Author Topic: DIRECT v3.0 - Thread 1  (Read 1251735 times)

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #120 on: 06/02/2009 01:26 pm »
Hi I'm new to this forum too.

Welcome to the site cixelsyD, (Nice name BTW!)


Quote
I read earlier that you believe that the SSME under much larger production would cost approximately 50% of what it does now. That seems like a pretty big if, since the SSME is more complex than the RS 68. How would having the SSMEs cost say $50m impact your forecasts.

The cost profiles for all the engines follow a traditional "Learning Curve", where there is a large "fixed" cost for setting up the production line and paying all the salaries, and then there is a smaller per-unit "variable" cost.   I've attached a chart which roughly details the current costs for all three engines we're talking about here, just for reference.

As you can see, if the fixed costs can only be amortized across a very small number of production units per year, the individual product costs are pretty steep -- for all of the solutions.   They all start to level-off around a dozen units per year and only gradually drop from there onward.

Not since the start of the Shuttle program have SSME's been produced in the 'flat' part of this curve.   But there's no reason why they can't be.

The published RS-68's costs ($15m each) are all based on an assumption of 6x Delta-IV's and 4x 5-engine Ares-V's per year = 26 units per year.   Add the extra costs for a human-rated Regen variant and this is where you end up.

This is why it is SO important to always question what the yardstick is.   Because if you don't know that, you will always be comparing Apples and Oranges -- in this case most people accidentally end up comparing the cost of SSME's at 3 per year vs. the cost of RS-68's at 26 per year.


Quote
Also couldn't 5 segment SRBs be continued to be researched, though at a much slower pace with fewer resources. It seems we could use them in much later missions such as Mars. It would be a shame to throw away all the research and testing that was done already and not use it.

That will all depend upon the available budget down the road.

Though personally, I want to see us fund more missions which can produce real *results* instead of simply funding development work just for the sakes of "make work".

As for Mars -- A Jupiter-246 can lift 100 tons of *dry* spacecraft to LEO at the start of a mission.   With a Depot architecture, that 100 ton spacecraft could then be topped-off with 500 tons of propellant (for both TMI and MOI) and you never need to develop any new launch vehicle hardware at all.

Its not the launch vehicle which really improves your capabilities, its the introduction of the Depot architectures which really open-up virtually unlimited capability for missions to NEO's, Mars, Jovian or Saturn destinations.

The one exception to that, IMHO, is some form of in-space nuclear propulsion system.   That is a development path which would offer a potentially enormous step-up in capability.   If we're going to improve the vehicles 10, 20 or 30 years down the road, that's the way to really go -- if the budget allows.

Ross.
« Last Edit: 06/02/2009 01:33 pm by kraisee »
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Offline Namechange User

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Re: DIRECT v3.0 - Thread 1
« Reply #121 on: 06/02/2009 02:07 pm »
So what is the plan, if any, for the Augustine Commission?
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Offline William Barton

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Re: DIRECT v3.0 - Thread 1
« Reply #122 on: 06/02/2009 02:22 pm »
The biggest selling point of the Jupiter 246 is, it's a modest and logical evolution of our *currently flying HLLV*, and though it may not be the launch vehicle of our wildest dreams, it is adequate for any mission the USA can reasonably anticipate flying any time in the next 40 years.

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #123 on: 06/02/2009 02:25 pm »
Right now, we are waiting for an official invite to present to them.

Ross.
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Re: DIRECT v3.0 - Thread 1
« Reply #124 on: 06/02/2009 02:42 pm »
Right now, we are waiting for an official invite to present to them.

Ross.

And if it doesn't come?
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Offline wannamoonbase

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Re: DIRECT v3.0 - Thread 1
« Reply #125 on: 06/02/2009 03:10 pm »
The biggest selling point of the Jupiter 246 is, it's a modest and logical evolution of our *currently flying HLLV*, and though it may not be the launch vehicle of our wildest dreams, it is adequate for any mission the USA can reasonably anticipate flying any time in the next 40 years.

Sadly, your 40 years maybe correct.

What I like about the Direct vehicles is that they provide a growth path as well.  If Direct vehicles fly for 30 or 40 years the last ones won't be the same as the first ones.
Starship, Vulcan and Ariane 6 have all reached orbit.  New Glenn, well we are waiting!

Offline Bill White

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Re: DIRECT v3.0 - Thread 1
« Reply #126 on: 06/02/2009 03:24 pm »
Right now, we are waiting for an official invite to present to them.

