ATK/EADS: Liberty Launch Vehicle Update Thread

[Chris Bergin]

Baseline article for the Unfunded SAA - plus vehicle overview:

http://www.nasaspaceflight.com/2011/09/atk-liberty-via-unfunded-nasa-space-act-agreement/

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Announcement Threads:

Pre:
http://forum.nasaspaceflight.com/index.php?topic=26737.0
During:
http://forum.nasaspaceflight.com/index.php?topic=26768.0

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This is an update thread. Keep it focusd on the specifics. Use other threads for splinter/general topics.

[Gary NASA]

Excellent article Chris!

And L2 members should have about a year's worth of reading with all the SRB and Ares First Stage presentations and videos in L2. Huge database, very impressive.

[Kaputnik]

Rombinger
“What’s really fascinating with is how well the Upper Stage matches up with our First Stage. You would think they would have been designed to go with each other, but in fact they weren’t – yet they matched up better than if we had intentionally designed it that way."

What does that say about their ability to design a LV :O


On a more serious note, what are the load paths on the EPC? Do the current Ariane SRBs lift from the bottom, or from the top?

Also, how important will the gravity losses be when the vehicle has only about a 0.6 T/W ratio at second stage ignition?

[Rocket Science]

And they say rockets aren’t Legos … Only if they are “French Legos” I guess…

Robert

[woods170]

Rombinger
“What’s really fascinating with is how well the Upper Stage matches up with our First Stage. You would think they would have been designed to go with each other, but in fact they weren’t – yet they matched up better than if we had intentionally designed it that way."

What does that say about their ability to design a LV :O


On a more serious note, what are the load paths on the EPC? Do the current Ariane SRBs lift from the bottom, or from the top?

Also, how important will the gravity losses be when the vehicle has only about a 0.6 T/W ratio at second stage ignition?

The current Ariane SRB's lift mainly from the top. The heavier LOX tank is at the top of the OPC stage. By the time the solids drop, load paths have relaxed enough to take lift solely from the bottom (thru Vulcain 2).

[pippin]

Does this thing really have a chance? I mean: I political engineering driving launch vehicle architecture these days?

Otherwise I don't really understand why EADS is participating in this.

I mean: from a technical standpoint this is a ridiculous proposal, isn't it?
The EPC is a FIRST STAGE. It has structure to attach big solids and carry an upper stage, this is waaay too much structure for an upper stage, it's not optimized for weight at all.

The engine is a first stage engine that does work at sea level, even if it's not optimized for that because such a big part of Ariane's flight profile is in vacuum, the expansion ratio and ISP is not ideal for an upper state engine plus it's not air startable so a lot of work has to go into it.

Flight control. That whole thing has to be new, I don't think that any of the characteristics of the Liberty vehicle will be similar to Ariane and we've seen on A501 what can happen in these cases, I don't think they would want to risk that again.

And in the end it doesn't even lift more than Ariane 5.

[wannamoonbase]

I'm as a big a fan of space exploration as anyone but this vehicle has not excited me at the least.

It was a performance and financial lemon when it was government funded, there is no reason to expect this version to be any different.

At best this is a public relations activity vehicle for ATK to make it look like they have a viable boost technology.

[Chris Bergin]

Excellent article Chris!

And L2 members should have about a year's worth of reading with all the SRB and Ares First Stage presentations and videos in L2. Huge database, very impressive.

Thanks Gary

[jeff.findley]

I want to know if the Vulcain 2 engine can easily be air started.  This was a known problem with the SSME, so why would Vulcain 2 be any different? 

Both engines were designed to be ignited on the ground.  Furthermore, both were designed to burn for some time to verify their operating conditions before lighting the solids on the vehicle.  It just seems that air starting either of these engines would, at a minimum, require them to be re-qualified to start in an entirely different environment.  I wonder if the ground facilities exist (in Europe) to qualify the air start of Vulcain 2...

[Alpha_Centauri]

Does this thing really have a chance? I mean: I political engineering driving launch vehicle architecture these days?

Otherwise I don't really understand why EADS is participating in this.

