Author Topic: DIRECT v2.0 - Thread 3  (Read 711802 times)

Offline Kaputnik

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Re: DIRECT v2.0 - Thread 3
« Reply #40 on: 01/14/2009 10:08 AM »
For the Jupiter 232 design to close, the ultralightweight upper stage has to meet the ambitious goals set by the Direct team and their anonymous engineers.

It doesn't get any more anonymous than Bernard Kutter, Manager of Advanced Programs at ULA - Lockheed-Martin publicly saying the JUS is verging on conservative, does it?

I suppose that once you make up your mind about something, no amount of authority in the field will convince you otherwise. You wouldn't be forgetting this point that was brought up to you earlier otherwise. Sure, believe Steve Cook, he's an expert on cryo upper stages.

Well it's still very new news. Up until a couple of days ago I would have sided with Will on this one- I was very worried about the JUS numbers. So give him a chance to change his mind based on new evidence...
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Offline Kaputnik

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Re: DIRECT v2.0 - Thread 3
« Reply #41 on: 01/14/2009 10:09 AM »
I have a question about the EDS.

It will have been sitting in orbit for a while when LSAM / CEV comes to dock with it. Is there any possibility that it will be tumbling by this point?

If so, how does the EDS stablise itself to allow docking to proceed? I don't see any thrusters in the EDS diagrams, nor any mass allocation (eg in figure 36 of http://www.launchcomplexmodels.com/Direct/documents/AIAA-2007-6231-LowRes.pdf).

cheers, Martin

AFAIK there will be an RCS on the stage. It would be impossible to achieve a docking without it. The same will apply for the Ares EDS.
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Offline ugordan

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Re: DIRECT v2.0 - Thread 3
« Reply #42 on: 01/14/2009 10:25 AM »
Well it's still very new news. Up until a couple of days ago I would have sided with Will on this one- I was very worried about the JUS numbers. So give him a chance to change his mind based on new evidence...

This "evidence" was pointed out by several people to him several days ago. Chuck even offered a couple of papers showing the kind of work that guy was involved in w/respect Centaur.

How long exactly does it take for something to sink in? I rather get the impression it's choosing not to believe rather than changing one's mind. If not, I'll shut up now.
« Last Edit: 01/14/2009 10:28 AM by ugordan »

Offline MP99

Re: DIRECT v2.0 - Thread 3
« Reply #43 on: 01/14/2009 10:58 AM »
I have a question about the EDS.

It will have been sitting in orbit for a while when LSAM / CEV comes to dock with it. Is there any possibility that it will be tumbling by this point?

If so, how does the EDS stablise itself to allow docking to proceed? I don't see any thrusters in the EDS diagrams, nor any mass allocation (eg in figure 36 of http://www.launchcomplexmodels.com/Direct/documents/AIAA-2007-6231-LowRes.pdf).

cheers, Martin

AFAIK there will be an RCS on the stage. It would be impossible to achieve a docking without it. The same will apply for the Ares EDS.

Ah, thanks, I see them now (eg on figure 25).

cheers, Martin

Offline Lampyridae

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Re: DIRECT v2.0 - Thread 3
« Reply #44 on: 01/14/2009 11:15 AM »
I'd have to go look it up to be certain, but I'm pretty sure J-2X uses a 5.5 : 1 mixture ratio.

Ross.

I think you are right. Shuttle IIRC also uses 5.5:1
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Offline Lampyridae

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Re: DIRECT v2.0 - Thread 3
« Reply #45 on: 01/14/2009 11:19 AM »
Lack of fuel destroys engines, which is why they run fuel rich.

I thought they also ran fuel rich to reduce the average molecular weight of the exhaust, which increases ISP.

Yes and no. Running stoichiometric (burn everything equally) means maximum energy is extracted from the chemical reaction. Running fuel or oxidiser rich means you are chucking more mass overboard for less chemical energy per unit mass... hence a lower collective exhaust velocity. However, it also means that the thermal energy is more efficiently distributed amongst molecules. It's easier to plunk thermal energy into H2 because it has one bond. H2O has 3 bonds so it gets squished out in the interactions.

(Real rocket engineers please feel free to correct me wherever I foul up).

