Originally Posted by soundlover
Why the fan stage is not considered to be the same as a propeller.... the only difference looks to be the number of blades!!!! hence it should behave as a propeller!!!!
Not so. A fan is ducted; a propellor is free from external constraints. That is why the propellor tested on an MD-80-class airframe, and its recent conceptual revivals, are known as "unducted fans".
PBL