Author Topic: SpaceX Dragon 2 Pad Abort Test - May 6 2015 - DISCUSSION THREAD  (Read 935378 times)

Online docmordrid

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CST-100 has integrated LAS too. It also aims to be a re-used capsule (not sure if they plan to do this when flying for Bigelow or what, but I did hear about it), including the heat shield and presumably the LAS too.

It has a pusher LAS in the trunk. It is abandoned before reentry.

And, according to Boeing, the heat shield drops off at 5,000 feet so the air bags can deploy. Can't see it being reused either.

Link....


Quote
After reentering the atmosphere, the CST-100's three main parachutes open at an altitude of approximately 12,000 feet. When the capsule reaches about 5,000 feet, the base heat shield drops away and six air bags inflate with a mixture of air and nitrogen two minutes before landing to cushion the passengers from the impact.
« Last Edit: 10/17/2014 01:07 pm by docmordrid »
DM

Offline Dudely

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Ah, good corrections; thanks.

Offline Heinrich

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There was a letter circulated from a NASA higher-up that explained the reasoning behind dropping SNC. The big issue was Dreamchaser could run into production or testing delays, which at this point would make the program laughably pointless if the ISS gets decommissioned in 2020. Not a difficult choice at all.

I haven't read anything about this yet, so could you expand a little on this? Is it leaked available somewhere or only word of mouth?
(and the SpaceX thread for a launch abort test might not be the correct place though)

Edit/Lar: It's not. There are other threads where this is discussed - see http://forum.nasaspaceflight.com/index.php?topic=35728.0  ... stay on topic guys, thanks!
« Last Edit: 10/17/2014 03:18 pm by Lar »

Offline Lourens

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Since their [SpaceX's] bid was lower to begin with, it's less risk to proceed and if the GAO rules against NASA, it's likely the higher cost bid goes away than the lower cost.

I'm not so sure about that.

It's not just about cost, it's also about technical and schedule risk.  Say what you will about Boeing, their processes are such that NASA has a higher confidence in their ability to meet schedule.  NASA is less confident in SpaceX, whose processes are not as mature, and who've had issues with schedule in the past.  They're a damn sight better than they were two years ago, but still.  Better to spend $4 bn on a system that's almost guaranteed to come in on time and to spec than $2 bn on a system that may be late or fail to meet spec.  Not that I expect SpaceX to fail or even be late; I'm just presenting the reasoning why it doesn't strictly come down to cost. 

If it comes down to choosing a single provider (which would be stupid for any number of reasons, but that's another thread), there's no way it won't be Boeing.   That's not (just) politics or pork.  NASA can make a good technical case for picking Boeing over SpaceX, regardless of the cost difference.
Completely missing from your analysis: unmanned Dragon capsule in orbit right now. SpaceX has demonstrated and operated a nearly identical design capsule in orbit (and, for most, at ISS) 6 times, now (with two Dragon 2 vehicles under advanced construction), while Boeing barely even has a pressure vessel and hasn't built a similar capsule system in decades. Also, SpaceX is way closer to demonstrating abort, both pad and in-flight. Also, they JUST developed Dragon v1 and flew to ISS, which proves they know how to get the job done quickly and at low budget, just like they claim.

Calling SpaceX "higher risk" than Boeing at this point is /absurd/.

I agree that SpaceX has shown that they "know how to get the job done quickly and at low budget". If you're interested in quickly and at low budget, it makes sense to accept some schedule and budget risk, since driving down that uncertainty costs increasing amounts of money and time. Provided that you can cover the risk, it's always cheaper to self-insure. That seems to be SpaceX's modus operandi.

To NASA, the total amount doesn't matter so much, as long as Congress is willing to spend it. Voters and taxpayers have no idea whether $4B for CCtCap is a reasonable amount of money or not, or how to judge whether any risk taken was a good risk. So what counts is the result: overrun that budget and you have a problem (see JWST). So what NASA wants is someone who can get the job done as quickly as they promised and for the budget they promised, provided that it's not so expensive that the program ends before it's started. And they're willing to pay good money for it. So Boeing wins, and the second least risky option is SpaceX.

In a way, this system inherently works better with proposals to just build stuff to spec for NASA use only, since in that case it doesn't matter whether the system is cheap enough for other uses, and so you can afford to buy down risk in the development process. Which kills off any scale advantage, and results in "commercial" not being any cheaper than doing it the traditional cost-plus way. But that's okay, it'll still look good on TV.

