ATK announce Liberty KSC test flights, reveal crew spacecraft with MLAS

[USFdon]

Although I don't know what the development cost would be vs. the cost per unit for the "off-the-shelf" alternative... wouldn't it be cheaper and probably faster for ATK to just go ahead and use the Orion LAS? Why reinvent the wheel for a device that was designed for the explicit purpose of an abort of an Orion (/orion-like capsule in this case) from an Ares 1/Liberty/Big Stick rocket. Or am I missing some performance / safety / cost reason?

A control reason.  The Orion LAS is an Orbital designed and contracted system, while the MLAS is an ATK.  The Orion LAS uses an Aerojet motor, while the MLAS uses all ATK motors.

To quote a pair of characters...

"Mo Money, Mo Money, Mo Money..."

The biggest motor in the OSC LAS is from ATK.... but man the whole contraption does look like a heavy beast.

[Ronsmytheiii]

Truth be told, if the Liberty spacecraft was decoupled from the LV, I would be really excited about it.  it is "Orion lite" using the outer mold line, systems, and synergy from testing from the CEV/MPCV program. 

If ATK were to propose the first few mission on an EELV, with Liberty LV funding coming from internal ATK only, would that ease concerns? ATK has a big incentive to fund Liberty LV if it really does help in the cost equation and gains a launch contract for Commercial Crew.

[Chris Bergin]

Thread trimmed of the childish posts over the last few hours. Up your game, or don't post.

[edkyle99]

Truth be told, if the Liberty spacecraft was decoupled from the LV, I would be really excited about it.  it is "Orion lite" using the outer mold line, systems, and synergy from testing from the CEV/MPCV program. 

To me, the really big news from last week was Lockheed Martin and "Orion Lite".   This is a game changer, one way or the other.  NASA might really like the idea of shared systems between its Commercial Crew and its SLS Orion spacecraft.  Or, it might not like the idea - if the idea slows down one at the expense of the other. 

If selected, both "Orion"'s would be assembled at KSC's Operations & Checkout Building.  My first question would be:  does O&C have the capacity to assemble and checkout both spacecraft lines in parallel?  And what about cargo-only variants that might appear, that would probably need Service Modules?

One additional thought:  Liberty seems to shut out California, a state that was knee deep in Apollo-Saturn and Shuttle.  Will that play a role?

 - Ed Kyle

[yg1968]

Truth be told, if the Liberty spacecraft was decoupled from the LV, I would be really excited about it.  it is "Orion lite" using the outer mold line, systems, and synergy from testing from the CEV/MPCV program. 

To me, the really big news from last week was Lockheed Martin and "Orion Lite".   This is a game changer, one way or the other.  NASA might really like the idea of shared systems between its Commercial Crew and its SLS Orion spacecraft.  Or, it might not like the idea - if the idea slows down one at the expense of the other. 

If selected, both "Orion"'s would be assembled at KSC's Operations & Checkout Building.  My first question would be:  does O&C have the capacity to assemble and checkout both spacecraft lines in parallel?  And what about cargo-only variants that might appear, that would probably need Service Modules?

One additional thought:  Liberty seems to shut out California, a state that was knee deep in Apollo-Saturn and Shuttle.  Will that play a role?

 - Ed Kyle

It's also a double edged sword and somewhat of a gamble by LM. If Orion/LM is allowed to compete for commercial crew then an improved CST-100 and an improved crewed Dragon should also logically be able to compete for BEO spacecraft duties. Same thing with the SLS Advanced Boosters, why not have competing boosters provided by at least two companies.  All of this is going against the compromise that was the 2010 NASA Authorization bill in my opinion.

To quote Lando in Star Wars, "This deal is getting worse all the time!".


<a href="http://www.youtube.com/v/og9tIQtmxko&rel=1" target="_blank">http://www.youtube.com/v/og9tIQtmxko&rel=1</a>

[Steven Pietrobon]

I think the reason for the reduced oscillations is that the EPC uses a double wall structure which could be stiffer than the single wall of the Ares I US. Having the LOX tank forward means that the tank walls need to be stronger, further increasing their stiffness. A stiffer structure implies a higher resonant frequency, taking you away from the lower resonant frequency of the first stage.

Ariane 5 EPC doesn't have a double wall structure...

Here's a reference that says the tanks are made from an Aluminium composite.

"Main tank
The main tanks is made of aluminium composite and is divided into two volumes by a common bulkhead. It contains 130 t of liquid oxygen at -180°C and 25 t of liquid hydrogen at -250°C. The metal case is made up of three bulkheads and seven cylinders."

