Author Topic: DIRECT v2.0 - Thread 2  (Read 544364 times)

Online gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4110 on: 01/09/2009 02:21 AM »
I also felt it tried to give both sides a chance, and was definitely left to the reader to take a position. But the overall tone was pro-Direct I feel.

The stories of people getting threatened and fired for speaking out, the engineer from ULA countering what Cooke had to say about the Jupiter upperstage. There was a slight Big Bad Government vs Innocent Small Guy feel to it.

Online TrueBlueWitt

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Re: DIRECT v2.0 - Thread 2
« Reply #4111 on: 01/09/2009 02:40 AM »
PM Cover and write-up is still not enough to make the front page of this site.

Hopefully the next shoe to drop on the 15th will qualify :)

What?  Why should it?  Chris and company I think have been very good giving the forum to discuss all of this.  It's up to him if he chooses to make a story out of it or not. 

This is a news site. As excited as I am that Direct and NSF are in Popular Mechanics, it is not a news story.

If NASA switches to Jupiter, then we will see a story.

I was stating a fact, and completely understand Chris's reasons.. I wasn't trying to be critical, and apologize if it came across that way.

 I am, however, truly hoping that what is happening behind the scenes with the Direct Team over the next few days, is something that is worthy of an article here.

Offline luke strawwalker

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Re: DIRECT v2.0 - Thread 2
« Reply #4112 on: 01/09/2009 03:27 AM »

Have the dangers of an ocean spash-down been added to the Ares-I LOC numbers?  All kinds of things can go wrong with an ocean splash-down, such as the capsule capsizing or sinking, or the flotation devices could malfunction.  Surely that would have an adverse affect on the safety ratings of the mission.  I can't imagine that there could be 2000 splash-downs without a serious event taking place at least once.

Mark S.

To the best of my knowledge, Ares-I LOM/LOC numbers do NOT include any spacecraft recovery events or milestones. IIRC, they are limited to the spacecraft launch. Someone please correct me if that is not right.

So, the Columbia accident should not count towards Shuttle LOC numbers, in that case.  Sure, the trigger event was during the launch, but they actually survived the launch, completed their science mission, and had left orbit.  Clearly, that line of logic does not hold up.

I would say that LOC/LOM numbers have to account for and include any possible loss while riding in, on, or around any NASA vehicle.  Once they are safely on board the Nimitz (or whatever), then NASA can be absolved of responsibility.

Didn't one of the Mercury capsules actually sink, and nearly take the astronaut down with it?

Mark S.

Being fair, there is a very big difference between Launch Vehicle LOM/LOC numbers and Mission LOM/LOC numbers. While there are certain launch events that can have an affect on the Mission numbers, as in Columbia, typically the Launch Vehicle numbers do not include Mission numbers but are considered and quoted separately. Launching the spacecraft is the job of the launch vehicle. The mission after orbital insertion is generally not affected by the launch vehicle. That's why the mission numbers are quoted separately from the launch event.

The falacy in this particular case (Orion/Ares vs. Orion/Jupiter) is the current design of Orion has been severly compromised by the performance limitations of Ares-I, making the spacecraft much less safe than it would have been otherwise. It is not UN-safe, it is LESS-safe. That does NOT include resulting spacecraft performance shortfalls, only safety considerations; things like lacking mmod protection, reduced survival time in the water after splashdown, and single fault tolerant systems vs. dual fault tolerant.

Kind of like saying foam strikes make shuttle "LESS safe"... unless of course you die because of it... I think that would tend to demonstrate the vehicle to be "UNsafe"...

No harm no foul?? Isn't that the sort of thinking that led to the Challenger and Columbia disasters, even though evidence of prior damage/failure during previous missions showed there was a problem that, in hindsight, should have been addressed, and if it had, could likely have prevented the loss of the crews involved??  I tend to think that pushes such a problem into the 'unsafe' category myself... OL JR :)
NO plan IS the plan...

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Offline kkattula

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Re: DIRECT v2.0 - Thread 2
« Reply #4113 on: 01/09/2009 05:17 AM »
Well, it isn't a real stage.

