Author Topic: SpaceX complete PDR on LAS  (Read 53807 times)

Offline Chris Bergin

SpaceX complete PDR on LAS
« on: 10/20/2011 03:27 pm »
SpaceX Completes Key Milestone to Fly Astronauts to International Space Station

Hawthorne, CA – Today, Space Exploration Technologies (SpaceX) announced it has successfully completed the preliminary design review of its revolutionary launch abort system, a system designed for manned missions using its Dragon spacecraft. This represents a major step toward creating an American-made successor to the Space Shuttle.

NASA’s approval of the latest design review marks the fourth successfully completed milestone under the agency’s Commercial Crew Development (CCDev) program and demonstrates the innovation that’s possible when NASA partners with the private sector.

“Each milestone we complete brings the United States one step closer to once again having domestic human spaceflight capability,” said former astronaut Garrett Reisman, one of the two program leads of SpaceX’s DragonRider, which is adding capabilities to the Dragon spacecraft for astronaut carriage.

Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.

As with all SpaceX designs, increased safety and reliability are paramount. "Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”

With the latest design review approved by NASA, SpaceX can now start building the hardware at the heart of its innovative launch abort system. The SpaceX design incorporates the escape engines into the side walls of Dragon, eliminating a failure mode of more traditional rocket escape towers, which must be successfully jettisoned during every launch. The integrated abort system also returns with the spacecraft, allowing for easy reuse and reductions in the cost of space transport. Over time, the same escape thrusters will also provide Dragon with the ability to land with pinpoint accuracy on Earth or another planet.

In its first flights, on June 4 and December 8, 2010, SpaceX's Falcon 9 launch vehicle achieved consecutive mission successes. The December mission, which was the first demonstration flight under NASA’s Commercial Orbital Transportation Services (COTS) program, marked Dragon’s historic debut and established SpaceX as the first private company to launch and recover a spacecraft from orbit. As a result, many Falcon 9 and Dragon components required for transporting humans to Earth orbit have already been demonstrated in flight.

PHOTO CAPTION: The new launch abort system provides crew with emergency escape capability throughout the entire flight and returns with the spacecraft, allowing for easy reuse. Credit: SpaceX

Offline david1971

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Re: SpaceX complete PDR on LAS
« Reply #1 on: 10/20/2011 03:59 pm »
When were they scheduled to complete this milestone?

Offline mr. mark

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Re: SpaceX complete PDR on LAS
« Reply #2 on: 10/20/2011 04:18 pm »
This should be good ammo for Spacex at the upcoming House Commercial Crew hearings. Nothing better than to state that they have cleared the design review and are going about starting testing with eventual production.

http://www.spacepolitics.com/2011/10/20/house-to-hold-commercial-crew-hearing-next-week/
« Last Edit: 10/20/2011 04:23 pm by mr. mark »

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #3 on: 10/20/2011 04:29 pm »
When were they scheduled to complete this milestone?

September 2011; see SpaceX CCDev-2 SAA.  Note that this is the LAS propulsion component PDR (milestone #4):
Quote
For purposes of CCDev 2, LAS Propulsion Components are defined as ... This definition of LAS Propulsion Components explicitly does not include a full flight configuration of the LAS Propulsion system, and is explicitly not a flight-like Dragon-integrated configuration.
Which gives the ok to fabricate component test articles (#8, Apr 2012), then initial component tests (#9, May 2012).  (Current SAA does not provide for integrated vehicle PDR or test.)

Offline Namechange User

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Re: SpaceX complete PDR on LAS
« Reply #4 on: 10/20/2011 04:53 pm »
This should be good ammo for Spacex at the upcoming House Commercial Crew hearings. Nothing better than to state that they have cleared the design review and are going about starting testing with eventual production.

http://www.spacepolitics.com/2011/10/20/house-to-hold-commercial-crew-hearing-next-week/

Is it your assumption that they will need "ammo"?  SpaceX completed a milestone, that they set (a month later than they said too, but that really is noise-level), at the component PDR level.  That's good and I congratulate them for making steady progress but I would caution on making this into more than it really is. 

The others are also completing their milestones so this is not something special and unique about SpaceX. 
Enjoying viewing the forum a little better now by filtering certain users.

Offline DavisSTS

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Re: SpaceX complete PDR on LAS
« Reply #5 on: 10/20/2011 04:55 pm »
"This represents a major step toward creating an American-made successor to the Space Shuttle."

Great! So Dragon is going to have a 40 ton payload capacity, robotic arms, air locks, six person crews, and an ability for massive downmass, before landing on preferred runways.

That's big news! :D

Offline mr. mark

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Re: SpaceX complete PDR on LAS
« Reply #6 on: 10/20/2011 05:14 pm »
I would say that all these commercial vehicles are successors. "Prefered" runways...  well that's another matter. Powered landings on any flat surface anywhere in the world well that's nothing to sneeze at. But, we have gone over this again and again. It clearly is a matter of preference. Spacex is not aiming at LEO in the far future so a winged vehicle is not along their evolutionary track.
« Last Edit: 10/20/2011 05:15 pm by mr. mark »

Offline majormajor42

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Re: SpaceX complete PDR on LAS
« Reply #7 on: 10/20/2011 05:17 pm »
Is it your assumption that they will need "ammo"? 
"This represents a major step toward creating an American-made successor to the Space Shuttle."

Great! So Dragon is going to have a 40 ton payload capacity, robotic arms, air locks, six person crews, and an ability for massive downmass, before landing on preferred runways.

That's big news! :D

Ammo might be needed after all.
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Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #8 on: 10/20/2011 05:20 pm »
This should be good ammo for Spacex at the upcoming House Commercial Crew hearings. Nothing better than to state that they have cleared the design review and are going about starting testing with eventual production.

http://www.spacepolitics.com/2011/10/20/house-to-hold-commercial-crew-hearing-next-week/

Is it your assumption that they will need "ammo"?  SpaceX completed a milestone, that they set (a month later than they said too, but that really is noise-level), at the component PDR level.  That's good and I congratulate them for making steady progress but I would caution on making this into more than it really is. 

The others are also completing their milestones so this is not something special and unique about SpaceX. 

He needs "ammo" because there are a number of anti-commercial Representatives on the committee. I am expecting fireworks too. Hopefully, they will let Musk talk.
« Last Edit: 10/20/2011 05:35 pm by yg1968 »

Offline go4mars

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Re: SpaceX complete PDR on LAS
« Reply #9 on: 10/20/2011 05:21 pm »
"This represents a major step toward creating an American-made successor to the Space Shuttle."

Great! So Dragon is going to have a 40 ton payload capacity, robotic arms, air locks, six person crews, and an ability for massive downmass, before landing on preferred runways.

That's big news! :D
It doesn't say equivalent.  It says successor.  Anyways, you can't pick and choose.  For example, compare shuttle abort modes, program cost, BEO return capability, etc.
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Offline baldusi

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Re: SpaceX complete PDR on LAS
« Reply #10 on: 10/20/2011 06:09 pm »
As with all SpaceX designs, increased safety and reliability are paramount. "Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”
You've gotta love them making names (DragonRider). But was it necessary to make such outrageous claim of what's sort of standard feature of any currently flying or about to fly crew vehicle? In fact, save for the Shuttle, Voskhod and Gemini, I think has always been a standard feature.

Offline Downix

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Re: SpaceX complete PDR on LAS
« Reply #11 on: 10/20/2011 06:09 pm »
Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.
Hold on a second.  Right now, the Dragon is costing NASA $160 million per launch.  This statement implies that SpaceX is going to change $140 million for the upgraded Dragon with crew ability.  This does not add up to me.
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Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #12 on: 10/20/2011 06:09 pm »
"This represents a major step toward creating an American-made successor to the Space Shuttle."

Great! So Dragon is going to have a 40 ton payload capacity, robotic arms, air locks, six person crews, and an ability for massive downmass, before landing on preferred runways.

That's big news! :D

I suggest that you look up the definition of "successor". It doesn't mean what you think it means. ;)

Offline koraldon

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Re: SpaceX complete PDR on LAS
« Reply #13 on: 10/20/2011 06:20 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.

In addition, a cost per seat to fly of 20$ million is not cheap. You can get a soyuz flight for around 15 to 20$ million as well... Space Adventures beat them to the price point (with actual ppl flying) more than a decade ago... definitely not unparalleled - The only sad thing is that russia "blackmailed" NASA for the seat costs (I assume that NASA also had more requirements than Space Adventures).

p.s. and of course a decent company would have written in the the photo caption that it is an artist's concept... I can easily see the press confused by the pic and think it is real...
« Last Edit: 10/20/2011 06:22 pm by koraldon »

Offline krytek

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Re: SpaceX complete PDR on LAS
« Reply #14 on: 10/20/2011 06:33 pm »
Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.
Hold on a second.  Right now, the Dragon is costing NASA $160 million per launch.  This statement implies that SpaceX is going to change $140 million for the upgraded Dragon with crew ability.  This does not add up to me.

Where did you get the 160M$ figure? Last I remember CRS was 80M$ per flight.

Quote
As was said - LAS is not a revolution, it's already there for 50 years or so
Where did you see a LAS type system 50 years ago?
« Last Edit: 10/20/2011 06:44 pm by krytek »

Offline MajorBringdown

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Re: SpaceX complete PDR on LAS
« Reply #15 on: 10/20/2011 06:39 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.


The original post does not claim that LAS is a revolution anywhere.  It says this:

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”

What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Please correct me if I'm mistaking in my interpretation of what I'm reading here, or if my facts are wrong.

Offline Jason1701

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Re: SpaceX complete PDR on LAS
« Reply #16 on: 10/20/2011 06:40 pm »
Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.
Hold on a second.  Right now, the Dragon is costing NASA $160 million per launch.  This statement implies that SpaceX is going to change $140 million for the upgraded Dragon with crew ability.  This does not add up to me.

Where did you get the 160M$ figure? Last I remember CRS was 80M$ per flight.

CRS is $133 million per launch. This was negotiated before SpaceX found that the Dragon could be reused. Future cargo resupply contracts would likely be cheaper if they include reusability.

koraldon - SpaceX's LAS design actually is groundbreaking. Show me who the Russians are charging $15 million per seat NOW. I don't care what their prices were 10 years ago before a host of major factors changed. You don't seem to understand the point of a press release; it's to present a company's achievement in a positive way. Russia is not blackmailing NASA, it simply learned capitalism.

Offline Jorge

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Re: SpaceX complete PDR on LAS
« Reply #17 on: 10/20/2011 06:40 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.

In addition, a cost per seat to fly of 20$ million is not cheap. You can get a soyuz flight for around 15 to 20$ million as well...

No, you can't. Not any more, anyway... even the Space Adventures tourist flights are in the $30-40M price range now. Largely due to appreciation of the ruble with respect to the dollar since 2001.

Not that price matters; by law, once a US commercial provider is available, NASA will buy their services in preference to Soyuz. SpaceX doesn't have to price-match Soyuz.

Quote
Space Adventures beat them to the price point (with actual ppl flying) more than a decade ago... definitely not unparalleled - The only sad thing is that russia "blackmailed" NASA for the seat costs (I assume that NASA also had more requirements than Space Adventures).

Duh. The NASA flights include crew training to the Flight Engineer-1 level (far more than the tourists get) and six months of Soyuz providing CRV lifeboat service while docked to ISS. No "blackmail" involved... you want more, you pay more. That simple.
JRF

Offline go4mars

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Re: SpaceX complete PDR on LAS
« Reply #18 on: 10/20/2011 06:42 pm »
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”
But was it necessary to make such outrageous claim of what's sort of standard feature of any currently flying or about to fly crew vehicle? In fact, save for the Shuttle, Voskhod and Gemini, I think has always been a standard feature.
Maybe Giger's quote was taken out of context (what he was referring to was not in the article).  I find it implausible that the guy in charge of the program was unaware of prior systems.  Maybe he was referring to the abort engine redundancy (8 instead of 4), or a reliability advantage bestowed by liquid vs solid or extra testing at various altitudes or something.  Agree that this was not written carefully enough.
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Offline butters

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Re: SpaceX complete PDR on LAS
« Reply #19 on: 10/20/2011 06:44 pm »
Only a month late on a significant milestone requiring NASA approval. That's a welcome improvement in schedule accuracy for SpaceX. Keep it up guys!

On the "unprecedented" nature of the LAS: to my knowledge, all previous LAS designs required a time-critical separation event during every nominal ascent to jettison the LAS, and failure to jettison would be a probable loss of crew situation. Correct me if I'm wrong, but Dragon's LAS is the first which will not be jettisoned during nominal ascent. It will also be the first potentially reusable LAS. These are substantial improvements.

Is it the first LAS of any kind? No, but I don't see where SpaceX made a claim like that in this press release or in previous statements.

Designing and building this LAS will be a lot easier than testing it. That's the difficult and extraordinarily expensive part of the development cycle. I mean, it's not nearly as bad as it would be to test Shuttle RTLS (shudder), but it's still a formidable and resource-intensive challenge that SpaceX has ahead of them.

