# eVTOL design starts with a battery energy constraint

Markdown copy of https://realalpha.app/s/evtol-design-starts-with-a-battery-energy-constraint/ on Real Alpha, the best minutes from long interviews with the people building AI. Cite and link the page, not this copy.

- Speaker: [Brett Adcock](https://realalpha.app/builders/brett-adcock/) · Brett Adcock is founder and CEO of Figure. · Founded Figure AI to build general-purpose humanoid robots; previously co-founded Archer Aviation and Vettery.
- Host: [Shawn Ryan](https://realalpha.app/people/shawn-ryan/) · Host, The Shawn Ryan Show
- Show: The Shawn Ryan Show
- Episode: [Brett Adcock - Shawn Ryan’s First Interview with a Robot | SRS #292](https://realalpha.app/v/99pOdGEGu6s/), Mar 30, 2026
- Moment: 28:44 to 35:17 of the episode (7 min), playing on https://realalpha.app/s/evtol-design-starts-with-a-battery-energy-constraint/; the episode from there: https://realalpha.app/v/99pOdGEGu6s/?t=1724

## Quote

> “In electric aircraft, the problem you're starting with is you have like **1 30th of the energy** as you do in kerosene in a battery pack.”
> — [Brett Adcock](https://realalpha.app/builders/brett-adcock/) at [30:54](https://realalpha.app/v/99pOdGEGu6s/?t=1854) · The Shawn Ryan Show

## Takeaways

1. He studied electrification, rotorcraft and fixed-wing aerodynamics from scratch.
2. He says batteries hold roughly 1/30 the energy of kerosene.
3. Small electric motors allow more rotors and greater redundancy.

## About this segment

Brett Adcock explains how he taught himself aviation and why battery energy shaped Archer’s aircraft design. That constraint drove trade-offs around rotor size, motor efficiency and redundancy.

From “Brett Adcock - Shawn Ryan’s First Interview with a Robot | SRS #292”, Mar 30, 2026. [Watch the full episode](https://realalpha.app/v/99pOdGEGu6s/)

## Transcript

Transcribed by machine (Whisper) from the episode’s audio, so a word may be off here and there.

[28:52](https://realalpha.app/v/99pOdGEGu6s/?t=1732) I know you just sold your business for $110 million, but where do you get the confidence to go, I'm going to build vertical takeoff and landing flying cars now? I mean, listen, I didn't wake up to this world learning how to build software. So I learned how to do that and run engineering and run the company. And there was a lot of through trial and error. um and uh i just felt like i just felt like i could learn it i started uh uh in industrial system engineering at university of florida so um and then you know ran engineering and ran the company at vetery uh so i basically just hit the books i tried to learn as much as possible about three subject areas first was like electrification which like you know at the time like electric vehicles were really doing well, and even drones.

[29:44](https://realalpha.app/v/99pOdGEGu6s/?t=1784) Vertical takeoff and landing, like vertical lift, which is like traditional rotorcraft or helicopter. And the third is like winged aircraft, like airplanes. You really need wings. So you basically have to learn about those three subjects. So I basically bought my basement downstairs at home, where there's every possible book on these subjects you could match in, and started reading as much as I possibly could.

[30:04](https://realalpha.app/v/99pOdGEGu6s/?t=1804) And this was during the year transition. As I was transitioning out of Vettery into Archer, I was reading every possible thing. And then I found a small community of folks that were like hosting, uh, onsite, uh, like either half week or week long courses for this. Um, and so I would go to these, sometimes they're sponsored by NASA or by colleges or whatever it would be on like basically rotorcraft or electric propulsion.

