Author Topic: SpaceX Dragon V2 Updates and Discussion  (Read 667805 times)

Offline Kansan52

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #860 on: 09/23/2015 11:15 pm »
So, maybe sensing sudden loss of sphincter control could automatically trigger an abort?

Anything that causes a sudden loss of sphincter control (with exceptions of convenience store sushi and such) will probably require use of an abort!

Offline okan170

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #861 on: 09/24/2015 12:01 am »
A little late to the game here, but I'm surprised no one has mentioned the apparent removal of the center window.

Quote from: http://www.spacex.com/crew-dragon
Crew Dragon was designed to be an enjoyable ride. With four windows, passengers can take in views of Earth, the Moon, and the wider Solar System right from their seats, which are made from the highest-grade carbon fiber and Alcantara cloth.

Sure looks like a window in that picture, though. We'll have to wait and see if that "four windows" comment was an oversight, or if it is indeed the new situation.

Does a porthole on the hatch count as a legit window?

Offline the_other_Doug

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #862 on: 09/25/2015 01:23 am »
Does a porthole on the hatch count as a legit window?

It always has.  On Gemini, Apollo and Shuttle it did.  I don't see why a hatch window is any the less a window.
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Offline ChrisWilson68

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #863 on: 09/25/2015 01:49 am »
They need a red, glowing eye in the middle of the control panel, and some rotating 3D status displays with big three-letter IDs, like ATM, PWR, NUC and so forth. And the crew should be in airline uniforms, with hats, and the stewardess should have a huge soft white egg on her head. And she should hand out a souvenir pen to the bored, sleepy passenger, subtly slipping it into his top pocket. Hey, don't disagree - this is the commercial flight to a space station we've been waiting for!

Just ignore any warnings about defective AE35 units and nothing could possibly go wornggggg...

I'm pretty sure btw that SpaceX will try to have easter eggs on the control panel. Something like a button combination brings out a huge SCE to AUX button on the screen.

I really doubt it.  Easter eggs that make a mission-critical system more complex are a really bad idea.  More complexity means more chances of bugs.

Offline meekGee

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #864 on: 09/25/2015 07:11 am »
They need a red, glowing eye in the middle of the control panel, and some rotating 3D status displays with big three-letter IDs, like ATM, PWR, NUC and so forth. And the crew should be in airline uniforms, with hats, and the stewardess should have a huge soft white egg on her head. And she should hand out a souvenir pen to the bored, sleepy passenger, subtly slipping it into his top pocket. Hey, don't disagree - this is the commercial flight to a space station we've been waiting for!

Just ignore any warnings about defective AE35 units and nothing could possibly go wornggggg...

I'm pretty sure btw that SpaceX will try to have easter eggs on the control panel. Something like a button combination brings out a huge SCE to AUX button on the screen.

I really doubt it.  Easter eggs that make a mission-critical system more complex are a really bad idea.  More complexity means more chances of bugs.

Pressing "Abort", "Depressurize Cabin", "Open hatch" and "Manual FTS" in a specific order makes the cabin lights do the lighting sequence from Close Encounters.

Of course if you get the order wrong then there's going to be some explaining to do.
ABCD - Always Be Counting Down

Offline coypu76

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #865 on: 09/27/2015 11:03 pm »
I'm not a scientist or engineer, just a space geek since I was a toddler back in 1961, so forgive any ignorance.  I'd like to ask if Crew Dragon's LES would have helped in the scenario of the CRS-7 loss.  It looks like when LOX tank overpressure blew out the end cap of the tank, O2 pressurized the trunk, destroying it.
Since the Crew Dragon depends on the trunk for passive aerodynamic stabilization (the reason for the lengthened trunk and its fins if I am correctly apprised), would the LES work in a similar scenario? 
Thanks for engaging the question.
coypu

Offline Coastal Ron

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #866 on: 09/27/2015 11:31 pm »
Good question.  Elon Musk stated that the Dragon Cargo that was riding on CRS-7 did not have the software to perform an escape from a failing launch vehicle, but that if it did that the capsule would have survived.  There are images showing the Dragon Cargo vehicle tumbling away from the debris, so it did survive intact, but the software to stabilize the vehicle and then deploy the parachutes was not loaded up.  Musk stated they will add that feature to the next launch so that this situation does not result in the loss of a Dragon.