I think you are wrong. Energy is not important, impulse (speed) is. Running LOX/LH non-stoichiometric gives you free H2 in the exhaust, which has highest possible speed of all gases at any given temperature. Thus, even though energy per kg of exhaust is not maximized, impulse (Isp) is.

IIRC Isp-optimal ratio for LOX/LH is 4:1 by mass, IOW, to use twice as much hydrogen compared to stoichiometric (which would be 8:1). Due to LH tankage inefficiencies, in practice ratios close to 6:1 are used.

Energy is lost in the vibrational modes in more complex molecules. That's the reality of it, and that's why extra LH is injected. There is a much better web page than this on the whys and wherefores of this argument, but for now Wikipedia will have to suffice.

http://en.wikipedia.org/wiki/Rocket_fuel#Mixture_ratio
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Offline Lampyridae

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Re: DIRECT v2.0 - Thread 3
« Reply #46 on: 01/14/2009 11:26 AM »
Discussed extensively in the old thread. But arguments for/against the feasibility of the Jupiter Upper Stage are as follows:

For:
- Less ambitious than ET mass fraction
- LM Centaur engineer says it is possible, even conservative (see Popular Mechanics article) (this pretty much convinces me :) )

Against:
- more ambitious than SII, SIVB, or Ares-V EDS
- NASA are squeezing more performance from Ares-V yet have not suggested such a high-performance upper stage as part of this
- Steve Cooke says it isn't possible.

Steve Cook says it isn't possible because it's the best his crew can come up with. His crew has not designed an upper stage and have no experience with it.

I think that partly explains his stance.

As for more ambitious, the Stick forerunner was called the worst shuttle-derived booster ever. They are trying to make it fly.  :P And yet propellant transfer is too risky? What?
SKYLON... The League of Extraordinary Gentlemen's preferred surface-to-orbit conveyance.

Offline MP99

Re: DIRECT v2.0 - Thread 3
« Reply #47 on: 01/14/2009 11:28 AM »
I have a question about the EDS.

It will have been sitting in orbit for a while when LSAM / CEV comes to dock with it. Is there any possibility that it will be tumbling by this point?

If so, how does the EDS stablise itself to allow docking to proceed? I don't see any thrusters in the EDS diagrams, nor any mass allocation (eg in figure 36 of http://www.launchcomplexmodels.com/Direct/documents/AIAA-2007-6231-LowRes.pdf).

cheers, Martin

AFAIK there will be an RCS on the stage. It would be impossible to achieve a docking without it. The same will apply for the Ares EDS.

Ah, thanks, I see them now (eg on figure 25).

D'oh!

cheers, Martin

Offline kevin-rf

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Re: DIRECT v2.0 - Thread 3
« Reply #48 on: 01/14/2009 12:26 PM »
Ross,

Remember when you where looking for additional missions for direct and everyone told you to stick to the base line.

Looks like someone in NASA is looking for additional uses for the Ares V along the same lines...

From today's NASA Science news :
Quote
NASA Science News for January 14, 2009

NASA's next great Moon rocket promises to do more than land astronauts on the Moon. In its spare time, it could revolutionize the science of astronomy.

FULL STORY at

http://science.nasa.gov/headlines/y2009/14jan_rocketastronomy.htm?list77474
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Offline wannamoonbase

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Re: DIRECT v2.0 - Thread 3
« Reply #49 on: 01/14/2009 12:26 PM »
That's the Achilles' heel of the Direct proposal. Ares now has a three year head start, and the gap is widening every day. A two launch solution was a fairly attractive option three years ago. Now, changing horses in midstream is a lot more expensive.

And there in lies the ingenius stroke of sticking with the stick even though there were performance and TO problems 18 and 24 months ago. 

Too many government programs are compromised because of this idea of having gone too far with a bad idea.  Since we are still looking at a 6 years till first flight, I think there is time to change.

Sticking with a bad idea long enough that other options become unacceptable is a horrid way to manage.
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline clongton

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Re: DIRECT v2.0 - Thread 3
« Reply #50 on: 01/14/2009 12:30 PM »

For the Jupiter 232 design to close, the ultralightweight upper stage has to meet the ambitious goals set by the Direct team and their anonymous engineers. ... That's the Achilles' heel of the Direct proposal.

