Author Topic: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)  (Read 119337 times)

Offline Joffan

Perhaps a separate emergency egress is not needed for astronauts in the capsule.

If it is mandated, then the need is moot.


Discussion of why the mandate is restrictive to exclude pad abort is welcome.
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Offline Sesquipedalian

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #241 on: 12/09/2013 06:59 pm »
Perhaps a separate emergency egress is not needed for astronauts in the capsule. As a discussion* concept, that's could be what the pad abort capability is for.

Pad abort is useful for problems with the booster, but what about problems with the spacecraft?  It wouldn't be helpful in an Apollo 1 situation.

Offline mgfitter

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #242 on: 12/09/2013 07:01 pm »
Reposting this to the correct thread, as advised...

How far downrange does the first stage land (or splashdown or crash) on these flights without the boost-back profile?

And (maybe this question should go in the Q&A thread, but I'll put it here for now), is there an easy way to calculate an approximate landing point for the first stage, assuming you know the vertical and horizontal velocities at separation?

Thanks!

-MG

Offline cambrianera

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #243 on: 12/09/2013 07:28 pm »
I was actually wondering, does the F9 use a common bulkhead for both stages? If so is this two flat sheets of metal with insulation between them? Isn't there a high thermal flux between the lox and the kerosene?

Or do they use spherical domes to cap of the separate tanks?

You've already got your answer from other members; here two pics related to F9 v1.0.
In the second pic you can see the common bulkhead from the LOX side during first stage construction.
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Offline Joffan

Perhaps a separate emergency egress is not needed for astronauts in the capsule. As a discussion* concept, that's could be what the pad abort capability is for.

Pad abort is useful for problems with the booster, but what about problems with the spacecraft?  It wouldn't be helpful in an Apollo 1 situation.

It's always possible to imagine a scenario so severe that a particular option would be no good. The question is whether the balance of risks mean that that option is ruled out as a result.

So, thinking about an in-spacecraft emergency - sufficiently severe that there is no time to wait (or too much risk to ground crew) for normal crew access, occurring in a period when a slidewire (for example) might conceivably do better. An external escape requiring seven astronauts to exit the capsule would not be quick either, of course. Perhaps there is a design refinement here of an optional "low altitude" pad escape profile, something that only takes say 10 seconds of SuperDraco thrust, 10 seconds of ballistic motion, allows ground/crew door opening at that point if necessary, deploys parachutes and is in recovery within a minute.

Now there are consequences to a pad abort, of course, but the lowered complexity of reusing an existing system might still mean that slightly increased risks in one phase are worth the reduction in risks across the entire scope of operations.

------------------------------

The issue I could have with using pad abort as the escape mechanism is the loss of diverse options. But emergencies of the sort we're thinking about - where escape of any sort is a practical life-saving option - are so few that the benefit of diverse options looks to be lower than the benefit of simplicity.
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Offline sdsds

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #245 on: 12/10/2013 10:09 pm »
The issue I could have with using pad abort as the escape mechanism is the loss of diverse options. But emergencies of the sort we're thinking about - where escape of any sort is a practical life-saving option - are so few that the benefit of diverse options looks to be lower than the benefit of simplicity.

I think the general view of American society regarding human spaceflight is that at every point where a crew might face a life-threatening situation, they must have some means which provides them with a plausible chance of survival. This includes situations at and around the pad before launch. Just as an example, what about a potential life-threatening situation that could occur while the ground support personnel were assisting the crew through the open hatchway of the spacecraft? How could any pad abort functionality provide in that type of situation, and for all the ground and flight crew members, a plausible chance of survival?
« Last Edit: 12/10/2013 10:14 pm by sdsds »
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Offline Sesquipedalian

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #246 on: 12/10/2013 10:19 pm »
It's always possible to imagine a scenario so severe that a particular option would be no good. The question is whether the balance of risks mean that that option is ruled out as a result.

This is a category error.  We imagine scenarios when we need to explore the unknown unknowns that we haven't experienced or accounted for in the history of spaceflight.

An Apollo 1 scenario is a known known, first because it has happened in the past, and second because we have an existing method that will satisfactorily accommodate it: open the door and slide down the chute.


Quote
Now there are consequences to a pad abort, of course, but the lowered complexity of reusing an existing system might still mean that slightly increased risks in one phase are worth the reduction in risks across the entire scope of operations.

There is no "lowered complexity" by using the pad abort.  It is increased complexity.  You are talking about additional time to exit the capsule, additional systems that must work together, and additional opportunities for something to go wrong.

