To me, it's amusing to see these pie-in-the-sky designs that supposedly will revolutionize point-to-point travel, that are being touted as "moments away" from general usage.
Spoiler alert: They're not.
Take all of these exposed propellers - sheesh. Are we to ignore what a hazard they pose to bystanders? Yes, I know they only start spinning moments before takeoff (unlike conventional helicopters that have to be spun-up well in advance of flight). But what about an inadvertent emergency landing? What happens if "something" goes wrong while landing in a city center? Oh, that should be interesting! I think it'll be a tough sell, convincing city council members that these things are safe to be operated in and around the general public.
If they ever do get permitted to operate in densely-populated areas, these aircraft will require heliports of the same size we're using now, not only to provide a safety buffer from the general public, but to ameliorate the downwash these things will create.
Downwash? Yep. A four-seat aircraft packed full of electric motors and batteries is going to weight about what an R-44 weighs now - unless the designers know something about repealing the laws of physics. To lift that weight will require a certain amount of thrust, no matter how you divide up that thrust from a single main rotor (R-44) into multiple little props. That thrust will come in the form of downwash.
So far, all of these wonderful new electric flivvers that we've seen have passenger cabins that are just little composite shells. Here's a newsflash: Passengers are going to demand that they ride in something a little more comfortable than the back seat of a police car or an amusement park ride. They're going to want decent seats...and carpeting...not to mention air conditioning and heating. These things all have a weight penalty that must be paid.
Speaking of seats... Oops, did we forget crashworthiness? These "vehicles" will not be exempt from the regulations regarding occupant-protection. Cabin structure and seats will have to be stout enough so that the passengers have a reasonable chance and expectation of surviving a crash.
Speaking of crashing... Should we even discuss the realistic wind limits on these oversize quadcopters? How will they behave in a big city environment, where they'll have to deal with the turbulence generated by tall buildings? Sure, the small ones seem fairly stable, but is that stability scalable? (Then again, I've never seen anyone operate their Mavic drone on a really gusty day.)
I think the people promoting these "electric drones" or "autonomous flying taxis" are overlooking certain realities of designing a viable, certifiable aircraft. The regulatory hurdles they'll have to clear will be incredible, and perhaps insurmountable. Governments are not going to suspend existing rules regarding safety because of the novelty of being able to zip around downtown in self-flying Ubers.
It's all very nice to demonstrate something like this single-seat BlackFly. Wonderful. It's cute. But when you think about it, it's about as useful as a gyrocopter. The bigger ones? Man, they're a LONG way off, if we ever see them at all.
Yes, you can call me a Luddite, that's fine. But seriously, there are going to have to be some miraculous advances in electric motor and battery technology before we'll even see a practical four-seat, pilot-less drone/taxi that someone would pay money to ride in from Point A to Point B.