Jetpack Aviation's David Mayman on his upcoming Speeder flying motorcycle

If somebody tells you they're building a flying motorcycle, it's probably appropriate to reply "yeah, right." But if that somebody is jetpack guru David Mayman, it's worth your while listening, because Mayman has some seriously impressive achievements under his belt.

For starters, by the age of 35 he'd already built a successful mining consultancy company in his home country of Australia, then sold it, made some smart investments in the internet sector, and retired. Very few people ever get to put themselves in that kind of position, and doubtless doors were open for Mayman to strike out into further business ventures, or simply relax into a life of luxury.

But Mayman had a dream, as well as the patience, persistence and means to make it happen. That dream was to build a jetpack – something like the one flown at the 1984 LA Olympics, but with a flight time much longer than the 30-odd seconds the original rocket belt could handle on its limited hydrogen peroxide rocket fuel. And after meeting fellow jetpack addict and engineer Nelson Tyler, the pair formed a small company called Jetpack Aviation, and flat out made it happen.

We first spoke with Mayman back in 2015, when he and the JB-9 jetpack made a spectacular public debut flying around the Statue of Liberty. Since then, JPA has built several new iterations of its personal flight device. Mayman's been gallivanting about the world making spectacular aerial appearances at air races, motor races, and wherever else a rocketman show is required. He's become FAA registered as the world's only certified jetpack trainer, and begun training civilians on how to fly the things.

Indeed, he's become one of the four superhero horsemen of a new personal flight revolution. Mayman, with his calm, methodical aviator's approach and multi-turbine jetpack, plays Buck Rogers. On the other end of the scale is Frenchman Franky Zapata, an extreme sports nut and former jet-ski champion whose turbine-powered Flyboard Air has been seen thundering across air and water throughout Europe and the US. Zapata makes a natural Green Goblin.

Then there's Richard Browning, a British martial arts master with a multi-turbine jet suit and a company called Gravity. Browning's suit places jets not only on his back, but on his arms, making him a shoo-in for Iron Man. And standing slightly apart from them all is ex-Swiss military pilot Yves Rossi, whose extraordinary Jetwing literally lets him dance with aeroplanes in the sky. It needs to be launched out of a plane, though, so while it certainly looks like an incredible experience to fly, it can't lift straight off the ground like the others.

These are indeed incredible times, and no doubt there are other inventors out there tinkering on other personal flight devices using these small jet turbines. There's the developing e-VTOL market too – effectively multicopter drones large enough to carry people, and Mayman and JPA looked seriously into building one of those, too. But while battery technology continues to struggle, the JPA team has decided to stick with jets for its next device: a flying motorcycle called the Speeder, named for the flying Biker Scout vehicles in Return of the Jedi.

We introduced the Speeder last week, and called Mayman in California to talk about the new project, and JPA's recent acceptance into the Y Combinator program. What follows is an edited transcript.

Loz: So flying motorcycles! Another new direction for you guys?

Mayman: Yeah, sort of. Every man and his dog has been getting involved in the e-VTOL world, and we looked realistically at the kind of endurance and speed that we were going to get without going hybrid. The flights end up being so short with current battery energy density that it didn't make sense.

The other thing is, we've got this great community around us, of people that really love sleek, innovative design, and the multicopter is sort of anything but that. If you look at the tech that's required these days to build an open rotor multicopter, compared to what we're doing it's relatively simple. The only question is how to make it fly longer.

So then we were talking to our military guys that we've got the jetpack development contract with. And they're asking how much longer we can fly a jetpack for, how much further, how much faster? And it's really only capped out by how much somebody can carry on their back, unless we go to turbofan engines, which are more efficient, or get into exoskeleton legs, so you can carry more fuel.

And they said "what about something you could just jump on?" And that's where the Speeder concept came from. We actually did start originally looking at the Blade Runner, the electric multirotor, for that purpose. And we sized it out, and to carry the kind of weight they were talking about, and the endurance they wanted, it ended up being a huge beast of a machine.

