California-based Ampaire is a startup looking to develop and certify a hybrid-electric propulsion system for the Cessna Grand Caravan. As part of that effort, it has been test flying the Eco Caravan prototype testbed since November. In a recent conversation with the AAM Report, Ampaire co-founder and CEO Kevin Noertker discussed the company’s business strategy and shared his views about advanced aviation technologies. An abridged transcript follows:

AAM Report: Why did you opt to pursue the retrofit propulsion system over a clean-sheet aircraft?

Noerkter: There are just so many factors that go into the development of any clean-sheet plane–let alone an aircraft that requires fundamentally new technology to come to market. The idea that somebody would develop a clean-sheet plane around propulsion tech that does not yet exist is concerning, and it runs the risk of that plane needing to be redesigned once they have deeper understanding of what that certifiable propulsion system actually looks like. Instead of going down that path, we decided to be more pragmatic. By starting with the propulsion system, we think of it as creating the building blocks or the operating system for electric aviation.  

So you think certifying the propulsion system is a more realistic approach?

Yes. We’ll get those systems retrofitted into Caravans and Twin Otters and King Airs and then scale it up into larger planes. Once we arrive at that point, it may actually make sense to design clean-sheet planes around concepts like distributed electric propulsion, boundary layer ingestion, ultra-STOL, eVTOL, and so on. There are a whole heap of designs that are very compelling, but in order to move from theory to actual implementation you need to be a little more than just visionary; you need to be pragmatic.

Is that pragmatic mindset also why you chose to go with a hybrid design rather than all-electric?

We’re trying to pursue baseline technologies that already exist. Originally, we thought about doing an all-electric design. But we did a detailed engineering assessment and were faced with some hard decisions when we looked at the probability of things like energy storage–specifically with lithium-ion battery improvements–and what it would take to actually achieve a fully electric plane. What we discovered is that while you can get fully electric planes to fly, they just won’t have the range to be commercially useful. So, in order to be commercially viable with technology that’s high probability to exist, we had to switch over to a hybrid-electric solution. Not only is it good for de-risking the availability of energy storage systems, but actually it’s got a lot of other really critical benefits. 

What are those benefits?

The first and foremost is about infrastructure. Hybrid-electric, in the embodiment we have at Ampaire, is a lot like a [Toyota] Prius, in that you don’t have to plug it in to charge. And so you can take off and land from any airport without worrying about whether it’s got EV plug chargers there. That is just a massive unlock opportunity that really enables anyone to adopt these planes. If you were to look at pure electric or hydrogen, for example, they’re categorically different. It’s going to be quite challenging for them to get the infrastructure that’s needed for commercial use. For early adopters, we think the unavailability of charging infrastructure or hydrogen refueling infrastructure is going to be a significant bottleneck. But also, fully electric is very short-range, and you end up losing a lot of passengers as far as revenue-generating seats you can carry in any given size plane. We’re able to maintain all those performance characteristics and even improve them with the hybrid. 

How long will it be until we see an Ampaire propulsion system on a large regional jet–or even a small mainline jet?

From a technology standpoint, we could integrate our system into an ATR today if that was the priority for us. Technology-wise, there is nothing stopping us from putting a distributed hybrid-electric propulsion system on one of those planes and getting a really cool demo–but that’s not what we’re after. I think that before you get to those larger planes, you probably want to optimize those systems around technology that’s better understood. I believe there will probably be a pathway to retrofitting larger aircraft by maybe the end of this decade, but I’d hesitate to say sooner.