Thus, I was under the impression that the whole tank was made from aluminium composite (an aluminium sandwich with an insulating middle) which is why I thought it was double walled. This reference says

"Design: the aluminium tank is divided into two sections by a common bulkhead, creating a 120 m3 LOX forward tank (pressurised to 3.5 bar by helium) and a 390 m3 LH2 aft tank (pressurised to 2.5 bar by gaseous H2). The tank’s external surface carries a 2 cm-thick insulation layer to help maintain the cryogenic temperatures"

Is there a better reference that says what the EPC tanks are made from?

[Steven Pietrobon]

You will want to have your heaviest tank (that being the LOX) closest to the vehicles center of balance. That implied having the LOX tank sitting above the LH2 tank.

Actually, you want the centre of gravity (CoG) to be ahead of the centre of pressure (CoP). Arrows do this by having a dense mass at the tip (moves CoG forward) with feathers at the tail (moves CoP back). Having the LOX tank forward moves the CoG forward, increasing stability. Similar for the Space Shuttle ET and the Saturn V S-IC (which also had fins to move the CoP back, giving a few extra seconds of stability for the vehicle in case of an abort). To reduce mass though, you want the heavier tank at the base (which is why the Saturn V S-II and S-IVB had their LOX tanks at the base).

Not quite, on Saturn V the S-IC LOx-tank was in front, but for SII and S-IVB the LOx tank was at the stage rear.

If you read carefully what I wrote, I say exactly that.

As I said in my previous post, the reduction of Moment of Inertia is more important than the reduction of distance between CoP and CoG for piloted vehicles.

What about the distance from the engines to the CoG? A longer distance implies you need less force to create an angular moment.

And the fins on Saturn V were really just needed for the second or two during an abort, when the vehicle is not piloted.

Again, if you carefully read what I wrote, I say that as well!

[Rocket Science]

I beg to differ slightly folks, the physics of a dart is not the ideal model analogy for a guided rocket under power …

[edkyle99]

The terrific EADS/Astrium press kits contain the following description of the H175 EPC. 

"Type C main cryogenic stage:
The EPC is over 30m high. It has a diameter of 5.4m and an empty mass of only 14.1
metric tons. It essentially comprises:
- large aluminium alloy tank,
-thrust frame transmitting engine thrust to the stage,
- forward skirt connecting the EPC to the upper composite, and transmitting the thrust
generated by the two solid propellant boosters."

Note that the forward thrust frame (the "JAVE") won't need to be as robust for Liberty, suggesting mass savings.  Offsetting this would be structural strengthening of, probably, the LH2 tank.

Everything I've seen tells me these are aluminum tanks covered in spray on foam insulation.

Here is one page from one of the best detailed references on EPC construction.  It tells us that Aluminum alloy 2219 is used for the tank walls.  The thrust frame is mostly aluminum, but also includes some composite elements.
http://www.capcomespace.net/dossiers/espace_europeen/ariane/ariane5/production_ariane5_EPC.htm

 - Ed Kyle

[spacejulien]

You will want to have your heaviest tank (that being the LOX) closest to the vehicles center of balance. That implied having the LOX tank sitting above the LH2 tank.

Actually, you want the centre of gravity (CoG) to be ahead of the centre of pressure (CoP). Arrows do this by having a dense mass at the tip (moves CoG forward) with feathers at the tail (moves CoP back). Having the LOX tank forward moves the CoG forward, increasing stability. Similar for the Space Shuttle ET and the Saturn V S-IC (which also had fins to move the CoP back, giving a few extra seconds of stability for the vehicle in case of an abort). To reduce mass though, you want the heavier tank at the base (which is why the Saturn V S-II and S-IVB had their LOX tanks at the base).

Not quite, on Saturn V the S-IC LOx-tank was in front, but for SII and S-IVB the LOx tank was at the stage rear.

If you read carefully what I wrote, I say exactly that.

As I said in my previous post, the reduction of Moment of Inertia is more important than the reduction of distance between CoP and CoG for piloted vehicles.

What about the distance from the engines to the CoG? A longer distance implies you need less force to create an angular moment.

Yes, but after you've achieved a feasible ratio of distance-between-gimbal-and-CoG divided by distance-between-CoG-and-CoP you're fine. Further optimisation of that ratio is then tertiary compared to reducing the moment of inertia and (as you've already mentioned) the reduction of structural mass by having the upper stage(s) heavier tank(s) at the base(s).

And the fins on Saturn V were really just needed for the second or two during an abort, when the vehicle is not piloted.

Again, if you carefully read what I wrote, I say that as well!

Steven, I must have read your original post too diagonally, all you've written is correct. I didn't in particular like the arrow analogy, as it is - for a piloted vehicle - one consideration that needs to be balanced with other effects. But you've covered that, too, so I assume I've been blined by my bias concerning the arrow analogy.

I'm sorry.

[yg1968]

I don't believe that this video of the ATK Liberty Announcements has been posted:

<a href="http://www.youtube.com/v/1asG5MbGI4w&rel=1" target="_blank">http://www.youtube.com/v/1asG5MbGI4w&rel=1</a>