Jet engines, like people, come in many shapes and sizes. There are sleek and narrow engines called turbojets that generate enormous thrust. Used almost exclusively by the military, they can fly a fighter jet faster than twice the speed of sound, but they also burn a lot of fuel. Engines from another big group, called high-bypass turbofans, are bulkier, slower, but much more fuel efficient. Everybody knows these engines. They are the heavy lifters of commercial aviation that hang from the wings of most passenger and cargo aircraft. They use a large fan at the front of the engine that pulls the plane forward like a powerful propeller.
GE engineers are now working to combine the benefits of both engine designs and create the ultimate flying machine: a revolutionary supersonic jet engine that is also fuel efficient. “We are taking this technology to the next step,” says Abe Levatter, project manager at GE Aviation. “The name of the game here is fuel economy. We are looking at fuel savings of 25 percent, which is huge. That extra fuel gives a military jet up to 35 percent more range. That’s key to mission capability.”
Top Gun: GE is looking at fuel savings of 25 percent and up to 35 percent more range with the new jet engine design, .
GE has invested billions to develop the latest high-bypass turbofan engines like the GE90, GEnx for Boeing’s Dreamliner, and LEAP for the next generation of single-aisle airplanes. The research has embraced new manufacturing technologies like 3-D printing and led to new materials like super-strong but lightweight ceramic matrix composites. They allow GE to manufacture highly efficient jet engines operating at temperatures above the melting point of steel.
GE is now applying all this know-how to the next generation military engine that can automatically switch between high power and high efficiency modes. “How much work can I get from every drop of jet fuel I put in?” Levatter says. “In the military world, you want to cruise as far as you can at subsonic speeds with very efficient fuel burn, but when you go to penetrate, you need to accelerate to supersonic speeds.”
GE and the U.S. Air Force Research Laboratory call this “variable” design ADVENT, short for adaptive versatile engine technology. The idea for the concept dates back to the 1970s and when jet engine pioneer Gerhard Neumann realized that he could manage and modify engine performance by controlling the amount of air that flows through the engine core. More flow through the core results in more thrust and speed, less flow in the core saves fuel.
Engineers designed the new engine, which includes parts made from ceramic composites and intricate “3-D printed” cooling components, to be easy to fly. “We want the engine to take care of itself and let the pilot focus on the mission,” Levatter says. “When the pilot says ‘I’m out of danger, I want to cruise home,’ the engine reconfigures itself. We take it upon ourselves to make the engine optimized for whatever the pilot wants.”
GE is now testing the engine’s core components and plans to run a full engine test in the middle of 2013.