are you talking about ducted fans? if so I've wondered the same thing. here's a plausible answer: https://aviation.stackexchange.com/questions/36726/why-dont-dr

are you talking about ducted fans? if so I've wondered the same thing. here's a plausible answer: https://aviation.stackexchange.com/questions/36726/why-dont-drones-use-ducted-fans/59437 https://aviation.stackexchange.com/questions/36726/why-dont-....