Author Topic: SpaceX complete PDR on LAS  (Read 53821 times)

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!

Offline 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.
JRF

Offline punder

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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 »
Remember: if we want this whole space thing to work out we have to optimize for cost!

Offline Robotbeat

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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.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline MajorBringdown

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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.
JRF

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 »
Remember: if we want this whole space thing to work out we have to optimize for cost!

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...

Online 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.

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