Last September, GE began wind-tunnel testing a one-fifth-scale set of the blades at NASA's Glenn Research Center. Using computational-design advances, engineers are redesigning the original blades to evenly distribute the air coming off the tips when they spin at supersonic speeds, which should reduce the noise. The setup more than triples the airflow through the blades, says Theresa Zeug, the project's lead engineer, and allows them to be 14 feet wide, four feet wider than today's largest. The engine also saves fuel by tilting the blades to control speed—rather than throttling up or down—which lets it run at a constant, efficient rate.