Author Topic: DIRECT v2.0  (Read 647048 times)

Offline jongoff

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Re: DIRECT v2.0
« Reply #40 on: 05/11/2007 03:17 PM »
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CFE - 10/5/2007  11:46 PM

Regarding the issues of tank diameter and propellant load, I have to ask: are the tanks being milled thicker on the inner surface, as opposed to the outer surface? It seems to me that doing so (reducing the inner diameter) would lead to a small (but considerable) decrease in your propellant volume compared to the baseline ET.  OTOH, if the inner diameter was kept constant and the outer skins were beefed up, it would force changes to the SRB attach struts in order to keep the pad footprint the same.

CFE, the difference is actually negligible when taken as a percentage of total tankage volume.  We're talking about a tank that is quite big.  Basically, for every extra cm of thickness, you're losing 0.2% of propellant....and I don't think you need even a cm of extra material to take the loads.  It's an effect, but it's pretty much roundoff error.

~Jon

Offline Flightstar

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Re: DIRECT v2.0
« Reply #41 on: 05/11/2007 03:34 PM »
Good work on the presentation. Sure would help pad integration problems.

Offline Steve G

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Re: DIRECT v2.0
« Reply #42 on: 05/11/2007 03:42 PM »
If NASA did select Direct, and had a fresh look at the VSE, what would be the benefits and disadvantages of having a dual lunar launch scenario where the LSAM would be launched to a high lunar orbit storage orbit, and Orion launched separately.  Orion would use a larger (Apollo-type) SM engine and then take the LSAM to it’s final orbit, preserving weight on the lander.

Since weight would no longer be a constraint to Orion, and we’ve just saved $30 billion, a mission module could be added making it a more comfortable flight, a small lab for lunar orbit studies, and a full 6 crew could be launched, with two remaining aboard the Orion (safer than an unmanned version) and conduct in orbit studies and in a better position to react to a major malfunction on either spacecraft.

One obvious advantage would also be the launch window.  If the Orion launch had a major last minute delay after the LSAM reached earth orbit, there wouldn’t be a propellant boil off issue and lose the entire mission.  LSAM could be stored in lunar orbit indefinitely.

Offline Jim

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Re: DIRECT v2.0
« Reply #43 on: 05/11/2007 04:07 PM »
Don't start will mission modules.  They aren't needed and cloud the advantages of the proposal.  Room is not needed.  Use the excess capability to put instruments on the CEV, just as Apollo but unlike Apollo, it need not be manned

there still would be boiloff issues unless the LSAM went with storable propellants and in that case, its mass would greatly increase

Offline NotGncDude

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Re: DIRECT v2.0
« Reply #44 on: 05/11/2007 04:10 PM »
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kraisee - 11/5/2007  9:50 AM

Just to clarify, the engines are mounted in-line to keep maximum distance between them and the SRB's.

While Chuck is correct that the center engine will not (probably) gimbal, it will actually still be an identical unit produced on the same production line as all the rest, only being a central engine, and will have the hardware allowing gimbal control, it simply isn't likely to be instructed to gimbal because the outboard engine pair offer greater control authority.

As you point out, the interchangeable common cores can also be flown without the central engine in the smaller 120 configuration.   The two outboard engines remain exactly where they are in either configuration.   The electrical & plumbing connections to the central engine will simply be capped & closed out that way for such flights.

Ross.

A center engine has nearly the same control authority as the side engines for pitch and yaw. So, it adds you a nice extra margin if you want it, at the expense of having to develop two control algorithms for 2 vs. 3 engines. Actually scratch that, that's a negligible expense. You're better off by getting rid of all the gimbaling support, saving that weight.

Offline clongton

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Re: DIRECT v2.0
« Reply #45 on: 05/11/2007 04:20 PM »
Quote
GncDude - 11/5/2007  12:10 PM

Quote
kraisee - 11/5/2007  9:50 AM

Just to clarify, the engines are mounted in-line to keep maximum distance between them and the SRB's.

While Chuck is correct that the center engine will not (probably) gimbal, it will actually still be an identical unit produced on the same production line as all the rest, only being a central engine, and will have the hardware allowing gimbal control, it simply isn't likely to be instructed to gimbal because the outboard engine pair offer greater control authority.

As you point out, the interchangeable common cores can also be flown without the central engine in the smaller 120 configuration.   The two outboard engines remain exactly where they are in either configuration.   The electrical & plumbing connections to the central engine will simply be capped & closed out that way for such flights.

