X-33 questions

From: Earl Colby Pottinger (earlcp_at_idirect.com)
Date: 11/27/04 

Date: Fri, 26 Nov 2004 18:15:34 -0600

larrison@my-deja.com (Larrison) :

> Earl Colby Pottinger <earlcp@idirect.com> wrote in message
> news:<W8WdnaR41dcZFjvcRVn-3Q@look.ca>...
> > "John Thingstad" <john.thingstad@chello.no> :
> >
> > > In this NASA still plays a role in putting money
> > > into long term research that would otherwise not be done.
> > > In the long run this still pays off.
> > > Of course not all research projects succeed..
> >
> > Ofcourse I think NASA should be used to research the things we don't
> > understand/know, however this case seems to be more a case of NIH and
'you
> > are not part of the true space boys'.
> >
> > Basicly, a small company like Scaled Composite who already showed that
> they
> > can build cryogenic tanks were bypassed for a company with no history
> > building cryogenic composite tanks, and it is also this 'one of the boys'
> > company who in the long run were a failure.
> >
> > So why was the job not given to SC or why were they not partnered to the
> > company doing the tank building?
>
> Hi Earl -- I'm not going to apologise for the X-33, as I didn't like
> the selection of LockMart to build it, nor their basic design for a
> number of reasons.

First, if you were not upper mangement at NASA or LockMart you have nothing
to apologize for. It was the people at the upper levels accepting and
forcing thru the bad features of the X-33 and not breaking the program down
to three or more test craft that were the real problem. It is well possible
that if one of the other designs were choosen that NASA would still burden it
with requirements that would still cause it to fail.

> But I think you're flaming about Scaled versus other companies for the
> X-33 cryo tanks.

Yes, I am flaming mad about that little detail - I guess it shows :)

> First accept that the cryo tank they needed to build
> for the X-33 was way and beyond Scaled's experience range -- they had
> build some small, low-load cryo tanks as experimental items.

First, you said yourself, they had built them and they worked. Second, how
much experience did the company that did build the tanks have with cryo ones.
 If none, then Scaled is still the one that should have been chosen for the
very same reasons that NASA is always claiming for not using one of the
smaller companies out there, ie lack of experience.

> I'm not
> a composites or cryo expert, but some of the folks I know in the
> business tell me the X-33 (and other company's designs) for cryo tanks
> needed to be made in a different manner and of different materials
> (particularly the expoxy matrix) than Scaled's usual working
> materials.

Needed to be diffirent, or choosen to be diffirent? - Remember NASA was the
contractor and they have the nasty habit of telling outside experts what
materials or tests should be used in a design.

> With 3 minutes of internet research, I found the company which build
> LockMart's tanks was Alliant Techsytems (ATK) in Utah. ATK is not a
> dummy about composites, and after reading through their site and some
> of the articles on them, I would be willing to bet they turn out more
> composite structures in a week than Scaled does in a year. They also
> build highly-loaded (pressure and acceleration) composite structures
> which I don't believe Scaled ever has really built, with SS1 being the
> first one I recall.

Maybe, I would have to look back over thier older designs but thier racing
masts for AeroRig boats are highly stressed too. But (a) had ATK built cryo
tanks before? (b) the X-33 was not a high-G design, it was not doing
anything that the ROTON or DC-X were not already planned to do and both of
these used tanks from Scaled.

> But it appears that ATK has two critical capabilities, which Scaled
> didn't have for large cryo tanks; fiber placement and fiber winding
> machines in large scale, as well as the autoclaves to cure large
> structures. Most (all?) of Scaled's work is hand layup.

Fiber machines, yes you are right. But it is my understanding that at the
time of the contract that ATK did not have an autoclave large enough either
and had it built after winning the contract. (Correct me if I am wrong - I
may have another company mixed in here) There is no reason that Scaled could
not do the same. And as for machine vs hand layup - it is clear that machine
layup did not save the design. If it gets laid by machine and fail or laid
by hand and works clearly using the machines as a reason to award the
contract is not a good one. No, I am not saying machine layup was at fault,
I am saying it is just like the present day NASA's management to look at the
shiny machines first before the skills of the hand layers.

> But for a
> light weight cryo tank that is going to have to take 6 G's or so in
> standard load with a pressurized capability, plus up to around 20 G's
> or so in emergency loads (estimate on my part, based upon the 20G
> emergency load requirement from the Shuttle) -- you really need to do
> fiber winding and fiber placement to get light weight with the right
> material and structural property.

You did read what you wrote above right? A SSTO that does 6 G's in normal
operation, if that is not a crazy requirement I don't know what is - almost
all SSTO designs work best at 2 to 3 Gs. Assuming you are right it is not
clear to me that Scaled who has been doing this sort of thing for years could
not do the placement by hand. Again I could be wrong, but I would not have
bet against them.
 
> I note that ATK produced more fiber placed and fiber-wound structures
> than the rest of the industry put together, if you believe their press
> releases.

But what precentage is precision placed fibers vs quick and ditry jobs that
get the needed job done? And do they have any cryogenic designs in use?

> Now -- why did the X-33 tank fail? It wasn't the cryo tank that failed
> -- it was the face *** on the honeycomb insulation that cracked and,
> coupled with something mis-manufactured (a piece of tape, left over
> from when the cryo insulation was applied on top of the composite tank
> structure), that encouraged crack formation, leading to cryo pumping
> and the failure of the insulation (debonding from the underlying
> composite structure).

It was my understanding that the debonding was in the composite itself or
directly affected the composite structure, if it was just the insulation they
could have just left it loose or reglue it as it was not a structural
element. At some level the composite tank itself was damaged.

> Who did the installation of the honeycomb insulation on the cryo tank?
> Was it ATK? Was it Lockheed Martin? or was it another contractor?

Don't know. Was not Scaled :)

> And I'm not sure if Scaled made the cryo LH2 tank for the DC-XA.

I was pretty sure they did but the following does not say so:
http://www.hq.nasa.gov/office/pao/History/x-33/dc-xa.htm
nor does the following:
http://media.armadilloaerospace.com/DCX/
I don't know why I thought it was Scaled who built the new hydrogen tank when
it became the DC-XA? But it looks like I am wrong:
http://www.findarticles.com/p/articles/mi_pasa/is_199601/ai_2638499539

> I
> dont' find any reference to them making the tank. That tank also had
> problems with cryo pumping leading to failure of the insulation during
> test cycles -- although not in as spectacular of a manner (it also
> wasn't integral to the structural integrity of the vehicle, if memory
> serves).

Cite? URL? I only know about hydrogen leaks but not debonding.

> However, there was a not-highly publicized announcement that Northrop
> Grumman had successfully completed 9 months of testing on a composite
> LH2 tank at a NASA test faciliity, including scores of fill,
> pressurized, drain, warm, refill etc cycles.

Again Cite? URL? Thank you.

                  Earl Colby Pottinger [ Idiot at Large, and we do mean large
:) ] 

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