Again you are right, flapping is much more efficient.BUT !=
=rotating motor with rotating propeller(s) can generate <10 kG thrust/kW +noise + safety problems !
=flapping (OSCILLATING) thrusters are as minimum ONE ORDER better,>100kG/kW !!! +lower NOISE +allmost SAFE for enviroment...
=strange "paradox" of Gray=fish needs little power for speed ...A problem with flapping wings is that speed will be limited I think, and large > 10 ton-50ton aircraft
+smoke generator ...to integrate a faux jet exhaust LED lightshow into the rear of the ducts.
leafed through it a bit and it discusses designingI would be surprised if that included fans that operated at transonic speeds.
I wonder if supersonic air tunnel design may be of use.
Use the Ski Doo 900 Ace Turbo snowmobile engine; it is the best suited and very little work needed for an aircraft.
You'll have to install a belt drive reduction to suit the propeller you use and the height of the thrust line; I don't think you'll get a geared redrive to work successfully, it may work, you'll have to do your own homework on that part.
Where are you located.
=the differential CR gear is much lighterThe counter rotating would be cool as long as I could build/install a spinner for it.
Any increase in hp?