Author Topic: DIRECT v3.0 - Thread 1  (Read 1228092 times)

Offline marsavian

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Re: DIRECT v3.0 - Thread 1
« Reply #1580 on: 06/24/2009 10:59 pm »

None of the ESAS TLI claims have proved accurate including Ares V which has had to be enlarged considerably from the SSME Classic to what they have now and it still comes up short so you can't rely on ESAS.

Ares V classic wasn't dumped because of a performance deficit (it probably would have worked pretty well), it was dumped on a supposed cost of engine basis.  So, NASA picked less efficient engines, and then wondered why making Ares V bigger and bigger wasn't having the desired effect... it didn't help any that upgrades to the RS-68 weren't hitting their performance targets (per Ross statements), or that the core stage was too heavy for the crawlerway.


It was because it couldn't deliver a 45mT lander.

p13-14
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002798_2007001569.pdf


Offline cixelsyD

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Re: DIRECT v3.0 - Thread 1
« Reply #1581 on: 06/24/2009 11:13 pm »
I don't know for sure what the real (as opposed to supposed) motivation was for dumping Space Shuttle Main Engines, Space Shuttle External Tanks (or at least very close approximations), and Space Shuttle SRBs from vehicles that were supposed to be Space Shuttle derived, but replacing them with unbuilt (hence needed development), untested (hence unknown performance), and unproven (hence unknown reliability) hardware sure has made the whole process a lot more complicated

Quoted for truth. Perhaps that post should have been mailed to the Augustine Commission  ;)

Offline deltaV

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Re: DIRECT v3.0 - Thread 1
« Reply #1582 on: 06/24/2009 11:24 pm »
That's a pretty concise summary of the situation.  As I've argued before, RS-68 and J-2X are disappointing engines whose development has come at the cost of fielding much more promising engines such as RS-84 and RL-60.  Delta IV will probably be the first and last vehicle to use RS-68, and J-2X (aka Vulcain reinvented for the NIH-afflicted) will probably never fly.

Eeek too many different types of engines to keep track of! I'm wishing I had a scatter plot with thrust on the horizontal axis (log scale), ISP on the vertical axis and one labeled point per engine, with symbol type denoting propellants. Does such a plot already exist or should I make it myself?

Edit: I just made such a chart; see attached (page 2). Don't look too closely at the ISPs; Merlin and SSME have relatively poor vacuum ISP because as first-stage engines they are optimized for sea-level ISP. The fuels aren't shown explicitly on the chart but the ISP indicates the fuel.
« Last Edit: 06/25/2009 01:27 am by deltaV »

Offline Eric Hedman

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Re: DIRECT v3.0 - Thread 1
« Reply #1583 on: 06/24/2009 11:43 pm »
There is on question that is nagging me about all the architectures using the Orion capsule that I don't remember reading anything about (maybe I missed it), but if Orion is returning from the Moon and the weather turns bad at the landing/splash down site, how rough of weather can the Orion hanging from parachutes take?  And how far out does the Orion have to be to significantly shift landing sites?  Just curious.

Online Lampyridae

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Re: DIRECT v3.0 - Thread 1
« Reply #1584 on: 06/25/2009 12:27 am »
I agree. But until this data is made public, or at least shows itself in some documented form, there is no way to alert the panel. Telling them you heard water-cooler talk that NASA did another review of Direct is not going to help.

You need to have the documents from NASA and the ESAS documents right there to show them side by side, and ask where the missing 15 tons went.

I can tell you where some of that went straight away. No common bulkhead. All you need to do is show Direct's EDS slide side by side with the NASA one.

Offline gladiator1332

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Re: DIRECT v3.0 - Thread 1
« Reply #1585 on: 06/25/2009 12:32 am »

None of the ESAS TLI claims have proved accurate including Ares V which has had to be enlarged considerably from the SSME Classic to what they have now and it still comes up short so you can't rely on ESAS.