Ross.

A center engine has nearly the same control authority as the side engines for pitch and yaw. So, it adds you a nice extra margin if you want it, at the expense of having to develop two control algorithms for 2 vs. 3 engines. Actually scratch that, that's a negligible expense. You're better off by getting rid of all the gimbaling support, saving that weight.
From the point of view of commonality and interchangeability, we are better off leaving all three engines as identical. That makes everything easier. This launch vehicle has more than enough margin to allow the design to be simplified by commonality. That’s the beauty of fielding a launch vehicle that starts life with lots of margin vs. starting life already maxed out.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline NotGncDude

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Re: DIRECT v2.0
« Reply #46 on: 05/11/2007 05:12 PM »
Quote
clongton - 11/5/2007  12:20 PM

Quote
GncDude - 11/5/2007  12:10 PM

A center engine has nearly the same control authority as the side engines for pitch and yaw. So, it adds you a nice extra margin if you want it, at the expense of having to develop two control algorithms for 2 vs. 3 engines. Actually scratch that, that's a negligible expense. You're better off by getting rid of all the gimbaling support, saving that weight.
From the point of view of commonality and interchangeability, we are better off leaving all three engines as identical. That makes everything easier. This launch vehicle has more than enough margin to allow the design to be simplified by commonality. That’s the beauty of fielding a launch vehicle that starts life with lots of margin vs. starting life already maxed out.

In that case you may as well gimbal it.

Offline veedriver22

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Re: DIRECT v2.0
« Reply #47 on: 05/11/2007 05:27 PM »
That just makes it more complicated, more things to fail.

Offline Lee Jay

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Re: DIRECT v2.0
« Reply #48 on: 05/11/2007 05:33 PM »
Wouldn't you want to gimbal the center engine in a side engine-out situation?

Offline Carl G

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Re: DIRECT v2.0
« Reply #49 on: 05/11/2007 05:34 PM »
On Direct 1, some people said it is a hybred of an MSFC concept. If this is true, what stops the MSFC version? Money, wrong time, showstoppers?

Offline NotGncDude

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Re: DIRECT v2.0
« Reply #50 on: 05/11/2007 06:23 PM »
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veedriver22 - 11/5/2007  1:27 PM

That just makes it more complicated, more things to fail.

Not really. If you are going to have all the mechanisms there and active (for commonality), the fact that you're moving them around versus not moving them adds minimal complexity, and buys you control margin.

Offline NotGncDude

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Re: DIRECT v2.0
« Reply #51 on: 05/11/2007 06:26 PM »
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Lee Jay - 11/5/2007  1:33 PM

Wouldn't you want to gimbal the center engine in a side engine-out situation?

Yes, but I think if this happens in DIRECT you lose the mission anyway. Right? I don't know if the 232's have engine out capability. Haven't looked.

Offline Smatcha

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RE: DIRECT v2.0
« Reply #52 on: 05/11/2007 06:28 PM »
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Ankle-bone12 - 10/5/2007  7:57 PM

Im not a rocket scientist, in fact far from it, but I would assume that it could have something to do with the publics appeal to the flashy name of "Jupiter". It could also be viewed as a "next step up" from the Saturn family of rockets.

Why Jupiter?  First off if we used Ares in some other form it would confuse everyone.

Second, when I asked a number of non space enthusiast’s individuals about the prior lunar mission many of them knew that the rocket was the Saturn V.

When I asked them which planet was the largest in the solar system they said Jupiter.

So I felt that not only did the Jupiter embody a connection to the first Lunar program but also indicated doing more in this next phase.  The Jupiter-2 can put more in orbit than the Saturn V.

Next the name Jupiter.  Jupiter son is Mars.  NASA has attempted to make a sideways relation to Zeus son being Ares but nobody I talked to (outside of us space geeks) knew what I was talking about unlike the Saturn-Jupiter connection.

I also like the whole 2001 and 2010 a Space Odyssey connection with Jupiter.  The name also implies other missions beyond Mars indicating the whole “beyond” part of VSE.

Back to other legacy associations:

The name the Hindus gave the planet Jupiter was Guru or “knowledge seeker” a very good association.

In Romans mythology Jupiter was the ruler of the gods, and their guardian and protector.

