I'm trying to design an aircraft with a long range, and I thought that an electric aircraft with a generator powered by the motor would be able to do that.

However, I've seen very few of these commercially not seen any aircraft that do this, and I was wondering why.

Is a fully electric aircraft too expensive/ not powerful enough to be feasible, economically or physically?

Also, is there possibly a way to generate enough power? An alternator/Magneto combination, perhaps?