I mean: from a technical standpoint this is a ridiculous proposal, isn't it?
The EPC is a FIRST STAGE. It has structure to attach big solids and carry an upper stage, this is waaay too much structure for an upper stage, it's not optimized for weight at all.

The engine is a first stage engine that does work at sea level, even if it's not optimized for that because such a big part of Ariane's flight profile is in vacuum, the expansion ratio and ISP is not ideal for an upper state engine plus it's not air startable so a lot of work has to go into it.

Flight control. That whole thing has to be new, I don't think that any of the characteristics of the Liberty vehicle will be similar to Ariane and we've seen on A501 what can happen in these cases, I don't think they would want to risk that again.

And in the end it doesn't even lift more than Ariane 5.

It lifting less than Ariane 5 is irrelevant as far as EADS Astrium are concerned, they are a manufacturer not an operator.  Whether Liberty lifts more or not they are still diversifying their business and crucially potentially breaking into the American government and commercial launch markets, which no European firm be it operator or manufacturer has so far been allowed to do in any significant capacity.  Liberty won't be competing with Ariane 5 for market share.  The risk for EADS is fairly low.

EADS' standpoint technically is probably related to the development of health-monitoring systems for the EPC, making adaptations for potential human spaceflight more politically acceptable for ESA member states.  Well, at least giving them less excuses.

[AnalogMan]

Here is the CCDEV2 Space Act Agreement between NASA and ATK:

http://procurement.ksc.nasa.gov/documents/NNK11MS06S-ATK.pdf

[simonbp]

Does this thing really have a chance?

Yeah, actually. In fact, I'd give a greater chance than Blue Origin's Biconic capsule of flying someday.

IMHO, the real point of Liberty to fly Orion/MPCV to LEO. If MPCV survives (and especially if SLS doesn't), then Liberty will fly. Then, they can offer their services to Boeing/SNC/BO/etc at a discount...

[Jim]

IMHO, the real point of Liberty to fly Orion/MPCV to LEO.

there is no connection and it will not be allowed due to foreign content

[Zond]

Does this thing really have a chance? I mean: I political engineering driving launch vehicle architecture these days?

Otherwise I don't really understand why EADS is participating in this.

One of the concepts studied for the successor of the Ariane 5 has two solids as the first stage. I think the Liberty is a way for EADS to gain more info about the advantages and drawbacks of a solid first stage.
http://esamultimedia.esa.int/multimedia/publications/ngl/pageflip.html

[Lars_J]

Yikes, that version composed of two first solid stages with solid boosters is a truly nasty thing.

[Alpha_Centauri]

One of the concepts studied for the successor of the Ariane 5 has two solids as the first stage. I think the Liberty is a way for EADS to gain more info about the advantages and drawbacks of a solid first stage.
http://esamultimedia.esa.int/multimedia/publications/ngl/pageflip.html

But they'd have no involvement in Liberty's first stage, they'd gain nothing more than they would with knowledge of Avio's experience with Vega.

Besides the down-selection of NGL architecture should happen next year, and I imagine final decision by about 2015, it's far too late to be of use for NGL.

[Downix]

I want to know if the Vulcain 2 engine can easily be air started.  This was a known problem with the SSME, so why would Vulcain 2 be any different? 

Both engines were designed to be ignited on the ground.  Furthermore, both were designed to burn for some time to verify their operating conditions before lighting the solids on the vehicle.  It just seems that air starting either of these engines would, at a minimum, require them to be re-qualified to start in an entirely different environment.  I wonder if the ground facilities exist (in Europe) to qualify the air start of Vulcain 2...

They start through very different methods, however.  The SSME uses a tank-head start with gravity alignment to start.  Basically, you need to pressurize the tank, feed lines, have all required components in a 1G alignment straight down to start ignition, using the pressure head (fluid dynamics at work here) to begin ignition.

The Vulcain on the other hand uses solid cartridges, basically small solid rocket motors, to start it's systems working.  The only concern I see with the Vulcain right now is that it has a lengthy cooldown period before ignition, pumping LH2 though the engine, which is mitigated on the ground through a burner below the engine.  However, the RL-10 has a similar cooldown, so that does not need be a game breaker.