Ares V classic wasn't dumped because of a performance deficit (it probably would have worked pretty well), it was dumped on a supposed cost of engine basis.  So, NASA picked less efficient engines, and then wondered why making Ares V bigger and bigger wasn't having the desired effect... it didn't help any that upgrades to the RS-68 weren't hitting their performance targets (per Ross statements), or that the core stage was too heavy for the crawlerway.

Ares I on the other hand, was dumped because the upper stage engine supposedly couldn't be made to air start, so they picked a less efficient engine, made the first stage bigger, and wondered why making the thing bigger wasn't having the desired effect... it didn't help any that the J-2X design was having a hard time hitting its performance targets (again, per Ross' statements), or that the first stage was too long to avoid resonance with the upper stage.

I don't know for sure what the real (as opposed to supposed) motivation was for dumping Space Shuttle Main Engines, Space Shuttle External Tanks (or at least very close approximations), and Space Shuttle SRBs from vehicles that were supposed to be Space Shuttle derived, but replacing them with unbuilt (hence needed development), untested (hence unknown performance), and unproven (hence unknown reliability) hardware sure has made the whole process a lot more complicated

And I think NASA is sorta coming to their senses on this. Shannon stated in his presentation that making the SSME expendable was not as bad as they first thought. I believe he went as far to say that it was just a "myth" that the SSME was too expensive to just throw away.

It is good that Direct came to this conclusion a bit earlier than NASA. So far Ares V is sticking with the RS-68, but I could see that changing if the panel is going to stick with the current plan.

Online Lampyridae

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Re: DIRECT v3.0 - Thread 1
« Reply #1586 on: 06/25/2009 12:42 am »
And I think NASA is sorta coming to their senses on this. Shannon stated in his presentation that making the SSME expendable was not as bad as they first thought. I believe he went as far to say that it was just a "myth" that the SSME was too expensive to just throw away.

It is good that Direct came to this conclusion a bit earlier than NASA. So far Ares V is sticking with the RS-68, but I could see that changing if the panel is going to stick with the current plan.

I don't think NASA will voluntarily switch back to SSME, because then they have something very like Direct and then it's just a short step away from ditching the Ares I and switching to 2-launch.

Hmmm, funny how a single 8.3m 4seg Ares V with 5 SSME could put the whole stack through TLI, yet now 2 x 4SSMEs J-246 can only lift the same as 2  x 3SSME Not Shuttle-C with its sidemount losses.

I hope somebody at the Augustine Panel takes note of this.

Offline guru

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Re: DIRECT v3.0 - Thread 1
« Reply #1587 on: 06/25/2009 01:01 am »

It was because it couldn't deliver a 45mT lander.

p13-14
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070002798_2007001569.pdf


Consider the differences between the SSME based vehicle compared in the report you referenced and the "Classic Ares V" from ESAS (www.nasa.gov/exploration/news/ESAS_report.html ... underlining in the shown attachment added by me) as shown in these two attachments.

At the time of ESAS, the official recommendation was to use 2 J-2S engines on the EDS.  This, according to the ESAS report, could lift a 44.9 mT lander with 1.4 tonnes of spare margin.

The later report that claims a 41 mT capability uses an EDS with only 1 x J-2X.  Notice how the two versions that use the J-2S on the later report conveniently also use a new propellant mixture for the SRBs, not allowing for a comparison against PBAN based SRBs with a 2 x J-2S engined EDS as originally specified in the ESAS report.

« Last Edit: 06/25/2009 02:13 am by guru »

Offline strangequark

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Re: DIRECT v3.0 - Thread 1
« Reply #1588 on: 06/25/2009 01:37 am »

Edit: I just made such a chart; see attached (page 2). Don't look too closely at the ISPs; Merlin and SSME have relatively poor vacuum ISP because as first-stage engines they are optimized for sea-level ISP. The fuels aren't shown explicitly on the chart but the ISP indicates the fuel.