The Dragon Crew, which will carry humans to space, is specifically designed to detect failures like the CRS-7 one, and the Dragon Crew vehicle has even better engines for moving the vehicle away from any conflagration.

How that helps.
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Offline MattMason

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #867 on: 09/27/2015 11:50 pm »
To add to Coastal Ron's answer:

The Crew Dragon has the SuperDraco engines to pull itself from a wayward Falcon, but the cargo Dragon would only have weak thrusters to separate mostly in a non-propulsive way. So, in CRS-7, if the parachute software were present, the Dragon (which was popped off the ship) would have survived. But cargo Dragon has no true LES. The passive separation it can do may not be enough to survive if the launch vehicle's destruction caused damage or serious tumbling to the Dragon.
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Online guckyfan

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #868 on: 09/28/2015 03:02 am »
One more point to add. Dragon was really mostly intact. They received telemetry from it until it was under the horizon and contact was lost for that reason.


Offline PreferToLurk

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #869 on: 09/28/2015 03:30 am »
Thanks for the replies but no one has really answered the OP, and I think the question is a pretty good one that I hadn't considered before. 

Could/would the crew dragon initiate an abort before the tank dome ruptures? 

If not, would a crew dragon with a damaged/destroyed trunk be able to abort safely?

Offline ChrisWilson68

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #870 on: 09/28/2015 03:39 am »
Thanks for the replies but no one has really answered the OP, and I think the question is a pretty good one that I hadn't considered before. 

Could/would the crew dragon initiate an abort before the tank dome ruptures? 

If not, would a crew dragon with a damaged/destroyed trunk be able to abort safely?

The point of some of the replies above was that even if the abort engines weren't used, if a crew Dragon had been on the CRS-7 booster instead of a cargo Dragon it very likely would have survived and saved the crew just with its parachutes.  It didn't need the full abort system in this case.

As to whether this particular emergency would have been detected in time to trigger the abort system before it destroyed the trunk, I don't think anyone outside SpaceX has enough information to know that right now.

Offline Coastal Ron

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #871 on: 09/28/2015 03:41 am »
Could/would the crew dragon initiate an abort before the tank dome ruptures?

Depends on what sensors they have.  They may be adding in them in now to detect this specific condition now that they know it can happen and what the effects are.

Quote
If not, would a crew dragon with a damaged/destroyed trunk be able to abort safely?

The Draco and SuperDraco engines that would be used to move the vehicle away from the damaged launch vehicle are part of the Dragon, not the trunk, so the engines would not be affected by a damaged trunk.  For Dragon Cargo it would jettison the trunk right away, but with the Dragon Crew the trunk is needed for directional control.  See this NSF thread on the Dragon Pad Abort Test.
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Offline PreferToLurk

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #872 on: 09/28/2015 04:10 am »

The Draco and SuperDraco engines that would be used to move the vehicle away from the damaged launch vehicle are part of the Dragon, not the trunk, so the engines would not be affected by a damaged trunk.  For Dragon Cargo it would jettison the trunk right away, but with the Dragon Crew the trunk is needed for directional control.  See this NSF thread on the Dragon Pad Abort Test.

Exactly, the trunk is needed for abort stability, so in a situation where the trunk is damaged/destroyed before the abort initiates...  will the crew still be safe?  A corkscrewing/tumbling dragon under full abort acceleration seems like a pretty dicey situation.  Much different than the cargo dragon passively falling away.  You can't say "cargo dragon just needed software to survive, so crew dragon will also survive" because a crew dragon isn't going to just passively fall off to one side. CRS-7 presented a scenario where the trunk could possibly be destroyed in the initial moments of a launch failure.

I doubt there is a good answer to this question at the moment, as it would likely require detailed systems knowledge of the crew dragon LAS.  But add this to the list of questions I would love to have Elon answer in his investigation wrap-up presser.  FYI, the other question I would love to ask is: Can the FTS system fire autonomously in the event of a failure, did it fire, and/or why not?

