General Electric has completed its initial design for the first commercial supersonic aircraft engine in decades, a major hurdle for developing private planes and, perhaps eventually, jetliners that fly faster than the speed of sound.

The twin-shaft, twin-fan design will slash travel times by hours after 50 years in which the average speed of private jets has increased only 10 percent, GE said in a statement Monday. The engine is being designed for Aerion, a startup backed by Texas billionaire Robert Bass, who has been trying to develop a supersonic business jet for more than a decade.