Offline Jorge

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Re: SpaceX complete PDR on LAS
« Reply #20 on: 10/20/2011 06:47 pm »
What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Which, while true, is not nearly as significant as SpaceX is claiming. On other systems, after the LAS is jettisoned, the spacecraft's propulsion system provides abort capability the rest of the way to orbit. Apollo used the SPS for Mode II and III aborts, Orion will use the OME, and Soyuz uses its SKD main engine. So abort capability from launch to orbit is not unique, just that Dragon uses a single system.
JRF

Offline LegendCJS

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Re: SpaceX complete PDR on LAS
« Reply #21 on: 10/20/2011 06:49 pm »
I see others beat me to it but I'm posting anyway.

SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.


SpaceX has a collection of grade A word smiths working for their company.  An example: Phrases like "first privately developed United States Launch vehicle in N? years launched from the ground" must be evaluated in a Vulcan kind of manner in order to see their truth.  "launched from the ground" rules out Pegasus (air) and floating platform launch (Sea Launch).

In your case you gripe about their claim that

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”


I call to your attention the words until the rocket reaches orbit.  If you look at all other "tractor tower" launch escape/ abort rockets designs, there is a period before the rocket reaches orbit when the tractor tower must jettison.  If it does not jettison then the launch will not have the power to make orbit.  This means that there is a period after which escape is impossible, but before the last stage of the launcher has shut down its engines and the craft is not in orbit.  The idea that the on-board thrusters could take the craft to orbit if it needed to detach after tractor tower jettison but before final stage engine shutdown might have been used to claim abort "all the way to orbit" was an option for the previous designs, but this scenario would not allow a tractor tower-less craft to make a rapid escape from a possible exploding upper stage like the dragon design does.

If you evaluate their words like a Vulcan you will find that they aren't lying.
« Last Edit: 10/20/2011 06:56 pm by LegendCJS »
Remember: if we want this whole space thing to work out we have to optimize for cost!

Online Robotbeat

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Re: SpaceX complete PDR on LAS
« Reply #22 on: 10/20/2011 06:50 pm »
Any news on test-firing of the abort engines? SpaceX seems to be pretty good at producing and testing new rocket engines, so I almost kind of expected them to have done some sort of test fire by now (it is pressure-fed, after all).
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Offline baldusi

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Re: SpaceX complete PDR on LAS
« Reply #23 on: 10/20/2011 06:51 pm »
Space Adventures beat them to the price point (with actual ppl flying) more than a decade ago... definitely not unparalleled - The only sad thing is that russia "blackmailed" NASA for the seat costs (I assume that NASA also had more requirements than Space Adventures).

Duh. The NASA flights include crew training to the Flight Engineer-1 level (far more than the tourists get) and six months of Soyuz providing CRV lifeboat service while docked to ISS. No "blackmail" involved... you want more, you pay more. That simple.
May I add two important factors: inflation, ten years ago meant at least 20% more today. And amount demanded. It's not the same to squeeze a seat each couple of years than asking to double production and ground ops.

Offline Jorge

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Re: SpaceX complete PDR on LAS
« Reply #24 on: 10/20/2011 06:55 pm »
I see others beat me to it but I'm posting anyway.

SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.


SpaceX has a collection of grade A word smiths working for their company.  An example: Phrases like "first privately developed United States Launch vehicle in N? years launched from the ground" must be evaluated in a Vulcan kind of manner in order to see their truth.  "launched from the ground" rules out Pegasus (air) and floating platform launch (Sea Launch).

In your case you gripe about their claim that

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”


I call to your attention the words until the rocket reaches orbit.  If you look at all other "tractor tower" launch escape/ abort rockets designs, there is a period before the rocket reaches orbit when the tractor tower must jettison.  If it does not jettison then the launch will not have the power to make orbit.  This means that there is a period after which escape is impossible, but before the last stage of the launcher has shut down its engines and the craft is not in orbit.  So if you evaluate their words like a Vulcan you will find that they aren't lying.

Incorrect. As I have stated, on other systems, after LAS jettison, escape capability is provided by the spacecraft engines. SpaceX's innovation is not "launch to orbit escape capability", it's that they're providing it with a single system over the entire profile.
JRF

Offline MajorBringdown

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Re: SpaceX complete PDR on LAS
« Reply #25 on: 10/20/2011 06:57 pm »
What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Which, while true, is not nearly as significant as SpaceX is claiming. On other systems, after the LAS is jettisoned, the spacecraft's propulsion system provides abort capability the rest of the way to orbit. Apollo used the SPS for Mode II and III aborts, Orion will use the OME, and Soyuz uses its SKD main engine. So abort capability from launch to orbit is not unique, just that Dragon uses a single system.

Ahh, I see.  Thank you for the clarification.  I wasn't aware the spacecraft took responsibility for aborting after the LAS jettison.

In the other systems, is there is a time window around the LAS jettison event where aborts can't happen due to the LAS tower being too close the spacecraft?  If so, is that window significant?

Offline koraldon

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Re: SpaceX complete PDR on LAS
« Reply #26 on: 10/20/2011 06:58 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.


The original post does not claim that LAS is a revolution anywhere.  It says this:

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”

What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Please correct me if I'm mistaking in my interpretation of what I'm reading here, or if my facts are wrong.


First paragraph of the PR
Quote
Hawthorne, CA – Today, Space Exploration Technologies (SpaceX) announced it has successfully completed the preliminary design review of its revolutionary launch abort system, a system designed for manned missions using its Dragon spacecraft. This represents a major step toward creating an American-made successor to the Space Shuttle.

Bold is mine.
I agree that the design is different and probably has adventages over the usual tower design - single system with retro-fire and probably other. I will be surprised if it offers the same g's as a regular tower... but those are valid design decisions made by technical team. It might be better overall - as i have no design experience or familiarity with abort systems, I have no clue.
Giger is good with his quote - no qualm there, just the first PR paragraph.


Offline Namechange User

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Re: SpaceX complete PDR on LAS
« Reply #27 on: 10/20/2011 06:59 pm »
This should be good ammo for Spacex at the upcoming House Commercial Crew hearings. Nothing better than to state that they have cleared the design review and are going about starting testing with eventual production.

http://www.spacepolitics.com/2011/10/20/house-to-hold-commercial-crew-hearing-next-week/

Is it your assumption that they will need "ammo"?  SpaceX completed a milestone, that they set (a month later than they said too, but that really is noise-level), at the component PDR level.  That's good and I congratulate them for making steady progress but I would caution on making this into more than it really is. 

The others are also completing their milestones so this is not something special and unique about SpaceX. 

He needs "ammo" because there are a number of anti-commercial Representatives on the committee. I am expecting fireworks too. Hopefully, they will let Musk talk.

Whatever.  To you anyone and everyone is anti-commercial if they do not believe something called "commercial" should be totally government funding and subsidization from cradle to grave. 
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Offline Jorge

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Re: SpaceX complete PDR on LAS
« Reply #28 on: 10/20/2011 07:00 pm »
What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Which, while true, is not nearly as significant as SpaceX is claiming. On other systems, after the LAS is jettisoned, the spacecraft's propulsion system provides abort capability the rest of the way to orbit. Apollo used the SPS for Mode II and III aborts, Orion will use the OME, and Soyuz uses its SKD main engine. So abort capability from launch to orbit is not unique, just that Dragon uses a single system.

Ahh, I see.  Thank you for the clarification.  I wasn't aware the spacecraft took responsibility for aborting after the LAS jettison.

In the other systems, is there is a time window around the LAS jettison event where aborts can't happen due to the LAS tower being too close the spacecraft?  If so, is that window significant?

Not really, on the order of seconds. Both the Apollo and Orion LAS jettison motors have a slight lateral thrust component to get them out of the way quickly. Don't know what Soyuz does, but since they copied their system from Mercury (which was similar to Apollo in concept) I imagine they do something similar.
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Re: SpaceX complete PDR on LAS
« Reply #29 on: 10/20/2011 07:00 pm »
What they may be saying is that there are no black zones during the ascent.  Maybe I'm wrong but all previous launchers with LASs had many "outs"--for example, after tower jettison on Mercury, the capsule could not escape from the booster if the sustainer engine was still running.  Abort during the first seconds of an Apollo launch would result in a "land landing" probably killing the crew.  Etc.

Wayne Hale had a series of blog posts on this...

Offline LegendCJS

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Re: SpaceX complete PDR on LAS
« Reply #30 on: 10/20/2011 07:01 pm »

Incorrect. As I have stated, on other systems, after LAS jettison, escape capability is provided by the spacecraft engines. SpaceX's innovation is not "launch to orbit escape capability", it's that they're providing it with a single system over the entire profile.


Note my edit:
The idea that the on-board thrusters could take the craft to orbit if it needed to detach after tractor tower jettison but before final stage engine shutdown might have been used to claim abort "all the way to orbit" was an option for the previous designs, but this scenario would not allow a tractor tower-less craft to make a rapid escape from a possible exploding upper stage like the dragon design does.
« Last Edit: 10/20/2011 07:02 pm by LegendCJS »
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Re: SpaceX complete PDR on LAS
« Reply #31 on: 10/20/2011 07:02 pm »
It's revolutionary in that it may eventually allow powered vertical landing (and not just a cushioning burst like the Soyuz has) and it's reusable (and doesn't have a critical jettison event) and its propellant is used for on-orbit maneuvering.
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Re: SpaceX complete PDR on LAS
« Reply #32 on: 10/20/2011 07:04 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.


The original post does not claim that LAS is a revolution anywhere.  It says this:

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”

What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Please correct me if I'm mistaking in my interpretation of what I'm reading here, or if my facts are wrong.


First paragraph of the PR
Quote
Hawthorne, CA – Today, Space Exploration Technologies (SpaceX) announced it has successfully completed the preliminary design review of its revolutionary launch abort system, a system designed for manned missions using its Dragon spacecraft. This represents a major step toward creating an American-made successor to the Space Shuttle.

Bold is mine.
I agree that the design is different and probably has adventages over the usual tower design - single system with retro-fire and probably other. I will be surprised if it offers the same g's as a regular tower... but those are valid design decisions made by technical team. It might be better overall - as i have no design experience or familiarity with abort systems, I have no clue.
Giger is good with his quote - no qualm there, just the first PR paragraph.



Ahh, I missed that one.  Guess I should read these things twice before posting! :)

Offline Jorge

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Re: SpaceX complete PDR on LAS
« Reply #33 on: 10/20/2011 07:05 pm »

Incorrect. As I have stated, on other systems, after LAS jettison, escape capability is provided by the spacecraft engines. SpaceX's innovation is not "launch to orbit escape capability", it's that they're providing it with a single system over the entire profile.


Note my edit:
The idea that the on-board thrusters could take the craft to orbit if it needed to detach after tractor tower jettison but before final stage engine shutdown might have been used to claim abort "all the way to orbit" was an option for the previous designs, but this scenario would not allow a tractor tower-less craft to make a rapid escape from a possible exploding upper stage like the dragon design does.

And you think the designers of Apollo, Orion, etc didn't account for this? The SPS and OME were *sized* to provide escape that is rapid *enough*, considering the less-dynamic situation once the LV is above the atmosphere. It's not as rapid as the LAS, but it doesn't *need* to be.
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Offline LegendCJS

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Re: SpaceX complete PDR on LAS
« Reply #34 on: 10/20/2011 07:10 pm »

Incorrect. As I have stated, on other systems, after LAS jettison, escape capability is provided by the spacecraft engines. SpaceX's innovation is not "launch to orbit escape capability", it's that they're providing it with a single system over the entire profile.


Note my edit:
The idea that the on-board thrusters could take the craft to orbit if it needed to detach after tractor tower jettison but before final stage engine shutdown might have been used to claim abort "all the way to orbit" was an option for the previous designs, but this scenario would not allow a tractor tower-less craft to make a rapid escape from a possible exploding upper stage like the dragon design does.

And you think the designers of Apollo, Orion, etc didn't account for this? The SPS and OME were *sized* to provide escape that is rapid *enough*, considering the less-dynamic situation once the LV is above the atmosphere. It's not as rapid as the LAS, but it doesn't *need* to be.

I'll give you Apollo, but my memory says that there were some black zones even still.  I don't think a "Vulcan" like evaluation of the SpaceX statement would consider Orion because it hasn't been flown yet (I know that is unfair because neither has LAS capable dragon flown.)  But even if Apollo had no black zones, the tractor tower still had to jettison if astronauts were going to survive- Apollo couldn't successfully deploy its parachutes unless the tractor tower was detached.
« Last Edit: 10/20/2011 07:13 pm by LegendCJS »
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Offline simonbp

Re: SpaceX complete PDR on LAS
« Reply #35 on: 10/20/2011 07:13 pm »
Not that price matters; by law, once a US commercial provider is available, NASA will buy their services in preference to Soyuz. SpaceX doesn't have to price-match Soyuz.

Excellent point, and one to keep in mind for all the CCDEV players...

