Rocket Science: New “Ceramic” Jet Engine Has Space Shuttle Pedigree
September 11, 2012
Soon after the Space Shuttle Columbia broke up on descent from orbit in February 2003, material scientists and engineers at GE’s plant in Newark, Delaware, started building a set of repair kits long thought impossible. Columbia suffered a crack in its left wing by a briefcase-sized insulating foam fragment that fell from a fuel tank during take-off. During her return, superheated air entered the spacecraft through the wound and ripped the shuttle apart 15 minutes before touchdown. The GE team, in collaboration with NASA and industry partners, helped design and fabricate unique patches to plug up in space similar damage on the shuttle’s wings and belly, and prevent disasters in the future.
Return to Flight: The Space Shuttle Discovery returned to flight in July 2005. It was the first shuttle to fly after the Columbia disaster. It carried two wing and body repair kits made from a revolutionary ceramic composite material developed by GE scientists.
The team designed the patches from a special ceramic composite material that could survive wild temperature swings, from minus 250 degrees Fahrenheit in orbit to a 3,000-degree inferno caused by the drag of Earth’s atmosphere during the shuttle’s 17,000 miles-per-hour descent. “You could bolt it on the wing leading edge in space and cover the damaged portion,” says Robert Klacka, technology marketing manager at GE Ceramic Composite Products. “The repair kit had 30 different patches that could cover a hole located on over 80 percent of the wing leading edge surface. The thin, flexible panels used a high temperature toggle bolt to attach it through the hole on the wing. Thankfully, we never had to use them.”
That’s not entirely true. The shuttle fleet retired last year, but the materials live on vicariously inside GE’s innovative LEAP engines, as steering components for ballistic missile defense systems, and as rocket motor thrusters for a new commercial space transportation aircraft. “The [Space Shuttle] kits were basically using the same family of materials,” Klacka says.
Ceramic materials can take a lot of heat but are notoriously fragile. Just think of the coffee mug. Scientists at GE Aviation, GE Global Research and at Klacka’s Delaware plant have spent the last two decades developing ceramic composites that are tough and one-third the weight of the best nickel super-alloys. They can work beyond the alloys’ melting temperatures, a property that allows jet engines like the LEAP to become more efficient.
GE makes two types of ceramic composites. Ceramics strengthened with carbon fibers withstand over 3,000 degrees Fahrenheit and serve as hot gas valves and thrusters inside of rocket systems, or heat shields for hypersonic aircraft and re-entry vehicles in the aerospace industry. The second group, which is reinforced with ceramic fibers and operates at 2,400 degrees, is more durable, and has applications as turbine tip shrouds, combustor liners, blades, and fairings in turbine and jet engines like the LEAP.
GE workers in Delaware make the composite parts from specially engineered fiber tapes that are formed into turbine engine components, infiltrated with silicon and converted to ceramic. “I’ve seen a lot of different materials,” says Klacka, who has been in the composites business for over 25 years. “Our materials have the strength, durability and manufacturability that other ceramic composites lack. That’s why they work.”