I understand a prop is like an "airscrew", screwing itself forward through the air and taking the airplane with it. It's exit velocity is related to the inlet velocity.
I understand a fan, is used for higher speed applications, and pushes the air back, it's exit velocity being unrelated to the aircraft's speed.
I understand a prop fan is a combination of both.
What is the difference physically between a 2 bladed prop, and a 2 bladed fan?
For NASA's X-57, and other distributed propulsion aircraft, use the prop/fan to accelerate air over the wing.
I understand Illium's jet uses a ducted fan and has roughly 20 blades.
It seem's NASA's X-57 and the blackfly, are just using a 2 bladed props, or is it a fan, or a prop/fan? How can you tell what it is?
What is the difference physically between a 2 bladed prop, and a 2 bladed fan, and a 2 bladed prop/fan, all unducted?