Cool stuff, thanks for the chart. If I may make a humble suggestion though, change the specific impulse scale to 250-500, maybe in major increments of 15, minor of 5 to give it more fidelity. I would also add the RL-10A-4-2 and J-2X.


Offline gladiator1332

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Re: DIRECT v3.0 - Thread 1
« Reply #1589 on: 06/25/2009 01:51 am »
This is all going to make a very good book someday.

I really just hope this panel does its business differently. I have no problem with groups pitching their ideas and fighting for their side. However, when you start fudging numbers, and changing around configurations to make your case stronger, then you've crossed the line in my book.

NASA has really screwed the pooch on this one.

Offline robertross

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Re: DIRECT v3.0 - Thread 1
« Reply #1590 on: 06/25/2009 01:54 am »

Edit: I just made such a chart; see attached (page 2). Don't look too closely at the ISPs; Merlin and SSME have relatively poor vacuum ISP because as first-stage engines they are optimized for sea-level ISP. The fuels aren't shown explicitly on the chart but the ISP indicates the fuel.

Nice chart. Shouldn't that be J-2X instead of J-2S?

Personally I hope J-2X isn't cancelled. It's a good engine, it's development just shouldn't be on the critical path.

Offline bluea

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Re: DIRECT v3.0 - Thread 1
« Reply #1591 on: 06/25/2009 02:02 am »
What would the performance of a J-256 look like? (5xSSMEs)

Offline JMSC

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Re: DIRECT v3.0 - Thread 1
« Reply #1592 on: 06/25/2009 02:03 am »
Which reminds me -- I just heard that NASA has gone and produced a new "Analysis" into DIRECT 3.0 in which the same old BS is apparently doing the rounds -- yet again.

While I've only heard a few details, they're b*tching about the pmf being something which NASA is unable to build (yeah, we know that, which is precisely why we want Industry to handle that element because of their much greater experience instead, duh!).


Ross, I honestly do admire you Chuck and the rest of the team for putting up with this for around 3 years now.  In order to have an honest comparision of the benefits of each system its necessary to come to a simple agreement that yes DIRECT (a 2-launch architecture) can do the same job as the Ares 1.5 launch architecture.  Maybe a 2-launch architecture will cost more than the DIRECT team says, maybe Ares I is theoretically safer, or maybe we really do need a monster cargo launch vehicle for Mars and other missions.  However, as long as NASA management can reduce this to a my expert said vs their expert said (and by the way who is their expert) they can essentially freeze the conversation in place and avoid doing the really important comparisions or asking the important questions about what is the most effective way to return to the moon and push mankinds presence further into space.

Don't give up the fight, it should be self evident to anyone who has looked at the all of the various shuttle derived architectures proposed over the years that SDLVs are excellent for launching payloads ranging from 50 mt to around 130 mt without too much in the way of extensive rengineering of the basic components, and Jupiter or something very similiar to it can launch 110 mt like the team claims and ergo send the required mass through TLI.  The fact that NASA upper management seems so intent on dismissing the obvious just shows that they really do understand how weak their claims are that Ares is the safest, simplest, least costly, quickest and best way to meet the nations stated exploration goals, and that if the firewall is breached there will simply be no way to justify Ares based on the really important questions dealing with the cost and performance of potential exploration architectures.

PS Although I am basically just a civil/environmental engineer, and not an aerospace or rocket guy by any stretch of the word I can say I do admire NASA a great deal and if not for Apollo and the Shuttle would have probably have pursued a career in accounting something else just as dreadfull.  I just have a problem when a leaderships collective pride in their solution blinds them from allowing an honest assesment of that solution or alternatives.

John
« Last Edit: 06/25/2009 06:16 am by JMSC »

Offline gladiator1332

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Re: DIRECT v3.0 - Thread 1
« Reply #1593 on: 06/25/2009 02:08 am »
Which reminds me -- I just heard that NASA has gone and produced a new "Analysis" into DIRECT 3.0 in which the same old BS is apparently doing the rounds -- yet again.