Sure it is; it's one with side-mounted, jettisonable engines and controls. :)

Structurally it's a stage.  Get over it and pick something else to poke at.


It's not a good idea to dismiss criticism.
DIRECT will be reviewed by NASA under their own terms. NASA have designed an upper stage for the Ares-V, and it comes out at a much more conservative dry mass than JUS. Hence they will try to criticise the JUS. A 'pre-rebuttal' is needed to ensure that JUS's numbers can be verifed.

I'm not dismissing crticism, I'm addressing and refuting it. The claim is that JUS is dubious because no hardware with equivalent performance has ever flown. I believe I have demonstrated that hardware with much better performance has flown, but that data was rejected due to semantics.

A much better criticism would be to analyze the forces & material properties, then show whether or not the structure is physically capable of performing as proposed. Neither the above posters nor NASA have done that.  Instead they point at the NASA design, say it's not as good as JUS, NASA are the experts, so JUS is not possible. That's a logical fallacy.

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My main worry about the JUS is thus: we all know that Ares-V is being pushed to greater performance (six engines, bigger SRBs, composites, etc). If a significantly better EDS is possible, why haven't NASA adopted such a design?


Good question to which the answer comes in several parts:
1) EDS and JUS are not designed to perform exactly the same tasks.
The environments & loads are somewhat different requiring different designs.
2) JUS is bigger which in itself leads to greater mass efficiency.
3) LM have much more experience with cryogenic upper stages, so you would expect their design to be more efficient.
4) NASA have not asked for outside help with EDS. They want to develop the design experience in-house.

None of these alone account for all the differences, but add them all up...

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Other than the EDS, my main worry for DIRECT is the cost numbers. How do you buy a much larger tank, PLF, and thrust structure, an RS68, an SRB nozzle and recovery system, and three SRB segments, for only $15m?*

It's all very well cutting DIRECT some slack in this forum. But don't expect NASA to play that nicely. We need the proposal to be as tough as nails to stand up to whatever NASA can throw at it.

* this number assumes that Ares-I's J2X costs $25m and an RS68 is only $20m.


Existing 4-seg SRB & RS-68 costs are fairly fixed. About $80m per J-120 stack. $100m per J-232.  Ares I and V SRB's and engines will be too, but at a higher rate for the RSB's because they will be 2 new designs with smaller production runs.

The big difference will be in the cost of building the Jupiter core & JUS vs ARES I US, Ares V core & EDS.

IIRC for 2 x ISS, 2 x Lunar Manned, 2 x Lunar Cargo you will need:

10 x Jupiter core, 8 x JUS   VS   4 x AUS, 4 x Ares V core, 4 x EDS

Many of the production costs are fixed, so if you make more copies of a stage, EACH ONE WILL COST LESS. Conversely, making only a few of each, drives up the individual cost.

Online MP99

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Re: DIRECT v2.0 - Thread 2
« Reply #4114 on: 01/09/2009 07:32 AM »
However, it would take the Direct team to provide me with an exclusive run on such news, because the other key element of this site is we never run second hand content.


Am I mis-reading this? ? ? ? You really won't report this unless DIRECT gives you an exclusive and refuses to talk to the rest of the press or any other news site? ? ? ? Hard not to understand your comment as meaning exactly this. Jeez.

I can understand if you need to hear directly from the source before you publish, but to say you won't list a news item just because someone else scooped you by 10 minutes is simply petty. It's still news (and directly from the souce), it's just not an exclusive.

I need to subscribe to some other news sites, I think, to hear all the news that you refuse to publish because someone beat you to it.

Martin

PS I'm very strongly tempted to apologise for such a dismissive tone, but if you really refuse to publish news because someone beat you to it, then you're not a news site, you're just screaming "first!" out to the internet. I would love to apologise if I've misunderstood the comment that I've quoted above, or its context.

Heh. I'll try and explain it better ;)

And I should try to be more civil! I reckon Mail Goggles (http://www.guardian.co.uk/technology/2008/oct/07/google.email) was invented for me. Apologies for the tone, which was completely unnecessary.


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We cover NASA and current vehicles - we are not covering Direct's development (and no news media site is). You're seeing numerous news media taking up a feature on Direct and that's cool - we've done the same back in 2006 and we've got the forum threads (also cool). No one is "missing" anything due to the update threads.