Offline MikeAtkinson

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Re: SpaceX complete PDR on LAS
« Reply #36 on: 10/20/2011 07:21 pm »
Tower designs of a LAS have a critical failure mode where the tower is not jettisoned. In that case there will be LOM and almost certainly LOC.

LAS tower jettison has to be performed on each launch, successful or not, so has to be very reliable so as not to adversly affect LOC probabilities.

Integrated pusher type systems do not have that failure mode.

Offline Namechange User

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Re: SpaceX complete PDR on LAS
« Reply #37 on: 10/20/2011 07:26 pm »
Tower designs of a LAS have a critical failure mode where the tower is not jettisoned. In that case there will be LOM and almost certainly LOC.

LAS tower jettison has to be performed on each launch, successful or not, so has to be very reliable so as not to adversly affect LOC probabilities.

Integrated pusher type systems do not have that failure mode.

True, but they have different failure modes.  Failure modes that could be carried throughout the entire mission. 

Like all things it is a trade based on a multitude of factors and this is a weak argument to suggest this proves superiority. 
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Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #38 on: 10/20/2011 07:36 pm »
Quick question - assuming it does fly, will this LAS (and CST-100's LAS) be the first liquid propelled LAS?

Offline Jim

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Re: SpaceX complete PDR on LAS
« Reply #39 on: 10/20/2011 07:43 pm »

Incorrect. As I have stated, on other systems, after LAS jettison, escape capability is provided by the spacecraft engines. SpaceX's innovation is not "launch to orbit escape capability", it's that they're providing it with a single system over the entire profile.


Note my edit:
The idea that the on-board thrusters could take the craft to orbit if it needed to detach after tractor tower jettison but before final stage engine shutdown might have been used to claim abort "all the way to orbit" was an option for the previous designs, but this scenario would not allow a tractor tower-less craft to make a rapid escape from a possible exploding upper stage like the dragon design does.

And you think the designers of Apollo, Orion, etc didn't account for this? The SPS and OME were *sized* to provide escape that is rapid *enough*, considering the less-dynamic situation once the LV is above the atmosphere. It's not as rapid as the LAS, but it doesn't *need* to be.

Yes, there is no shock wave and therefore no need for high G LES.

Offline majormajor42

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Re: SpaceX complete PDR on LAS
« Reply #40 on: 10/20/2011 07:44 pm »
It's revolutionary in that it may eventually allow powered vertical landing (and not just a cushioning burst like the Soyuz has) and it's reusable (and doesn't have a critical jettison event) and its propellant is used for on-orbit maneuvering.

when I initially read the release, it was the reusable, liquid, integrated, multipurpose nature of their LAS that I took for being revolutionary. So I think it is significant that NASA has approved this design and that is worthy of the press release.

Have any other non-tower tractor LAS's been approved yet? Blue Origin?

Now, considering that we can all agree that we want the American HSF gap to be as small as possible (although we may differ on how we think that should be accomplished) I wonder if this pusher LAS is adding excessive time to closing the gap? SpaceX is ahead with their flying rocket and flying unmanned capsule for the time being. Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology? If SpaceX was purely focused on closing the gap, in addition to everything else they have to do, would using a tractor system help launch people sooner?

I also wonder if this new Dragon LAS design has been designed looking ahead to also satisfying the needs of a manned Dragon capsule riding on top of a FH? Does that change things much?
« Last Edit: 10/20/2011 07:46 pm by majormajor42 »
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Offline Jim

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Re: SpaceX complete PDR on LAS
« Reply #41 on: 10/20/2011 07:50 pm »
Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology? ?

Boeing is using a pusher

Offline majormajor42

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Re: SpaceX complete PDR on LAS
« Reply #42 on: 10/20/2011 07:53 pm »
Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology? ?

Boeing is using a pusher

well, there goes that theory. Maybe I was thinking of Orion on top of an EELV. Thanks.
...water is life and it is out there, where we intend to go. I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man or machine on a body such as the Moon and harvest a cup of water for a human to drink or process into fuel for their craft.

Offline Namechange User

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Re: SpaceX complete PDR on LAS
« Reply #43 on: 10/20/2011 07:58 pm »
So I think it is significant that NASA has approved this design and that is worthy of the press release.


NASA nor anyone has approved the design.  It was a component PDR. 
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Offline Danny Dot

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Re: SpaceX complete PDR on LAS
« Reply #44 on: 10/20/2011 08:00 pm »
Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.
Hold on a second.  Right now, the Dragon is costing NASA $160 million per launch.  This statement implies that SpaceX is going to change $140 million for the upgraded Dragon with crew ability.  This does not add up to me.

Where did you get the 160M$ figure? Last I remember CRS was 80M$ per flight.

Quote
As was said - LAS is not a revolution, it's already there for 50 years or so
Where did you see a LAS type system 50 years ago?

Mercury (Gemini had ejection seats and no LAS.)
« Last Edit: 10/20/2011 08:01 pm by Danny Dot »
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Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #45 on: 10/20/2011 08:02 pm »
Now that the Space Shuttle program has ended, the United States relies on the Russian Soyuz spacecraft for astronaut transport, costing American taxpayers as much as $62 million a seat. By comparison, Dragon is designed to carry seven astronauts at a time for an unparalleled $20 million per seat.
Hold on a second.  Right now, the Dragon is costing NASA $160 million per launch.  This statement implies that SpaceX is going to change $140 million for the upgraded Dragon with crew ability.  This does not add up to me.

Where did you get the 160M$ figure? Last I remember CRS was 80M$ per flight.

CRS is $133 million per launch. This was negotiated before SpaceX found that the Dragon could be reused. Future cargo resupply contracts would likely be cheaper if they include reusability.

koraldon - SpaceX's LAS design actually is groundbreaking. Show me who the Russians are charging $15 million per seat NOW. I don't care what their prices were 10 years ago before a host of major factors changed. You don't seem to understand the point of a press release; it's to present a company's achievement in a positive way. Russia is not blackmailing NASA, it simply learned capitalism.

You are right about the price. It was $1.6B for 12 flights and I am not sure if that includes the price for downmass.
http://www.nasa.gov/offices/c3po/home/CRS-Announcement-Dec-08.html

As far as the reusibility, I believe that NASA did not want to take any chances and did not want re-used Dragons.  I am not sure what SpaceX will do with its old Dragons.
« Last Edit: 10/20/2011 08:30 pm by yg1968 »

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Re: SpaceX complete PDR on LAS
« Reply #46 on: 10/20/2011 08:06 pm »
As far as the reusibility, I believe that NASA did not want to take any chances and did not want re-used Dragons.  I am not sure what SpaceX will do with its old Dragons.

Elon has lots of plans for space that do not include NASA. His reusable Dragons will find a home for all his commercial and personal ventures, paid for by NASA. Effective thinking and just plain good business to get somebody else to pay for your hardware.
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Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #47 on: 10/20/2011 08:08 pm »
Yes you are right. I think that's where DragonLab comes into play.

Offline renclod

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Re: SpaceX complete PDR on LAS
« Reply #48 on: 10/20/2011 08:30 pm »
... (Current SAA does not provide for integrated vehicle PDR ....)

Patience... is a virtue.

My question is, will NASA buy an integrated Dragon design that does not provide for main landing parachutes ?


Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #49 on: 10/20/2011 08:35 pm »
... (Current SAA does not provide for integrated vehicle PDR ....)

Patience... is a virtue.

My question is, will NASA buy an integrated Dragon design that does not provide for main landing parachutes ?

Which Dragon design does not have a main parachute??

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Re: SpaceX complete PDR on LAS
« Reply #50 on: 10/20/2011 08:45 pm »
As with all SpaceX designs, increased safety and reliability are paramount. "Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”
You've gotta love them making names (DragonRider). But was it necessary to make such outrageous claim of what's sort of standard feature of any currently flying or about to fly crew vehicle? In fact, save for the Shuttle, Voskhod and Gemini, I think has always been a standard feature.
I believe the reasoning is that on Mercury, Apollo, Soyuz, and Shenzhou the launch abort system separation adds risk to the mission.

SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
You're misinterpreting the press release.
« Last Edit: 10/20/2011 08:47 pm by manboy »
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Re: SpaceX complete PDR on LAS
« Reply #51 on: 10/20/2011 08:47 pm »
SpaceX should really replace it's PR team with all the false facts they put there..... I mean, marketing always tend to lie about engineering capabilities, but not in such a blatant and incompetent way.

As was said - LAS is not a revolution, it's already there for 50 years or so... This is a basic capability for a capsule based manned spacecraft, which was required from them.
Good that they made the PDR, it is still a long way off from development completion, wish them success - but really stop the empty boasting / lies on press releases.


The original post does not claim that LAS is a revolution anywhere.  It says this:

Quote
"Dragon’s integrated launch abort system provides astronauts with the ability to safely escape from the beginning of the launch until the rocket reaches orbit,” explained David Giger, co-lead of the DragonRider program. “This level of protection is unprecedented in manned spaceflight history.”

What they are saying is that the integrated nature of the LAS provides escape from launch to orbit.  A LAS that requires jettisoning means you lose that capability after that point in the flight.  If I recall correctly, in other launchers/capsules, that jettison happens well before orbit is reached.

Please correct me if I'm mistaking in my interpretation of what I'm reading here, or if my facts are wrong.


A good rule of thumb is to get rid of it once out of the atmosphere - where the risk of breakup and explosions goes down.  Abort is still an option using much less thrust using RCS and/or SM engine.  Taking the LAS to orbit hurts performance - a lot.
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Offline Cherokee43v6

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Re: SpaceX complete PDR on LAS
« Reply #52 on: 10/20/2011 08:49 pm »

As far as the reusibility, I believe that NASA did not want to take any chances and did not want re-used Dragons.  I am not sure what SpaceX will do with its old Dragons.

Well, he has at least two Dragonlab missions on the books.

While it is not written anywhere I think NASA would want him to prove 'safe' reusability before they would consider allowing him to perform multiple missions to the ISS with a Dragon.
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Offline Cherokee43v6

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Re: SpaceX complete PDR on LAS
« Reply #53 on: 10/20/2011 08:55 pm »

A good rule of thumb is to get rid of it once out of the atmosphere - where the risk of breakup and explosions goes down.  Abort is still an option using much less thrust using RCS and/or SM engine.  Taking the LAS to orbit hurts performance - a lot.

Ah... the difference between having 'great' performance or meerly having 'good enough' performance.

Early on, Elon talked about his rocket's design philosophy.  The idea was to make it robust and simple, not to make it on the bleeding edge of performance.  SpaceX made a conscious decision to trade total mass to orbit in exchange for things like reusability.  Sure, they could strip out their extra margin and increase the total tonnage they could launch per F9, but that makes the rocket much more expensive due to tighter tolerances and more intensive quality control proceedures to make up for the loss of robustness in the vehicle.

Their decision to use a pusher/reusable LAS definitely fits within this philosophy.
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Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #54 on: 10/20/2011 09:00 pm »
CRS is $133 million per launch. This was negotiated before SpaceX found that the Dragon could be reused. Future cargo resupply contracts would likely be cheaper if they include reusability.

You are right about the price. It was $1.6B for 12 flights and I could be wrong but I believe that this price does not include the downmass option. Downmass is an option if I remember correctly that would increase the price.

As far as the reusibility, I believe that NASA did not want to take any chances and did not want re-used Dragons.  I am not sure what SpaceX will do with its old Dragons.

OT but for the record...

The contract pricing is nominally by mass.  Guaranteed minimum of 20mT total upmass; per/kg pricing "assumes cargo mass capacity fully utilized" (3310kg/flight combined up); if cargo is volume limited "per mission pricing applies", unclear if that means NASA pays for 3310kg/flight whether or not they use it.  There is also a base option for 3mT total downmass as part of the contract (up to 2500kg/flight), which presumably SpaceX accepted.

There is nothing in the CRS contract (at least the public part) that requires a new Dragon for each flight.  I believe the reason there aren't any refurb Dragons for CRS is that refurb cost/price was at the time unknown and unknowable; including reusability would have been a very high financial risk to SpaceX, and thus a high program risk to NASA.  In the original COTS proposal, SpaceX was pushing reusability but cautioned:
Quote
...the costs as proposed assume no reusability economics. Until a given launch system has flown several times and all costs are understood, it is very risky to make reusability cost assumptions.
As the CRS contract was signed before any F9/Dragon flights, presumably that logic and caution still held.

Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #55 on: 10/20/2011 09:14 pm »
CRS is $133 million per launch. This was negotiated before SpaceX found that the Dragon could be reused. Future cargo resupply contracts would likely be cheaper if they include reusability.

You are right about the price. It was $1.6B for 12 flights and I could be wrong but I believe that this price does not include the downmass option. Downmass is an option if I remember correctly that would increase the price.

As far as the reusibility, I believe that NASA did not want to take any chances and did not want re-used Dragons.  I am not sure what SpaceX will do with its old Dragons.

OT but for the record...