Ross.

And if it doesn't come?

If the Augustine Commission fails to incorporate a substantive evaluation of the Direct 3.0 architecture into its deliberations - in a transparent fashion - its final report shall deserve (and will receive IMHO) far less credibility and political support than it would otherwise receive and going forward thereafter, NASA shall have a more difficult time rallying public support.

A candid, transparent honest evaluation is all that I am referring to (or seek) combined with a vigorous rejection of arguments premised on fait accompli.
 
This observation is also true for every other significant architecture option out there, including the leverage capabilities found in ISRU and propellant depots, and the need to integrate commercial opportunities and non-US participants into the VSE. 

To do otherwise shall undermine the political viability of the VSE and shall damage NASA as an agency.

To avoid these bad consequences, we should all endeavor to spread the idea that closed minds will not build the  political consensus needed to sustain NASA in the years and decades to come while doing this as politely and professionally as possible. 

= = =

As for Team Direct (of which I am merely a fan-boy) if it becomes apparent that they shall be frozen out of the process, the insiders should deliberate amongst themselves in strict confidence concerning how to best handle that situation and then act at a time and place and in a manner of their own choosing -- without telling us first (as much as I would love to eavesdrop on those conversations).

Hopefully, it won't come to that.
« Last Edit: 06/02/2009 03:29 pm by Bill White »
EML architectures should be seen as ratchet opportunities

Offline cixelsyD

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Re: DIRECT v3.0 - Thread 1
« Reply #127 on: 06/02/2009 03:27 pm »
Thank you Ross for your very thorough response. Is there an equivilant forum someplace for the Ares program I wonder?

How does Direct 3 change your plans for test flights? As Constellation progresses and nears closer to when it first services the ISS, that makes switching to direct less viable, would you happen to know an approximation for when it would be too late to switch? In your Direct 2.0 timeline you already have a test article delivered to KSC in May 2009, now an impossiblity since no decision to switch to Direct has been made.

The Augustine commission delivers in late August I believe? Does that give you plenty of time to develop and test?

Edit: Also, when will the direct site be updated with Direct 3? I'd love to read through the presentation.
« Last Edit: 06/02/2009 03:30 pm by cixelsyD »

Offline Magnus_Redin

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Re: DIRECT v3.0 - Thread 1
« Reply #128 on: 06/02/2009 03:38 pm »
And no, the LOX tank is sized to precisely the same capacity as the current ET's Ogive tank.

We do still have an option to increase the capacity of both the LOX and LH2 tanks by ~7-9% (in the same way as NLS was going to), but right now, mostly for simplicity sake, we have simply chosen not to mess around with altering the capacities.   We can close all performance requirements comfortably without it.

I find it sad if the easy tankage structure changes that give lots of performace per kg of structure are not done when the hard ones are done. Why design a long engine thrust structure when you can elongate the LH2 tank and design a smaller thrust structure? What is the additional design work with making the LOX barrel section a little longer when you anyway redesign the tank for inline launch?

The only engineering reason for not doing this that I can think of is if you add to much tankage mass and no longer hit the sweet spot for the 3 SSME verison.

I find the political reason weak, who cares if the fuel load is aprox 8% larger when it looks the same on the pretty pictures? If you are that sensitive about looks you ought to have made the thrust structure design more expensive buy having two versions to center the mid engine. That would of course be a bad redesign from a system cost perspective.

Starting out in the "high end" of the tankage volume and mass sweet spot ought to be beneficial for future engine upgrades of the SSME:s or SRB:s.
« Last Edit: 06/02/2009 03:39 pm by Magnus_Redin »

Offline BogoMIPS

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Re: DIRECT v3.0 - Thread 1
« Reply #129 on: 06/02/2009 04:03 pm »
I find it sad if the easy tankage structure changes that give lots of performace per kg of structure are not done when the hard ones are done. Why design a long engine thrust structure when you can elongate the LH2 tank and design a smaller thrust structure? What is the additional design work with making the LOX barrel section a little longer when you anyway redesign the tank for inline launch?

I get your point, but the entire DIRECT approach seems to be make as few changes to the existing STS stack as possible.

Maybe it is an easy (in the grand scheme of things) modification, but it isn't needed *right now* to close the targets.

Why complicate things more than you have to right now?

