Apr 15 2019

Furthering the Flying Car Thought Experiment

I love the conversation stemming from my last post on flying cars, and also our discussion on the SGU. Some great points were raised, and I want to further the conversation by addressing them.

I will begin by more explicitly laying out the various ways to frame the question of what impact flying cars may have. Whenever we ask a question about how something will affect a complex system, the answer always seems to be – it depends. It depends on exactly what question you ask and how you try to measure the effect. Are air dryers better than paper towels? It depends on what factors you think are important, and on several variables.

Thinking about the flying car question more deeply, it seems to me there are three levels to consider when it comes to efficiency. The first level is trip efficiency – what is the energy cost of making one trip for one passenger from point A to point B, comparing an electric flying car to a gasoline ground car and electric ground car? This was the level of the analysis of the recent paper I was discussing.

What they found is that flying cars can be more efficient than gasoline ground cars if the travel distance is long enough. For a 100 km trip they found that flying cars are 35% more efficient than gasoline, but 28% less efficient than electric vehicles. So that’ right in the middle of the pack.

Further, for longer trips the relative efficiency improves, but also if we consider geography and traffic the flying car, in some situations, may become the most efficient option. The authors point out that the average commute is 17 miles (which is close to other sources I found, some say 16 miles) but this also translates into 1 hour round trip travel time. But actually this is not enough information. We also need to know the average trip efficiency of these commutes. In other words – how much does the commute path deviate from a straight line? Also, how long does the commute take compared to no-traffic travel times? And further, how much of that commute is city driving vs highway?

In other words – how much of an advantage would a straight line, no traffic or light or delays flying car have over ground transportation? If we knew the trip distance and the trip efficiency, we could calculate the relative efficiency of air vs ground travel. I wonder what percentage of commuters would be better off in a flying car.

This all also does not consider the time efficiency. If a 2 hour commute turns into a 1 hour commute, that is a huge improvement in quality of life and work efficiency.

The bottom line is that if we consider all these variables there will be a niche for which a flying car is efficient, and this will provide a market. As the technology improves (or as traffic worsens), the market will increase.

A second way to look as efficiency is ownership efficiency. What will my total five year cost and energy expenditure be if I own a flying car vs a ground car? This will largely depend on the nature of my commute, but also overall travel habits. It will also depend on whether I am an individual or a family, in which case I can have a ground and flying car and then use whichever one is most efficient for any particular trip.

This analysis is difficult because we don’t yet have any mass produced flying cars on the market. But when we get to the point where ownership efficiency makes it worth it (including time savings) the market will take off. To emphasize time saving, however, if you save 1 hour per day on your  commute (30 minutes each way) then that is 5 hours per week, or 250 hours per year for 50 weeks. What is the value of that?

Ownership efficiency is also not important for when companies adopt an Uber style flying car service. Even those who cannot afford to own a flying car, or for whom it does not make sense, can simply use them like a taxi or public transportation when the trip makes sense.

Finally there is societal efficiency – what will be the impact of flying cars on the transportation efficiency of our entire society? This is where there was the most debate. You cannot really argue with the trip efficiency arguments, because the researchers ran the numbers and there are clearly trips for which flying cars will be more efficient. But several people argued that adding flying cars will not decrease congestion and traffic, making the analogy to adding lanes to roads. However, I think this is the wrong analogy.

The better analogy is adding public transport – a different travel option. Here the data is mixed, but after looking into it I think the best answer is that adding an additional transportation option that does not use the roads will reduce traffic for the trips they replace. Some studies look at overall traffic, but those that look at traffic in the corridor of the public transport show that traffic is reduced.

Consider that trip efficiency may be largely determined by traffic, meaning that taking a flying car will be most useful (in terms of both energy and time savings) in high traffic areas. Those are also exactly the situations in which adding another travel option reduces traffic. To the extent that flying cars do reduce the worst traffic congestion, this can be a massive benefit to society. Then, every car experiencing reduced traffic will have improved travel efficiency.

This is, in fact, precisely why cities add public transportation options. But flying cars have an advantage over other options, which brings me to the next major point of contention – infrastructure. How much infrastructure will a fleet of flying cars need? On the positive side, they will not need roads, bridges, tunnels, or rails and all the upkeep and maintenance they require. Essentially they will need safe places to take off and land, recharging stations, and air lanes (which is really a virtual infrastructure).

As the number of flying cars grows, this infrastructure will need to be developed, but this hardly seems like a major obstacle given the infrastructure we developed for cars, for example. The top levels of parking garages and low buildings can be reserved and adapted for flying cars. Landing pads can be added to service stations. Home driveways can be adapted to accommodate landing. Bus stop-like landing pads can be created for flying car services. And we are already putting in place an infrastructure of recharging stations for electric cars.

The advantage here is that this infrastructure can easily adapt to need – to the highest traffic areas, for example. Geography is not a limitation.

One thought I had is that electric wires are a potential problem. It would be advantageous to bury all power lines. This is a huge infrastructure project, but we should already be doing this for other reasons. This would be just one more reason to safely bury the lines. I know this is a complex topic in itself, mainly because of the expense, but as we upgrade the grid anyway, we should consider the option of burying, clearing the way for the flying cars of the future.

The final major concern raised is air-traffic. Airspace is actually quite challenging to manage, and requires an infrastructure to handle. We can’t have people flying around willy-nilly.

This is a valid point, but I think will take care of itself. It will take at least 20 years, and likely more, before there is any serious penetration of flying cars into the transportation market. We already have self-driving cars (although not quite ready for full implementation). In 20 years the technology will be much better, and will only continue to improve. My guess is that flying is actually easier, in that there are no road obstacles, no kids running out into traffic, and no traffic lights. Using GPS, a communications network among the cars themselves, and coordination with ground locations, it seems pretty clear that an entire fleet of self-flying cars is completely plausible.

What about airplane traffic? They will have to share airspace. The system will have to adapt, just like reallocating bandwidth as technologies come and go. Again – this is not an unsolvable problem, and will likely not be a deal-breaker.

Obviously we cannot instantly graft a vast fleet of flying cars onto our existing infrastructure and regulations. But that is not what is being proposed, or what is likely to happen. Rather, we will see a slow adoption as prices come down and efficiencies improve. The infrastructure and regulations will grow along with the market, and there will be to some extent an organic evolution.

Of course I have no idea what will actually happen. My primary point is – that because flying cars can be cost, energy, and time efficient there will be pressure to own and/or use them. This pressure may be enough to create a viable market. It is unclear exactly how and when this would happen. I suspect flying cars will not replace ground cars, likely ever, but will simply be another option used in situations where they make sense.

I hope I get to see how this plays out.

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