Author Topic: DIRECT v2.0 - Thread 3  (Read 1123238 times)

Offline zapkitty

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Re: DIRECT v2.0 - Thread 3
« Reply #2340 on: 03/29/2009 02:16 am »
... 2017... By that time, the man rated EELV should own the LEO sky.

And as for Dragon et al? Or are you counting them in with the EELVs?

Offline HIP2BSQRE

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Re: DIRECT v2.0 - Thread 3
« Reply #2341 on: 03/29/2009 02:51 am »
Direct Team,

When will the rebuttal be ready?

Offline kraisee

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Re: DIRECT v2.0 - Thread 3
« Reply #2342 on: 03/29/2009 03:49 am »
HIP,
We have been very distracted by 1) the baseline change which you've now seen come together, and 2) a very important meeting which had to take precedent over all other work -- and no, I can't go into any details about the meeting, sorry, its going to have to remain private.

Most of us have been focused completely on those for the last many weeks, and only one of the team has really been able to continue doing any work on editing the rebuttal over the last few weeks (thank-you David!).


Anyway, we just completed the work for the baseline change about a week ago and we just had this important meeting yesterday.   We now have some follow-up work to do next week on both of those.   But most of the team is flying back home and will need a day or two to recover from the extremely long hours we've all put in over the last weeks (and jet lag for some).

So some time next week will be our first opportunity in quite a while to get seriously back into this again.


What I will say about the Rebuttal right now is that we have already decided to release it in sections, because we don't want to have to wait any more for the few sections which are holding us up so much.

So we're going to release about 75% of the rebuttal ASAP, including the real core issues which we have with NASA's claims.   We will then follow this core document up with extra appendices just as soon as they can be completed. That will at least get 75% of our complaints aired publicly.

That will simply have to do for now because we have another big project which is needed for May which is going to start requiring another concerted effort from us all.

Ross.
« Last Edit: 03/29/2009 03:52 am by kraisee »
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Offline VoodooForce

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Re: DIRECT v2.0 - Thread 3
« Reply #2343 on: 03/29/2009 03:55 am »
Awesome

Offline guru

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Re: DIRECT v2.0 - Thread 3
« Reply #2344 on: 03/29/2009 12:49 pm »

Switching to the SSME for our baseline does not imply any change at this time regarding using the J-2X verses the RL-10 or even an RL-60 option.   At this moment the J-2X remains our baseline, although discussions are on-going.


Does this mean you intend to stick with the current 2 engine JUS, or the smaller 1 engine configuration (J-231 type) you mentioned earlier?

Offline Nathan

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Re: DIRECT v2.0 - Thread 3
« Reply #2345 on: 03/29/2009 12:50 pm »
Interesting to hear about the change. Basically you guys have now come up with two rocket designs that are quicker to develop and have greater mission performance than NASA could design...
(yeah not fair - direct is designed by NASA personel - it's NASA decision makers that are at fault)

So I guess the thought is - will there be a summary of the new baseline put up on the directlauncher website soon? Is there any need to bring DeltaIV into the mix or is that unneccessary now that RS68 is gone.

And could a crash design program using all that stimulus package money be put into action to get a basic J130 test vehicle flying within a year?
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline guru

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Re: DIRECT v2.0 - Thread 3
« Reply #2346 on: 03/29/2009 01:06 pm »

And could a crash design program using all that stimulus package money be put into action to get a basic J130 test vehicle flying within a year?

I think a J-130 X (with a dummy core stage, like Ares-IX has a dummy upper stage) could be ready in a year, and even that would be pretty cool.

Online robertross

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Re: DIRECT v2.0 - Thread 3
« Reply #2347 on: 03/29/2009 02:30 pm »

What I will say about the Rebuttal right now is that we have already decided to release it in sections, because we don't want to have to wait any more for the few sections which are holding us up so much.

So we're going to release about 75% of the rebuttal ASAP, including the real core issues which we have with NASA's claims.   We will then follow this core document up with extra appendices just as soon as they can be completed. That will at least get 75% of our complaints aired publicly.

That will simply have to do for now because we have another big project which is needed for May which is going to start requiring another concerted effort from us all.

Ross.