Loz: The Blade Runner?

That's the electric multirotor. It had the six arms and coaxial props.

Loz: I didn't realize that was called the Blade Runner.

Yeah. We actually got that name trademarked. And the Speeder as well, we just keep going for film references.

So when we looked at it, they wanted to carry between 300-500 pounds (126-237 kg) of payload, and it ends up being way, way bigger than anything you can tow behind a Bradley or a Humvee or anything like that.

So maybe we could do something with sections that could be folded out … but it just became huge. So we pitched them on the concept of a turbine VTOL that's fully stabilized. Something you can sit on, kneel on, lie on – we weren't too specific about that at that point. That got a lot of interest and a lot of traction.

So we started out just modeling how many engines it would need, what would be the fuel consumption if we had all the engines providing vertical thrust, could we gimbal them to also provide horizontal thrust for pitch and roll and yaw?

The answer to that so far is yes. We've started flying a one-third scale prototype. It's still early days. We're not 100 percent sure yet. Think about having five engines, and having them all locked to the same plane, but that plane is able to move in two dimensions – forward and aft for pitch, and sideways for roll and yaw.

Loz: So do the jets move, or do they angle?

The whole bank of engines angle. It's not just vectoring the thrust, it's vectoring the whole engine. Pretty much like how we are on the jetpacks now – when you go forward, you're pushing down on the handles, which are connected to the arms, which are connected to the engines, and that tilts the entire engine forward at the top, backward at the bottom. And you fly forward.

If you need to put all the engines together, you lock them together on one plate, and then gimbal that plate in 2D.

Loz: So obviously with the jetpacks you've got some big, heavy legs dangling down underneath where the thrust is coming from, and the weight of your legs helps you balance. Putting somebody on top of a motorcycle, you don't get that.

Exactly.

Loz: And you look at any of these electric multirotor style things, like the Hoversurf Scorpion, they've got the motors right out at each corner. You've got your thrust centralized right under the middle. How do you balance that?

OK, so here's the logic. If you have the engines distributed, out like spider legs, and you have a catastrophic failure, it's absolutely impossible to right the machine. You'll have an uncontrollable pitch or yaw moment.

The way the e-VTOL guys get around that is they have two motors, upper and lower, in a coaxial configuration. And if one fails, well, you've still got another one. But of course, if both fail, you're still going topsy turvy.

Or you can go the Volocopter route, where you have so many motors that you'd have to have a whole bank on one side fail. And possibly that's true.

But if you want to have something really small, like we do, we can't have single jets out on pods. If we had a failure it would not be recoverable. So the logic is that you cluster the engines tightly together, as closely as you can, and still have accessible air flow into each of the engines. So, then, if you lose an engine, you actually have minimal asymmetric effect. You don't get a great roll or pitch moment. You get loss of thrust.

But then what you have is the issue of, if the engines are all together in the middle, where do you put the person and the fuel? The fuel can be slung around the outside of the engines, fairly low, and that helps to keep the weight low, until you bleed off the fuel. Same with the batteries and the electronics.

But the pilot has to be on top. So the thing is literally dynamically unstable. Inherently unstable. And it has to be flown by computer. So that's what we're building. And the prototype is exactly that. The engines are clustered together, we purposely put the weight above that, and then we try to fly it.

Loz: So it's almost a bit like those rockets Elon Musk's landing lately that vector their way down.

It's exactly like any rocket. You think of a rocket taking off, it's like balancing a pencil on your finger. The only thing keeping it straight is that you're moving that finger around. Or in the case of a rocket, you're gimbaling that rocket motor inside the body. And it's the same for landing, SpaceX has them doing a suicide burn at the end, and gimbaling that to keep it straight and level.

That's exactly our concept, and that's what we're testing. It's tricky, because we can't just go to all the open source sites and download all the software that's available for the flight controllers that have been built for drones. That'd make life really simple.