The contract pricing is nominally by mass.  Guaranteed minimum of 20mT total upmass; per/kg pricing "assumes cargo mass capacity fully utilized" (3310kg/flight combined up); if cargo is volume limited "per mission pricing applies", unclear if that means NASA pays for 3310kg/flight whether or not they use it.  There is also a base option for 3mT total downmass as part of the contract (up to 2500kg/flight), which presumably SpaceX accepted.

There is nothing in the CRS contract (at least the public part) that requires a new Dragon for each flight.  I believe the reason there aren't any refurb Dragons for CRS is that refurb cost/price was at the time unknown and unknowable; including reusability would have been a very high financial risk to SpaceX, and thus a high program risk to NASA.  In the original COTS proposal, SpaceX was pushing reusability but cautioned:
Quote
...the costs as proposed assume no reusability economics. Until a given launch system has flown several times and all costs are understood, it is very risky to make reusability cost assumptions.
As the CRS contract was signed before any F9/Dragon flights, presumably that logic and caution still held.

Thanks but I am still confused as to whether the amount of $1.6B includes the downmass option or if that option is extra. I haven't seen anything conclusive on this. I believe that it is extra because the NASA press release does not mention downmass but I could be wrong.
« Last Edit: 10/20/2011 09:15 pm by yg1968 »

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #56 on: 10/20/2011 09:25 pm »
Thanks but I am still confused as to whether the amount of $1.6B includes the downmass option or if that option is extra. I haven't seen anything conclusive on this. I believe that it is extra because the NASA press release does not mention downmass but I could be wrong.

I believe it includes 3mT downmass; beyond that (as beyond 20mT up), it would be extra.  I can't state that with certainty (key part redacted), but unless there were serious doubts about Dragon's reentry capabilities, there's no reason for SpaceX not to sign up for it as it increases the contract value (pg 5):
Quote
If the contract includes the acceptance of Sub-CLIN 0001AC, an additional guaranteed minimum value of this contract is increased by the negotiated value of 3,000 kg (3 MT) of Return Cargo Downmass, based on the values established in Clause I.A.4.

Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #57 on: 10/20/2011 09:36 pm »
Thanks but I am still confused as to whether the amount of $1.6B includes the downmass option or if that option is extra. I haven't seen anything conclusive on this. I believe that it is extra because the NASA press release does not mention downmass but I could be wrong.

I believe it includes 3mT downmass; beyond that (as beyond 20mT up), it would be extra.  I can't state that with certainty (key part redacted), but unless there were serious doubts about Dragon's reentry capabilities, there's no reason for SpaceX not to sign up for it as it increases the contract value (pg 5):
Quote
If the contract includes the acceptance of Sub-CLIN 0001AC, an additional guaranteed minimum value of this contract is increased by the negotiated value of 3,000 kg (3 MT) of Return Cargo Downmass, based on the values established in Clause I.A.4.

Right but how do we know if Sub-CLIN 0001AC was picked up by SpaceX in December 2008 and if it was picked up by SpaceX in December 2008 at what price was it picked up. The fact that the NASA press release only mentions upmass makes me think that the downmass option is not included in the $1.6B amount but as I said I don't know that for sure. If I remember correctly, Orbital's contract is almost identical and also has the downmass option.

Offline renclod

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Re: SpaceX complete PDR on LAS
« Reply #58 on: 10/20/2011 09:52 pm »


My question is, will NASA buy an integrated Dragon design that does not provide for main landing parachutes ?

Which Dragon design does not have a main parachute??

Sorry, bad phrasing.

I was looking at this:
"Over time, the same escape thrusters will also provide Dragon with the ability to land with pinpoint accuracy on Earth"
 also this:
"The new launch abort system provides crew with emergency escape capability throughout the entire flight and returns with the spacecraft, allowing for easy reuse."

"easy reuse" + "pinpoint accuracy" in my mind equates with land landing w/o parachutes = under retro thrust from the abort system.

The parachutes are dead weight when landing on thrusters, right ? they may as well jettison the parachutes before igniting the thrusters - except for reuseability, yes.

But even if you carry them on board, you don't have parachutes available for deceleration, when you land on thrusters.

And I wonder when/if NASA will agree to (and pay for) a capsule landing on thrusters, design.


Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #59 on: 10/20/2011 09:53 pm »
Right but how do we know if Sub-CLIN 0001AC was picked up by SpaceX in December 2008 and if it was picked up by SpaceX in December 2008 at what price was it picked up. The fact that the NASA press release only mentions upmass makes me think that the downmass option is not included in the $1.6B amount but as I said I don't know that for sure. If I remember correctly, Orbital's contract is almost identical and also has the downmass option.

As mentioned, can't say for certain that the downmass option was picked up with SpaceX.  However, we know it wasn't with OSC and I'd expect to see the same annotation in the SpaceX contract as with OSC if it wasn't (pg. 1, emphasis added):
Quote
If the contract includes the acceptance of Sub-CL1N0001AE, an additional guaranteed minimum value of this contract is increased by the negotiated value of 3,000 kg (3 MT) of Return Cargo Downmass, based on the values established in Clause I.A.4 (at award, the Government declined Sub-CLIN0001AE).

edit: clarify basis for SpaceX downmass option.
« Last Edit: 10/20/2011 10:08 pm by joek »

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Re: SpaceX complete PDR on LAS
« Reply #60 on: 10/20/2011 10:11 pm »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.
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Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #61 on: 10/20/2011 10:27 pm »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.

Both OSC and SpaceX CRS contracts provide for unrecoverable/disposal "downmass", and those are not options.  As you'd expect, the substantive difference is that for OSC it's pressurized; for SpaceX it's unpressurized (in the trunk).  Although nothing stopping NASA from returning trash in the Dragon (pressurized), probably not the best use of $/capabilities.

Offline LegendCJS

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Re: SpaceX complete PDR on LAS
« Reply #62 on: 10/20/2011 10:34 pm »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.

Both OSC and SpaceX CRS contracts provide for unrecoverable/disposal "downmass", and those are not options.  As you'd expect, the substantive difference is that for OSC it's pressurized; for SpaceX it's unpressurized (in the trunk).  Although nothing stopping NASA from returning trash in the Dragon (pressurized), probably not the best use of $/capabilities.

Trash bags coming loose in a Cygnus and bouncing around inside the capsule while it burns up is no concern.  Trash bags or any pressurized return down-mass coming loose and bouncing around inside a re-entering Dragon is a concern.  So providing for secure strap in for return mass will be an extra feature = extra cost and probably a new/ additional contract/ option. 
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #63 on: 10/20/2011 10:58 pm »
Trash bags coming loose in a Cygnus and bouncing around inside the capsule while it burns up is no concern.  Trash bags or any pressurized return down-mass coming loose and bouncing around inside a re-entering Dragon is a concern.  So providing for secure strap in for return mass will be an extra feature = extra cost and probably a new/ additional contract/ option. 

Yes, that presumably is why per the CRS contracts downmass comes in two flavors: one is priced at all-you-can-eat $X up to Ykg downmass (disposable, OSC and SpaceX); and the other is per-kg-costs-you-$X downmass (recoverable, SpaceX).  However, no, not a new/additional contract/option; price and conditions are set per CRS contract for both.

Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #64 on: 10/20/2011 11:44 pm »
Right but how do we know if Sub-CLIN 0001AC was picked up by SpaceX in December 2008 and if it was picked up by SpaceX in December 2008 at what price was it picked up. The fact that the NASA press release only mentions upmass makes me think that the downmass option is not included in the $1.6B amount but as I said I don't know that for sure. If I remember correctly, Orbital's contract is almost identical and also has the downmass option.

As mentioned, can't say for certain that the downmass option was picked up with SpaceX.  However, we know it wasn't with OSC and I'd expect to see the same annotation in the SpaceX contract as with OSC if it wasn't (pg. 1, emphasis added):
Quote
If the contract includes the acceptance of Sub-CL1N0001AE, an additional guaranteed minimum value of this contract is increased by the negotiated value of 3,000 kg (3 MT) of Return Cargo Downmass, based on the values established in Clause I.A.4 (at award, the Government declined Sub-CLIN0001AE).

edit: clarify basis for SpaceX downmass option.

OK, I found the answer in a recent House hearing and it turns out that you were right, the return services are included in the amount of $1.6B:

Quote
NASA ordered 12 CRS flights valued at $1.59 billion from SpaceX.

-SpaceX will provide pressurized and unpressurized upmass and return services.

-SpaceX currently has completed 14 funding milestones for the four CRS missions in process in FY 2011. In addition, one more CRS mission may be turned on if progress continues. Finally, two milestones in support of COTS demonstration cargo have been paid.

-The schedule margin that existed when the CRS contracts were initially awarded has gotten smaller over the last two years. Parallel development and mission activities have been challenging for a relatively small company that depends heavily on in-house capabilities, yet both cargo and external integration activities have begun and are proceeding. This next year will demonstrate the company’s ability to manage multiple missions. The first SpaceX CRS flight is currently scheduled for late January 2012, and the company is currently slated to fly three CRS missions each fiscal year from 2012 through 2015. The January 2012 date is dependent on SpaceX’s successful completion of its COTS demo flights.

To date, NASA has paid SpaceX $181 million for 14 CRS mission milestones and $4.8 million for two demonstration cargo milestones (the latter from the above-mentioned augmentation funding).

NASA ordered eight CRS flights valued at $1.88 billion from OSC.

-OSC will provide pressurized upmass and disposal services.

See page 5:
http://www.hq.nasa.gov/legislative/hearings/5-26-11%20GERSTENMAIER.pdf

« Last Edit: 10/21/2011 12:06 am by yg1968 »

Offline Lurker Steve

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Re: SpaceX complete PDR on LAS
« Reply #65 on: 10/21/2011 12:24 am »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.

Both OSC and SpaceX CRS contracts provide for unrecoverable/disposal "downmass", and those are not options.  As you'd expect, the substantive difference is that for OSC it's pressurized; for SpaceX it's unpressurized (in the trunk).  Although nothing stopping NASA from returning trash in the Dragon (pressurized), probably not the best use of $/capabilities.

How do you propose getting the trash from inside the ISS to the unpressurized trunk on the Dragon ?

Offline kch

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Re: SpaceX complete PDR on LAS
« Reply #66 on: 10/21/2011 12:35 am »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.

Both OSC and SpaceX CRS contracts provide for unrecoverable/disposal "downmass", and those are not options.  As you'd expect, the substantive difference is that for OSC it's pressurized; for SpaceX it's unpressurized (in the trunk).  Although nothing stopping NASA from returning trash in the Dragon (pressurized), probably not the best use of $/capabilities.

How do you propose getting the trash from inside the ISS to the unpressurized trunk on the Dragon ?


The same way you get your household trash from your house or apartment to the dumpster -- bag it, put on your "outdoor clothes", haul the bags to the "dumpster", put them in, go back in the "house", take off your "outdoor clothes".  That chore's done -- next!  :)

Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #67 on: 10/21/2011 12:48 am »
Or get Robonaut to take out the trash for you ;)
« Last Edit: 10/21/2011 12:49 am by yg1968 »

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #68 on: 10/21/2011 12:59 am »
OK, I found the answer in a recent House hearing and it turns out that you were right, the return services are included in the amount of $1.6B:

Thanks!  You got the facts in black-and-white; I was running on supposition.  Kudos for digging that out,

Offline Jim

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Re: SpaceX complete PDR on LAS
« Reply #69 on: 10/21/2011 01:34 am »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.Gaetano Marano

Both OSC and SpaceX CRS contracts provide for unrecoverable/disposal "downmass", and those are not options.  As you'd expect, the substantive difference is that for OSC it's pressurized; for SpaceX it's unpressurized (in the trunk).  Although nothing stopping NASA from returning trash in the Dragon (pressurized), probably not the best use of $/capabilities.

How do you propose getting the trash from inside the ISS to the unpressurized trunk on the Dragon ?


The same way you get your household trash from your house or apartment to the dumpster -- bag it, put on your "outdoor clothes", haul the bags to the "dumpster", put them in, go back in the "house", take off your "outdoor clothes".  That chore's done -- next!  :)

Not going to be donecthatcway

Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #70 on: 10/21/2011 01:39 am »
He was kidding. But how is it going to be done?

Offline Jim

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Re: SpaceX complete PDR on LAS
« Reply #71 on: 10/21/2011 01:55 am »
He was kidding. But how is it going to be done?

Internal trash stays internal.  The trunk is only for disposing of external equipment.

Offline Lurker Steve

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Re: SpaceX complete PDR on LAS
« Reply #72 on: 10/21/2011 02:51 am »
He was kidding. But how is it going to be done?

Internal trash stays internal.  The trunk is only for disposing of external equipment.

Now if SpaceX were to develop a trash compactor for the Dragon that would reduce the volume of the trash placed in the bin, then transferred the compacted trash container thru an airlock and securely affixed the trash bag to an appropriate location in the trunk so that it didn't adversly affect the center of gravity for the Dragon capsule, that would be truly "revolutionary".

