Author Topic: DIRECT v2.0  (Read 650094 times)

Offline Alpha Control

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RE: DIRECT v2.0
« Reply #20 on: 05/11/2007 04:36 AM »
You know, I didn't find out the correct pronunciation of the 6th planet for many years.  In the original Greek, it is UR-an-us, with the accent on the 1st syllable. Uranus was one of the original gods, prior to the Olympian gods.

When I was growing up, the accent was always on the 2nd syllable, which of course provided endless mirth for school age boys.

But back to the naming scheme, since Ares represents Mars, you could say that Jupiter, being the next planet, would therefore be a step up.

David
Space launches attended:
Antares/Cygnus ORB-D1 Wallops Island, VA Sept 2013 | STS-123 KSC, FL March 2008 | SpaceShipOne Mojave, CA June 2004

Offline bad_astra

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Re: DIRECT v2.0
« Reply #21 on: 05/11/2007 05:12 AM »
Let NASA call it Ares 1b for all I care. This is tremendous work. I hope some politicians can get a look at this.
"Contact Light" -Buzz Aldrin

Offline CFE

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Re: DIRECT v2.0
« Reply #22 on: 05/11/2007 06:46 AM »
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.
"Black Zones" never stopped NASA from flying the shuttle.

Offline JIS

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Re: DIRECT v2.0
« Reply #23 on: 05/11/2007 10:07 AM »
If I understand that correctly you are requiring to scrap current Orion SM proposal.
For EOR-LOR DIRECT architecture Orion has to perform LOI.
For LOR-LOR DIRECT architecture Orion has the same weight as LSAM. Therefore, some propellants transfer between them will be required.
Also still mysterious is the Direct EDS which has the same dry weight as ESAS original EDS (with 2xJ2S+) but 40% more propellants.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline JIS

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Re: DIRECT v2.0
« Reply #24 on: 05/11/2007 10:34 AM »
Quote
kraisee - 11/5/2007  4:21 AM

I won't be around tomorrow to field questions, but let me have a stab at these ones so far...

Marsman: The 232 can place a 38mT LSAM into LEO immediately and perform a routine EOR-LOR mission in precisely the same fashion as Ares-I/V.

However, with 45mT of lift capability, the CLV flight has a 'spare' 23mT of performance available on top of lifting the Orion to orbit.   This extra capacity is not initially required, but as the program evolves and confidence is built with the equipment, it could be utilised to increase performance later for almost no additional cost.

Unfortunatelly the extra integration costs are not negligible. See current EELV launches.

Quote
Extra payload can theoretically be transferred to the LSAM during the 3 day voyage between the Earth and the Moon.   The most logical material to transfer would be a single type of propellant or oxidixer.   Note: For safety only one or the other should be transferred, not both.

From where?

Quote
This general technique also applied to the 232/232 LOR-LOR mission profile available later too.   The first 232 is capable of launching a 48mT, partially fuelled LSAM to Lunar Orbit.   The second brings the 22mT Orion and 28mT of extra propellant to the LSAM.   The propellant is transferred to the LSAM prior to descent, and suddenly you have a 76mT LSAM in Lunar orbit and you're still only using a 2-launch strategy based on one single launch vehicle design.

Again, you are not serious. This is just quick armchair idea which has nothing together with the mission architecture.
The second DIRECT launch brings 22mT Orion and 28mT extra popellant in a second new spaceship wighting 0mT?
Even if the first Direct is able to get 48mT LSAM to LLO and the second Direct 22mT Orion and 28mT(sic) second new spaceship to the LLO (that's 50mT together) I still can't see any 76mT LSAM.
Certainly not 76mT LSAM which could work.




