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Keeping it cool in space

Features | June 5, 2015 | By:

A full mission dress rehearsal was held for NASA’s Low-Density Supersonic Decelerator (LDSD) in May 2015 at the U.S. Navy Pacific Missile Range Facility (PMRF) in Kauai, Hawaii. Photo: NASA/Bill Ingalls.

Specialized textiles play an important role in thermal control for an evolving aerospace marketplace.

Where there are flights, space missions and satellites, there are advanced textiles. For composites used in aircraft engines, multi-layer insulation (MLI) blankets for launch support and satellites, or—of course—space wear for participants of manned space exploration, textiles and textile components are critical elements that are, in some ways, the unsung workhorses of successful aerospace endeavors.

Privatization and commercialization

One change that affects how fiber and textile manufacturers operate within the aerospace industry is how the marketplace is configured. Privatization and commercialization have opened up the playing field in ways that aren’t completely realized yet, which means more potential opportunities for fabricators.

“Privatization is a new paradigm in the aerospace business,” says Bruce Olson, technical staff at Sheldahl Inc., Northfield, Minn., which manufactures composites and laminates used in MLI blankets. “Right now it’s tough to tell who the big players in the private sector are because it’s a web of different people doing different things—it’s not like the old days where you had maybe five or six significant customers that pretty much took care of all the aerospace movement in the free world.”

Bud Weisbart, IFM, vice president of A & R Tarpaulins, also notes that privately owned companies, which design, manufacture and launch rockets and spacecraft such as SpaceX and Blue Horizon, are a significant industry development. A & R Tarpaulins is the parent company of AR Tech, Fontana, Calif. It manufactures technical and engineered fabric products for aerospace applications. “There are also other companies that hadn’t previously been involved that now are in the area of launch satellites,” Weisbart says. “Our job now is to create and develop relationships with these companies as well.”

AR Tech collaborates on the design and manufacture of aerospace products to meet specifications, as well as acting in a consultant capacity with rocket scientists when fabric is an element they require for a project. “Several times a year we have engineers come to us with their ideas, wondering what kind of fabrics would be best to address their purposes,” he says. “In some cases, such as work we’ve done with SpaceX, they already have their own tailoring capabilities, so we help them with preparation. It’s truly a partnership.”

Smaller satellites, smaller covers

Part of the evolving marketplace stems from the miniaturization of satellites and components in them. “You’ve got these little ‘CubeSats’ that include optics, cameras and electronic, high-frequency communication. They might be the size of a shoebox now where in the past they were the size of a Volkswagen,” Olson says. “It takes a lot less money to get something like that into orbit and it changes the way people are looking at things.”

Although miniaturization decreases the amount of materials needed for satellite covers, there are more satellites being put into orbit by more companies so the bottom-line demand has remained steady, according to Olson.

Thermal protection

Composites and laminates have been used for years in MLI blankets that protect spacecraft hardware from thermal cycles in a vacuum and control the temperature of satellites. They are also used to protect jet airplane cowlings. The prevailing technology has also been around for years. “A metal or metalloid is deposited on a ceramic, thin polymer film, used to control solar absorption and IR emissivity,” Olson says. “We mostly use polyesters, fiberglass, Nomex and Kevlar and for some very special projects, Astroquartz quartz fiber products.”

JPS Composite Materials manufactures Astroquartz II products made from high-purity quartz crystals for space and missile applications. The company also offers Astroquartz III, a new low-cost alternative to the Astroquartz II products. Astroquartz III fabrics are woven from high-tensile strength, high-purity fused silica fiber yarns. Both offer low dielectrics, near-zero coefficients of thermal expansion, high temperature performance and excellent mechanical properties in composites.

Also new to the aerospace market are comingled yarns (carbon fiber combined with a variety of different thermoplastic fibers) and 3D preforms made from twisted carbon fiber, both produced by Concordia Fibers, Coventry, R.I. “Though thermoplastics and 3D weaving have been around for a while, both are now beginning to make significant inroads into aerospace (as well as other fields such as automotive, sporting goods, and the oil and gas industry,” says Randal Spencer, president and CEO of Concordia Fibers.

The company’s thermoplastic commingled yarns are used in applications where parts may be exposed to jet fuel or high temperatures. “The commingled yarns are essentially a flexible thermoplastic pre pegs. (Prepegs” is short for pre-impregnated, meaning the matrix material is already combined with the reinforcing carbon fiber.) “After the commingled yarn is woven or braided into a fabric, the fabric is placed in a mold and put under heat and pressure,” Spencer says. “The thermoplastic component melts and becomes the matrix of the composite part—no epoxy or other resins are used.”

The biggest application for carbon twisting/3D composites is in the high bypass turbofan LEAP engine made by CFM International, a joint venture between General Electric and French aircraft and rocket engine manufacturer, Snecma S.A. “For the 3D preforms carbon fiber is twisted so it can be woven into 3d preforms (think floppy jet engine fan blade) before being injected with an epoxy resin to form the final part,” Spencer says. “The ability to produce 3D preforms in high volumes is a recent development. We typically start with a 12K fiber and can combine many ends together through precision twisting without damaging the fiber. Our largest combination to date has been 156K.”

Innovation and adaptability factor into the creation of new fibers and specialized textiles for aerospace, as well as applications for the materials. “People in our industry should develop confidence to diversify so they can address whatever walks through the door,” Weisbart says. “Associations like IFAI have a role to play in supporting its membership in this way. And the way to be adaptable is by creating as much of a knowledge base of the resources that you’re going to need to be responsive.”

A sentiment echoed by Sheldahl’s Bruce Olson. “Sheldahl is quite diversified so the composites and laminates we make that are used in MLI blankets is just one of many things we work on,” Olson says. “In many respects this can be a business where there isn’t a lot of growth but you want to stay in there because one never knows what you may wake up to tomorrow. And when that happens, there can be a lot of demand.”

Sigrid Tornquist is associate editor of InTents and a regular contributor to Specialty Fabrics Review and Advanced Textiles Source.

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