Offline 8900

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Re: SpaceX complete PDR on LAS
« Reply #73 on: 10/21/2011 04:33 am »
OSC's Cygnus will provide unrecoverable down-mass. It's a pretty important function! We can be pretty sure Cygnus will be filled with trash before burning up in the atmosphere, so I'm sure the unrecoverable downmass option will be at least somewhat exercised.
It is always possible to pack waste into a dragon capsule and throw the rubbish into landfill on Earth, although this is a terrible waste of downmass capacity

Offline Downix

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Re: SpaceX complete PDR on LAS
« Reply #74 on: 10/21/2011 05:17 am »
Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology?
Catch up?  Um, dude, Boeing's pusher LAS system passed this point ages ago.  Here's footage of some test firings of it:



The motor is not new, it began life for the Bantam in the 90's.  Here's a Boeing press release on a series of tests of the motor, in 2004: http://www.boeing.com/news/releases/2004/q1/nr_040129m.html
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Offline douglas100

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Re: SpaceX complete PDR on LAS
« Reply #75 on: 10/21/2011 09:16 am »

Now if SpaceX were to develop a trash compactor for the Dragon that would reduce the volume of the trash placed in the bin, then transferred the compacted trash container thru an airlock and securely affixed the trash bag to an appropriate location in the trunk so that it didn't adversly affect the center of gravity for the Dragon capsule, that would be truly "revolutionary".

A trash compactor sounds like a good idea. (But why should it be SpaceX which develops it?) It makes more sense to put compacted trash into Cygnus, Progress, ATV or HTV and leave Dragon's unique downmass capability for recovering important items.
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Offline Crispy

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Re: SpaceX complete PDR on LAS
« Reply #76 on: 10/21/2011 11:34 am »
Put the trash compactor on the station and eject the compacted trash at high speed, to save on reboost propellant.

:) <- Smiley added to indicate joke
« Last Edit: 10/21/2011 11:41 am by Crispy »

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Re: SpaceX complete PDR on LAS
« Reply #77 on: 10/21/2011 11:38 am »
He was kidding. But how is it going to be done?

Internal trash stays internal.  The trunk is only for disposing of external equipment.

Now if SpaceX were to develop a trash compactor for the Dragon that would reduce the volume of the trash placed in the bin, then transferred the compacted trash container thru an airlock and securely affixed the trash bag to an appropriate location in the trunk so that it didn't adversly affect the center of gravity for the Dragon capsule, that would be truly "revolutionary".

not going to do an EVA for this

Offline Lurker Steve

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Re: SpaceX complete PDR on LAS
« Reply #78 on: 10/21/2011 12:16 pm »
He was kidding. But how is it going to be done?

Internal trash stays internal.  The trunk is only for disposing of external equipment.

Now if SpaceX were to develop a trash compactor for the Dragon that would reduce the volume of the trash placed in the bin, then transferred the compacted trash container thru an airlock and securely affixed the trash bag to an appropriate location in the trunk so that it didn't adversly affect the center of gravity for the Dragon capsule, that would be truly "revolutionary".

not going to do an EVA for this

No, I was suggesting that SpaceX could develop a new capability to transfer items from the pressurized compartment of the Dragon, to the unpressurized portion of the Dragon, without those items being touched by Human or Robotnaut hands. Of course, there's a whole lot of Dragon components located between the pressurized and unpressurized compartments, including the heatshield, so it's not really possible unless Musk has some Star Trek transporter technology in his back pocket that we don't know about.

Offline Rifleman

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Re: SpaceX complete PDR on LAS
« Reply #79 on: 10/21/2011 01:27 pm »
All dragons manned dragons, even the powered landing variants, will still need to have parachutes. In the event of an abort, the fuel that would be used for the soft landing will be used in the abort, making parachute landing the only way to get the crew back onto the ground in one piece (unless of course they are planning on carrying enough fuel for both abort and landing, but I would think chutes would have a lower mass penalty than a double load of fuel.)

Offline simonbp

Re: SpaceX complete PDR on LAS
« Reply #80 on: 10/21/2011 03:14 pm »
All dragons manned dragons, even the powered landing variants, will still need to have parachutes.

And I seem to recall Elon saying as much a few months ago...

Offline Comga

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Re: SpaceX complete PDR on LAS
« Reply #81 on: 10/21/2011 05:40 pm »
He was kidding. But how is it going to be done?

Internal trash stays internal.  The trunk is only for disposing of external equipment.
Now if SpaceX were to develop a trash compactor for the Dragon that would reduce the volume of the trash placed in the bin, then transferred the compacted trash container thru an airlock and securely affixed the trash bag to an appropriate location in the trunk so that it didn't adversly affect the center of gravity for the Dragon capsule, that would be truly "revolutionary".

not going to do an EVA for this
Can we take this trash and downmass discussion over to the the general SpaceX thread
It isn't related to the LAS or the LAS component PDR.
« Last Edit: 10/21/2011 05:48 pm by Comga »
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline majormajor42

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Re: SpaceX complete PDR on LAS
« Reply #82 on: 10/21/2011 06:33 pm »
Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology?
Catch up?  Um, dude, Boeing's pusher LAS system passed this point ages ago.  Here's footage of some test firings of it:
The motor is not new, it began life for the Bantam in the 90's.  Here's a Boeing press release on a series of tests of the motor, in 2004: http://www.boeing.com/news/releases/2004/q1/nr_040129m.html

I can't watch youtube at work but I'll check it out later. I'd ask how far along they are now (I see things about splash tests and airbags and windtunnels tests) but I'll just wait to next week's testimony. hopefully it will all be laid out there. ULA will be in attendance as well so they may be able to say when the first Atlas will be available to accommodate Boeing as well. It would be something if it emerged that CST/Atlas was closer to flight (or even a full LAS test) than Dragon/Falcon.
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Offline Cherokee43v6

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Re: SpaceX complete PDR on LAS
« Reply #83 on: 10/21/2011 06:50 pm »
Will another group catch up, such as Boeing, with their design that uses proven tractor tower LAS technology?
Catch up?  Um, dude, Boeing's pusher LAS system passed this point ages ago.  Here's footage of some test firings of it:
The motor is not new, it began life for the Bantam in the 90's.  Here's a Boeing press release on a series of tests of the motor, in 2004: http://www.boeing.com/news/releases/2004/q1/nr_040129m.html

I can't watch youtube at work but I'll check it out later. I'd ask how far along they are now (I see things about splash tests and airbags and windtunnels tests) but I'll just wait to next week's testimony. hopefully it will all be laid out there. ULA will be in attendance as well so they may be able to say when the first Atlas will be available to accommodate Boeing as well. It would be something if it emerged that CST/Atlas was closer to flight (or even a full LAS test) than Dragon/Falcon.

Now that would be a (space)race!  Eat your heart out NASCAR ;)
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Offline krytek

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Re: SpaceX complete PDR on LAS
« Reply #84 on: 10/21/2011 06:53 pm »
There's a big difference between an engine test and a systems test.
I remember reading about SpaceX test firing a Super Draco some time ago as well (can't remember the source).

Offline Danny Dot

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Re: SpaceX complete PDR on LAS
« Reply #85 on: 10/22/2011 12:07 am »
How is the Dragon kept stable during a LAS burn at max q?
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Re: SpaceX complete PDR on LAS
« Reply #86 on: 10/22/2011 12:27 am »
How is the Dragon kept stable during a LAS burn at max q?
Presumably, either with throttling the LAS motors or with using the Draco thrusters (if they work properly at those altitudes, which they may not).
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Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #87 on: 10/22/2011 12:27 am »
How is the Dragon kept stable during a LAS burn at max q?

Differential throttling, I presume.

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #88 on: 10/22/2011 12:37 am »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.
« Last Edit: 10/22/2011 12:38 am by joek »

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Re: SpaceX complete PDR on LAS
« Reply #89 on: 10/22/2011 12:48 am »
How is the Dragon kept stable during a LAS burn at max q?
Also, I think (correct me if I'm wrong!) the abort thrusters all point through (or nearly through) the Dragon's center of mass, which is a pretty stable configuration.
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Offline Danny Dot

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Re: SpaceX complete PDR on LAS
« Reply #90 on: 10/22/2011 12:53 am »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.
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Re: SpaceX complete PDR on LAS
« Reply #91 on: 10/22/2011 12:57 am »
How is the Dragon kept stable during a LAS burn at max q?
Also, I think (correct me if I'm wrong!) the abort thrusters all point through (or nearly through) the Dragon's center of mass, which is a pretty stable configuration.

How about aero forces?



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Offline clongton

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Re: SpaceX complete PDR on LAS
« Reply #92 on: 10/22/2011 01:23 am »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.
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Offline Lee Jay

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Re: SpaceX complete PDR on LAS
« Reply #93 on: 10/22/2011 01:30 am »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.

How is this not the pendulum rocket fallacy?  I thought stability was only dictated by the location of the CG and the aerodynamic center of pressure (CG must be in front for stability).  Thrust location is irrelevant.  No?

Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #94 on: 10/22/2011 01:38 am »
How is the Dragon kept stable during a LAS burn at max q?
Also, I think (correct me if I'm wrong!) the abort thrusters all point through (or nearly through) the Dragon's center of mass, which is a pretty stable configuration.

No, I'm pretty sure the abort thruster vectors meet quite a bit ABOVE the center of mass.

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Re: SpaceX complete PDR on LAS
« Reply #95 on: 10/22/2011 02:08 am »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.

How is this not the pendulum rocket fallacy?  I thought stability was only dictated by the location of the CG and the aerodynamic center of pressure (CG must be in front for stability).  Thrust location is irrelevant.  No?

You are correct.  Tower LAS systems are not stable because they are pullers, they are stable because they move the CG in front of the center of pressure.  And I am doubtfull throttle reaction time is quick enough to stablize the capsule - especially at max q.
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Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #96 on: 10/22/2011 03:39 am »
It is a problem with pushers in general.

I've been wondering about that... Boeing, SNC and SpaceX all seem to be going pusher, so it appears they think they can solve the problems (or have).  Everyone headed in the same direction is suggestive.  Are there significant and recent advancements in propulsion, GN&C, or whatever that would explain such a sea change?

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Re: SpaceX complete PDR on LAS
« Reply #97 on: 10/22/2011 03:53 am »
I don't think we've seen the complete Dragon launch escape system design.  There may be additional components they have yet to make public, e.g. an active steering component.  (NB Orion LAS uses a separate attitude control motor with eight valves for this function.)

Repeating a previously mentioned bit the PDR for these, "LAS Propulsion Components explicitly does not include a full flight configuration of the LAS Propulsion system"
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Re: SpaceX complete PDR on LAS
« Reply #98 on: 10/22/2011 01:03 pm »
This was asked earlier in the thread but not answered:
- has a liquid-propellant LAS ever been developed before?
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Re: SpaceX complete PDR on LAS
« Reply #99 on: 10/22/2011 01:10 pm »
This was asked earlier in the thread but not answered:
- has a liquid-propellant LAS ever been developed before?

No.
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Offline yg1968

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Re: SpaceX complete PDR on LAS
« Reply #100 on: 10/22/2011 02:19 pm »
This was asked earlier in the thread but not answered:
- has a liquid-propellant LAS ever been developed before?

I believe that pusher LAS was considered for the Appollo program but the tractor LAS was considered to be safer. I suspect that the pusher LAS is prefered by Boeing and SpaceX because of its cost and versatility. 
« Last Edit: 10/22/2011 02:23 pm by yg1968 »

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Re: SpaceX complete PDR on LAS
« Reply #101 on: 10/22/2011 03:08 pm »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.

How is this not the pendulum rocket fallacy?  I thought stability was only dictated by the location of the CG and the aerodynamic center of pressure (CG must be in front for stability).  Thrust location is irrelevant.  No?

You are correct.  Tower LAS systems are not stable because they are pullers, they are stable because they move the CG in front of the center of pressure.  And I am doubtfull throttle reaction time is quick enough to stablize the capsule - especially at max q.
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Offline JayP

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Re: SpaceX complete PDR on LAS
« Reply #102 on: 10/22/2011 04:02 pm »
No, I was suggesting that SpaceX could develop a new capability to transfer items from the pressurized compartment of the Dragon, to the unpressurized portion of the Dragon, without those items being touched by Human or Robotnaut hands. Of course, there's a whole lot of Dragon components located between the pressurized and unpressurized compartments, including the heatshield, so it's not really possible unless Musk has some Star Trek transporter technology in his back pocket that we don't know about.
From a purly technical standpoint, it wouldn't require anything from Star Trek. All of the rquired technology has flown in space before. Skylab and Salyut had trash airlocks. The ISS has 2 airlocks for moving small loads outside roboticaly without doing an EVA (admitedly, one isn't installed yet, but it is up there). Gemini-MOL tested a hatch thru a heat shield.

All they would need to do is mount a small airlock in the aft section of the presurised compartment with it's outer hatch thru the heat shield. In the trunk, they mount a big bag with its opening up against the hatch. The bag is folded up against the forward face on the way up and allowed to open up after the cargo is removed from the trunk. The bag keeps the trash in place until the trunk burns up.