[Downix]

Rombinger
“What’s really fascinating with is how well the Upper Stage matches up with our First Stage. You would think they would have been designed to go with each other, but in fact they weren’t – yet they matched up better than if we had intentionally designed it that way."

What does that say about their ability to design a LV :O


On a more serious note, what are the load paths on the EPC? Do the current Ariane SRBs lift from the bottom, or from the top?

Also, how important will the gravity losses be when the vehicle has only about a 0.6 T/W ratio at second stage ignition?

The SRB's lift from the top, but rather than a support beam, as the Shuttle ET uses, they structurally reinforced the sides of the tank, and the load is actually carried up the sides of the EPC stage.

[spacejulien]

The EPC is a FIRST STAGE. It has structure to attach big solids and carry an upper stage, this is waaay too much structure for an upper stage, it's not optimized for weight at all.

Concerning the stage structures:
The tank, which makes up 25 of the 30m is very much optimised. In fact the tank does only transfer the Vulcain loads, the booster axial loads transfer into the core above the tank, at the so-called front skirt.
The structure of the front skirt weighs about 2(metric) tons (all metric over here ;-). This could definitely be made lighter w/o the booster load introductions at the side. And then there is the thrust frame to which the Vinci is attached.

My first thought when first reading about this proposal was "you need a completely new stage". The tank cylinder can not handle MaxQ of Liberty, being in compression between the first stage thrust and aerodynamic drag on the payload. So you need stiffened cylinder segments on the tank. You don't need the complexity and mass of the front skirt, so replace it with a cylindrical CFRP structure. So the mass you loose on the tank cylinder you could conter by reducing front skirt mass. And the thrust frame needs to attach to (and separate from) the first stage, so you have to redesign that one, too. Alltogether, that's an awful lot of development effort.

After the airshow in LeBourget a fromer colleague told me, that they plan to build a gridwork around the upper stage. First, I thought "this must be an error in understanding". But it somehow does make sense, the compressive loads would be transferred by this gridwork and introduced into the front skirt. So no changes to the thrust frame needed, no stiffening of the cylinder shell and you need the booster attachments on the front skirt. Obviously, this can not be the most mass efficient design, but maybe is more investment-efficient, especially as they haven't secured any external funding yet. Definitely, it is quite risky, such a design does not exist as of today. Personally, I doubt that it would work out.

The engine is a first stage engine that does work at sea level, even if it's not optimized for that because such a big part of Ariane's flight profile is in vacuum, the expansion ratio and ISP is not ideal for an upper state engine plus it's not air startable so a lot of work has to go into it.

I want to know if the Vulcain 2 engine can easily be air started.  This was a known problem with the SSME, so why would Vulcain 2 be any different? 

The Vulcain's chill-down and start-up would need to be tweaked (shortened!), tested and the whole thing re-qualified, but there is no general obstacle to making Vulcain air-startable. See also Downix's post:

They start through very different methods, however.  The SSME uses a tank-head start with gravity alignment to start.  Basically, you need to pressurize the tank, feed lines, have all required components in a 1G alignment straight down to start ignition, using the pressure head (fluid dynamics at work here) to begin ignition.

The Vulcain on the other hand uses solid cartridges, basically small solid rocket motors, to start it's systems working.  The only concern I see with the Vulcain right now is that it has a lengthy cooldown period before ignition, pumping LH2 though the engine, which is mitigated on the ground through a burner below the engine.  However, the RL-10 has a similar cooldown, so that does not need be a game breaker.

I wonder if the ground facilities exist (in Europe) to qualify the air start of Vulcain 2...

I think this would be a case for Plum Brook, no such facilities exist in Europe.

[simonbp]

I think this would be a case for Plum Brook, no such facilities exist in Europe.

Huh; that's an interesting aspect. Presumably another unfunded SAA with Glenn would be needed? Or, more likely, an SAA for the A-3 stand at Stennis...