a classic phrase in nautical language: the best time to reefing (reduce the main sail) is the first time you think about it ....
it's never pleasant to withdraw from a project, but the first time you think about it is the sign of a dificult or boring proyect.... from there all the time you spend on this is a waste of time and money...
how avoid this risk: (my personal point of view of course)
-plan ahead... all the process is a chain...objetive of the project, whish is the motor-prop , then maximum thrust-speed, maximum weight, wing area and so on... check parameters in the process...
-start simple to prove the basic concept and check all the basic aspect are ok )CG, weight, motor etc etc.... the add more complexity step by step
-use mathematics!!! lot of this hobby are predictable thanks to mathematics and lot of online tools
-read a lot a find solution for the same problems in other sites... you dont need discover the wheel all the time... check similar ideas, improve and simplify them
tx Futaba 9CAP & 8U