As others have pointed out, they would never ACTUALLY do this. There are much better way of getting rid of the staton's trash.

Offline baldusi

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Re: SpaceX complete PDR on LAS
« Reply #103 on: 10/22/2011 04:32 pm »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.
I'm totally ignorant on this, but wouldn't you want to push forward and slightly above the rocket's vector to let it pass above you in case you have turned it off or is a catastrophic explosion, and the other way if it has lost it's attitude control?

Offline simonbp

Re: SpaceX complete PDR on LAS
« Reply #104 on: 10/22/2011 05:10 pm »
And I am doubtfull throttle reaction time is quick enough to stablize the capsule - especially at max q.

Considering this is a vehicle designed to land using throttling of the very same thrusters, I would not underestimate their reaction time.

Plus, recall that all of Dragon's RCS is on the capsule itself (rather than the trunk), so they still have full RCS authority during abort. Considering that's all CST-100 has for control during abort, I think Dragon is going to be fine.

Offline Downix

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Re: SpaceX complete PDR on LAS
« Reply #105 on: 10/22/2011 05:31 pm »
This was asked earlier in the thread but not answered:
- has a liquid-propellant LAS ever been developed before?

Yes.  The Almaz recovery capsule abort system was a Hypergolic liquid fueled system.
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Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #106 on: 10/22/2011 09:24 pm »
And I am doubtfull throttle reaction time is quick enough to stablize the capsule - especially at max q.
Considering this is a vehicle designed to land using throttling of the very same thrusters, I would not underestimate their reaction time.

Plus, recall that all of Dragon's RCS is on the capsule itself (rather than the trunk), so they still have full RCS authority during abort. Considering that's all CST-100 has for control during abort, I think Dragon is going to be fine.

CST-100 appears to have 4 main LAS engines, 16 SM LAS control thrusters, 24 SM RCS thrusters. and 12 CM RCS thrusters.  Some may do double duty, but there certainly seem to be quite a few of them, with a number apparently dedicated to LAS.  (Excluding the LAS main engines, a total of 12 thrusters on the CM, and 40 on the SM.)

That appears to be a significant difference between CST-100 and Dragon (at least from what we've seen) and suggests Boeing believes LAS control requires a significantly different approach that what can be provided alone by dual-purposing RCS thrusters (?).
« Last Edit: 10/22/2011 09:31 pm by joek »

Offline watermod

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Re: SpaceX complete PDR on LAS
« Reply #107 on: 10/24/2011 09:23 pm »
As to the ISS trash compactor argument - It seems NASA had a recent SBIR on that: http://www.sbir.nasa.gov/SBIR/abstracts/09/sbir/phase/SBIR-09-2-X2.02-9461.html

Quote
TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
The innovative High Efficiency, High Output Plastic Melt Waste Compactor (HEHO-PMWC) is a trash dewatering and volume reduction system that uses heat melt compaction to remove nearly 100% of water from trash and reduce the volume by up to 11 times. The HEHO-PMWC system incorporates novel methods to compress the trash, recover water, and remove the resultant plastic tiles. This system requires access to power, data, and cooling interfaces. The system is suitable for recovering water and compacting all trash sources on the ISS. The system has also been designed to recover water from brine solutions produced by primary wastewater processing systems.
The HEHO-PMWC works by heating and compressing trash simultaneously to first remove water and then to melt plastic in the trash. The melted plastic encapsulates the trash into a 16 inch square tile, approximately ½ inch thick. The square tile is easier to store than a round tile and is a more effective radiation shield.
Variables such as transport vehicle availability, ISS mass, power and space availability, and ISS cooling capabilities were considered. The resulting HEHO-PWMC system, proposed here, was sized to process 3-4 kg of trash per batch while operating three times per day.

Offline pippin

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Re: SpaceX complete PDR on LAS
« Reply #108 on: 10/24/2011 10:49 pm »
How is the Dragon kept stable during a LAS burn at max q?

Is that a concern with pusher in general, or something specific about SpaceX's configuration (at least what we know about it)?  E.g., CST-100's LAS appears to be entirely (?predominately?) in the service module (including ACS/RCS), whereas SpaceX's appears to be entirely (?predominately?) in the capsule.

It is a problem with pushers in general.

Think rear wheel drive vs. front wheel drive on a slippery road.

Actually the pendulum rocket fallacy applies to cars in a similar way.
It's generally the REAR wheel drives that are stable on a slippery road, not the front-wheel ones. Try riding a forklift truck at speed and you know what I mean.

Apart from that you can tweak a lot with how you set up the chassis and actually the same is probably true for capsules.

Anyway, a tractor LAS should in no case be much better off maybe except for initially carrying a heavy solid up in the front (if you use solids) but in both cases you have a "big end" which helps a lot to get CP back.

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Re: SpaceX complete PDR on LAS
« Reply #109 on: 10/25/2011 03:08 am »
As to the ISS trash compactor argument - It seems NASA had a recent SBIR on that: http://www.sbir.nasa.gov/SBIR/abstracts/09/sbir/phase/SBIR-09-2-X2.02-9461.html

Quote
TECHNICAL ABSTRACT (Limit 2000 characters, approximately 200 words)
The innovative High Efficiency, High Output Plastic Melt Waste Compactor (HEHO-PMWC) is a trash dewatering and volume reduction system that uses heat melt compaction to remove nearly 100% of water from trash and reduce the volume by up to 11 times. The HEHO-PMWC system incorporates novel methods to compress the trash, recover water, and remove the resultant plastic tiles. This system requires access to power, data, and cooling interfaces. The system is suitable for recovering water and compacting all trash sources on the ISS. The system has also been designed to recover water from brine solutions produced by primary wastewater processing systems.
The HEHO-PMWC works by heating and compressing trash simultaneously to first remove water and then to melt plastic in the trash. The melted plastic encapsulates the trash into a 16 inch square tile, approximately ½ inch thick. The square tile is easier to store than a round tile and is a more effective radiation shield.
Variables such as transport vehicle availability, ISS mass, power and space availability, and ISS cooling capabilities were considered. The resulting HEHO-PWMC system, proposed here, was sized to process 3-4 kg of trash per batch while operating three times per day.
GREAT idea!
Instead of throwing that mass away, it makes sense to extract all the water and melt the rest into radiation shielding. Good SBIR investment. Technically, the first (purposeful) manufacturing in space.
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Offline kkattula

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Re: SpaceX complete PDR on LAS
« Reply #110 on: 10/25/2011 03:17 am »
...
Instead of throwing that mass away, it makes sense to extract all the water and melt the rest into radiation shielding. Good SBIR investment. Technically, the first (purposeful) manufacturing in space.

I suspect the oxygen generating equipment on ISS could be defined as (purposeful) manufacturing in space.

It too takes a waste product, (water), and makes something useful.

Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #111 on: 10/25/2011 03:22 am »
This is going off-topic. Again.

Offline spectre9

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Re: SpaceX complete PDR on LAS
« Reply #112 on: 10/25/2011 03:49 am »
I'm new here and I must comment this is one of the worst forums I've ever seen for going off topic.

If you want to discuss something else start a new thread. Not that hard I would've thought.

Mods can delete this post when they see it as it's off topic too.

The people on this board need to learn how to use a forum.

Offline Crispy

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Re: SpaceX complete PDR on LAS
« Reply #113 on: 10/25/2011 07:30 am »
I'm new here and I must comment this is one of the worst forums I've ever seen for going off topic.
Then you can't have been here long (or have spent time on some severely strict forums!). The moderation is generally excellent

Offline beancounter

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Re: SpaceX complete PDR on LAS
« Reply #114 on: 10/26/2011 01:09 am »
As far as I understand these things, the completion of the PDR for the LAS now allows for the next stage which is actual design and fabrication of the components of the system.  Does anyone know which milestone is related to actual testing of the hardware and about how far further on, timewise that is?
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Offline Confusador

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Re: SpaceX complete PDR on LAS
« Reply #115 on: 10/26/2011 01:56 am »
As far as I understand these things, the completion of the PDR for the LAS now allows for the next stage which is actual design and fabrication of the components of the system.  Does anyone know which milestone is related to actual testing of the hardware and about how far further on, timewise that is?

See here (pdf), from the CCDev updates thread.
This was milestone 4, "LAS Propulsion Component Initial Test Cycle" is milestone 9 which the current schedule has toward the end of Q2.

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #116 on: 10/26/2011 02:20 am »
As far as I understand these things, the completion of the PDR for the LAS now allows for the next stage which is actual design and fabrication of the components of the system.  Does anyone know which milestone is related to actual testing of the hardware and about how far further on, timewise that is?
See here (pdf), from the CCDev updates thread.
This was milestone 4, "LAS Propulsion Component Initial Test Cycle" is milestone 9 which the current schedule has toward the end of Q2.

Yes; per the SAA and projected date (per Oct timeline):
- Milestone #4 -- LAS Propulsion Components Preliminary Desigh Review (Sep 2011, done)
- Milestone #8 -- LAS Propulsion Component Test Articles Complete (Apr 2012)
- Milestone #9 -- LAS Propulsion Component Initial Test Cycle (May 2012)

Offline PhillyJimi

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Re: SpaceX complete PDR on LAS
« Reply #117 on: 10/26/2011 04:25 am »
From the beginning the LAS for Dragon's job is a bit different then what the LAS had to do for the Ares I/Orion configuration. 

When designing the LAS for a Falcon you can factor into it you're on a rocket that can be shut down if something goes wrong.  With the Ares I, since you're riding on top of a Roman Candle, with no shut OFF switch.  This becomes a major consideration when designing a LAS.  The Ares I requires a much more powerful LAS.

I am not a rocket scientist but I would think getting the Dragon and crew away from danger is less of a challenge when the booster can be shut down.  Not saying aborting a launch is easy.  I would also think even if the Dragon LAS fails, as long as the main engines shut down and if Dragon can just detach, the capsule could still have a chance of floating clear of the danger of smacking into the shut down booster stage. 

I also like the push style system just because if there was a problem with the tractor style system detaching from the capsule it would create a situation where you're going to have a really bad day.  The least not being you're parachutes can't deploy.  So with with a tractor system the LAS, MUST work perfectly every time. 

Offline beancounter

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Re: SpaceX complete PDR on LAS
« Reply #118 on: 10/26/2011 07:47 am »
As far as I understand these things, the completion of the PDR for the LAS now allows for the next stage which is actual design and fabrication of the components of the system.  Does anyone know which milestone is related to actual testing of the hardware and about how far further on, timewise that is?
See here (pdf), from the CCDev updates thread.
This was milestone 4, "LAS Propulsion Component Initial Test Cycle" is milestone 9 which the current schedule has toward the end of Q2.

Yes; per the SAA and projected date (per Oct timeline):
- Milestone #4 -- LAS Propulsion Components Preliminary Desigh Review (Sep 2011, done)
- Milestone #8 -- LAS Propulsion Component Test Articles Complete (Apr 2012)
- Milestone #9 -- LAS Propulsion Component Initial Test Cycle (May 2012)


Thanks for the info'. :)
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Offline Nomadd

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Re: SpaceX complete PDR on LAS
« Reply #119 on: 10/26/2011 11:24 am »
From the beginning the LAS for Dragon's job is a bit different then what the LAS had to do for the Ares I/Orion configuration. 

When designing the LAS for a Falcon you can factor into it you're on a rocket that can be shut down if something goes wrong.  With the Ares I, since you're riding on top of a Roman Candle, with no shut OFF switch.  This becomes a major consideration when designing a LAS.  The Ares I requires a much more powerful LAS.

I don't think that's true. I'm pretty sure the LAS has to be able to pull Dragon away from a still accelerating stage.
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Offline baldusi

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Re: SpaceX complete PDR on LAS
« Reply #120 on: 10/26/2011 12:26 pm »
The two critical moments, if I'm not mistaken, are pad abort and max-q abort. Doing a pad abort simulation is relatively cheap. But at least Boeing is planning on doing an abort test at max-q. So I think that SpaceX will qualify doing something similar. Unless they can get a nine engined Grashopper. All it would have to do is reach max-q, then return.

Offline baldusi

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Re: SpaceX complete PDR on LAS
« Reply #121 on: 10/26/2011 03:35 pm »
Elon has stated, in today's Hearing, that they will demonstrate the SuperDracos by the end of this year  :o In his written statement said they were finishing the testing stand in Texas.

Offline go4mars

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Re: SpaceX complete PDR on LAS
« Reply #122 on: 10/26/2011 05:08 pm »
The two critical moments, if I'm not mistaken, are pad abort and max-q abort. Doing a pad abort simulation is relatively cheap. But at least Boeing is planning on doing an abort test at max-q. So I think that SpaceX will qualify doing something similar. Unless they can get a nine engined Grashopper. All it would have to do is reach max-q, then return.

I might be wrong, but I don't think it would necessarily take 9 engines to get to maxQ.  If they put a dragon on top of a mostly empty stage (and no second stage), the acceleration could be intense and velocity could be signficant while still in the lower atmosphere.   They might be able do a max-q approximation with grasshopper. 

