Jeeves, the ashtray is full -- buy a new (flying) car!

For imbeciles (like me, and you [?]), "VTOL aircraft" stands for a "vertical take-off and landing" apparatus. Yes they do exist, like in the British Harrier Jump Jet, invented several decades ago. However, unlike helicopters, most of such VTOL machines are actually "V/STOL (vertical/short takeoff and landing) aircraft that require short runways or light loads. Moreover, they are not powered by electric batteries. In fact, they all use plenty of "high-octane" hydrocarbons, like in Jet-A fuel, a standard aircraft type of kerosene.

The Future is Nigh

More information on this futuristic idea is available from the purveyors of such concepts; just see the slick graphics at Audi and Airbus work together on a passenger drone/electric car hybrid , like the one shown nearby. If you believe it all, we'll soon have nothing but electric drone-like self-driving cars and self-flying (VTOL) aircrafts and, most importantly--they will be powered by the electric energy obtained from wind and sunshine, i.e. for next to no cost; (assuming that wind and sunshine will not become taxable, soon, too!) Of course, that's all total nonsense. Just in case, you would like to put down some (futuristic) dollars to "cash in" on this vision. Before you do though, perhaps you might want to understand the energy requirements and energy storage facilities that exist. Let's look at the energy requirements for a flying machine.

Energy Requirements of Aircrafts

Of course the amount of fuel needed depends on the load and distance plus reserves for unforeseen changes due to headwinds etc. For smaller commuter flights, the typical fuel requirements are in the order of 5L per passenger and 100 km flight distance. Larger airplanes on long distance flights have a lower rate of consumption, more in the order of 3L per 100 km and passenger. There is a simple reason for that. A significant part of the fuel is required to reach cruising altitude (typically around 12km). Once that's reached, less fuel is required to maintain cruising altitude and speed. Even a small (4-6 seat) winged, single ~200 HP engine aircraft and a range of 1,000 km needs to have 200L (50 US gallons) fuel on board at take-off. A similar size (4 passenger) helicopter needs a more powerful engine (~ 400 HP) and, correspondingly, more fuel. In order to understand the relationship between the different energy sources, very roughly, 1L (0.8 kg) of hydrocarbon fuel is equivalent to 40 kg of the best, brand new and fully charged electric battery. So, for your small Piper airplane, you would need (instead of 200L kerosene) only 200 x 40 kg = 8,000 kg of battery, and yet much more for an electric chopper. Of course, such weights are already multiples of their entire potential payloads. I think you get the picture: unless battery charging times are substantially reduced, no time-deteriorating of available battery power, and 40-fold increase of the currently available energy density can be achieved, that electric flying machine is nothing but a pipe dream. So, the questions then are:

1. Do electric (battery-powered) drone-cars/aircraft have a great future?

My answer: Clearly not!

2. Can the world live and prosper without hydrocarbon energy?

My answer: Clearly not.