In astrology Jupiter is associated with growth, expansion, higher education, prosperity, and protecting roles.   All very positive associations.  If we ever have an asteroid with our name on it the protecting role would also be most appropriate.

Onto Ares, he was the son of Zeus (the Greek king of the gods).  He is not so much the god of war but more accurately the god of savage or unnecessary war.  Associations which I think take a back seat to Jupiter in all ways.

Though savage and unnecessary certainly would describe the last two years to a tee so maybe Ares is good name after all for this point in time.
“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

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Offline clongton

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Re: DIRECT v2.0
« Reply #53 on: 05/11/2007 06:33 PM »
Quote
GncDude - 11/5/2007  2:26 PM

Quote
Lee Jay - 11/5/2007  1:33 PM

Wouldn't you want to gimbal the center engine in a side engine-out situation?

Yes, but I think if this happens in DIRECT you lose the mission anyway. Right? I don't know if the 232's have engine out capability. Haven't looked.
The 232 does have engine-out capability, though not to the extent of the 120
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline zinfab

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Re: DIRECT v2.0
« Reply #54 on: 05/11/2007 06:50 PM »
Thanks for this update. I hope someone listens when it REALLY counts.

Offline marsavian

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Re: DIRECT v2.0
« Reply #55 on: 05/11/2007 07:03 PM »
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zinfab - 11/5/2007  1:50 PM

Thanks for this update. I hope someone listens when it REALLY counts.

I think the Democrats will listen and if they win the Presidency they will probably install an Administrator to drop Ares I/V for DIRECT as it will allow them to beef up Science in Nasa whilst still keeping VSE going well even on a flat budget. I have reluctantly come round to Jim's way of thinking in believing that Griffin and Horowitz are so in bed with ATK they will persist with the current architecture come what may and they probably will return there to collect their rewards in 2008. This DIRECT proposal should be continued regardless to shine a light on the current architecture's failings for possible use when a different NASA power base is established.

Offline Smatcha

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Re: DIRECT v2.0
« Reply #56 on: 05/11/2007 07:19 PM »
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marsavian - 11/5/2007  12:03 PM

Quote
zinfab - 11/5/2007  1:50 PM

Thanks for this update. I hope someone listens when it REALLY counts.

I think the Democrats will listen and if they win the Presidency they will probably install an Administrator to drop Ares I/V for DIRECT as it will allow them to beef up Science in Nasa whilst still keeping VSE going well even on a flat budget. I have reluctantly come round to Jim's way of thinking in believing that Griffin and Horowitz are so in bed with ATK they will persist with the current architecture come what may and they probably will return there to collect their rewards in 2008. This DIRECT proposal should be continued regardless to shine a light on the current architecture's failings for possible use when a different NASA power base is established.

ATK actual benefits more with DIRECT.  So Mike and Scott can still do the right thing and get rewarded for it all at the same time.  

Now how often does that happen? :)

Once again it’s better to lucky than smart.



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John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline marsavian

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Re: DIRECT v2.0
« Reply #57 on: 05/11/2007 07:21 PM »
I think ATK want Ares I so they can use it commercially vs EELVs, that's the real reason I believe.

Offline clongton

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Re: DIRECT v2.0
« Reply #58 on: 05/11/2007 07:34 PM »
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marsavian - 11/5/2007  3:21 PM

I think ATK want Ares I so they can use it commercially vs EELVs, that's the real reason I believe.
The DIRECT Launch manifest on page 4 of the proposal shows (26) 4-segment flights between 2009 and 2017. That’s 8 years. How many Ares-1 flights (5-segment) will there be in that same time period? Anybody know? This is assuming of course, that Jupiter gets the same funding as Ares would have.

Let’s see:
26 Flights x 2 SRB’s each = 54 SRB’s
54 SRB’s x 4 segments each = 208 segments for ATK to refurbish and repack.

Vs. how many 5-segment SRB’s for Ares-1 in the same timeframe?
How much does ATK get paid for each refurbished 4-segment SRB? Does anybody know?

Bottom line – ATK makes one hell of a lot more money with the Jupiter than it does with the Ares-1, or even if they were to compete against Atlas and Delta. And, if the Falcon becomes viable, what percentage of the market could they realistically expect? Somebody needs to seriously re-teach the execs at ATK just what “bottom line” means to the shareholders.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline marsavian

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Re: DIRECT v2.0
« Reply #59 on: 05/11/2007 07:42 PM »
Heh,  perhaps  ;)

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