Offline darkenfast

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #873 on: 09/28/2015 04:39 am »
I'm going to guess that the trunk's aerodynamic features help Dragon in aborts from the pad and up past max-Q, after which, the advantages slowly taper off as the altitude increase.  The question becomes: at the altitude of the disintegration, were the aerodynamic forces on the capsule strong enough to overcome the Dragon's ability to control its flight?  Just how strong is that slipstream?  Of course, an abort system might have detected the rupture in the second stage fast enough to get the capsule/trunk combination away before the stage crumpled enough to make the trunk useless.  I don't know. 
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Offline cdleonard

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #874 on: 09/28/2015 10:26 am »
Exactly, the trunk is needed for abort stability, so in a situation where the trunk is damaged/destroyed before the abort initiates...  will the crew still be safe?  A corkscrewing/tumbling dragon under full abort acceleration seems like a pretty dicey situation.

But if you watch the video of CRS-7 disintegrating there are several seconds between the first signs of malfunction (a leaking second stage) and the dragon falling away. For the crewed version I assume that the abort engines would have fired based on the abnormal pressure readings from the second stage.

If the top of the second stage blows up into the trunk without warning then it probably won't help much. It's not clear that this is what happened on CRS-7.

Offline rocx

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #875 on: 09/28/2015 03:41 pm »
Exactly, the trunk is needed for abort stability, so in a situation where the trunk is damaged/destroyed before the abort initiates...  will the crew still be safe?  A corkscrewing/tumbling dragon under full abort acceleration seems like a pretty dicey situation.

The trunk isn't the only thing stabilising the crew dragon during abort. While the SuperDraco engines are still running, they are actively throttled to steer the capsule:
Quote from: http://www.spacex.com/news/2015/05/06/crew-dragon-completes-pad-abort-test
After half a second of vertical flight, Crew Dragon pitched toward the ocean and continued its controlled burn. The SuperDraco engines throttled to control the trajectory based on real-time measurements from the vehicle’s sensors.
So it's only after the escape burn that a damaged trunk may cause the capsule to tumble.
Any day with a rocket landing is a fantastic day.

Offline docmordrid

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #876 on: 11/05/2015 06:28 pm »
https://twitter.com/StephenClark1/status/662325113816133632

@syephenclark1
SpaceX’s Reed: New plan is to use four parachutes for Crew Dragon water landings, not three chutes.

Hmmmm....softer splashdown?

https://twitter.com/SciGuySpace/status/662320752247500801

@SpaceX says it remains on time for a demo flight of crew capsule to ISS at the end of 2016.

https://twitter.com/SciGuySpace/status/662321591674499072

@SpaceX says it is looking at March 2017 for first crewed flight of its Dragon spacecraft, with NASA astronauts.
« Last Edit: 11/05/2015 06:29 pm by docmordrid »
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Offline yg1968

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #877 on: 11/06/2015 02:13 am »
A bit more from the NAC meeting on Dragon 2:

Quote
Reed: finished CDR for crew dragon spacecraft last week; in final review at NASA now. Went “very well.”
https://twitter.com/jeff_foust/status/662323434379067392

Quote
SpaceX’s Reed: Wrapped up Crew Dragon CDR last week, currently under review by NASA. Delta CDR in December.
https://twitter.com/StephenClark1/status/662323730111029248
« Last Edit: 11/06/2015 02:22 am by yg1968 »

Offline Zed_Noir

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #878 on: 11/06/2015 04:00 am »
https://twitter.com/StephenClark1/status/662325113816133632

@syephenclark1
SpaceX’s Reed: New plan is to use four parachutes for Crew Dragon water landings, not three chutes.

Hmmmm....softer splashdown?

<snip>

Maybe redundancy in case one of the chute doesn't deployed properly.

Or four smaller chutes is easier to installed and deployed.

Online Semmel

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Re: SpaceX Dragon V2 Updates and Discussion
« Reply #879 on: 11/06/2015 06:16 am »
Wouldn't that invalidate the parachute drop test that they already did?

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