Author Topic: DIRECT v2.0 - Thread 2  (Read 728339 times)

Offline kraisee

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DIRECT v2.0 - Thread 2
« on: 03/21/2008 06:37 PM »
Starting a new thread because the other one just hit 250 pages!

Please continue discussions here.   Chris will lock the old thread now.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Alpha Control

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RE: DIRECT v2.0 - Thread 2
« Reply #1 on: 03/21/2008 07:16 PM »
I guess I'm the first one here!  :)

Looking forward to following the continuing discussions.
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

Offline clongton

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RE: DIRECT v2.0 - Thread 2
« Reply #2 on: 03/21/2008 07:48 PM »
Quote
Alpha Control - 21/3/2008  4:16 PM

I guess I'm the first one here!  :)

Looking forward to following the continuing discussions.
No Fair! I was driving. ;)
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Eerie

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Re: DIRECT v2.0 - Thread 2
« Reply #3 on: 03/21/2008 08:02 PM »
At was stage Ares V will be easier to develop than Jupiter-232? (It also defines the point after which DIRECT will no longer be relevant).

I just wonder what are the chances of a future where Ares 1 exists, but Ares V gets replaced by DIRECT-like alternative.
Quote from: Jim
Wrong.

Offline kraisee

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Re: DIRECT v2.0 - Thread 2
« Reply #4 on: 03/21/2008 08:34 PM »
Is there a point where Ares-V is easier to develop?

Considering that both Jupiter-120 and Jupiter-232 together cost less than *either* Ares-I or Ares-V separately, the point of loss is a long way off.   I would say that up until ~2 years before Ares-V becomes operational Jupiter would still be a strong competitor.

Of course, that assumes Ares-V ever receives funding in the first place - which seems virtually impossible at this stage according to almost everyone I've talked to in the last 6 months.   More than 90% of the NASA folk involved in CxP I have spoken with all-but laugh at the idea.   Right now they're all just praying they keep their jobs in an Orion-to-ISS world.

Right now I think Constellation is heading straight for the total-cancellation brick-wall where even Ares-I will be thrown out.   What I'm most concerned about avoiding is that the whole VSE gets thrown out at the same time.

On the one hand are the "shut it all down" crowd (Obama for example) and on the other are those who believe NASA when they tell them Ares-I/V (VI?) is the only way to get VSE working (most people in Congress and the Public).

But the truth is that the VSE is a *great* plan for the US to follow.   It is purely the *IMPLEMENTATION* - in the form of Ares - that what is sucking all the life out of the effort and creating such vast delays and high costs.

There are viable alternatives.   And that is why we're working our butts off to get ours recognized before its too late.

As a group, our #1 overriding priority is to ensure we don't lose the moon, Mars and Beyond plans.   Nothing else - vehicle design included - matters to us compared to that.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Eerie

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Re: DIRECT v2.0 - Thread 2
« Reply #5 on: 03/21/2008 09:22 PM »
I apologize for asking a question that I`m sure was already asked and answered, but the first thread is a bit too long to read.

What, in short, are the reasons that NASA currently pursues Ares I\V? (I mean - how they explain it, and not what may be behind it.)
Quote from: Jim
Wrong.

Offline kraisee

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Re: DIRECT v2.0 - Thread 2
« Reply #6 on: 03/22/2008 03:55 AM »
I'm quite happy to answer questions again Eerie.   I'm sure you aren't the only person who has come to DIRECT since these questions were first asked :)


The current response from NASA for more than a year has boiled down to: "Its what were are already working on. We need to continue. Its too late to change".


The real reason is simple though.   A small group of people came up with the basic idea before Columbia but there was no funding available to study it fully so they just sat on it.   Key individuals were obviously Mike and Scott, but there were others too.

When the VSE was announced O'Keefe wanted to abandon the STS infrastructure to remove development costs.   This was not popular in Washington.   O'Keefe left NASA.   There are no coincidences.

Griffin was appointed because he had a proposal which he claimed would not get bogged down with two or three years of studies trying to find a solution.   He had a pre-potted solution ready to go.   He got the job.   He implemented his solution.

They got rid of people who were doing such studies internally and brought their own team in to validate the concept with the ESAS Report.   I think most informed people these days believe ESAS was a wash.

The sad fact is that Ares-I/Orion has since gotten bogged down by its own two years of endless studies - the result of not doing a proper analysis first - and it looks like there are now plenty more delays coming down the pipe too.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Michael Bloxham

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Re: DIRECT v2.0 - Thread 2
« Reply #7 on: 03/22/2008 08:25 AM »
Ross, is there perhaps another issue here: That adopting DIRECT would put the whole Shuttle-era in an even worse light; because DIRECT, by its very nature, is virtually the shuttle system, but with more than triple the capacity, and is also much simpler and cheaper to boot? ;-)
Please help us to develop our high return-on-investment Humans-to-Mars architecture concept: http://forum.nasaspaceflight.com/index.php?topic=17360.msg636212#msg636212 Thanks!

