Posted on 04/12/2005 1:00:30 PM PDT by BenLurkin
MOJAVE - XCOR Aerospace will continue its own work in developing a composite liquid oxygen fuel tank for NASA's new space exploration plans under a $7 million contract announced Monday. The Mojave-based rocket engine company won the competitive contract as part of the space agency's effort to develop key technologies for manned exploration of the moon, Mars and beyond.
"We get a chance to do what we want to do to the benefit of us, to the benefit of NASA and other folks," company co-founder Aleta Jackson said.
Over the last few years, XCOR has developed a combination of materials and techniques that appear promising for creating liquid oxygen fuel tanks from composite materials, a concept NASA would like to see advanced, XCOR President Jeff Greason said.
A composite fuel tank may be integrated into the structure of a reusable space launch vehicle in much the same way fuel tanks in aircraft are part of the structure, eliminating the dead weight of a separate tank. In aircraft, for instance, fuel is often stored inside the wings.
The concept is complicated for ultra-cold liquid oxygen fuel, however, in that the extreme cold required will cause most tank materials to shrink. This causes problems for metal tanks bonded to a composite vehicle structure, because the tank would shrink when full of fuel, stressing the bonding points, Greason said.
Composite materials are lighter for a given strength than other materials and also shrink less, making it possible to incorporate a composite fuel tank in the vehicle structure.
The concept itself is nothing new, Greason said. However, most composite materials previously used in this technique are flammable.
XCOR's breakthrough approach to the problem is in using materials that are intrinsically nonflammable, he said.
Under the NASA contract, the company will perform additional materials research and build a series of test pieces and tanks, culminating in a tank capable of holding 1,000 kilograms of liquid oxygen. The data collected in this process will be turned over to NASA.
Instead of delivering a piece of flight hardware, XCOR will deliver the knowledge of how to build it, Greason said.
The NASA contract, worth $7 million over four years with all options included, is the largest ever for the up-and-coming company. Previously, its largest contract was work for the Defense Advanced Research Projects Agency at about $900,000, Greason said.
Smart move. If they get a workable composite fuel tank to work, a single stage to orbit will become a reality, cutting launch costs.
The X-33 Space plane was aborted because its composite fuel tank failed.
Space ping.
Exactly!
(Note: The occurance of this could unfortunately bring about an outbreak of AlGore, as he was a big backer of the X-33 flop.)
Yes, and apparently, NASA think so too. It will probably have a new name.
It is probably more accurate to say that NASA's latest objection to SSTO will need to replaced with a new one.
The headline scared me. XCOR looked like a Chinese firm at first glance.
Hey, it's believable. We've thrown everything else to them.
My idea was to build internal cables that would act like the fibrulae in the human heart. In high school I dissected a beef heart for a science fair and learned how these internal devices help to maintain the structure of the heart during the beat cycle. I suggested a similar internal structure for the Venture Star tank. Heck, I'm a bean counter so no one listened!
Please tell me you patented this concept before sharing it with the entire world via FR.
8^)
Did Arthur Clarke patent communications satellites?
> Please tell me you patented this concept ...
Such things have already been done. Goodyear perfected "airmat" back in the 1950s which used the same idea to allow for the construction of oddball pressurized shapes likes wings. Last I heard, airmat structures remain the strongest for their weight, even compared to carbon fiber.
Follow up information.
> I suggested a similar internal structure for the Venture Star tank.
In effect, the V* tanks already had such an internal structure.
Huh.
To prove my point, I did a search for images of the X-33/V* tanks, images of which used to litter the net. Now mostly gone. Oh well. Anyway, these multilobe tanks were not pure empty volume. Think of them like balloons that you mash together... there is a structural web between the lobes. The X-33 tanks were the same way, but with some lightening holes. However, that wasn't the issue with these tanks... their odd shape and porous nature led them to be suseptible to cryopumping, which wrecked at least one tank in testing.
Nerd Note - cryopumping defined:
The tanks were at room temperature. Then they were dropped in temperature drastically when the cryogenic liquids were poured in. As a result, the air around the tanks *also* dropped in temperature. The tanks themselves got, as you might expect, cryogenically cold. The air on their outer surfaces did as well, and some air liquified (nitrogen and oxygen). Gases within the porous tank structure also liquified, leaving vacuum in the voids. This vacuum sucked in air from outside, which of course also liquified(this is cryopumping). Not a real big issue. Then, the liquid hydrogen was pumped out, and the tanks were allowed to return to room temperature. However, the liquid gasses trapped inside could only *seep* back out... not fast enough. So the liquified gasses within the composite structure warmed, returned to gas phase, and blew the structure apart as they super-pressurized.
Ooops.
An aluminum-lithium tank was built and tested, and worked just fine. Metals don't cryopump. But they weigh more.
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