1/2 rho (v^2). 
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Offline Comga

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Re: SpaceX complete PDR on LAS
« Reply #123 on: 10/26/2011 05:20 pm »
peter-b pointed out that Musk's written statement includes a plan for max-Q abort test, too.

"Crew-related modifications that have yet to reach a CDR-equivalent level of maturity include the remaining work on the launch abort system. The most significant remaining milestones will be full-scale pad abort and max-drag abort flight tests."

(emphasis mine)
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Offline neilh

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Re: SpaceX complete PDR on LAS
« Reply #124 on: 10/26/2011 05:24 pm »
The two critical moments, if I'm not mistaken, are pad abort and max-q abort. Doing a pad abort simulation is relatively cheap. But at least Boeing is planning on doing an abort test at max-q. So I think that SpaceX will qualify doing something similar. Unless they can get a nine engined Grashopper. All it would have to do is reach max-q, then return.

I might be wrong, but I don't think it would necessarily take 9 engines to get to maxQ.  If they put a dragon on top of a mostly empty stage (and no second stage), the acceleration could be intense and velocity could be signficant while still in the lower atmosphere.   They might be able do a max-q approximation with grasshopper. 

1/2 rho (v^2). 

Possibly, although I'm also guessing the marginal cost per engine for the Merlin 1d is pretty low for them, so saving a few engines might not be worth the extra cost//risk of a new configuration.
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Offline Zed_Noir

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Re: SpaceX complete PDR on LAS
« Reply #125 on: 10/26/2011 05:30 pm »
The two critical moments, if I'm not mistaken, are pad abort and max-q abort. Doing a pad abort simulation is relatively cheap. But at least Boeing is planning on doing an abort test at max-q. So I think that SpaceX will qualify doing something similar. Unless they can get a nine engined Grashopper. All it would have to do is reach max-q, then return.

I might be wrong, but I don't think it would necessarily take 9 engines to get to maxQ.  If they put a dragon on top of a mostly empty stage (and no second stage), the acceleration could be intense and velocity could be signficant while still in the lower atmosphere.   They might be able do a max-q approximation with grasshopper. 

1/2 rho (v^2). 

Alternately put a Dragon on a F9 upper stage with one or more  regular Merlin engine and the 1st stage thrust structure. This would use the avionics already in the upper stage.

Offline ugordan

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Re: SpaceX complete PDR on LAS
« Reply #126 on: 10/26/2011 05:45 pm »
Alternately put a Dragon on a F9 upper stage with one or more  regular Merlin engine and the 1st stage thrust structure. This would use the avionics already in the upper stage.

No guarantee that configuration would be within F9 upperstage's control margins during transsonic flight. A wide but short stage.

Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #127 on: 10/26/2011 06:00 pm »
Elon Musk's prepared statement for Congress today has some LAS info: http://science.house.gov/sites/republicans.science.house.gov/files/documents/hearings/102611_Musk.pdf

A lot of this we have already guessed, but here are some quotes:

Quote
The Dragon  LAS  is a vehicle-integrated, side-mounted engine system selected for its safety, reliability and performance after a system-level analysis conducted by SpaceX. Eight abort engines (known as SuperDracos because they are modified versions of Dragon’s existing Draco thrusters) are located around the periphery of the Dragon service section and fed by hypergolic
propellant stored in the spacecraft propellant tanks.

The LAS will be enabled after crew ingress and securing on the pad and will be disabled on orbit after Dragon separation from the second stage.  The launch vehicle malfunction detection system for automatic abort will monitor  the Falcon 9 and Dragon for engine failures, flight control failure, failure of the booster propellant tank and failure of the booster’s primary structure, among other signatures.

Abort responses will be determined by failure(s) detected and the phase of flight, in order to maximize survivability. For example, a significantly off-nominal change in tank pressure while the vehicle is on the pad may result in an instantaneous high-acceleration abort, while a performance-related failure of the second-stage engine during ascent may result in a delayed abort until ideal entry conditions are met, a pre-abort shutdown of the second-stage engine and a low-acceleration abort profile.

There is also some information about other aspects of the crew Dragon design:

Quote
SpaceX is designing the Dragon to carry seven crewmembers seated in two rows. The seats will be conformal and a mechanical force accommodation system will cushion any off-nominal landing impacts to assure crew safety. The crew will wear spacesuits to protect them from any rapid cabin depressurization emergency event. The suits will be rated for operation at vacuum and provide communication and cooling systems.

The Dragon environmental control and life support systems will provide the crew with fresh air ventilation, remove carbon dioxide and control humidity and cabin pressure. Fire detection and suppression systems will protect the crew in the event of an emergency. Accommodations will be provided for food preparation and waste disposal.

During the span of the CCDev2 SAA, SpaceX is completing preliminary designs on modifications to our launch pad and mission control center to be ready to fly astronauts. The launch pad will have a new tower and access arm to allow crew to enter the Dragon and egress quickly in the event of a launch pad emergency. Mission control will have a new console position for a flight surgeon for human missions.

In addition to these crew vehicle systems, the operation of the vehicle for nominal, contingency and emergency situations is being outlined for all phases of flight. A crew cabin mock-up is being constructed to allow NASA astronauts to evaluate crew accommodations and other human factors considerations. We are conducting preliminary designs for crew display and manual control hardware. The detailed operation of the launch abort system is also being characterized by defining abort modes, triggering events and abort trajectories. Finally, the safety and mission assurance analyses are being  evaluated with the goal of ensuring that the Dragon and Falcon 9 vehicle will achieve a level of safety better than any human spacecraft ever flown.

Offline go4mars

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Re: SpaceX complete PDR on LAS
« Reply #128 on: 10/26/2011 09:09 pm »
The two critical moments, if I'm not mistaken, are pad abort and max-q abort. Doing a pad abort simulation is relatively cheap. But at least Boeing is planning on doing an abort test at max-q. So I think that SpaceX will qualify doing something similar. Unless they can get a nine engined Grashopper. All it would have to do is reach max-q, then return.

I might be wrong, but I don't think it would necessarily take 9 engines to get to maxQ.  If they put a dragon on top of a mostly empty stage (and no second stage), the acceleration could be intense and velocity could be signficant while still in the lower atmosphere.   They might be able do a max-q approximation with grasshopper. 

1/2 rho (v^2). 

Alternately put a Dragon on a F9 upper stage with one or more  regular Merlin engine and the 1st stage thrust structure. This would use the avionics already in the upper stage.
  I think it is fair to assume that grasshopper will have suitable avionics. 
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Re: SpaceX complete PDR on LAS
« Reply #129 on: 10/26/2011 09:22 pm »
Could they combine max-q abort test with first stage/second stage reuse test?
« Last Edit: 10/26/2011 09:22 pm by oiorionsbelt »

Offline go4mars

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Re: SpaceX complete PDR on LAS
« Reply #130 on: 10/26/2011 09:23 pm »
Quote
For example, a significantly off-nominal change in tank pressure while the vehicle is on the pad may result in an instantaneous high-acceleration abort, while a performance-related failure of the second-stage engine during ascent may result in a delayed abort until ideal entry conditions are met, a pre-abort shutdown of the second-stage engine and a low-acceleration abort profile.
  Can't do that with solids.  How beneficial is this actually? 

Quote
Accommodations will be provided for food preparation and waste disposal.
I wonder how that's going to work.  A little place with a curtain on the ceiling of dragon?  I wonder if the seat fold away once they are in zero-G for more space to do stuff.  I've never heard either way.

Quote
The launch pad will have a new tower and access arm to allow crew to enter the Dragon and egress quickly in the event of a launch pad emergency.
It will be interesting to see if their approach involves nifty ideas for saving money, but still provides the functionality required.

Quote
Mission control will have a new console position for a flight surgeon for human missions.
Is "flight surgeon" the typical term?  Or is that just a nod to old Leonard McCoy?

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Offline Jim

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Re: SpaceX complete PDR on LAS
« Reply #131 on: 10/26/2011 10:59 pm »
Is "flight surgeon" the typical term?  Or is that just a nod to old Leonard McCoy?


Old term for doctors for pilots that predates the space age.

Offline Proponent

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Re: SpaceX complete PDR on LAS
« Reply #132 on: 10/27/2011 05:39 am »
From the beginning the LAS for Dragon's job is a bit different then what the LAS had to do for the Ares I/Orion configuration. 

When designing the LAS for a Falcon you can factor into it you're on a rocket that can be shut down if something goes wrong.  With the Ares I, since you're riding on top of a Roman Candle, with no shut OFF switch.  This becomes a major consideration when designing a LAS.  The Ares I requires a much more powerful LAS.

I don't think that's true. I'm pretty sure the LAS has to be able to pull Dragon away from a still accelerating stage.

I don't see why you wouldn't count on shutting the engines down in an abort: it's pretty easy to do.  It was certainly part of the Apollo abort procedure.

It is possible to reduce the thrust of an solid stage in flight: open a vent or, as Charlie Precourt suggested in a Space Show interview several months ago, "unzip" nozzle.   IIRC correctly, however, in the same interview he mentioned that this capability was not currently planned for Liberty.
« Last Edit: 10/27/2011 05:39 am by Proponent »

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Re: SpaceX complete PDR on LAS
« Reply #133 on: 10/27/2011 08:29 am »

I don't see why you wouldn't count on shutting the engines down in an abort: it's pretty easy to do.  It was certainly part of the Apollo abort procedure.
{snip}

Trying to shut down the engines is a good idea.  Relying on the engines to shut down when performing an abort is inadvisable.  For instance the control cables could have been severed by the fault.

Offline Proponent

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Re: SpaceX complete PDR on LAS
« Reply #134 on: 10/27/2011 09:23 am »

I don't see why you wouldn't count on shutting the engines down in an abort: it's pretty easy to do.  It was certainly part of the Apollo abort procedure.
{snip}

Trying to shut down the engines is a good idea.  Relying on the engines to shut down when performing an abort is inadvisable.  For instance the control cables could have been severed by the fault.

Note that this situation requires that control of the engines is no longer possible, but the engines are still operating.  That's pretty unlikely, but if you're worried about it, install an independent thrust-termination system as a back-up.  That will be easier, cheaper and lighter than beefing up the escape system to deliver several extra Gs and the crew capsule to withstand it.

For the most part, successful escapes are likely to require some advance warning (Apollo needed 2-3 seconds if the crew was to survive an exploding booster).  If the launch vehicle has already suffered structural damage (control cables severed), it's quite possibly too late to save the crew anyway.

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Re: SpaceX complete PDR on LAS
« Reply #135 on: 10/27/2011 12:39 pm »
Not true, severing of the cables itself is a reason to abort

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Re: SpaceX complete PDR on LAS
« Reply #136 on: 10/27/2011 02:32 pm »
   Accommodations will be provided for food preparation
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Offline Comga

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Re: SpaceX complete PDR on LAS
« Reply #137 on: 10/27/2011 02:56 pm »
Not true, severing of the cables itself is a reason to abort

Excuse me Jim, but which way does your statement cut?  Because severing the cables is itself a reason to abort, does the LAS have to outrun a thrusting first stage?  is that a credible failure mode, cables severed but first stage flight continuing?
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Re: SpaceX complete PDR on LAS
« Reply #138 on: 10/27/2011 03:39 pm »
Not true, severing of the cables itself is a reason to abort

Excuse me Jim, but which way does your statement cut?  Because severing the cables is itself a reason to abort, does the LAS have to outrun a thrusting first stage?  is that a credible failure mode, cables severed but first stage flight continuing?

Interruption of LV power and data to the abort system is cause for abort.  Any abort does three things, shut down engines, fire LAS and initiate destruct.

Offline PhillyJimi

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Re: SpaceX complete PDR on LAS
« Reply #139 on: 10/27/2011 08:20 pm »
From the beginning the LAS for Dragon's job is a bit different then what the LAS had to do for the Ares I/Orion configuration. 

When designing the LAS for a Falcon you can factor into it you're on a rocket that can be shut down if something goes wrong.  With the Ares I, since you're riding on top of a Roman Candle, with no shut OFF switch.  This becomes a major consideration when designing a LAS.  The Ares I requires a much more powerful LAS.

I don't think that's true. I'm pretty sure the LAS has to be able to pull Dragon away from a still accelerating stage.

Well we don't know exactly what the LAS specs are but I would think the last thing you would want is to successfully separate from the booster but still have that thing chasing you down from behind.  If you can shut it down you're going to want to.

I just remember watching interviews with the Apollo astronauts talking about staging where once the 1st stages engines cut off how they were thrown forward then as the 2nd stage engines fired up they were slammed back into their seats. 

It would seem like the best automated LAS approach would release the dragon from the booster, shut the booster down, the Dragon's inertia will pull it away from the top of the booster then fire the LAS.  This can't be done with a SRB. 

Of course there may be a situation where the stage can't be shut off and you still have to attempt to get away from the rocket.  I would think this would more likely early in the launch so the LAS system doesn't need as much speed to out race the slower moving 1st booster while it is closer to the ground. 