While I've only heard a few details, they're b*tching about the pmf being something which NASA is unable to build (yeah, we know that, which is precisely why we want Industry to handle that element because of their much greater experience instead, duh!).


Ross, I honestly do admire you Chuck and the rest of the team for putting up with this for around 3 years now.  In order to have an honest comparision of the benefits of each system its necessary to come to a simple agreement that yes DIRECT (a 2-launch architerure) can do the same job as the Ares 1.5 launch architecture.  Maybe a 2-launch architecture will cost more than the DIRECT team says, maybe Ares I is theoretically safer, or maybe we really do need a monster cargo launch vehicle for Mars and other missions.  However, as long as NASA management can reduce this to a my expert said vs their expert said (and by the way who is their expert) they can essentially freeze the conversation in place and avoid doing the really important comparisions or asking the important questions about what is the most effective way to return to the moon and push mankinds presence further into space.

Don't give up the fight, it should be self evident to anyone who has looked at the all of the various shuttle derived architectures proposed over the years that an SDLVs are excellent for launching payloads ranging from 50 mt to around 130 mt without too much in the way of extensive rengineering of the basic components, and Jupiter or something very similiar to it can launch 110 mt like the team claims and ergo send the required mass through TLI.  The fact that NASA upper management seems so intent on dismissing the obvious just shows that they really do understand how weak their claims are that Ares is the safest, simplest, least costly, quickest and best way to meet the nations stated exploration goals, and that if the firewall is breached there will simply be no way to justify Ares based on the really important questions dealing with the cost and performance of potential exploration architectures.

PS Although I am basically just a civil/environmental engineer, and not an aerospace or rocket guy by any stretch of the word I can say I do admire NASA a great deal and if not for Apollo and the Shuttle would have probably have pursued a career in accounting something else just as dreadfull.  I just have a problem when a leaderships collective pride in their solution blinds them from allowing an honest assesment of that solution or alternatives.

John

Great post. I think it sums up how a lot of us feel. Ross and the guys, as well as all of us "amazing peoples" love space flight and what NASA does.

It angers me to see Cx shoot themselves in the foot with this architecture.

« Last Edit: 06/25/2009 02:10 am by gladiator1332 »

Offline deltaV

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Re: DIRECT v3.0 - Thread 1
« Reply #1594 on: 06/25/2009 02:18 am »
Cool stuff, thanks for the chart. If I may make a humble suggestion though, change the specific impulse scale to 250-500, maybe in major increments of 15, minor of 5 to give it more fidelity. I would also add the RL-10A-4-2 and J-2X.

I added those two engines and adjusted the axes.

Edit: added a few more engines.
« Last Edit: 06/25/2009 02:56 am by deltaV »

Offline cixelsyD

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Re: DIRECT v3.0 - Thread 1
« Reply #1595 on: 06/25/2009 02:27 am »
Which reminds me -- I just heard that NASA has gone and produced a new "Analysis" into DIRECT 3.0 in which the same old BS is apparently doing the rounds -- yet again.

While I've only heard a few details, they're b*tching about the pmf being something which NASA is unable to build (yeah, we know that, which is precisely why we want Industry to handle that element because of their much greater experience instead, duh!).

That seems pretty weak. If rebuttals of Direct are no longer about performance, safety or cost, I think they're out of ideas. If that's all they have, they're just dragging their heels, and I would lose a lot of faith in the Augustine Commission if they didn't see that.

We can't get that built, or we *won't* get that built. Seems pretty subjective to me.

Offline gladiator1332

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Re: DIRECT v3.0 - Thread 1
« Reply #1596 on: 06/25/2009 02:35 am »
Which reminds me -- I just heard that NASA has gone and produced a new "Analysis" into DIRECT 3.0 in which the same old BS is apparently doing the rounds -- yet again.