The clue is there in the NSF name. Loving the forum.


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It was intimated why we had not run another article on Direct based on (a) The latest magazine feature. Reason: not a viable news story for us to run with for the reasons given in my other post,

Yeah, just what I need - another news feed rehashing the same thing yet again.


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and (b) That we might pending any big news that directly (pun intended) relates to NASA's CxP direction.

I noted (b) would be viable if we get the news off the Direct team. Reason: It is unviable as a news site to rehash something already reported by another site. Some sites do re-write previously run content (with the "according to a report in the Blah Blah news...", but not us - we break news here for the reasons given of bringing something new to the party. But we still would run something if we had an additional angle. Basically, it HAS to be fresh news. No one here wants to re-read something they already know, and rightly so.

"Exclusive run" means breaking the news, it does not mean "do not to speak to another site." They are under no obligation to come to me with a breaking development, but the point is if they did, then I would run it (which answers the orginal question).

You've given excellent support, and I hope you get your scoop (assuming it's on-topic, of course). This forum has done a lot to get DIRECT's ideas out there and they've said more than once that your moderation has been important to this.


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So the bottom line is "yes" I would write a news article about Direct (I believe the intimation is I'm avoiding such content), but "no" I wouldn't write an article on news already reported, as the readership of this site expects me to give them something new in the articles.

cheers, Martin

Offline Matthew Raymond

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Re: DIRECT v2.0 - Thread 2
« Reply #4115 on: 01/09/2009 11:30 AM »
The big difference will be in the cost of building the Jupiter core & JUS vs ARES I US, Ares V core & EDS.

IIRC for 2 x ISS, 2 x Lunar Manned, 2 x Lunar Cargo you will need:

10 x Jupiter core, 8 x JUS   VS   4 x AUS, 4 x Ares V core, 4 x EDS

Many of the production costs are fixed, so if you make more copies of a stage, EACH ONE WILL COST LESS. Conversely, making only a few of each, drives up the individual cost.

Well, what we're really seeing here is the advantages of a common core stage between the J-120 and J-232. Think about it:

1) All your flights use the same core rather than having two separate designs.

2) The design keeps most of the external fuel tank, so you can use current facilities to produce the Jupiter core with minimal retooling, as opposed to making massive changes to your equipment to accommodate a new, larger design for Ares V or a new, smaller design for Ares I.

These two things alone would result in massive cost reductions when going with Jupiter. However, we can extend this out to the actual preparation and launch. Experience with prepping the J-120 in the VAB would be transferable to the J-232. You can't say the same for the Ares I and V, because they have different VAB platforms, crawlers, launch pads, et cetera. Once the Ares V rolls out, you'd practically need to retrain everyone who was working on the Ares I to work on the Ares V. However, with the J-232, you pretty much just train them on the upper stage and you're done. Not to mention the fact that NASA already has people who know how to put standard SRBs on something derived from the shuttle external fuel tank.

I just don't understand what's so mysterious about the Direct 2.0 numbers. It seems like people are just fishing for a problem. Everything is derivative on the Jupiter:

* Core fuel tank is the Shuttle ET.
* Engines are from the Delta IV.
* SRBs aren't even derivative, they're the SRBs.
* Upper stage is a resized Atlas Centaur.
* J2-X is a modified J2.

Direct 2.0 does have the burden of explaining the numbers and reasoning, but I find the level of skepticism a bit excessive.

Offline kkattula

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Re: DIRECT v2.0 - Thread 2
« Reply #4116 on: 01/09/2009 11:44 AM »
...
Direct 2.0 does have the burden of explaining the numbers and reasoning, but I find the level of skepticism a bit excessive.
Exactly.  I'd like to see a bit more constructive criticism from the skeptics and less "appeals to authority" & cries of "it's too good to be true".

Offline spacecase

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Re: DIRECT v2.0 - Thread 2
« Reply #4117 on: 01/09/2009 02:09 PM »
One additional point to be made regarding the production of Jupiter vs Aries.