Will, did you not read the PM article, specifically p57 4th and 5th paragraphs from the bottom?

The engineering team that advised on the JUS design and analyzed the final product is not anonymous. Please stop saying they are. With ULA Lockheed-Martin permission, the manager of the Atlas Advanced Systems team, Barnard Kutter, has opened the window on their involvement. The man is among the most respected upper stage designers in the world! The Achilles heel no longer exists.
« Last Edit: 01/14/2009 12:34 PM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline alexterrell

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Re: DIRECT v2.0 - Thread 3
« Reply #51 on: 01/14/2009 12:50 PM »
Lastly, to one of you guys who have all the numbers at your finger tips, could there be even a scaled down version of Jupiter 120 for launching Orion and the SM to the ISS?
What I mean by that is could you actually forgo the SRB's for a core with 3 RS68's?  Would they even produce enough thrust to get off the ground?

What you could do is dispense with the ET, and use just a single SRB. Then put an upper stage on top the SRB.

That way, you'd get a Jupiter 110.

But the whole idea sucks and would cost billions, so no one in their right minds would even consider it.

Offline zapkitty

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Re: DIRECT v2.0 - Thread 3
« Reply #52 on: 01/14/2009 12:53 PM »
Playing catchup from thread #2...

http://forum.nasaspaceflight.com/index.php?topic=12379.msg353981#msg353981
Quote from: gladiator1332
   Just wondering, would it be possible to provide the image that is currently the background at directlauncher.com?
Really great image.

I don't do too much with images myself ;) but would this be what you mean?

http://www.launchcomplexmodels.com/Direct//graphics/homebanner2.jpg

Offline beb

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Re: DIRECT v2.0 - Thread 3
« Reply #53 on: 01/14/2009 12:55 PM »

[snip]
 It's easier to plunk thermal energy into H2 because it has one bond. H2O has 3 bonds so it gets squished out in the interactions.

Just a nit, but H20 has only two bonds. Three atoms but only two bonds.

Offline clongton

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Re: DIRECT v2.0 - Thread 3
« Reply #54 on: 01/14/2009 01:13 PM »
I think we all just want to know why the tech used in the JUS isn't used in the Ares-V vehicle and if it was then what would the performance of the Ares-V be? NASA does consult with Boeing & Lockheed regularly so the tech cannot be unknown to them.

It was a decision Griffin made early on. He wants to rebuild the NASA “in-house” design force so that NASA can function independently from the contractors. He has assembled an impressive team of design engineers. They are top shelf designers but do not consult with the contractors in the manner you assume. The knowledge of how to do this is locked away in the contractor design engineers' heads and the knowledge base with hardware know-how is proprietary. There is no one on the teams, that I’m aware of, that has the upper stage design experience that either Boeing or Lockheed-Martin has. The contractors have 40+ years of experience designing and flying cryo upper stages. The in-house designers just do not know how to do what the contractors can do. Over the years the contractors have developed a knowledge base that simply does not exist at NASA. As good as they are, the NASA designers simply do not know how to do what the contractors can do. They are on the bottom end of the learning curve wrt cryo upper stage design ability. That’s not to be interpreted as a slap on them; it’s just a simple statement of fact. You can’t assemble a top-shelf team of designers and expect that to magically make 40 years of specialized experience advantage go away.

The guys at NASA that claim the JUS doesn't work have NEVER successfully designed a cryo upper stage in their lives.
The contractor design engineers that say the JUS DOES work have been designing and flying cryo upper stages for decades. They even had a major hand in the JUS design.

It comes down to credability.
Do you believe the guys with or without the appropriate qualifications?
« Last Edit: 01/14/2009 01:20 PM by clongton »
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline sandrot

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Re: DIRECT v2.0 - Thread 3
« Reply #55 on: 01/14/2009 01:52 PM »
[...]

The guys at NASA that claim the JUS doesn't work have NEVER successfully designed a cryo upper stage in their lives. [...]

