Author Topic: Are we asking too much of Orion?  (Read 16129 times)

Offline clongton

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Re: Are we asking too much of Orion?
« Reply #40 on: 08/21/2008 05:05 PM »
Well it seems as though Ares I is moving to the right rather briskly. If NASA holds fast to the plan to abandon the ISS in 2016 is it even necessary to retain the six-man capability for Orion? Will dropping that requirement relieve any schedule/weight requirements?

No idea. But NASA isn't holding fast to any plan to drop the ISS. As far as I can tell, NASA ran a few years ago some budget projections based on the assumption that the ISS is abandoned in 2016. But I wouldn't call that a plan since they aren't doing anything now that would change if they decided one way or the other.

Unless I missed something NASA is still planning on transferring the annual ~$2b ISS funding to the Constellation program post 2016.

That may be Griffin’s plan, but not NASA’s. It is the Congress, and the Congress alone, that has the authority to define what NASA can spend and on what. And please note: not only has Congress indicated that it has no intention of dumping the ISS, but by 2016 Griffin will be long, long gone.
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Offline bfowler

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Re: Are we asking too much of Orion?
« Reply #41 on: 08/21/2008 06:14 PM »
The term "man rated launch vehicle" means whatever NASA wants it to mean.  It should come as no surprise to anyone that man rating was used as part of the bait and switch that is Ares I.

"Man rating" has a very concrete and specific meaning, which includes, but not limited to, instrumenting the LV to detect catastrophic failures and triggering the LAS.  AIUI, there is a pretty broad consensus on what "man rating" means -- just read about Ariane 5 and Hermes.

Somebody with first hand knowledge/experience like Jim could perhaps elaborate on what it means in general, and (hypothetically), how it might apply to EELV...
« Last Edit: 08/21/2008 06:15 PM by bfowler »
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Offline Jim

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Re: Are we asking too much of Orion?
« Reply #42 on: 08/21/2008 07:32 PM »
The term "man rated launch vehicle" means whatever NASA wants it to mean.  It should come as no surprise to anyone that man rating was used as part of the bait and switch that is Ares I.

"Man rating" has a very concrete and specific meaning, which includes, but not limited to, instrumenting the LV to detect catastrophic failures and triggering the LAS.  AIUI, there is a pretty broad consensus on what "man rating" means -- just read about Ariane 5 and Hermes.

Somebody with first hand knowledge/experience like Jim could perhaps elaborate on what it means in general, and (hypothetically), how it might apply to EELV...


Jeff is more correct.  It is a mushy definition.

"instrumenting the LV to detect catastrophic failures and triggering the LAS"  is one of the things that are needed for manrating.  The fuzzy part is safety factors and  redundancy requirements. 

Offline kraisee

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Re: Are we asking too much of Orion?
« Reply #43 on: 08/21/2008 08:28 PM »
It doesn't help that the various bars keep getting moved to better suit whatever the "policy-of-the-day" is.

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Offline Patchouli

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Re: Are we asking too much of Orion?
« Reply #44 on: 08/21/2008 09:04 PM »
Don't for get manrating also involves adding a 1.4 safety margin on all systems and making the vehicle fault tolerant in that it can tolerate a few failures and still complete it's mission see the Shuttle.

All avionics must be triple redundant though I don't have first hand experience but this is the case with commercial airlines.

Back on OT no we are not asking too much from Orion it's only problem is it lacks a proper LV that must be 26T or larger 24 T is not big enough these things should have a good performance margin.

The only problem is Ares I cannot deliver the goods and the single j2 upper stage is anything but ideal in that it suffers from very high gravity losses due to it's poor thrust to weight.


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