While I've only heard a few details, they're b*tching about the pmf being something which NASA is unable to build (yeah, we know that, which is precisely why we want Industry to handle that element because of their much greater experience instead, duh!).

That seems pretty weak. If rebuttals of Direct are no longer about performance, safety or cost, I think they're out of ideas. If that's all they have, they're just dragging their heels, and I would lose a lot of faith in the Augustine Commission if they didn't see that.

We can't get that built, or we *won't* get that built. Seems pretty subjective to me.

And when you already put a man on the Moon, it's pretty tough to believe an argument of "we can't build that".

Saying Jupiter can't be built because it defies the laws of physics...isn't that what they told those two guys from Ohio who had that crazy flying machine idea?

Offline fotoguzzi

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Re: DIRECT v3.0 - Thread 1
« Reply #1597 on: 06/25/2009 06:39 am »
duh!).
subjective to me.
...isn't that what they told those two guys from Ohio who had that crazy flying machine idea?
More like, isn't that what the Ohio guys might have told Glenn Curtis in 1904 or so?
My other rocket is a DIRECT Project 2

Offline MP99

Re: DIRECT v3.0 - Thread 1
« Reply #1598 on: 06/25/2009 07:31 am »
It really seems like a DIRECT/ULA alliance would be the best way to counter NASA's FUD about upper stage pmf.

The alliance should propose a common upper stage (5m Centaur with 45 mT GLOW) to be used on Atlas/Delta (expended after ascent) and Jupiter (fueled EDS).

With this common upper stage as the EDS, J-130 puts a 25 mT spacecraft through TLI.  With L2 rendezvous, both CEV and LSAM are less than 25 mT through TLI.

ULA needs a new upper stage to get the most out of their existing first stages.  DIRECT needs a new upper stage to get out of earth orbit.  NASA can't develop these upper stages, but ULA can.

So tell ULA that if NASA chooses DIRECT for lunar missions, they'll get funding to develop the 5m Centaur they've been wanting, but they need to convince NASA that it doesn't violate the laws of physics.


ULA say they can build a stage with certain mass & performance, NASA say they can't. Let ULA prove it.

So how about a COTS-style programme? NASA develops the core, whilst providing "seed-corn" or milestone funding to ULA to develop Jupiter Upper Stage, but ULA take most of the risk. If the stage doesn't perform, they don't get paid.

If the stage does perform, they get a certain guaranteed level of business over a 10 year period to earn back their investment. Set the price up-front, with minor adjustments up or down for allowable minor variations in performance (if JUS really is conservative, they'd earn a bit more per stage for a higher payload).

I don't know whether this would also provide a basis for ULA to then develop their high-performance EELV common upper stage, which would provide benefit down the road to DOD, too?


NASA gets it's upper stage without having to make an up-front investment, so the programmes can run in parallel.

Downsides:-

* this implies the US would / could be ready sooner, which might rush the development of the Altair / Lunar Orion.

* ULA would have to price their stage to recover their investment at commercial interest rates. Could their basic design be cheaper than NASA's anyway (pure speculation on my part, but I think DIVHCUS is quite reasonably priced)?

* Big, big downside - if ULA fails to deliver, CxP is in deep trouble.

cheers, Martin

Offline MP99

Re: DIRECT v3.0 - Thread 1
« Reply #1599 on: 06/25/2009 07:32 am »
Which reminds me -- I just heard that NASA has gone and produced a new "Analysis" into DIRECT 3.0 in which the same old BS is apparently doing the rounds -- yet again.

While I've only heard a few details, they're b*tching about the pmf being something which NASA is unable to build (yeah, we know that, which is precisely why we want Industry to handle that element because of their much greater experience instead, duh!).

And they're trying to depict the architecture as only being able to send a 29mT lander through TLI.


That's even going to make 2x J-246 Heavy a bit of a stretch to close CxP, isn't it?

cheers, Martin

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