Thanks for the update Ross.

The 'team' meeting in Florida (KSC area) over the weekend & flying back home. Big project for May. [1]. Getting the rebuttal out soon. That speaks volumes in of itself.  :)

EDIT: [1] and what appears to be a new administrator having been chosen.
« Last Edit: 03/29/2009 02:31 pm by robertross »

Offline Ben the Space Brit

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Re: DIRECT v2.0 - Thread 3
« Reply #2348 on: 03/29/2009 03:08 pm »
I think a J-130 X (with a dummy core stage, like Ares-IX has a dummy upper stage) could be ready in a year, and even that would be pretty cool.

Stick some thermal sensors in the fake thrust skirt and the mission would even return some useful data, such as the thermal environment under the ET during RSRM burn.  That way, the degree to which RS-68 would need to be upgraded to operate on a Jupiter could be calculated.
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Offline Namechange User

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Re: DIRECT v2.0 - Thread 3
« Reply #2349 on: 03/29/2009 03:17 pm »
I think a J-130 X (with a dummy core stage, like Ares-IX has a dummy upper stage) could be ready in a year, and even that would be pretty cool.

Stick some thermal sensors in the fake thrust skirt and the mission would even return some useful data, such as the thermal environment under the ET during RSRM burn.  That way, the degree to which RS-68 would need to be upgraded to operate on a Jupiter could be calculated.

What would be the point of that?  It wouldn't even have the same thermal environment because the core stage is a dummy.  It would not have the same acceleration profile.  This would be a mega waste of money, even more so than Ares 1-X
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Offline Lee Jay

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Re: DIRECT v2.0 - Thread 3
« Reply #2350 on: 03/29/2009 03:26 pm »
CECE is derived from the RL-10 one probably could even call it an RL-10 variant but I think they completely reworked the injector design and turbo pump.

So, is this the human-rated RL10 Ross was talking about or is that a separate development?

Online robertross

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Re: DIRECT v2.0 - Thread 3
« Reply #2351 on: 03/29/2009 03:34 pm »
CECE is derived from the RL-10 one probably could even call it an RL-10 variant but I think they completely reworked the injector design and turbo pump.

So, is this the human-rated RL10 Ross was talking about or is that a separate development?

Both, it looks like. It would have to be human-rated for Altair use, but it is also different than the baselined RL-10. So the lessons learned and hardware implemented to human-rate the CECE should be close to (or identical) to that required for the RL-10.

That means reduced costs. The question is whether human-rating is even being looked at at this stage of CECE development, or because Altair is so far out still, it has taken second (or third place) to the actual deep throttling development requirements. I'd say it hasn't been designed yet, only looked at.

Offline Ben the Space Brit

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Re: DIRECT v2.0 - Thread 3
« Reply #2352 on: 03/29/2009 03:35 pm »
It wouldn't even have the same thermal environment because the core stage is a dummy. 

I'll take your word for it. 

However, it should be noted that, AFAIK there is currently zero data about base heating around the base of an ET (and I strongly recommend using a real ET) with thrust skirt.  It would be something worth having and plugging into the specification requirements for RS-25 (the expendable version of SSME).
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Offline Kaputnik

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Re: DIRECT v2.0 - Thread 3
« Reply #2353 on: 03/29/2009 04:25 pm »
Also to my surprise a methane fuel option though I'd hate to see how many an ERV would need to get off Mars then again it can't be any worse then Falcon 9.

Not many people still cling to a Zubrin-esque ERV capable of supporting a crew from Mars ascent right through to landing on Earth.
A far more realistic concept is to have rendezvous in Mars orbit with the ERV. This reduces the launch mass of the Mars Ascent Vehicle to something like 15-25,000kg. Given the much lower gravity on Mars, one or two RL10s would be perfect for this application.
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Offline clongton

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Re: DIRECT v2.0 - Thread 3
« Reply #2354 on: 03/29/2009 04:43 pm »

The 'team' meeting in Florida (KSC area) over the weekend & flying back home. Big project for May. [1]. Getting the rebuttal out soon. That speaks volumes in of itself.  :)