Offline kraisee

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Re: DIRECT v3.0 - Thread 1
« Reply #130 on: 06/02/2009 04:21 pm »
And it isn't quite so straight-forward either.   The SRB Aft supports would then be located on the LH2 tank wall, no longer where the lower ring-frame is situated.   To implement the stretch you either have to relocate the SRB attachments lower on the SRB's (requiring re-qual) of you would have to strengthen that region of the tank with an extra ringframe inside the LH2 tank.   While both are possible, neither is a trivial change and both add $$$ and time to the development -- and delays = job losses.

Given that we already comfortably exceed all of the performance requirements, we don't see this as a worthy trade in Phase 1 of our proposal.

Ross.
« Last Edit: 06/02/2009 04:23 pm by kraisee »
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Offline Yegor

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Re: DIRECT v3.0 - Thread 1
« Reply #131 on: 06/02/2009 04:51 pm »

What is "SSME Bk-IIA" and "SSME Bk-III"?


Offline TrueBlueWitt

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Re: DIRECT v3.0 - Thread 1
« Reply #132 on: 06/02/2009 05:12 pm »
what % thrust are SSMEs being run at?
given  no re-use could they be pushed higher?

Offline dlapine

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Re: DIRECT v3.0 - Thread 1
« Reply #133 on: 06/02/2009 05:42 pm »

What is "SSME Bk-IIA" and "SSME Bk-III"?

Short answer:

SSME BK-IIA = Space Shuttle Main Engine Block IIA (current model)

The Block III is a proposed update to the current version- I don't remember offhand if the Block III is designed for lower costs or better performance.

Direct 3.0 only requires the current Block IIA version to get the job done.

Offline dlapine

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Re: DIRECT v3.0 - Thread 1
« Reply #134 on: 06/02/2009 06:01 pm »
what % thrust are SSMEs being run at?
given  no re-use could they be pushed higher?

I believe that it's still 104%, same as current shuttle engine practice.

Good question, I have no idea. If only there were a rocket scientist nearby...  ;D

But, I think it's safe to say that Direct 3.0 has enough spare lift capacity for J-130 that the extra thrust isn't needed, or desired for safety reasons during the normal flight regimes.

Offline William Barton

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Re: DIRECT v3.0 - Thread 1
« Reply #135 on: 06/02/2009 06:08 pm »
The biggest selling point of the Jupiter 246 is, it's a modest and logical evolution of our *currently flying HLLV*, and though it may not be the launch vehicle of our wildest dreams, it is adequate for any mission the USA can reasonably anticipate flying any time in the next 40 years.

Sadly, your 40 years maybe correct.

What I like about the Direct vehicles is that they provide a growth path as well.  If Direct vehicles fly for 30 or 40 years the last ones won't be the same as the first ones.

If Jupiter 246 flies, I expect the Jupiter family to fly as long or longer than the Shuttle itself (40 years as of April 2011). I would expect to see things like simplifcation of SSME and development of a follow-on upper stage engine (RL-60 or J-2X, perhaps). But if it just flies, it will give us a lot of options. Affordable or not, 40 years of Saturn V would have meant a different space program across the board. I always like to imagine one of the proposals, an unmanned Mars lander probe the size of the LM, actually having happened in the 1970s.

Offline Namechange User

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Re: DIRECT v3.0 - Thread 1
« Reply #136 on: 06/02/2009 06:13 pm »
It'll be 30 years in April 2011, not 40.
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Offline psloss

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Re: DIRECT v3.0 - Thread 1
« Reply #137 on: 06/02/2009 06:25 pm »
SSME BK-IIA = Space Shuttle Main Engine Block IIA (current model)
Not exactly; the current engines are Block II.  Block IIA engines would be with the earlier generation HPFTP, versus the ones that are flying today.

Offline William Barton

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Re: DIRECT v3.0 - Thread 1
« Reply #138 on: 06/02/2009 06:28 pm »
It'll be 30 years in April 2011, not 40.

I knew I should've taken off my shoes before attempting that calculation...

Offline dlapine

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Re: DIRECT v3.0 - Thread 1
« Reply #139 on: 06/02/2009 06:43 pm »
SSME BK-IIA = Space Shuttle Main Engine Block IIA (current model)
Not exactly; the current engines are Block II.  Block IIA engines would be with the earlier generation HPFTP, versus the ones that are flying today.


Ah interesting- The current baseball cards show Block IIA for some reason.

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