Edit/Lar: STAY ON TOPIC. This isn't on topic. Thank you.
« Last Edit: 10/17/2014 03:19 pm by Lar »

Offline ser848

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Offline OxyAstro

"Significantly more noticeable" sounds like significantly more engines. Maybe an initial test with 9+ engines for the Falcon Heavy?

Online e of pi

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"Louder-that-usual" is their standard language for any 9-engine full-stage test. The "daily" firings they refer to are the single-engine Merlin acceptance firings, and even an F9 on the stand is thus "louder-than-usual". I won't say it's not Dragon 2 related, but it's probably just Falcons.

Offline ser848

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So its probably the CRS-5 booster. I doubt 4 super-dracos would sound louder than 9 merlins anyway.

Offline Robotbeat

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I bet it's the next core after CRS5.
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Offline clongton

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CST-100 has integrated LAS too. It also aims to be a re-used capsule (not sure if they plan to do this when flying for Bigelow or what, but I did hear about it), including the heat shield and presumably the LAS too.

It has a pusher LAS in the trunk. It is abandoned before reentry.

CST-100 does not have a trunk. Only Dragon has that.
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Online guckyfan

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It has a pusher LAS in the trunk. It is abandoned before reentry.

CST-100 does not have a trunk. Only Dragon has that.

You are right. Is it called a SM with CST-100?

Offline enkarha

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You are right. Is it called a SM with CST-100?

Yes.
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Offline MP99

As far as "off the shelf" non rad-hardened components. . . have you seen the equipment that flies on the ISS? They use basic laptops with no problem. Many modern rockets and satellites don't use rad-hardened components. Lets also not forget that they had triple redundancy for Dragon 1 too, including the rocket, and they were not required to do this. They also had 30% engineering margins.

Laptops on ISS absolutely do not operate "with no problem". Radiation causes regular issues.

Dragon / F9 couldn't get close to flying without it.

Cheers, Martin

Offline baldusi

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It has a pusher LAS in the trunk. It is abandoned before reentry.

CST-100 does not have a trunk. Only Dragon has that.

You are right. Is it called a SM with CST-100?
The names are descriptive. The thunk is little more than a mechanical transfer tube. Yes, it holds the solar panels and act as radiator. That's it. The CST SM has the LaS, the RCS, propellant and many extra things. Is a different way or arranging the vehicle.

Offline Antares

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1) They use basic laptops with no problem.
2) Many modern rockets and satellites don't use rad-hardened components.
3) Lets also not forget that they had triple redundancy for ... the rocket
4) They also had 30% engineering margins.

1) Not for safety critical systems
2) They do for CPUs, memory, etc.
3) V1.0 was not three-string
4) 40% in most cases
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Offline TOG

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It's gettint late into October (and a little off topic), so, if I may ask, what kind of activity is being observed at the pad?  Have we seen any sign of the platform or the test article?

(If this is proprietary to L2, please let me know and remove the question - thank you)
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Offline Patchouli

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[

You are right. Is it called a SM with CST-100?

Well they're two completely different things though.

Dragon's trunk doesn't contain any consumables,major avionic systems,or propulsion like a traditional service module.
In some ways Dragon is setup more like a space plane then a tradition capsule in that most of the major system are inside the reentry vehicle.


1) Not for safety critical systems
2) They do for CPUs, memory, etc.
3) V1.0 was not three-string
4) 40% in most cases

I'm actually very surprised to hear V 1.0 was not triple redundant.

Offline xanmarus

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I'm actually very surprised to hear V 1.0 was not triple redundant.
It was triple redundant. More here http://www.parabolicarc.com/2012/11/14/44264/
« Last Edit: 10/23/2014 05:26 am by xanmarus »

Online ugordan

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I'm actually very surprised to hear V 1.0 was not triple redundant.
It was triple redundant. More here http://www.parabolicarc.com/2012/11/14/44264/

Antares said the v1.0 rocket wasn't triple redundant. And it wasn't.

Offline fast

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It has a pusher LAS in the trunk. It is abandoned before reentry.

CST-100 does not have a trunk. Only Dragon has that.

You are right. Is it called a SM with CST-100?
The names are descriptive. The thunk is little more than a mechanical transfer tube. Yes, it holds the solar panels and act as radiator. That's it. The CST SM has the LaS, the RCS, propellant and many extra things. Is a different way or arranging the vehicle.

That is right, CST SM with LAS discarded before reentry, so no reuse for LAS.

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