Blast from the Past: Edison Discovery Powers Next-Gen Jet Engines
Everyone knows that Thomas Edison created the modern light bulb, but a lesser known Edison discovery tied to the bulb’s birth is now enjoying the limelight. In 1879, the inventor and GE founder exposed thin slices of bamboo to scorching heat at his lab in Menlo Park, N.J. The cellulose inside the bamboo quickly carbonized and transformed the splinters into the first carbon fibers. The fibers could conduct electricity and handle intense heat, and Edison used them as filaments in his early light bulbs.
In 1906, however, GE engineers invented the modern tungsten filament and carbon fiber was quickly forgotten. It remained dormant for the next 80 years, until NASA engineers re-discovered the material in the 1960s. They were seeking an edge in the space race with the Soviet Union and carbon fiber’s combination of toughness and light weight made it an ideal space age material.
Designers were soon crafting composite parts made from “prepregs,” layers of carbon fiber mats impregnated with resin. These parts were tougher, stronger and lighter than steel and aluminum alloys. They quickly started replacing metals in the fuselage and other structural parts of planes and missiles.
New York’s Museum of Modern Art included a GE90 blade made from carbon fiber composites in its Architecture and Design Collection. Carbon filaments did the trick, but they darkened the inside of the light bulb. Edison replaced it with Tungsten wire. The GEnx jet engine has fan blades and fan case made from carbon fiber composites. Boeing’s Dreamliner has sections of its fuselage made from carbon fiber composites. The BMW i3 all-electric concept car is the first all-composite car. Carbon fiber composite parts from GE’s plant in Hamble, UK, serve on the wing trailing edge of the A350, the latest passenger get built by Airbus.
The early carbon fiber cost as much as $400 per pound. But production innovation brought down price, and composites quickly spread. Today, BMW and Tesla Motors cars have carbon fiber bodies, there are carbon fiber golf clubs and tennis rackets, and Boeing and Airbus build large portions of their next-generation planes, the Dreamliner and the A350, from the material.
But no company went further than GE. GE spent several decades developing a version of carbon fiber composites that could replace the metal fan blades at the front of the jet engine and make it lighter and more efficient.
“This was a huge, expensive and risky project,” says Shridhar Nath, who leads the composites lab at GE Global Research. “We planned to replace titanium with what is essentially plastic. We were starting from scratch and we did not know how carbon fiber blades will respond to rain, hail, snow and sand, and the large forces inside the engine.”
The bet paid off. It allowed GE engineers to shed hundreds of pounds from the fan and build the GE90, the world’s largest and most powerful jet engine. The fan blades and fan case in the GEnx, GE’s latest and most fuel efficient large jet engine, are made from the material. But GE engineers are already looking for new applications.They are experimenting with carbon fiber wind turbine blades, riser pipes for the oil and gas industry, and patient tables for X-Ray and CT machines that are transparent to radiation and improve image quality.
“Over the next 15 years, you are going to see carbon fiber explode across areas where we have not seen them before,” says Nath. “Everybody is interested in reducing weight and increasing strength. That’s what’s carbon fiber composites got.”