[30:26](https://realalpha.app/v/99pOdGEGu6s/?t=1826) or winged aircraft aerodynamics and I would basically like try to like like learn as much as possible. It got to the point where I was like completely obsessed with this algorithm I was building on electric aircraft sizing. Like how how do you actually like how would you actually build an electric aircraft? So electric aircraft which interesting is like in rotorcraft like you basically want to make to create the most efficient lifting device possible. You need as much of like as the rotor disc area like in terms of surface area as you possibly can. That's why the helicopter rotors are so large. We want that to be really large. That'll reduce power and get you up off the ground. In electric aircraft, the problem you're starting with is you have like 1 30th of the energy as you do in kerosene in a battery pack. So you're just like you're off the

[31:11](https://realalpha.app/v/99pOdGEGu6s/?t=1871) bat of 1 30th less range or 1 30th less energy. And so power becomes like the dominating factor of how to basically build electric aircraft. Like, how do you get power down as much as possible? You really want a lot of disk area. A lot of disk area is, well, one, it could be good for power, but it's also bad because you have no redundancy in the system. You have one rotor blade. If it doesn't go well, you go down.

[31:37](https://realalpha.app/v/99pOdGEGu6s/?t=1897) With electrification, you can basically build much smaller, like, basically, rotors and be able to fully electric. And the reason you can't do that with traditional kind of like turbo fans or engines is it gets too inefficient at these sizes. You can't build 12 like propellers on a helicopter. The efficiency just drops like to nothing. So with electrification, you can. You can size down electric motors to small sizes and they're still 90% efficient.

[32:04](https://realalpha.app/v/99pOdGEGu6s/?t=1924) So like small electric motor on the table or a big one the size of your chair, same efficiency. When you do that, you create a lot of redundancy across the system. So you can build like an aircraft with 12 electric motors. So the rotors are underneath? Are they underneath? The problem here is you can design it however you want. You can put a bunch of rotors along the wings. You can put them laterally across the fuselage.

[32:27](https://realalpha.app/v/99pOdGEGu6s/?t=1947) You can make one big one. You can make 30 small ones. So how do you design it? That's the problem I hit in 2018, was how do you actually do this? And so it basically was like a crazy man trying to design this algorithm to what is the ideal aircraft design? design, and then how do I go build it? So I was actually at a Hyatt Regency Hotel in Atlanta in 2018. It was an electric propulsion week-long design course and like an aerodynamics course for winged aircraft. And I met a guy there that was basically in the engineering department at University of Florida. He was doing his PhD in aerospace and I asked him what he was doing there. And he's like, I'm from University of Florida. I was like, oh, I went to school there as well. And he's like, I'm like, what are you doing here? He's like, oh, I want to go like do a career in E-VTOL aircraft. And it's called electric vertical

[33:21](https://realalpha.app/v/99pOdGEGu6s/?t=2001) takeoff and landing. So, you know, a helicopter is a VTOL and you put a little E in front, it's over electric. And he's like, I asked me what I'm doing here. I was like, oh, I'm starting a company to do this and I need to figure out how to go build these things. And he's like, well, listen, my professor runs a small drone lab. He's got a full building. He's got 12 PhDs. why don't you come down and like meet him and see if you can start building aircraft with him so i flew down that weekend to go meet um his professor that runs all of basically mechanical engineering aerospace and uh long story short is i ended up taking over like his lab and um and me and him and his team started building aircraft in 2018 and 2019 down at university of florida and i temporarily moved down there with my my daughter at the time and my wife

[34:04](https://realalpha.app/v/99pOdGEGu6s/?t=2044) living in Gainesville, Florida, like, um, and, um, and it was great. Like we ended up building, I ended up funding a lab, uh, right off of Archer road, a new lab, cause we needed more space. I mean, I'm calling the business Archer aviation is the main road down of university of Florida. And I spent the next like year, year and a half, basically like, um, modeling and ...holding electric eVTOL aircraft.

[34:27](https://realalpha.app/v/99pOdGEGu6s/?t=2067) Holy shit. Yeah, and it was a great time in my life. And the problem is there was no intersection of folks that knew electric, new rotorcraft, or new airplanes. There was no Venn diagram of overlap. Gotcha. So there was nobody in the world that understood how this all stuff works. So I had to go from scratch, like learn it, from first principles. And then ended up moving the company out to California basically a few years into the business.

[34:56](https://realalpha.app/v/99pOdGEGu6s/?t=2096) And then, you know, things took off from there. We, like, built bigger aircraft. I took the company public within three years of starting it. We're a $6 billion publicly traded company today. And, yeah, designed basically, like, now four or five generations of aircraft at Archer.