Direct would require 3 production lines: Shuttle RSRB, Core stage, EDS

Aries would require 5 produciton lines: 5Seg RSRB, 5.5 Seg SRB, Aries I US, Aries V Core, Aries V US

The Shuttle RSRB lines exist, the Direct core stage line reuses a lot of ET production equipment, and the Jupiter EDS is a new line

All 5 production lines for Aries are new

----------------
As far as the JUS being a magical stage, at least one company thinks they can make it. All the Direct team is looking for is a review of the designs on an even playing field.

Offline bad_astra

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Re: DIRECT v2.0 - Thread 2
« Reply #4118 on: 01/09/2009 02:16 PM »
Hope posting a link to another site won't get me in trouble:
http://www.nasawatch.com/archives/2009/01/transition_team_4.html

"Word has it Buzz was going with them"
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Offline Will

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Re: DIRECT v2.0 - Thread 2
« Reply #4119 on: 01/09/2009 02:39 PM »
One additional point to be made regarding the production of Jupiter vs Aries.

Direct would require 3 production lines: Shuttle RSRB, Core stage, EDS

Aries would require 5 produciton lines: 5Seg RSRB, 5.5 Seg SRB, Aries I US, Aries V Core, Aries V US

The Shuttle RSRB lines exist, the Direct core stage line reuses a lot of ET production equipment, and the Jupiter EDS is a new line

All 5 production lines for Aries are new

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As far as the JUS being a magical stage, at least one company thinks they can make it. All the Direct team is looking for is a review of the designs on an even playing field.

If a contractor can actually build the ultalightweight EDS claimed by Direct, Ares V will not need 5.5 segments.
« Last Edit: 01/09/2009 02:40 PM by Will »

Online spacedem

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Re: DIRECT v2.0 - Thread 2
« Reply #4120 on: 01/09/2009 02:42 PM »
Hope posting a link to another site won't get me in trouble:
http://www.nasawatch.com/archives/2009/01/transition_team_4.html

"Word has it Buzz was going with them"

I've been wondering that for months, given his earlier support for shuttle C type solutions and the curious silence on the subject on his part for a while.

Offline gospacex

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Re: DIRECT v2.0 - Thread 2
« Reply #4121 on: 01/09/2009 02:43 PM »
If a contractor can actually build the ultalightweight EDS claimed by Direct, Ares V will not need 5.5 segments.

This assumes NASA is willing to let contractor build such an EDS. So far NASA wanted to do it "their way", and considering that NASA does not have required experience, no wonder "NASA way" EDS is worse.

Offline Mark S

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Re: DIRECT v2.0 - Thread 2
« Reply #4122 on: 01/09/2009 02:45 PM »
Hope posting a link to another site won't get me in trouble:
http://www.nasawatch.com/archives/2009/01/transition_team_4.html

"Word has it Buzz was going with them"

Now that is interesting.  I know Buzz has his own ideas, but if DIRECT can get his endorsement it would be a big boost in credibility.

As for the "other site", that harbors over-the-top hostility towards DIRECT.  I suppose he must have his reasons, but even in the very first DIRECT article archived on his site, he comes down hard on DIRECT and any favorable posts.

Mark S.

« Last Edit: 01/09/2009 07:44 PM by Chris Bergin »

Online Herb Schaltegger

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Re: DIRECT v2.0 - Thread 2
« Reply #4123 on: 01/09/2009 03:08 PM »
This assumes NASA is willing to let contractor build such an EDS. So far NASA wanted to do it "their way", and considering that NASA does not have required experience, no wonder "NASA way" EDS is worse.

This gets back to an earlier criticism of mine (and many others with industry experience):  NASA does NOT need to do detailed design!  Their highest, best role in the process should be as an overseer of the prime contractors selected.  The recent PDR debacle demonstrates that clearly.  NASA should focus its limited resources on generating top-level mission requirements and level one design requirements and then getting out of the way until PDR except in a general way. 
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Online gladiator1332

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Re: DIRECT v2.0 - Thread 2
« Reply #4124 on: 01/09/2009 03:12 PM »
Good to see that Buzz may be on board!
« Last Edit: 01/09/2009 05:45 PM by gladiator1332 »

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