Podcast: San Francisco To Tokyo—In One Hour!

Joe Anselmo: 

 Welcome to Aviation Week's Check Six podcast. I'm Joe Anselmo, Aviation Week's Editorial Director and Editor-in-Chief of Aviation Week and Space Technology magazine. Imagine waking up at San Francisco, flying to Tokyo for a business meeting and then being back in California in time for dinner. Pretty audacious, right? Venus Aerospace, a Houston-based startup believes such radical advances in travel aren't just science fiction. Venus's idea is to use a combination of jet engines and rocket engines to fly at Mach 9. You heard that, right? Mach 9. Traversing a distance of 5,000 miles in just one hour and flying in an altitude of 150,000 ft. So far, Venus has raised more than $40 million from investors to pursue its research, and one of its investors is a company you might've heard of: Airbus Ventures. Joining us to explain their idea are Venus CEO and Co-founder Sassy Duggleby, and Co-founder and Chief Technology Officer, Dr. Andrew Duggleby.

And joining us for a reality check is Graham Warwick, Aviation Week's Chief Technology Editor, who has covered many ventures in his 45 years as an aerospace journalist - perhaps not one just like this. Sassy, take it away. Tell us exactly what you guys are up to.

Sassy Duggleby:    

Thanks so much for having us. I feel like you nailed exactly what we're working on. So at Venus, we're commercializing a new type of rocket engine. It's called the rotating detonation rocket engine. And, at the end of the day, it truly enables super-high-speed missions. So San Francisco to Tokyo in one hour is our ultimate goal, but really we're starting with missions more for the DoD, for flight testing and multi-mission drones for the Department of Defense on our way to hopefully commercial travel.

Joe:

So you're going to start out in defense and then ultimately take this to a... I don't even know what you call it. It's not really...a jet. It's really a rocket, right?

Andrew Duggleby:      

It is a rocket plane. In fact, the easiest way to think about what we're doing is to go back in history. So 1960s, many people remember the X-1. We broke the sound barrier. Not many people remember the X-2 and not many people at all remember the X-15, because at the same time as the X-15 was flying Mach 6 and a 100,000 ft. there was a much larger program trying to get humans to the moon. But over the course of almost a decade, it did a hundred different flights. Not all of them were at Mach 6, but many, many, many times they hit Mach 6 and a 100,000 ft. So really you can frame what we're doing is just giving the X-15 an engine upgrade. We're not trying to fly necessarily any crazier. In fact, we'll back off a little bit on what they did from a temperature point of view. Flight just a little bit higher than they were capable of.

But the X-15 was one of the first reusable rocket engines and really with our detonation engine on the back of it would go Mach 9 and not Mach 6. So that's the easiest way to frame it. And by flying high as well - we fly at 150,000 ft. - it actually keeps the temperatures pretty reasonable. That's the benefit of being a rocket engine. Rockets are defined by you carry your own oxygen. And since we're carrying our own oxygen, we're not forced to have to get it from the atmosphere. If we were, we'd have to fly much lower where the air is denser, but that dense air leads to more heat, so we'll go ahead and carry our oxygen and fly high.

Sassie Duggleby

We actually joke that Top Gun Maverick's been the best marketing tool for us ever because what happens in the opening scenes - and sorry to give this away if any of your listeners haven't already seen it, shame on them. But in the opening scenes, Maverick's trying to push his vehicle to Mach 10 and as an air-breathing plane, he melts his vehicle and has to eject and then just drinks a glass of water. But that's really the difference. Are we a fast-flying jet or a slow-flying, higher-flying rocket? And that's our ultimate goal.

Joe:           

 I remember seeing that movie and remember some people in the audience laughing at the notion of him going that fast. But the X-15 is fascinating because that was 60 years ago. We actually did write about that in Aviation Week quite a bit, but it was well before my time.

Andrew:   

 Yeah, that's right. A really impressive platform. And it did many things, right. It helped us understand high-speed flight, but it also did a bunch of exoatmospheric stuff. So the vehicle itself was designed to leave the atmosphere and come back in. One thing we don't plan on doing, we don't plan on leaving the atmosphere. The vehicle that we'll fly at 150,000 ft. will maintain flight control the whole time and not have to worry about any of the other crazy maneuvers the X-15 team was doing.