But the 1/3 scale prototype is getting there, and we feel it's possible. If we have to, we can move the engines a little further apart and then gimbal them individually. That's another concept we're looking at, but hopefully it won't be necessary. Doing it this way, with all of the motors gimbaled together on the one plate, is a heck of a lot simpler.

Loz: It almost becomes a little more like what Franky Zapata's doing, except he's doing all of that manually.

Right, exactly. He's got a low center of thrust underneath him, with the engine cluster. And a high center of weight, which is his body, and he's just using weight shift and body control to manage all of that.

So instead of holding a pencil on your finger, it's maybe more like balancing on a beach ball. Ours is more akin to the rocket scenario, where we're actively moving the engines around to maintain balance. So the pilot should be able to move around on the machine, within reason, and change weight, and the engines can balance out against that.

Loz: So if it's fly by wire, and the computer's controlling what the gimbal is doing, what's your control scheme going to be like?

What controls would the pilot have? The idea at the moment is that on the pilot's left hand, they have what's effectively like a cyclic control in a helicopter. If you push forward, you're biasing the gyros that are maintaining the stability to give you pitch forward. So the engines are tilting slightly backward and you're pitching forward. And at that point you're actually losing some of the vertical component of your thrust, so you need to power up. That'll be part of the flight algorithm.

So the left stick gives you fore and aft if you push backwards and forwards. Roll would be left and right on that one stick.

Loz: Roll or yaw? This thing's going to tilt as it goes?

Yeah, if you imagine riding along on a motorcycle, and going into a corner there's a natural tilt, you don't think about it. In the Speeder, you'd move your left hand control over to the left, and the aircraft will bank to the left, very much like a helicopter would.

And then – this is one of the concepts we're still working on – but that same left hand controller might rotate in your hand for yaw. So if you twist it around to the left, you'll pirouette the aircraft to the left. So on a left hand turn, you'd push it sideways, and kind of twist it a little as well to rotate it.

Loz: You know, I'm sitting here doing that with my hand as you speak! It might be a more complex movement than just having a thumb switch on the top.

Yeah, we've thought about a little thumb twiddle thing, but we want something you can move a reasonable amount, to give you some finesse and control. The other concept we've looked at is that we could have the yaw controlled by the feet of the pilot, so if they push harder down on the left hand footpeg, the aircraft might yaw to the left.

Loz: I guess once the thing's all working dynamically and the software's sorted out, this is all fly by wire, so you guys can experiment with the control scheme until it feels good to fly.

Exactly. The big challenge is to get it stable. What we're experiencing with the test prototype, it's not so much getting it to come up and hover, it's moving to forward flight while still maintaining height, that sort of thing. We're getting there.

Loz: Yes, going back to the pencil on the finger idea, as soon as you start trying to move that, it gets a lot more difficult than just balancing it.

Yes, and just say you start moving the thing backwards, well, the fuel starts sloshing forwards. In some ways it's actually very much like a Segway, and we hope it's just as simple to fly. Talking to the guys in the military, in the end, the plan would be that you could literally say to somebody "ok, this control does this, this control does that, see you later."

And just like the Airbus won't let you drive it into the ground, or it shouldn't, you have a protective envelope, anybody should be able to jump on it, and away you go.

So the right hand control will be your thrust, or your power level basically.

Loz: So that'll be a lever, not something like a motorbike throttle.

At the moment we're thinking of it as something vertical, like it is on the jet pack. It's a motorcycle throttle, but it's tilted to sit vertically rather than horizontal.

Loz: A little like the collective on a helicopter.

Yeah, exactly, on the left-hand side is your cyclic, on the right is your collective, it's the reverse if you're a helicopter pilot, but there you go.

That advantage to having it fly by wire is that you can have it flown autonomously as well. Some of the use cases and missions that we're looking at for the military are, for instance, medevac missions, where you might put a bed on it. It may not be able to fly as fast, it's aerodynamically limited compared to the piloted version.