I don't profess to be an expert on the history of rocket failures so I don't know if what makes it to the top of likely situations that has to be accounted for in a LAS design.  From what I know about rocket failures is they are mainly due to a lost of thrust/fuel pumps or the rocket's trajectory is starting to become unstable.  If you're designing a LAS you'll try to account for every possible situation but you want to make sure you account for the most likely first then address the most unlikely if you can. 

After all a car could be built with triple redundant air bags, an ejection seats and a taco fart explosion suppression systems.  At some point a line has to be drawn.

Of course SpaceX isn't going to release a realistic video of it's 1st stage failing, where Dragon has to use the LAS because it is starting to tumble and then show the stage self destructing.  It just isn't good PR. Their videos are going to show the 1st stage working just fine and the capsule cleanly pulling away using the LAS.   

Offline Jason1701

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Re: SpaceX complete PDR on LAS
« Reply #140 on: 10/27/2011 11:59 pm »
the Dragon's inertia will pull it away from the top of the booster then fire the LAS.

The whole stack would undergo a jerk (change in acceleration), but the Dragon would not then move faster than the booster. LAS is required to initiate separation.

Offline Lars_J

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Re: SpaceX complete PDR on LAS
« Reply #141 on: 10/28/2011 12:15 am »
Yep... and the later in the flight the LAS activation occurs, the faster the stack is accelerating. Won't it be 4-5 g (or more) as MECO is approached?

You just cannot rely on any capsule "inertia" to separate it from the stack. The capsule MUST accelerate away from it on its own.
« Last Edit: 10/28/2011 12:15 am by Lars_J »

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Re: SpaceX complete PDR on LAS
« Reply #142 on: 10/28/2011 12:36 am »
It will have no more inertia than the booster rocket whether the engines are thrusting or not because it is mechanically attached. The LAS has to first fire to initiate the Dragon separation from the rocket.
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Offline Kaputnik

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Re: SpaceX complete PDR on LAS
« Reply #143 on: 10/29/2011 07:52 am »
Will the Dragon LAS be capable of ATO?
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Offline Jason1701

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Re: SpaceX complete PDR on LAS
« Reply #144 on: 10/29/2011 08:12 am »
Will the Dragon LAS be capable of ATO?

Depends where the abort occurs. If it occurs less than thirty seconds before SECO, maybe. Earlier, no.

Offline Kaputnik

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Re: SpaceX complete PDR on LAS
« Reply #145 on: 10/29/2011 08:27 am »
Will the Dragon LAS be capable of ATO?

Depends where the abort occurs. If it occurs less than thirty seconds before SECO, maybe. Earlier, no.

Ok. I was thinking that perhaps the LAS couldn't fire whilst the trunk was still attached.
Did I read somewhere that the LAS uses the same propellant supply as the main Dragon OMS? So choosing whether to use the LAS or the normal Dracos would depend only on how much thrust you needed.
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Re: SpaceX complete PDR on LAS
« Reply #146 on: 10/29/2011 02:03 pm »
I'm pretty sure they wouldn't use the LAS for abort to orbit. They'd likely use just the thrusters if they did it at all.
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Re: SpaceX complete PDR on LAS
« Reply #147 on: 10/29/2011 02:41 pm »
I was thinking that perhaps the LAS couldn't fire whilst the trunk was still attached.
If not, how would it abort from the Pad?
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Re: SpaceX complete PDR on LAS
« Reply #148 on: 10/29/2011 02:43 pm »
I was thinking that perhaps the LAS couldn't fire whilst the trunk was still attached.
If not, how would it abort from the Pad?
He meant that the capsule seperates from the trunk when the LAS fires (and you could maybe "abort to orbit" in such a case if you're close enough to orbit, but you'd have to come down from orbit rather quickly without the trunk).
« Last Edit: 10/29/2011 04:03 pm by Robotbeat »
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Re: SpaceX complete PDR on LAS
« Reply #149 on: 10/29/2011 03:27 pm »
He meant that the capsule seperates from the capsule when the LAS fires[/quote]
Huh? ???
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Re: SpaceX complete PDR on LAS
« Reply #150 on: 10/29/2011 04:02 pm »
He meant that the capsule seperates from the capsule when the LAS fires
Huh? ???
D'oh! :) I meant:
the capsule seperates from the trunk when the LAS fires
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Offline Kaputnik

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Re: SpaceX complete PDR on LAS
« Reply #151 on: 10/29/2011 05:13 pm »
Sorry if I've caused some confusion!
What I meant was, a conventional LAS is only of use early in ascent, after which it is jettisoned and the OMS takes over the role of an abort, either to a sub-orbital trajectory or an abort to orbit (and perhaps a reduced scope mission).
Dragon could of course follow the same pattern, using its LAS for aborts during early ascent and the normal Dracos after that. But Dragon is different to previous manned craft in that the LAS is not jettisoned. So what I was wondering was whether the Super-Dracos might be used for aborts throughout ascent, including potentially ATO. Secondly, might it be possible that the LAS propellant could be used for an ATO in case of LV under-performance, 'saving' the mission at the cost of having to do a harder landing under parachute.
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.

Hope that makes sense!
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Offline Cherokee43v6

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Re: SpaceX complete PDR on LAS
« Reply #152 on: 10/29/2011 05:34 pm »
Sorry if I've caused some confusion!
What I meant was, a conventional LAS is only of use early in ascent, after which it is jettisoned and the OMS takes over the role of an abort, either to a sub-orbital trajectory or an abort to orbit (and perhaps a reduced scope mission).
Dragon could of course follow the same pattern, using its LAS for aborts during early ascent and the normal Dracos after that. But Dragon is different to previous manned craft in that the LAS is not jettisoned. So what I was wondering was whether the Super-Dracos might be used for aborts throughout ascent, including potentially ATO. Secondly, might it be possible that the LAS propellant could be used for an ATO in case of LV under-performance, 'saving' the mission at the cost of having to do a harder landing under parachute.
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.

Hope that makes sense!

Dragon has a slightly larger diameter than its service trunk. (Note all the photos/artist work on the two parts together)  Additionally, would you want the LAS thrusters firing through ports in the heat shield?  Talk about a major possible point of failure, that would be the only way the thrusters would be occluded by the trunk.

On the other hand, what are the LAS thruster locations as relates to the mounting position for the solar panels?  Would the thruster plume impinge on the panels while stowed?
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Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #153 on: 10/29/2011 06:06 pm »
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.

Is that a known for both cases?  Although the SuperDraco's may be part of the capsule (per Elon "integrated into the sidewalls"), do we know that all the required LAS propellant would also carried in the capsule?*

Cargo Dragon can purportedly carry 1230kg of propellant. Also, there's not much spare room in the service section; stuff 8 SuperDraco's in there, and presumably the on-board propellant capacity would decrease.

Extrapolating from cargo dragon, assuming ~8000kg capsule+crew/cargp, my BOTE suggests 1230kg propellant is getting marginal for LAS (but I admit my envelope is old and tattered).  Anyone have better numbers/calcs?


*  edit: Specifically, propellant required for ascent abort vs. what is required for landing.  Obviously no trunk on landing so sufficient propellant must be carried entirely within the capsule, but IIRC propulsive landing  is a future and not a given for CC.
« Last Edit: 10/29/2011 06:13 pm by joek »

Offline MikeAtkinson

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Re: SpaceX complete PDR on LAS
« Reply #154 on: 10/29/2011 06:49 pm »
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.

Is that a known for both cases?  Although the SuperDraco's may be part of the capsule (per Elon "integrated into the sidewalls"), do we know that all the required LAS propellant would also carried in the capsule?

Yes we do. The abort video shows a trunk-less dragon doing the abort.

Cargo Dragon can purportedly carry 1230kg of propellant. Also, there's not much spare room in the service section; stuff 8 SuperDraco's in there, and presumably the on-board propellant capacity would decrease.

The 1230kg of propellant is with spherical tanks, it looks like there is room for perhaps 50-100% more using conformal tanks. This might create problems for presurisation and ullage, but that depends on detailed engineering that we are not in a position to make a judgement on.

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #155 on: 10/30/2011 01:05 am »
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.
Is that a known for both cases?  Although the SuperDraco's may be part of the capsule (per Elon "integrated into the sidewalls"), do we know that all the required LAS propellant would also carried in the capsule?
Yes we do. The abort video shows a trunk-less dragon doing the abort.

Ahhh... :facepalm:

Quote
The 1230kg of propellant is with spherical tanks, it looks like there is room for perhaps 50-100% more using conformal tanks. This might create problems for presurisation and ullage, but that depends on detailed engineering that we are not in a position to make a judgement on.

That would be interesting.  More fodder for speculation.  On that note, per the SpaceX CCDev SAA (note singular): milestone #4 "the LAS propellant tank"; #8 "LAS propellant tank test article"; #9 "initial testing of the tank".

I wonder if they have a pool at SpaceX based on how the latest batch of tea leaves will be interpreted.

Offline Downix

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Re: SpaceX complete PDR on LAS
« Reply #156 on: 10/30/2011 01:28 am »
For this to work, though, it would be necessary that the Super-Dracos are able to fire before trunk-sep. The two currently planned uses of the system envisage that the trunk has been jettisoned.
Is that a known for both cases?  Although the SuperDraco's may be part of the capsule (per Elon "integrated into the sidewalls"), do we know that all the required LAS propellant would also carried in the capsule?
Yes we do. The abort video shows a trunk-less dragon doing the abort.

Ahhh... :facepalm:

Quote
The 1230kg of propellant is with spherical tanks, it looks like there is room for perhaps 50-100% more using conformal tanks. This might create problems for presurisation and ullage, but that depends on detailed engineering that we are not in a position to make a judgement on.

That would be interesting.  More fodder for speculation.  On that note, per the SpaceX CCDev SAA (note singular): milestone #4 "the LAS propellant tank"; #8 "LAS propellant tank test article"; #9 "initial testing of the tank".

I wonder if they have a pool at SpaceX based on how the latest batch of tea leaves will be interpreted.
"They said spherical tank!"
"Take a drink!"
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Online docmordrid

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Re: SpaceX complete PDR on LAS
« Reply #157 on: 10/30/2011 02:17 am »
Quote from: MikeAtkinson link=topic=27127.msg823551#msg823551
>
This might create problems for presurisation and ullage, but that depends on detailed engineering that we are not in a position to make a judgement on.

Since we're speculating - could they use a double-walled internal bladder with gas pressure added between the layers and large cavity  open cell foam acting as a baffle?  An evolved version of what we used in racing cars.
« Last Edit: 10/30/2011 02:21 am by docmordrid »
DM

Offline joek

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Re: SpaceX complete PDR on LAS
« Reply #158 on: 10/30/2011 02:21 am »
"They said spherical tank!"
"Take a drink!"
The kids are excited and getting ready, so excuse my lapse *cough*...

They said tank! We have brew'd and hew'd and this Hallow the entrails are clear!  One tank to rule them all!!?? Could it be!? Can it be? Yes! Yes! It must be! NOFBX rulez!

Offline HMXHMX

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Re: SpaceX complete PDR on LAS
« Reply #159 on: 10/30/2011 02:47 am »
"They said spherical tank!"
"Take a drink!"
The kids are excited and getting ready, so excuse my lapse *cough*...

They said tank! We have brew'd and hew'd and this Hallow the entrails are clear!  One tank to rule them all!!?? Could it be!? Can it be? Yes! Yes! It must be! NOFBX rulez!

Possibly.  But storable propellant vessels are the same size for both fuel and oxidizer.  So testing one vessel is all that is needed.

I saw a small dragon fly three times backwards around the Capitoline Hill so I am sure I'm right.  ;)

Offline HIP2BSQRE

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Re: SpaceX complete PDR on LAS
« Reply #160 on: 11/04/2011 04:37 pm »
"They said spherical tank!"
"Take a drink!"
The kids are excited and getting ready, so excuse my lapse *cough*...

They said tank! We have brew'd and hew'd and this Hallow the entrails are clear!  One tank to rule them all!!?? Could it be!? Can it be? Yes! Yes! It must be! NOFBX rulez!

Possibly.  But storable propellant vessels are the same size for both fuel and oxidizer.  So testing one vessel is all that is needed.

I saw a small dragon fly three times backwards around the Capitoline Hill so I am sure I'm right.  ;)

So do we have any ideas if SpaceX is talking 1 or more tanks???  When might we know or would that be proprietary info???

Offline butters

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Re: SpaceX complete PDR on LAS
« Reply #161 on: 11/04/2011 05:04 pm »
So do we have any ideas if SpaceX is talking 1 or more tanks???  When might we know or would that be proprietary info???

My understanding is that the Super Dracos are plumbed to the same tank sets as the Dracos and that the bounding case (pad abort) is covered by the existing propellant load. Currently they use NTO/MMH. There has been some speculation that SpaceX may be considering NOFBX for the future, but I think that would entail a fairly different engine design involving a catalytic bed gas generator and whatnot.

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