Joe:        

So give or take, you're about halfway to the Karman line, right? Halfway to space?

Andrew:      

That's right. But what's fun is that at around 80,000 ft. is when really the sky goes blue to black. So you talk about the experience that people are getting right now when they go up on SpaceShipOne or Blue Origin, you're going to see curve to the Earth. You're going to get that aha! moment and we'll be doing it and getting you to the far side of the world at the same time.

Joe:           

Well, let me turn this over to someone much more qualified than me to ask these questions, Graham Warwick, and Graham, what do you think about what you're hearing?

Graham Warwick:    

Well, it's very interesting. I mean the core of this is the engine. And so as I understand it, using the rotating detonation rocket engine, the increase in efficiency that you get over a conventional rocket motor is what allows you to turn this from a rocket vehicle into an airplane-type vehicle. You can start to put on the things that make it an airplane versus just a one-way booster because you've got that additional efficiency. Can you talk a little bit about the RDRE, the rotating detonation rocket engine, and why you get that extra efficiency?

Andrew:       

Yeah, you bet. And, in fact, the best way to describe the rotating detonation rocket engine is actually to think in your mind of a rocket launch and look at that bright plume coming off the back of the engine. So next time you see a rocket launch, I want everybody to kind of shed a tear with me. What you're actually seeing is how much thermal energy we left on the table, right? Now we had extracted all of the energy we could out of it. We converted as much of that thermal energy into kinetic energy as we could in that rocket chamber. What's happening inside of a detonation engine - and the rotating part just means that the detonation wave is actually rotating around the engine. There's no actual rotating pieces. By detonating, which is just the scientific term for supersonic combustion. So when we combust supersonically, you effectively burn all that fuel and oxidizer almost instantly.

 And so you get pressure gain, or the technical term would be constant-volume combustion. What it does is it gives you a higher pressure. And so our engine, because it gets to a higher pressure, we're able to extract just 10% - maybe 15% is what some of the research has shown - more efficiency out of that thermal energy and get more thrust out of it. And it really stacks up. A 10% increase in thrust is a really big deal. And you're right, you kind of framed it well, which is rockets are pretty flimsy. Most of a rocket is 90% propellant by weight. And so we're talking about something that'll be closer to 65% propellant by weight because of that efficiency. And we fly aircraft right now that are 65% propellent by weight. So you've got room for landing gear, you've got room for jet engine engines for takeoff, you have room for safety systems.

Sassie:     

Wings.

Andrew:        

Wings. Things that keep the passengers alive. All of that is now possible. Certainly still a challenge and you might surmise there's a good ways off until we get to the point where we're flying these stargazers and even from a certification point of view we have to work with FAA to figure out what are the right safety systems to have and get all of those pieces together.

Graham:       

So where are you in the development of this technology? I mean, it's pretty new and still pretty small scale, isn't it? I mean, can you tell us where you are and then how you're going to get to where you need to get to?

Andrew:   

 That's right. Well, the first thing we did, a lot of us... Half our company comes from the rocket launch field and what you do in the rocket launch is a lot of times you're playing with cryogenic propellants. It's just liquid oxygen or maybe you're doing liquid hydrogen or liquid methane. We knew immediately that, in the world of aviation, you can't afford to freeze a valve and try again two days later. You can't afford to wait too long on the launchpad or the runway, whatever you're talking about, and then have to go back because you missed your [takeoff] point. So we knew we immediately had to get away from all of those cryogenic, -300 Fahrenheit-type fluids and get to room temperature storable. And so that took us most of the year to kind of get all of this rotating detonation working with jet fuel and then hydrogen peroxide.

So the hydrogen peroxide you have in your bathroom, that's really about 3% hydrogen peroxide, which is H202, and then the rest of it is water. This [our fuel] is all stuff that's 90% or above hydrogen peroxide. And so it's basically water with an extra oxygen molecule and we use that in the engine, but again its room temperature storable. And so it gives you that ability to land, load, go again. If you've got to sit on the taxiway because someone else is in front of you, it's okay. So that was really step one. And then from a [matter of] scale, these engines you're seeing that we've posted on videos on the internet, those are all about 8-in. engines and making about a 1,000 lb. of thrust out of those right now. And so really as the next step for us is going up in thrust and getting it up to the right kind of thrust class, and we've been able to get to the point now of having regeneratively cooled systems that we'll share with the world here pretty soon on some good videos.