'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline JIS

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Re: DIRECT v2.0
« Reply #25 on: 05/11/2007 10:51 AM »
What is the performance margin for the new components (EDS, Core, shrouds)?
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline JIS

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Re: DIRECT v2.0
« Reply #26 on: 05/11/2007 01:00 PM »
Are those 3 RS-68 inline ... or in star :. arrangement?
If it is the star one there will be somewhat higher bending moment for the two engine core than for Ares 1 / Ares 5 config. Could the recent Orion with LSAM stand this lateral load?
If it is an inline config can 3 engine nozzles fit under the 27.5' core? Ofcourse, there could be some aerodynamic (debris) shield above them with wider and loger thrust structure.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline Jim

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Re: DIRECT v2.0
« Reply #27 on: 05/11/2007 01:06 PM »
There isn't a lateral load for a .: 3 engine configuration.  It is symmetrical

Offline clongton

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Re: DIRECT v2.0
« Reply #28 on: 05/11/2007 01:09 PM »

Quote
JIS - 11/5/2007 9:00 AM

Are those 3 RS-68 inline ... or in star :. arrangement?
If it is the star one there will be somewhat higher bending moment for the two engine core than for Ares 1 / Ares 5 config. Could the recent Orion with LSAM stand this lateral load?
If it is an inline config can 3 engine nozzles fit under the 27.5' core? Ofcourse, there could be some aerodynamic (debris) shield above them with wider and loger thrust structure.
3-Engine is in-line with aerodynamic skirts, like Saturn-V
Outboard engines gimbal, center engine fixed, again, like Saturn-V

"3-Engine

Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline JIS

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Re: DIRECT v2.0
« Reply #29 on: 05/11/2007 01:17 PM »
Quote
Jim - 11/5/2007  2:06 PM

There isn't a lateral load for a .: 3 engine configuration.  It is symmetrical
But there is also Direct with only two engines. Anyway, its inline config.
'Old age and treachery will overcome youth and skill' - Old Greek experience

Offline rumble

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Re: DIRECT v2.0
« Reply #30 on: 05/11/2007 01:24 PM »
Quote
JIS - 11/5/2007  8:17 AM

Quote
Jim - 11/5/2007  2:06 PM

There isn't a lateral load for a .: 3 engine configuration.  It is symmetrical
But there is also Direct with only two engines. Anyway, its inline config.
Right.  Like Chuck said, the 3-engine Jupiter has 3 inline engines with skirts around the outer two.  The 2-engine variant IS the 3-engine variant with the center engine removed and its feed lines plugged.

DIRECT team:  Nice presentation of some good detailed work.  Kudos.

Offline kraisee

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Re: DIRECT v2.0
« Reply #31 on: 05/11/2007 01:32 PM »
Quote
JIS - 11/5/2007  6:07 AM

If I understand that correctly you are requiring to scrap current Orion SM proposal.

Of course not.   That would be wasteful.

For the first generation, we can use whatever variant was planned to fly on Ares-I, although because Jupiter is far less sensitive to "growth" of a payload than Ares-I, at this stage they can now afford to steer away from highly expensive "exotic" solutions in favour of cheaper, slightly heavier items.   This will help to reduce the costs of the spacecraft manufacturing noticeably.

We can actually reduce the size of the MMH/N2O2 tanking in the Block I and Block II versions - because the CEV is no longer required to complete the ascent to LEO - Jupiter handles all that except the final circularization burn.   That means the CEV can carry 4 tons less propellant at liftoff than at present.

We need a little of that back (I don't have the current figure in front of me, but it's about 1.2 tons IIRC) for the LOI burn, but we have an overall mass benefit in the region of 2.8mT less propellant on every spacecraft.


For later missions, a Block III Service Module would include extra tanking for the LSAM's propellant.   That would be for around 2020, so is still quite a ways off.   In the interim trades would need to be done to figure out which propellant would be best to transfer.   If the SM and AS both use the same propellant, then MMH or N2O2 might be a fair choice.   Or perhaps 20+ tons of LOX would be better for the DS.   The only way we're going to know optimal performance is by examining suitable trade studies - and that would be NASA's purview over the next decade.

And there's nothing mysterious about our EDS.   For a start it does not "weight the same" as ESAS'.   It weighs about 2,200lb more, which is about 5% more.   It also doesn't use the same manufacturing approach.   Anyone can go read the AIAA papers into the ICES stage and you'll learn how it is noticably more efficient than the stage NASA designed for the ESAS CaLV.

ESAS used a methodology which assumed separate tanking, and old technologies for boiloff control.   ICES saves mass instantly by using a common bulkhead (which NASA learned was the way to go on the US for Ares-I too) and uses a number of new technology elements for boiloff control which are lighter in construction than ESAS ever planned.   A *LOT* has been learned from Centaur over the years, and ICES is the result.

