All one has to do is look at the issues plaguing the current crop of geared turbo-fans to see where this really struggles in the real world. Attaching an ultra

All one has to do is look at the issues plaguing the current crop of geared turbo-fans to see where this really struggles in the real world. Attaching an ultra high RPM gas turbine to a relatively slow moving fan, whether a prop or ducted fan, is not an easy engineering exercise. The amount of heat generated in the gear box, the expensive materials that heat requires, and the operational needs of many start/stop cycles are making these engine styles difficult. That's not to say its not a worthy goal. It just seems that we're just on the cusp of making these things a reality and I think the geared turbofan will end up being the winner vs the propfan.