Electric Airplanes As Concept Cars

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When I was listening to some of the presentations at the Sustainable Aviation Foundation symposium this week, it occurred to me that much of what I was hearing was simply an extension of the AUVSI event I covered earlier in the week. The lines between general aviation, manned aircraft in general and autonomous aircraft are being blurred. It’s practically at the point that whether a person is aboard whatever thing happens to be flying is either incidental or irrelevant.

One of the most interesting presentations at SAF was by Parimal Kopardekar, a NASA manager who’s neck deep in figuring out how the millions of drones that will soon choke the sky will be separated from each other and from manned aircraft. At last week’s AUVSI event, I listened to Amazon’s Gur Kimchi describe that company’s vision of how its envisioned fleet of delivery drones will be managed and separated. I remember thinking after listening to his broad-brush treatment that for all their tech savvy, these guys don’t have this figured out yet. Or if they do, they’re not able to explain it. But Kopardekar added convincing detail and after his presentation, he told me NASA has been working with Amazon (and Google, I suspect) for years to develop the strategies that will segregate manned aircraft from drones and drones from each other. It’s a complex problem and the solution, as Amazon’s Kimchi described, will have to be overlapping and collaborative. It’s wholly impractical to expect human controllers to have much of a role in this task, although they may have some. To a very large degree, the flying machines themselves will have to figure this out literally on the fly.

Kopardekar explained what he called UTM or unmanned traffic management as ultimately being cloud-based and largely autonomous and transparent to all users of the airspace. What that means is that it will be collaborative between air vehicles, whether manned or not, through sense-and-avoid technologies and onboard or cloud-based collision avoidance. What are the sense-and-avoid strategies? Good question. There are a number of technologies being tested, including laser and LIDAR-based methods and collaborative UAT-type communication between vehicles. After his presentation, I asked Kopardekar if ground-processed ADS-B would be a player. Probably not, he said. Too much spectral overload and lack of reliable reception at the low altitudes most UAS will inhabit. Segregation and “fence-in, fence-out” strategies will be part of this. It also suggests there may be some new technologies for light aircraft operating in drone-dense airspace. If Amazon’s plan comes to fruition, the airspace could be dense enough in some places to preclude visual see-and-avoid. Suffice to say it’s going to get very interesting in about three to five years.

Even if ADS-B has a secondary role here, it will have some role and some drones in some airspace will require ADS-B systems and/or transponders of some type. At AUVSI, I shot a brief video about a new startup that’s building relatively inexpensive miniaturized ADS-B units that drones can carry. But the interesting thing to me is that they’ll be targeting the experimental segment of general aviation with these devices. That’s another example of convergence in which a man (or woman) in the cockpit is immaterial to the developmental task at hand. This company will be displaying at AirVenture and in addition to the video, which I’ll get published next week, we’ll do some more coverage.

In listening to presentations at a technical symposium like this, it’s common to hear a mixed message. Researchers involved at the bleeding edge tend to assume that because they’ve eliminated–or see a way to eliminate–obvious technical barriers to a technology, it’s thus ready for commercialization. But usually, they’re not the ones doing the investment and figuring out the ROI. An example of this was a discussion of hydrogen fuel cell technology, which you can hear about in my podcast with Josef Kallo of Germany’s DLR. I think commercially practical hydrogen fuel cells are more distant than he imagines, mainly for cost and marketability factors against traditional hydrocarbon fuels, which remain abundant and relatively inexpensive.

Then there’s the infrastructure problem. The facilities to produce and distribute hydrogen will need to be built and this is a very tall order if hydrogen is to become the equivalent of gasoline. Think about how easy it is to find a gas station or even an FBO with 100LL. In another SAF presentation, NASA chief scientist Dennis Bushnell, in a soaring tour of the technological horizon, said there were no barriers to a hydrogen infrastructure. While I agree that this is true technically, there’s always the question of the Benjamins. Somebody has to convince an Exxon or a Shell (or a Google) to go big enough in hydrogen to reach critical mass and market viability. I’ll be surprised if any company sees a workable market in hydrogen distribution just based on customer preference. As I’ve said before, it will take taxation or regulation based on climate concerns to make this market appealing for the near term. Petroleum-derived fuels are still too cheap and displacing them for purely altruistic reasons strikes me as a pipe dream.

Another interesting proposal using off-the-shelf technology was given by Cris Hawkins of Hawkjet. He showed a concept vehicle that’s basically an aerodynamically low-drag pod with a pair of electric motors, a high-aspect-ratio wing and an energy-absorbing landing gear system. He calls this aircraft a V/ESTOL for Vertical/Extremely Short Take Off and Landing. Like others, Hawkins envisions an Uber-like on-demand air taxi system summoned by an app and operating entirely autonomously. Recognizing that vertical vehicles like the Velocopter I reported on at Aero require more energy for takeoff and climb than fixed-wing aircraft do, Hawkins is effectively splitting the difference, optimizing on the low drag of a high-aspect-ratio wing but giving it high-lift devices so it can get off a short runway. He thinks you’d need a bunch of pocket airparks to make it work.

Hawkins also gives these vehicles about 120 miles of range using current battery energy density. I think that’s a little optimistic if you build in the kind of margins you’d want in a commercial transportation system, which his concept is intended to be. I think you’d need twice the current energy density, something like 300 wh/kg. Battery experts tell me that’s at least 10 years off, if not closer to 20. Hybrids are another solution, of course, but I don’t know if they work in this context. He also assumed quick change battery packs as a solution to low energy density. But at Aero, Pipistrel told me that even before its Alpha Electro was fielded in large numbers, customers have said they don’t like the quick change idea and prefer to just plug the aircraft in for a recharge. Some are proposing to do the quick change robotically, but I can’t help but think there’s a limit to all this automation. It’s a big investment for what may be a tiny revenue stream.

As far as the practicality of any of these ideas, they aren’t there yet, but you can draw out the trend lines to make them viable. But … not if they have to compete with hydrocarbon fuels on a level field. Unless hydrocarbon fuels become vastly more expensive by dint of scarcity, regulation or taxation, the electrics will struggle economically for the foreseeable future, which I think is about a decade. Beyond that, the technology and economics are, in my view, certain to make them niche players at first, then a significant part of the aviation ecosystem. People who think they’ll never play a role make the mistake of assuming technology stands still and it never does. We’ll see developments we never imagined possible. Motorola’s Marty Cooper probably couldn’t have foreseen the iPhone, but it sure as hell came to pass.

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