Advanced Concepts Back to the Purdue AAE Propulsion main page. There are several ways to go straight up and end up flying, though the means of doing so is usually much heavier and less economical than doing one or the other exclusively. There will be others. The propfan bridges the gap between the turboprop and turbofan. Turbines power large, short span, wide chord fans without a duct around them.
Performance is somewhere between a turboprop and a turbofan.
As yet, the propfan's economy has yet to outweigh the noise problems and lower operating speed.