Where are the Ares' upper stages coming from? Any inspiration from S-IVb? Was that such a horrid US?
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Offline Will

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Re: DIRECT v2.0 - Thread 3
« Reply #56 on: 01/14/2009 02:01 PM »

For the Jupiter 232 design to close, the ultralightweight upper stage has to meet the ambitious goals set by the Direct team and their anonymous engineers. ... That's the Achilles' heel of the Direct proposal.

Will, did you not read the PM article, specifically p57 4th and 5th paragraphs from the bottom?

The engineering team that advised on the JUS design and analyzed the final product is not anonymous. Please stop saying they are. With ULA Lockheed-Martin permission, the manager of the Atlas Advanced Systems team, Barnard Kutter, has opened the window on their involvement. The man is among the most respected upper stage designers in the world! The Achilles heel no longer exists.

Is Bernard Kutter willing to state on the record that the JUS design will not require pressurization during assembly, transport, stacking or rollout?

Offline clongton

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Re: DIRECT v2.0 - Thread 3
« Reply #57 on: 01/14/2009 02:30 PM »

For the Jupiter 232 design to close, the ultralightweight upper stage has to meet the ambitious goals set by the Direct team and their anonymous engineers. ... That's the Achilles' heel of the Direct proposal.

Will, did you not read the PM article, specifically p57 4th and 5th paragraphs from the bottom?

The engineering team that advised on the JUS design and analyzed the final product is not anonymous. Please stop saying they are. With ULA Lockheed-Martin permission, the manager of the Atlas Advanced Systems team, Barnard Kutter, has opened the window on their involvement. The man is among the most respected upper stage designers in the world! The Achilles heel no longer exists.

Is Bernard Kutter willing to state on the record that the JUS design will not require pressurization during assembly, transport, stacking or rollout?

What's the difference? Do you personally have the engineering qualifications to pass judgement on either the JUS design or his unqualified support for it? There are only a handful of design engineers in the world with his level of expertise. If you are one of them then I would like to meet you.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Will

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Re: DIRECT v2.0 - Thread 3
« Reply #58 on: 01/14/2009 03:00 PM »

For the Jupiter 232 design to close, the ultralightweight upper stage has to meet the ambitious goals set by the Direct team and their anonymous engineers. ... That's the Achilles' heel of the Direct proposal.

Will, did you not read the PM article, specifically p57 4th and 5th paragraphs from the bottom?

The engineering team that advised on the JUS design and analyzed the final product is not anonymous. Please stop saying they are. With ULA Lockheed-Martin permission, the manager of the Atlas Advanced Systems team, Barnard Kutter, has opened the window on their involvement. The man is among the most respected upper stage designers in the world! The Achilles heel no longer exists.

Is Bernard Kutter willing to state on the record that the JUS design will not require pressurization during assembly, transport, stacking or rollout?

What's the difference?

It has implications for ground processing. Pressure stabilization is an important ingredient of current and past Centaur stages. If he believes and will state that the JUS can achieve Centaur-like mass fraction without any use of pressure stabilization in ground handling, that's important information for a layman evaluating the practicality of the design.

If he is assuming that there *will* be some use of pressurization, that's important information as well. 
« Last Edit: 01/14/2009 03:20 PM by Will »

Offline zapkitty

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Re: DIRECT v2.0 - Thread 3
« Reply #59 on: 01/14/2009 03:57 PM »
It has implications for ground processing. Pressure stabilization is an important ingredient of current and past Centaur stages. If he believes and will state that the JUS can achieve Centaur-like mass fraction without any use of pressure stabilization in ground handling, that's important information for a layman evaluating the practicality of the design.

If he is assuming that there *will* be some use of pressurization, that's important information as well. 

But why and how is pressurization relevant? Surely you can tell us now... it's not as if Chuck can declare it one way or the other depending on your answer at this stage.

*(unless that's the secret to one vs. two JUS engines :) )

And at this point some reassurance that you have valid concerns and are not seeking a strawman to pin opposition to Direct on would be welcome.

Sorry, but your obtuseness to certain corrrections made in answer to you have left a denialist aroma behind.

Playing "gotcha" with word games is a childish antic I might pull when I'm bored with a hopelessly outmatched opponent... it's not a basis for continued debate.

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