August 07, 2013
Hawthorne, Calif.-based Microcosm, Inc. has found a way to make strong, lightweight tanks for space applications that it says can handle high pressure as well as the low temperatures needed to hold cryogenic propellants.
That capability could come in handy as some of the new-space entrepreneurs look to pressure-fed propulsion systems to get their payloads off the ground. While Hawthorne-based Space Exploration Technologies (SpaceX) tries to develop its big Falcon 9 rocket with government seed money, Microcosm and its spin-off, Scorpius Space Launch Company, are using a proprietary resin to fabricate lightweight one-piece rocket-propulsion tanks tested at 400-600 psi and 321-175F with liquid oxygen and liquid nitrogen.
Robert Conger, executive vice president of Microcosm, says the company’s tanks get stronger the colder they get, so they should be able to hold liquid hydrogen as well, even though they have not yet been tested with the super-cold fuel.
Boeing recently tested a 2.4-meter composite liquid hydrogen cryotank with liquid hydrogen at -423F in a NASA-backed fill-and-drain run at Marshall Space Flight Center. That test, which avoided the composite delamination that was blamed for termination of the old X-33 single-stage-to-orbit suborbital testbed project, set the stage for future testing with a 5.5-meter composite tank and liquid hydrogen.
The microcosm tanks are much smaller. The liquid oxygen tanks measure 42 in. in diameter, and can be built out to 18 ft. in length — dimensions limited by the winding equipment the company owns. The tanks are cured out of autoclave at room temperature, and are fabricated as a single piece of composite, including end flanges and internal slosh baffles, according to Conger, who says the technology has started to draw interest from startup space companies.
“We have other folks now who are in the space business who have become very enamored with the work we are doing and the properties of these tanks,” he says. “Not only are they liner-less, if you will. They are all composite, but they’re all composite up to and including the boss [end flanges]. In the cryogenic world that is a significant effort, because what we’re trying to do is eliminate any thermal differentials in the materials.” Microcosm is keeping the formula for its Saphire 77 resin a company secret, and has patents or patents pending for the wet-layup techniques it is using to produce the tanks and integrated features.
“We call this a unibody tank, meaning that the whole tank shell and its overwrap are continuous buildup,” says Markus Rufer, who heads up the Scorpius spin-off that does a lot of the tankage work. “The tanks are basically seamless, made in one piece, and they’re being cured and matured as a one-piece structure. So we are not joining pieces, and we are not gluing stuff together.”
The resulting tanks are strong enough to be the primary structure on a launch vehicle, Rufer says, and can be delivered very quickly compared to metal tanks. Before Armadillo Aerospace fell on hard financial times and went into what founder John Carmack calls “hibernation,” it turned to Microcosm for a small, high-pressure tank when the surplus pressurization tank it was using proved too heavy at 63 lb. for the Centennial Challenges competition it had entered. Rufer says his technicians were able to trim the weight to 24 lb. for two tanks combined, in time for the competition.