We don't want to let a too-big impression come from that. The "Team" meeting was a social opportunity for a few of the team to get together in the KSC area with anyone else that wanted to meet any of us, share a small meal, have a beer and just say hi. It was not an "official" working meeting of any kind. That happened earlier in the day.
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Online robertross

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Re: DIRECT v2.0 - Thread 3
« Reply #2355 on: 03/29/2009 05:28 pm »

The 'team' meeting in Florida (KSC area) over the weekend & flying back home. Big project for May. [1]. Getting the rebuttal out soon. That speaks volumes in of itself.  :)

We don't want to let a too-big impression come from that. The "Team" meeting was a social opportunity for a few of the team to get together in the KSC area with anyone else that wanted to meet any of us, share a small meal, have a beer and just say hi. It was not an "official" working meeting of any kind. That happened earlier in the day.

That was sort of my point...  ;)

Offline kraisee

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Re: DIRECT v2.0 - Thread 3
« Reply #2356 on: 03/29/2009 07:19 pm »
Does this mean you intend to stick with the current 2 engine JUS, or the smaller 1 engine configuration (J-231 type) you mentioned earlier?

Our analysis shows that when using RS-68's to power the Core Stage, you end up staging at an early enough point where the additional thrust produced by a 2-engine Upper Stage produces more effective results than a 1-engine Upper Stage.

But when using the more efficient SSME's to power the Core Stage, you find that you stage a lot later in the flight, a lot closer to the velocity you need for orbit, so you don't need as much power from your Upper Stage any more.   This means that the optimum performance for that configuration actually comes by minimizing the weight of that Upper Stage as much as possible.   So a single J-2X actually produces better performance on that vehicle than 2 x J-2X's do.   And our analysis goes on to show that some other (lower-thrust but higher Isp) engine options become possible too, like the clusters of RL-10's or RL-60's.


I'm not sure how clear it is from these charts, but here are three charts for showing the relationship between Altitude, Time and Staging for the older RS-68-powered Jupiter-232 configuration verses the new SSME-powered Jupiter-241 (J-2X) and Jupiter-246 (RL-10B-2) vehicles.

If you look closely, you will see the difference in altitude where the staging events occur for the different vehicles, not to mention the different "proportions" of the work being done by each stage.   I think you will agree that the different vehicles work quite differently.

Ross.
« Last Edit: 03/29/2009 07:40 pm by kraisee »
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Offline Danny Dot

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Re: DIRECT v2.0 - Thread 3
« Reply #2357 on: 03/29/2009 07:25 pm »
I vote for EELV in the near term and Direct to become Ares V.  I would be glad to help anyway I can.  Where does Direct stand if we assume an EELV is manrated in the short term?  Do we still manrate a version of Direct?

Danny Deger
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Offline A_M_Swallow

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Re: DIRECT v2.0 - Thread 3
« Reply #2358 on: 03/29/2009 07:35 pm »
What is the cost difference between a man rated JS-130 and a non-man rated JS-130?

The approx 20 mT cargo plus people in the same launch is still attractive.  Or simply carrying the extra propellant needed to leave LEO.

Offline strangequark

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Re: DIRECT v2.0 - Thread 3
« Reply #2359 on: 03/29/2009 07:42 pm »
And our analysis goes on to show that some other (lower-thrust but higher Isp) engine options become possible too, like the clusters of RL-10's or RL-60's.

Ross.

Speaking of which, what's the optimal engine number if you did an upper stage with the RL-60 (if you happen to have the number off hand). As you know, I like the RL-10 option over J2-X, but six is an awful lot of engines. Engine out capability is nice, but if you lose more than one engine, it's probably wise to abort anyway. Basically wondering if the RL-60 hits any kind of balancing sweet spot between redundancy and system complexity (the Isp they were talking about, if achieved, is pretty sweet unto itself). Also curious how much it would cost to restart the program, and how easy it would be to begin with RL-10s, and shift to RL-60s as a later option, given the latter was meant to be as near to a "drop-in" replacement for the RL-10 as possible in rocket science. Again, only if you happen to have the answers lying around somewhere, in the dusty corners of your computer or mind. I've gotten the vague impression that you currently have more important activities than tracking down the answers to all of our little vagaries and whims ;-).

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