But if you could just download your position, and literally tell the thing to fly autonomously from this spot to this spot … at the moment, if they put a Black Hawk helicopter in for medevac, they risk the Black Hawk itself, then there's the crew on board. Helicopters are very easy targets for RPGs or even small arms fire.

These things can be flown in potentially faster than a Black Hawk, they can do higher air speeds than a Black Hawk, and they can swarm. If you have four people that need to be picked up, you can send four of these in.

That's the concept. We're not there yet, and we've got work to do before we can have them self-separate and all of that kind of stuff. But once we solve the first problem of stabilization, a lot of it gets easier.

Loz: And you're only going to build 20 for the public, is that right?

At this stage, yes. It's a limited edition. The focus is on the US Navy contract we've got. That's what really drove the Speeder specs.

Loz: Well, it's time for you guys to spin some cash out of this business so you can keep on going with the stuff you really want to do in personal flight.

Right. Yep. And just in case we get our pricing wrong as well, I didn't want to take orders for thousands of these things and then find out they cost a lot more money than we thought.

Loz: So you've taken this particular idea to Y Combinator, is that how that works?

Yeah. Through the application process, there are 12,000 applications and I think they accepted about 200. A one point something percent success rate. Basically, what we showed them was our 1/3 scale prototype, and our development plans for it. We showed them what we've done with the jetpack, we showed them what the processes were in terms of technology, and what the guts were.

And they got us on board, brought us into the program. And it's been a bit of an eye opener! We're not the typical Y Combinator Company. We're not mid-20s MIT Ph.Ds. We're pretty hardcore into the hardware. But they love it, it's a pretty amazing experience for us really, just refining what the business case is, who will be interested, how big could it be, what we could achieve if we could raise this or that level of capital, where could we be in five years, et cetera.

Loz: Yeah, I guess you guys have been laboring away by yourselves more or less, for the last … how long have you been at it with JPA?

Oh, a long time. Even before we technically formed JPA, we were designing concepts and whatnot. We've been at it in some form or another since 2008 or something.

It's a complete change of direction to being head down, in the workshop, hands on tools and building these things all the time. We now have the opportunity to work on the business, and really gear up to do what you've dreamed of.

On one hand, it's kind of surreal, but on the other hand it feels kind of right because I honestly believe it can be done. I honestly believe that one day, we'll have flying cars. And if we have flying cars, why not flying motorcycles? They both fill a certain mission card. This will happen. If you look at how much money's being spent on e-VTOL at the moment, it's billions of dollars.

But everyone else is focusing on flying cars. So we're going to focus on flying motorcycles.

Loz: Just going back to the Y Combinator thing, obviously you've got a lot of business success behind you in your past life in mining, and with True Local (an online directory for Australian businesses) and whatever else you were up to before you became the jetpack guy. And it's kind of cool that you're willing to go back to school and learn to suck eggs again in the new economy.

I know mate! And we've got a couple of other Aussies in the program as well. I'm definitely one of the crustier ones! But I am willing to learn. I'm not American. I didn't grow up in Silicon Valley. And there's a particular way that they think, and that they do business here. There really is.

And there's some really smart money there for futuristic moon shot type ventures like this. But you have to learn how to approach it. How to look at your technology, look at your business, and how to explain it. It's really tricky.

Loz: I imagine it's also great for making contacts with other innovators.

Yeah. They have a huge number of alumni, maybe 4,000 founders who have been through the program now, and you have access to all of them through the program. And everyone's super helpful to one another, because we're all going through the same thing.

We've been at it for a long time, we've achieved a reasonable amount, particularly considering how much we've had to invest. I think if Lockheed had set out to achieve what we've achieved, they would probably have thrown a hundred million at it.

You've met me, you know what I'm like. I'm happy to stand out back being the hands-on engineer, nitty gritty, turning the wrenches, which is what I've been doing for years.

