Do you happen to remember the name of the type of engine that they experimented with in, I think, the 80’s, maybe early 90’s? It was kind of like a turboprop, but the it looked more like a jet engine. The defining feature was that the “propeller” blades were short and stubby and mounted on what would look like the exhaust cone of a turbine engine, and there were a lot more of of these stubby blades than you’d see on a turboprop. It basically looked like if you took one of the compressor stages off a turbine engine and rotated it inside out so the blades all stuck outward from a central ring, and then slid that ring up onto the exhaust cone of a turbine engine.

I’ve been trying to remember the name of this thing for a long time but have had a dammed hard time finding it. Apparently they were supposed to have the efficiency of something between a turboprop and a turbine, and so airlines really wanted them, but no one pursued them because they thought the general public would think they are “scary-looking” and wouldn’t want to fly on them