Offline llanitedave

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #247 on: 12/10/2013 11:08 pm »
Eventually, you're putting in so many escape and abort scenarios that the added complexity and points of failure increase risk, rather than relieving it.
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Offline Joffan

The issue I could have with using pad abort as the escape mechanism is the loss of diverse options. But emergencies of the sort we're thinking about - where escape of any sort is a practical life-saving option - are so few that the benefit of diverse options looks to be lower than the benefit of simplicity.

I think the general view of American society regarding human spaceflight is that at every point where a crew might face a life-threatening situation, they must have some means which provides them with a plausible chance of survival. This includes situations at and around the pad before launch. Just as an example, what about a potential life-threatening situation that could occur while the ground support personnel were assisting the crew through the open hatchway of the spacecraft? How could any pad abort functionality provide in that type of situation, and for all the ground and flight crew members, a plausible chance of survival?

Well, the answer depends on the life-threatening situation being faced. Pad abort is obviously not going to be available until the astronauts are strapped into the capsule, but the sequence of launch preparation could also mean that possible life-threatening scenarios are seriously unlikely at that stage. So you have to examine the issues case-by-case and determine the likelihood of the scenario and the chances that any proposed escape scheme will (a) be operative in that scenario and (b) will make a significant difference to the outcome.

You can also decide whether there are restrictions to activity that will avoid that scenario altogether - for example, stop launch processing and make safe in conditions that have a chance of lightning.


Specific to your scenario, and without knowing what actual threat you are proposing, access to the vertical spacecraft might be by a swing arm - if the arm can rotate away by 180 degrees, this might be sufficient escape from most possible problems that offer a realistic chance of escape in the first place.
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Offline Joffan

It's always possible to imagine a scenario so severe that a particular option would be no good. The question is whether the balance of risks mean that that option is ruled out as a result.

An Apollo 1 scenario is a known known, first because it has happened in the past, and second because we have an existing method that will satisfactorily accommodate it: open the door and slide down the chute.

Except that the likelihood of a recurrence of the Apollo 1 tragedy is zero. It has been avoided by the shift away from pure oxygen environments.

Quote
Now there are consequences to a pad abort, of course, but the lowered complexity of reusing an existing system might still mean that slightly increased risks in one phase are worth the reduction in risks across the entire scope of operations.

There is no "lowered complexity" by using the pad abort.  It is increased complexity.  You are talking about additional time to exit the capsule, additional systems that must work together, and additional opportunities for something to go wrong.

Of course there is lower complexity by not loading additional infrastructure on the pad. The pad abort is already there as a necessarily-working option. I don't understand what you are talking about here.
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Offline Lars_J

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #250 on: 12/11/2013 12:01 am »
Except that the likelihood of a recurrence of the Apollo 1 tragedy is zero. It has been avoided by the shift away from pure oxygen environments.

We cured fire? ;D Good to know.

Offline Herb Schaltegger

This thread is getting WAAAAY off-topic, mainly due to one user's exceedingly argumentative (and mostly incorrect) assertions regarding human spaceflight safety standards. Please read the thread topic and stick to it before someone gets a Mod all frakked off.

Thank you.
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Offline pathfinder_01

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #252 on: 12/11/2013 12:10 am »

I think the general view of American society regarding human spaceflight is that at every point where a crew might face a life-threatening situation, they must have some means which provides them with a plausible chance of survival. This includes situations at and around the pad before launch. Just as an example, what about a potential life-threatening situation that could occur while the ground support personnel were assisting the crew through the open hatchway of the spacecraft? How could any pad abort functionality provide in that type of situation, and for all the ground and flight crew members, a plausible chance of survival?

While a pad abort won't help here having methods of escape built into the tower could get crew and support staff to the ground and away from the rocket. An on pad abort would help when the crew is buttoned up and the count down is going and something happens.  It is sort of like a ship not everything will work all the time but having the capability is useful(i.e. fire extinguishers, water tight doors, life jackets, life boats). Situations like chemical leak and fire and the kind that would need a tower escape system. Situations like rocket about to explode bellow you would need pad abort.

Offline Avron

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Re: SpaceX Falcon 9 v1.1 DISCUSSION AND UPDATES (THREAD 5)
« Reply #253 on: 12/11/2013 12:56 am »
to quote Elon -"If one set a standard that you couldn't have loss of life, then there would be no transport. You wouldn't even be allowed to walk. " .. so there comes a time where all the aborts in the world, just will not help,

Online Chris Bergin

Decided it would be best to lock this one that's wandering and move to thread 6:
http://forum.nasaspaceflight.com/index.php?topic=33497.0
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