Ross.
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Offline Jim

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Re: DIRECT v2.0
« Reply #32 on: 05/11/2007 01:32 PM »
Just a little encouragement for the Direct team.  Think of Direct 2.0 as your mulligan (golfers know what I am talking about).  Just as the Stick was non-viable (4 segments with SSME) in the beginning and it went through a "redesign".  So as a counter to the SSS website trashing Direct, just point out that Stick 1.0 wouldn't work either.

Offline NotGncDude

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Re: DIRECT v2.0
« Reply #33 on: 05/11/2007 01:34 PM »
Quote
clongton - 11/5/2007  9:09 AM

Quote
JIS - 11/5/2007 9:00 AM

Are those 3 RS-68 inline ... or in star :. arrangement?
If it is the star one there will be somewhat higher bending moment for the two engine core than for Ares 1 / Ares 5 config. Could the recent Orion with LSAM stand this lateral load?
If it is an inline config can 3 engine nozzles fit under the 27.5' core? Ofcourse, there could be some aerodynamic (debris) shield above them with wider and loger thrust structure.
3-Engine is in-line with aerodynamic skirts, like Saturn-V
Outboard engines gimbal, center engine fixed, again, like Saturn-V

"3-Engine


3 engines inline is also the Kistler's K1 config. BTW I love the D2 presentation.

Offline kraisee

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Re: DIRECT v2.0
« Reply #34 on: 05/11/2007 01:42 PM »
Quote
JIS - 11/5/2007  6:51 AM

What is the performance margin for the new components (EDS, Core, shrouds)?

All ESAS GRA's and margins were matched initially, and then, as always with DIRECT analysis, we have added a further 2% margin on top of those, to give us even more margin.

Additionally, we are ***not*** utilizing the NASA Ares-V specification RS-68 (414.2s vac Isp), we are retaining the current 409s Isp performance variant, so we have additional and very realistic upgrades available to all performance numbers if/when required.   Not to mention the Delta-IV Regen engine with 418s Isp which is coming too (although is likely to be rather costly, so isn't so useful).

Nor are we using the higher specification J-2X with 293,000lb, 448s vac Isp, we are sticking with the lower spec, lower cost, and easier to achieve specification of the initial J-2X"D" variant with just 273,500lb, 448s performance.

These are two, very straight-forward and highly achievable upgrade paths available to us in the future, which would increase performance of the smaller vehicle to around 52mT to LEO, and of the larger to around 115mT, but we are not relying upon even those for this proposal.

We have more margin than either CLV or CaLV had originally, and have additional performance alternatives available almost immediately - which is something neither Ares-I nor Ares-V have.

"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline kraisee

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Re: DIRECT v2.0
« Reply #35 on: 05/11/2007 01:50 PM »
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.
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Offline clongton

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Re: DIRECT v2.0
« Reply #36 on: 05/11/2007 02:01 PM »
After examining the move and shock envelope around each engine, allowing for the full range of gimbal motion, plus margin, and addressing the design of an appropriate thrust structure, the distance between the two outboard engines, center to center, is approximately the same as NASA currently baselines for the Ares-V outboard engines. In addition, the engine skirt design used these same design parameters and closely resembles the engine skirts around the Saturn-V F1 engines.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline kevin-rf

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Re: DIRECT v2.0
« Reply #37 on: 05/11/2007 02:10 PM »
So Chris, any chance of getting Dr. Doug Stanley back to comment on Direct 2.0?

Good job Ross...
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Offline Jon_Jones

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Re: DIRECT v2.0
« Reply #38 on: 05/11/2007 02:17 PM »
Thanks very much Ross for your considerate reply.
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Offline Chris Bergin

Re: DIRECT v2.0
« Reply #39 on: 05/11/2007 03:13 PM »
Quote
kevin-rf - 11/5/2007  3:10 PM

So Chris, any chance of getting Dr. Doug Stanley back to comment on Direct 2.0?


Dr Stanley's a busy man, so it'd all depend on his time and his willingness.

Although, probably not, if it results in an ATK site - run by what appears to be a bunch of monkeys - then using his comments without correct sourcing, context or objectivity in some attempt to have a Stick group hug. However, I am encouraged to see that they've worked out how to copy and paste over there in ATK web propaganda HQ. ;)

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