Offline Eerie

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Re: DIRECT v2.0 - Thread 2
« Reply #8 on: 03/22/2008 08:53 AM »
Quote
Michael Bloxham - 22/3/2008  4:25 AM

Ross, is there perhaps another issue here: That adopting DIRECT would put the whole Shuttle-era in an even worse light; because DIRECT, by its very nature, is virtually the shuttle system, but with more than triple the capacity, and is also much simpler and cheaper to boot? ;-)

But was it the current administration that built the Shuttle system?
Quote from: Jim
Wrong.

Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #9 on: 03/22/2008 12:46 PM »
Shuttle, as a system, played a completely different role in spaceflight. It was specifically designed to be a reusable winged spacecraft, which VSE does not require. Replacing Shuttle with Orion is not an indictment of Shuttle by any stretch of the imagination. It is an acknowledgement that for the VSE, we need a different system. Itís simply time to move on, thatís all.

The debate now centers around the launch system for Orion; and from among all the potential candidates, DIRECT is the best.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Eerie

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Re: DIRECT v2.0 - Thread 2
« Reply #10 on: 03/22/2008 01:02 PM »
clongton; Shuttle what used lately to carry people to ISS and back, so Orion is kind of a replacement for that function...

But my point was that I don`t see how adopting DIRECT will show Shuttle in a bad light. I mean, it supposed to be the opposite, DIRECT is almost Shuttle, just without the plane...
Quote from: Jim
Wrong.

Offline kraisee

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Re: DIRECT v2.0 - Thread 2
« Reply #11 on: 03/22/2008 09:27 PM »
I think that the NASA Authorization Act of 2005 made it explicitly clear that Congress *wants* a Shuttle-derived solution and doesn't see much, if anything, bad from such a position.

And as long as we address all of the safety issues we identified after Columbia was lost, we essentially keep all the good part of Shuttle, but can remove all of the bad.

But there are Shuttle derivatives and there are Shuttle derivatives.   Not all are equal.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline KSC Sage

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Re: DIRECT v2.0 - Thread 2
« Reply #12 on: 03/22/2008 09:52 PM »
Ross,

By chance, has your team looked at the Jupiter 120 using the RD-180 engine on the core stage?  (I know its a political issue)  I would assume two RD-180s would be about the same thrust as two RS-68s, but I don't know if the tanks would have to change for the different type of propellents (RP1 vs H2).  Just as a thought on maybe a faster development and cheaper engine.

Thanks

Offline guru

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Re: DIRECT v2.0 - Thread 2
« Reply #13 on: 03/23/2008 02:42 AM »
I'm no real fan of what the Ares program has turned into, but, as far as I can tell, the plan was an okay plan to start with.  They just didn't know a couple of technical things - 1) that the SSME wouldn't be useful in the plan, and 2) that the SRBs shake too much to be used without additional damping.  When they couldn't air start the SSME, they had to dump the SSME for the ARES 1 in favor of a gas-generator cycle engine (J-2X) that had lower ISP.  The SSME was also more costly than they assumed, and they dumped it from the ARES V and replaced it with the RS-68.

So what happened?  The four segment SRB couldn't provide sufficient impulse needed to lift the ARES 1 upper-stage and payload to the necessary separation velocity.  The RS-68 fell short of the needed performance.  The result was a switch to a five-segment ARES V first stage, and the widening of the ARES V core stage from 8.5 meters (ET diameter) to 10 meters.  In one fell swoop, every common component with the space shuttle transportation system was removed from ARES.  It ceased to be an upgrade which only required a few new structural elements (upper-stage tank set, thrust structure, shroud) and became a development project for two completely new rockets.

The politics is another story.

Offline kraisee

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Re: DIRECT v2.0 - Thread 2
« Reply #14 on: 03/23/2008 02:45 AM »
KSC Sage,
There would have to be a lot more extensive changes to the tanking.   The density of RP1 is radically different from LH2, and the proportions required are also considerably different.   There would be virtually no commonality to the existing ET tanking.

But the key issue is that RP-1/LOX does not have anywhere near the efficiency in vacuum of LH2/LOX.   RP-1/LOX has great thrust, and so are very good options for lower-down in the atmosphere, but you want high efficiency once you get up into vacuum and are just trying to build velocity to reach orbital speeds (the bigger portion of any ascent).

RP-1/LOX works really great for first stages and boosters.   LH2/LOX is far better for upper stages or stages which fly all the way from the ground to orbit - which is what the Jupiter-120 Core (and Shuttle) does.


Now, the Jupiter-232 Core is disposed of part way through the flight.   There is some potential advantage to re-designing it to use RP-1/LOX at some point in the future.   The Upper Stage takes over for the last half of the flight, so high-density, high-thrust performance is desirable there and efficiency is not so important.

