landing scheme because thrusters have a probability to malfunction even higher than chutes.



#132 OP DocM

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Posted 20 January 2014 - 00:49

....thrusters have a probability to malfunction even higher than chutes..

The reverse is true.

Parachutes are complex with numerous failure modes. Hypergolic thusters are inherently extremely reliable, which is why they're still in use after almost 70 years.

With parachutes the mortar can fail to fire, the deployment controller can fail, the altimeter or inertial sensors can fail, drogues can fail to deploy and/or tangle, the mains can fail to deploy and/or tangle, ANY of the parachutes or drogues can fail to inflate or shred, etc.

For a parachute to fail any one of several things in a sequence can bring down the whole thing. Having 3 redundant parachutes can help, but on a bad day they can also take each other out.

Failure examples: Venera 7, Soyuz 7K-OK (Vladimir Komarov death), Genesis spacecraft, 2008 Orion parachute test, etc. etc. etc.

Hypergolic thrusters use a fuel and oxidizer that ignite on contact, so no igniter is needed, and there are no pumps as both tanks are gas pressurized, with backups.

All that's needed for thrusters to work is for a release valve set to open, and there is not only a backup flow path & valve set (or several) but in DragonRider the avionics computer that controls the valves is quad-redundant.

For thrusters to totally fail a lot of things have to break at once, and in the case of SuperDtaco's even they are redundant - DragonRider can lose 1-2 thrusters and still land or, at worst, deploy the parachutes.

#133 FloatingFatMan

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Posted 20 January 2014 - 13:18

Hey Doc.. you're doing what you advised me not to do! Silly. :p



#134 OP DocM

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Posted 20 January 2014 - 14:12

Partly, but it had to be said.

Channel re-closed.

#135 bguy_1986

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Posted 20 January 2014 - 17:30

Partly, but it had to be said.

Channel re-closed.

It helps me understand more when you answer him sometimes.