[image from eBay]
But the flapping wing thing is much less efficient than an airfoil, plus it doesn't glide very efficently, so it has much less range than your standard rubber band powered balsa wood plane.
OTOH, I scoff at the idea that his "aerial screw" had anything to do with the development of the helicopter.
For starters, it was simple a re-purprosing of the Archimedean screw. Then again, the Wrights get credited for inventing the airplane when everything on the Wright Flyers was invented by someone else.
Secondly, the Chinese were making toy "helicopters" more than a thousand years before da Vinci was born.
And the Aerial Screw design only looks intuitive if you don't understand how helicopters fly. They don't fly by blowing air downward, they fly by generating lift by the spinning of long, skinny airfoils. They blow some air down as a byproduct but that's a minor contrubtor to lift (except when in ground effect).
If the Chinese thought to bevel the edges on their toy for streamlining, theirs also would have had primitive airfoils.
So in that respect, this design probably served more as misdirection than as inspiration because it had would-be inventors chasing the wrong idea for centuries (which is evident from some of the early failed prototypes).
Plus he apparently offers four capstan bars for propulsion, as if four people were going to turn the capstan by running in circles really fast, like hamsters in a wheel. Meaning he was orders of magnitude off on the power requirement.
And there are no flight control surfaces, no flight controls, and no pilot's station.
It's not a very efficient method for moving air, less so than a bog-standard rotating fan. There have been working "toy" models built from composites and mylar with modern tiny hi-torque electric motors. They got around the lack of control surfaces by using four separate aerial screws, one at each corner, and they controled flight by manipulating the rpms of the individual screws.
https://www.youtube.com/watch?v=YsG-Mcn29kg
Which proves nothing because you can make an ironing board fly, provided you put enough horsepower on it.
https://www.youtube.com/watch?v=QpTyfjYMlNc
The world record endurance for a human-powered helicopter is 64 seconds. The world record endurance for a human-powered airplane is almost 220 times longer, six minutes short of four hours. Both were powered by elite cyclists. Which should give you some idea of difference in the relative efficiencies of fixed wing flight versus rotary wing.
https://en.wikipedia.org/wiki/List_of_human-powered_aircraft
Call the aerial screw "a notion." Even to call it "an idea" is a bit of an overqualification because it doesn't address so many of the major requirements for even a primitive working model.
But an invention? Not even close.