As we continue to explore electrifying everything everywhere all at once, the current focus is on aviation. As discussed, the end game is batteries and biofuels, often in hybrid-electric aircraft. But we aren’t in the end game. What will the next few years look like?
I’ve spoken a few times with aerospace engineer Kevin Antcliff, formerly of NASA where he led development of the regional air mobility report and now of XWing where he is product lead for their leading autonomous freight aviation service. I also sit on the advisory board of FLIMAX, a UK firm developing an electric flight seeing and air taxi aircraft, whose rendering is at the top of this article. And I’ve spent a lot of time talking to industry leaders in this space like Anders Forslund, co-founder and CEO of Heart Aerospace, arguably the leader at present with their 30-seat hybrid electric turboprop, and the founders of Electron Aviation, focused on a four-passenger electric air taxi and light cargo offering.
So what is regional air mobility? Let’s cast our minds back a few decades. There were many more airlines flying much shorter routes between smaller airports. The airplanes were smaller and propellor driven aircraft were much more dominant than they are today.
And then the passenger aviation industry started shifting to bigger planes, bigger airports and bigger jet engines. Some of this was just economies of scale. More passengers per flight amortized the cost of expensive planes, fuel and flight crew more effectively. More passengers flowing through bigger terminals created more opportunities to sell them more duty free perfume and gadgets.
Jet engines especially became more and more efficient. At least, as long as they were flying at 38,000 feet at optimal cruising speed. Modern large diameter jet engines are miracles of engineering, turning a full 50% of their fuel’s energy into forward motion under those conditions. However, when taxiing or waiting on a runway or even taking off, it’s like pouring kerosene onto the tarmac. The economics of the engines favor longer flights.
In the USA, where so many smaller aircraft were manufactured, there was another duck through the windshield, product liability. The legal environment of the era allowed virtually unlimited liability for airframes even decades after manufacturing. Insurance costs sky rocketed, many small aircraft manufacturers went out of business and larger firms stopped making smaller aircraft.
This was recognized and Congress passed the 1994 General Aviation Rehabilitation Act or GARA, which limited airframe liability to 18 years. With GARA, smaller aircraft started being produced again, albeit in smaller numbers. The die was cast however, for passenger aviation with larger jets prevailing and few new larger turboprops supplementing the aging aircraft servicing the remaining shorter routes.
The combination meant that although there are over 5,000 airports in the United States and thousands more in Europe, under 1% of them service over 70% of passengers. Once a business model is baked in, it takes something disruptive to transform it.
And battery electric aircraft are that thing, as well as a couple of overlapping technologies. But why?
Before the regional air mobility study that Antcliff led, NASA did the Zip aviation study, which modeled out the economics of small, electric, autonomous passenger aircraft flying from small fields. The study found that the combination could drop the cost of flying to the point where it was still more expensive to fly 300 miles than to drive, but the savings in cost and driving stress would cause a massive uptick in flights.
But why are electric airplanes cheaper to fly? For the same reason that electric cars are cheaper to drive. Electric drive trains are vastly more efficient than ones that burn fuel. While the 50% efficiency of modern jet engines is amazing and modern gas turbine aviation engines see that efficiency at optimal speeds, battery electric aviation drive trains are 95% efficient. Further, they are 95% efficient or more when rolling around on runways or sitting still. Pre-flight checks with battery electric aircraft don’t need to keep the propellor turning, something that is causing confusion on small airfields the first few times electric aircraft fly there.
And the simplicity of battery electric drive trains reduces maintenance costs as well. Instead of fuel tanks, fuel pumps, fuel lines, complex engines, exhausts, radiators and lubrication systems with many, many moving parts, electrons flow along wires from a battery to an electric motor that turns the propellors, with a single moving part in the motor. This significantly reduces the duration of all maintenance and inspection activities, allowing the plane to fly more hours with less human intervention.
And simple, battery electric, fixed wing aircraft will be cheaper to certify in the future. At present they are novel, but civil aircraft certification is an n times n safety cross check, with every combination of conditions having to be validated in manufacturing and flight tests before NASA or EASA will allow passengers to be carried. With electric aircraft, there are a lot fewer n times n combinations because there are so many fewer moving parts and sub-systems.
This doesn’t apply to the urban air mobility Jetson dreams of electric vertical take off and landing aircraft by the way. They are complex, have multiple novelties and many more failure conditions, so certification is likely to be US$1.5 billion per machine, money that companies like Archer and Joby don’t have and realistic assessments of their business cases don’t support. More on that in a future article.
Battery energy density is not as significant a constraint as many have been assuming. Yes, batteries carrying the same energy as aviation fuels are much heavier than the fuels, but the efficiency cuts into that. With current energy density and smaller aircraft, ranges of over 200 miles are easily achievable. With CATL’s new condensed matter batteries, shipping this year, double that range with the same weight is viable.
But civil aviation currently requires pilots as well. That’s a more constraining factor, for now. Two additional emerging factors come into play as well, digital air traffic control and autonomous flight systems. The maturation of these three elements is projected through 2040 in a scenario I developed a couple of years ago in the chart above.
Let’s return to Xwing, Antcliff’s new professional home. That firm is operating a smaller regional cargo delivery aviation service as it works to automate flying. For now a trained pilot is always observing in the cockpit, ready to take control. But they’ve performed multiple flights from apron to apron fully under the automation’s control.
Automating aircraft flight is actually easier than automating driving to work. Airport aprons and runways are carefully controlled environments with many fewer moving vehicles, much lower speeds and no children on tricycles. Once in the air, it’s actually quite hard to hit anything except the ground. There isn’t a lot up there and there’s a lot of room in all directions to go around anything which shares airspace. Autopilots have been able to land and takeoff for a long time and big jets frequently use it, especially in low wind, low visibility circumstances. although there is still plenty of pilot involvement and oversight.
But how, you ask, does air traffic control talk to the aircraft? Right now it’s a bit Rube Goldberg, with the aircraft’s radio connected to its digital communication system relaying air traffic controllers’ voices back to a ground control station which responds and enters flight path changes into the system.
In the future, enter digital air traffic control. One of the first requirements for that is digital transponders on everything that we put into the sky. That is now a requirement even for drones. Next is a computerized system for air traffic controllers to enter flight plan changes for communication through digital communication to aircraft. The lingua franca of air traffic control will change from English to computerese, with humans overseeing the process.
When that occurs, the pilots can leave the cockpits and oversight can be from the ground. This is starting with smaller cargo aircraft flying carefully designed low-risk routes. No school yards will be overflown for years.
And so we have the emerging trifecta of much cheaper to operate and maintain smaller aircraft that will increasingly be able to fly without pilots in them, starting with cargo. That in turn unlocks the massive cost savings that will enable business models that leverage all of those airports.
Flight seeing, air taxis, light cargo deliveries and the like will flourish. And many passengers will be taking cheap electric flights for 200 to 400 miles instead of going through big airports and getting in big jets. Over time, more and more passengers will be drawn out of the hub and spoke model, which will lose the shortest, most expensive routes and be maintained for longer haul flights.
In my battery pessimistic projection, most within-continent flights will be serviced by up to 100 passenger hybrid electric turboprops which have an onboard biofuel generator solely for divert and reserve. I won’t be flying from my home in Vancouver to Miami that way, but it would be very reasonable to fly to Seattle or even San Francisco on cheaper, quieter, smaller aircraft. That’s within the range of known battery chemistries, with my bet being on silicon.
In my battery optimistic scenario, the sky is the limit, with the potential for transcontinental electric flights.