But to really keep costs and schedule down, DIRECT chooses not to build two rockets - but to reuse the first one as the basis for a "big brother".   We choose to re-use the same Core from Jupiter-120 - the booster which closes the "gap" to the smallest possible amount.

An RP-1 option might be a future upgrade option at some point in the future when we have lots of money available.   Until then, this option just provides a very realistically achievable solution without breaking the bank.

We were told in no-uncertain-terms that NASA had veto'd use of a Russian engine and would even bother to look at any proposal which included one.   We were also told that F-1, F-1A and RS-84 were all considered too expensive to consider on the critical path to close the gap.   Of course, in the light of 5-seg SRB and J-2X I'm not convinced of this, but that was what we were told we must avoid to have any chance at all.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline kkattula2

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Re: DIRECT v2.0 - Thread 2
« Reply #15 on: 03/23/2008 11:29 AM »
Yes, within reason, propellant density is more important than Isp for a first stage.

A Single Stage To Orbit IS a first stage.

A LOX / RP-1 core using ET derived tanking and RD-180 engines, should put more mass into LEO than J-120, WITHOUT needing any SRB's. It would, however, need 6 or 7 engines. Not 2 plus 2 SRB's.

But yes, using RD-180's is politically unacceptable, and so is stopping use of SRB's.  So Direct is the best all around solution to ALL the requirements.

Offline BogoMIPS

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Re: DIRECT v2.0 - Thread 2
« Reply #16 on: 03/23/2008 01:27 PM »
I'm a huge proponent of a LOX/RP-1 booster stage, but I wholeheartedly agree that DIRECT is not a good application for it in the near future.

You can certainly build an 8.4m core stage that burns RP-1 instead of LH2, but aside from the diameter, everything else would be significantly different.  

Even if you have a politically-viable and immediately-available RP-1 engine right now... if you go with RP-1, it's not DIRECT anymore.  It's probably better-classed as an 8.4m Atlas-derivative.

DIRECT's biggest advantages over Ares how little it "rocks the boat".  Same boosters, similar core tankage, and compared to Ares, dramatically-minimized pad/VAB changes.  

Despite all of RP-1's thrust advantages as a booster stage, it adds complications that DIRECT intentionally avoids.

Offline clongton

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Re: DIRECT v2.0 - Thread 2
« Reply #17 on: 03/23/2008 01:50 PM »
Quote
BogoMIPS - 23/3/2008  10:27 AM

I'm a huge proponent of a LOX/RP-1 booster stage, but I wholeheartedly agree that DIRECT is not a good application for it in the near future.

You can certainly build an 8.4m core stage that burns RP-1 instead of LH2, but aside from the diameter, everything else would be significantly different.  

Even if you have a politically-viable and immediately-available RP-1 engine right now... if you go with RP-1, it's not DIRECT anymore.  It's probably better-classed as an 8.4m Atlas-derivative.

DIRECT's biggest advantages over Ares how little it "rocks the boat".  Same boosters, similar core tankage, and compared to Ares, dramatically-minimized pad/VAB changes.  

Despite all of RP-1's thrust advantages as a booster stage, it adds complications that DIRECT intentionally avoids.
You are absolutely correct; we specifically avoid anything like that for the foreseeable future. All kinds of possibilities present themselves later down the line however. For example, see the post over on the DIRECT Derived Vehicles thread
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=12377#M260221
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Zachstar

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RE: DIRECT v2.0 - Thread 2
« Reply #18 on: 03/23/2008 02:08 PM »
I just want to note here people.

What Obama says while on the road and what he will do behind the desk are two TOTALLY different things.

I advise the Direct team to not name names when talking politics of the big dogs. If they have anyone that wants to check up on this they may not take kindly to such talk.

Don't get me wrong! I love Direct. I love it not because of the fact that is the first system designed outside the norms of the industry, but to the fact that I believe it is the ONLY remaining politically possible near term solution for a moon landing and large cargo to orbit.

I get the whole Obama = delays etc.. etc... but lets be clear here.

You are either going to have McCain (Extremely Unlikely due to events in the past few years, Only way he wins is Clinton gets the democratic nomination and screws up badly) or Obama (Extremely Likely)

So with that in mind perhaps you need to FOCUS these efforts on convincing the Obama Administration that Direct is a VIABLE solution that can be done SOON rather than praying for Ares-V funding later.

Offline Ronsmytheiii

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Re: DIRECT v2.0 - Thread 2
« Reply #19 on: 03/23/2008 02:20 PM »
How many MLPs will be modified, and how long will each take?  I believe shuttle started out with two MLP's during the 80's while the last one was only finished in the early 90's.  For Jupiter-120 flights I can see only needing one at first then maybe a back-up, but with Jupiter-232 dual launches it seems prudent to have three.

Edit:  Also, I remember there being mentioned using Orion as a servicing platform on the DIRECT side.  Have you considered using a modified Strela crane for robotics operations?

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