Apr 12 2019

We May See Flying Cars Yet.

Over the years I have waxed and waned in terms of my optimism that one day flying cars will be a reality – and not just prototypes, but in general use for transportation. I was at an ebb in my enthusiasm, but a recent article has nudged me toward more optimism.

By “flying car” I mean a vehicle used for personal transportation that can fly but also be driven by someone with about the level of training required to drive a regular car. If you need a pilot’s license, have to land an an airport, and the vehicle primarily uses wings for lift, then it’s not a “car”, it’s a plane. Occasionally developers put forward what is essentially a driving plane and claim it is a flying car, but I would not put it in that category.

The flying car has been a science-fiction promise for over half a century. Just about every vision of even the near future contains flying cars. It is a fixture in our mental image of the “future.” I think part of the reason it has so captured our imagination is the obvious utility. Who does not fantasize about flying over frustrating traffic and taking a straight line unobstructed path to your destination?

There have essentially been two hurdles to the development of the flying car. The first is safety – designing something that the average person can operate with moderate training and with minimal accidents, at the level of driving a regular car or lower. This nut has essentially been cracked. Computer algorithms can handle the difficult aspects of maintaining stability, and can even mostly fly themselves. Fifty years ago this was an issue, it no longer is.

The remaining hurdle is simply the efficiency. It’s just really efficient to roll something along the ground. However, lifting weight into the air takes a lot of energy. This limits flying cars in two important ways. First, their range is limited by the fuel (in whatever form) they have to carry. Second, the expense of operating them is much greater than a regular car. This also relates to the carbon footprint of transportation, which is an increasingly important issue.

Because of this factor, I was extremely pessimistic about flying cars ever being practical. At best they would be a novelty, or a rich person’s toy or extreme convenience. But this takes us to a recent analysis that paints a more optimistic picture. They write:

For our base case, traveling 100‚ÄČkm (point-to-point) with one pilot in a VTOL results in well-to-wing/wheel GHG emissions that are 35% lower but 28% higher than a one-occupant internal combustion engine vehicle (ICEV) and battery electric vehicle (BEV), respectively. Comparing fully loaded VTOLs (three passengers) with ground-based cars with an average occupancy of 1.54, VTOL GHG emissions per passenger-kilometer are 52% lower than ICEVs and 6% lower than BEVs. VTOLs offer fast, predictable transportation and could have a niche role in sustainable mobility.

This means that for a 100 km trip, a flying electric vehicle (think of a drone big enough to take passengers) would be more efficient than a current internal combustion vehicle (both with one occupant), but less efficient than an electric vehicle. If, however, we limit VTOL (vertical take off and landing) craft to at least three passengers, and compare that to the average occupancy of a car (1.54), the VTOL craft is more efficient than both.

What all this means is that a VTOL craft would be right there in the mix in terms of efficiency, and not horribly less efficient than any ground-based car. VTOL can be more efficient if we limit them to longer trips and more passengers. The authors therefore conclude that they may have a niche role in transportation.

Having a niche role is always tricky. That means you probably can’t just have one flying car as your family car. This is what has limited the market for all-electric vehicles. They have a limited range and long recharge, so having that as your only car can be limiting. But they are great for regular commutes, so for families with more than one car, an electric car can take up one slot. Eventually we will get the range long enough and the recharge time short enough that this will no longer be a barrier to adoption.

There is a similar situation with solar panels. They were cost effective first in very sunny locations, but as the technology improves the map of where solar panels are cost effective expands until within a few years it will essentially include everywhere. This allows for niche early adoption to bootstrap the industry.

We may be able to get to the same situation with flying cars, where they are actually more efficient for some types of travel and this will result in some early adoption. The big inefficiency is lifting off the ground and gaining altitude, but once at cruising altitude they are actually very efficient. This is why shorter trips are less efficient overall.

There is also another situation that the authors refer to in the body of their paper but did not highlight in their conclusions for some reason – traffic. Even if the distance of your trip is short, if you are stuck in morning traffic, those 20km can take you an hour or more. Flying over traffic even that short distance can therefore be much more efficient.

This has another advantage – for every flying car there would be one or more (depending on car pooling) fewer regular cars on the road. If we decrease traffic by 10%, say, that would increase the efficiency of everyone’s commute. Therefore cities and other congested traffic areas could be a massively big and efficient niche for flying cars.

The authors also point out that geography is another variable. If you are traveling from Detroit to Cleveland, for example, you have to go around Lake Erie. A flying car could just go straight across, however, with greater efficiency.

The final point in the favor of flying cars actually coming into use is the Uber model – it is becoming more practical for more people to ride share than to own your own car. So you may never own a flying car, but you may be able to summon one with an app, perhaps even a self-driving flying car, to take that trip for which it is particularly efficient (because of distance, geography, or traffic).

A flying car infrastucture will then likely spontaneously emerge. They will be made available where they are most useful, and we may even build specific locations in cities for them to take off and land, like a bus stop. Hotels, for example, now have Uber/Lyft lanes. They have adapted to this new model. Cities will adapt to flying cars, making their use even more efficient and convenient.

Meanwhile the technology itself will continue to advance. Self-driving algorithms are only getting better. But perhaps the most important advance will be in battery technology, which has been steadily improving every year. Even if we don’t have a major breakthrough, if we just continue the steady incremental advances, in 20-30 years batteries will provide for great range and efficiency for electric vehicles, and then continue to improve from there.

So perhaps our future will be full of flying cars zipping over the streets of our cities, and taking us between cities at great convenience. I didn’t mention that the authors noted a flying car could easily travel at 150 mph. That would significantly decrease travel time, in addition to the straighter path, and avoidance of traffic (and tolls). Why drive or even take the train from New York to DC when you have have an Uber self-driving VTOL fly you there faster and probably cheaper?

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