This is forcing me to stand back and say OK, how could these really be used, not in one year, but in five years, 10 years? What are the use cases? Who would use them? What would it take to prove that up? What's the likely path to certification? I'm enjoying that, but I also love getting my hands dirty.

Loz: How long does the Y Combinator program last?

Three months.

Loz: Fairly intensive?

You basically dedicate those three months to being up in Silicon Valley. Obviously I need to travel to meet up with vendors, and our engine guys, and some of our sponsors from time to time, but they really ask you to be in the Bay Area. We started on the 3rd of January, and it wraps up in late March.

Loz: Back on the Speeder itself, a couple of things – is there any kind of seat belt arrangement to keep people on top of it? And what are you going to do about the failsafe stuff?

The 64-million-dollar question! With the seatbelt, we're looking at two options. One is a harness system. You wouldn't see it from the back or the side. It's a clip that goes from the pilot's belt down to the airframe. The machine is designed to be flown in a way that you're not doing aerobatics. It won't let you do negative Gs, so it's not technically possible for you to fly off the back – you should always be at 1G. So you'll have a central point that locks you onto the airframe, with a belt latch.

On the safety side of things, we're looking at two things. Initially we're looking at a simple ballistic parachute system. One for the pilot, one for the Speeder. There'll be a pyrotechnic cutter that'll cut that belt strap, so the pilot will be free to exit the Speeder. The ballistic parachutes will go through a sequence and then would open.

To keep the regulators happy, the aircraft will also have a drogue chute to bring it down. That's all good and well as we know, when you're above the red zone at X height.

Loz: Is that red zone still around a hundred feet (30 m)?

Well it's about that for just the pilot. Because now we're just saving a pilot, not a pilot and a jetpack, which is what we've been looking at in the past, and it's a larger weight so it needs a bigger chute, which takes longer to extract.

The Speeder is a lot heavier than the jetpack. So if it's going to come down at an acceptable decent rate, it's going to need to start from higher. It's not as crucial as the pilot, obviously.

The next thing is – and a lot of the e-VTOL guys will tell you the same thing – is redundancy. And we can definitely do that. With five engines, depending on your fuel state, you can lose one of them, and still come down very nicely balanced in terms of attitude and descent rate, and land.

If you lost two of them, you could still come down in a balanced way, and perhaps at the speed of, say, a regular square parachute landing – five or six meters a second. More engines failing than that would be classified as a catastrophic failure. If you're above the red zone, you're firing a parachute. If you're below the red zone, that's the 64-million-dollar question that we're working on. And at this point I have to be very careful about what I can and can't tell you!

Clearly, if we set out to solve this, it's not the sort of thing that can be solved for a couple of million dollars. If we're successful in raising capital now, then going to that ultimate safety solution may be after a Series A or a Series B round.

Loz: Well, thanks for your time, it's always great to catch up.

Cheers Loz, I like chatting with you, and I do shoot it straight with you – you can't always with everybody. And people might think what we're doing is odd, but I do really love this stuff. In my lifetime, I want to see this stuff happen.

Loz: Well, you've put yourself in a position with your previous business pursuits where you could've done anything you wanted. You could've lived in the mountains, or had a fleet of supercars, or whatever. But it's obvious, this is the dream, it's what you're putting all your time into. And I totally respect that. I think it's terrific.

Thanks, yeah. And there will be little pivots from time to time, as we work out this is better than that, or we should spend more time on this.

I was always kind of apologetic about turbojets. But the real position at the moment in the marketplace is that battery tech is just taking longer than everybody thought. It's not following Moore's law for computer chips. It's grinding away very slowly. So what's wrong with turbojets in the meantime? Especially if we're talking about saving lives? I don't think anyone cares too much about the noise, or if we have to use fossil fuel for that kind of mission. I think there's a place for this.

Source: Jetpack Aviation