Graham:  

 What size do you need to get to for a practical vehicle?

Andrew:    

 Yeah, that's a great question. So there’s a couple of key technologies if you go back in history that really enabled the rotating detonation engine to start working. One of them is 3D printing. And so there's a very natural [size] limit. Some of these larger 3D printers are 12 in. [in part size]. I think some of them are starting to push 16 in. right now. And so that kind of puts a natural size limit on us. So each one of those engines will push about 20,000-30,000 lb. of thrust. So in the end, Stargazer [our vehicle] will have multiples of these engines on it and that's good. You want the ability to turn off some of these engines - humans tend not to want to accelerate at 5Gs like satellites do. So we will keep that tame and you really want to design this thing as where everybody can come on board.

Sassie:    

 Yeah, I would actually say that's a question we get a lot in terms of do you have to be a SEAL Team Six member to ride in our vehicle? But thankfully it'll be a gentle climb. Maybe it's a little faster if you are SealTeam Six, but…

Graham:    

 You've ground tested, what's the first thing you go fly?

Andrew:    

 Yeah, we've actually been developing our own drone and vehicle system as well in order to do that. We know we had to control our own destiny. And so while we're making the engine, in parallel we've been getting into flight tests. We first made a very, very small Stargazer-like system, about 5ft., just to practice takeoff and landing in crosswinds. The shape itself is a waverider, which is a little bit nonstandard. But what we're doing with the waverider, anytime you're supersonic, you're generating a shockwave. And when you get somewhere around Mach 5, maybe it's Mach 6, the higher you get in Mach number, that shock actually gets closer and closer to the vehicle. And around Mach 5 it's actually now worth it to extend your vehicle just a little bit out and kind of touch that shockwave and it traps air because the air can't go anywhere. You actually get a little bit more lift out of the system, but it makes for a weird shape. So if you kind of look at that pencil-nose shape you're seeing on some of our videos, it's a little weird.

And so we had a big question of, well what does this do for takeoff and landing? We like it at Mach 5 and above, but what about on the runway? And so we built it, just small vehicle. It was under 55 lb. and so we were able to get permission from the FAA to go fly and we learned a lot. We crashed the first one, we celebrated, we made some adjustments and took off the next one. And then at the same time we've been developing the supersonic drones. We've got about an 8 ft. drone that we've been developing and we've gotten it so far to the point of safe separation from a carrier aircraft and we're stepping into powered flight here in the next couple of weeks. I'm excited to share that to the world. And so it's kind of building up a vehicle so that we can go fly, test it ourselves and truly demonstrate to the world, hey, what can this really start doing?

Graham:    

So that's going to be like a jet-powered flight, is that that initial... Or are you're going to fly with your engine from the beginning of it?

Andrew:

 We are.

Graham:     

 All right.

Andrew:         

Yeah, we are. So we're using existing aircraft to carry it. So we take off and carry it with a certified aircraft and then go to a range where we have permission to drop it.

Graham: 

And do you launch at the speed that you need for your engine to start or do you have to boost it a bit to get it to the speed where your engine kicks in?

Andrew:         

That's what great part about being a rocket engine. Since you carry both your fuel and your oxidizer, you don't need anything from the air.

Graham:     

Right.

Andrew:  

Yeah. So this rocket engine works at Mach 0 and works at Mach 25. So we'll drop at a Mach number that we like, that keeps us, the humans, involved in the aircraft at the safest and then launch it.

Joe:         

Speaking about those humans, I'm sure some of the listeners that heard my intro are wondering, I want to do this. When can I get a ticket? How much is it going to cost? How many passengers on this vehicle? Can you share any of those details?

Sassie:  

Yeah, so obviously we're still early in the journey. We've said from the very beginning that it would be no sooner than 2030, and 2030 is already creeping closer, right? We quit our jobs in June 2020 to go chase this dream. And then even from a price standpoint, really we want it to be similar to first class ticket prices. It's not going to be the Southwest super-cheap flight across the globe, but when you're going global, really what is your time worth? And so a lot of the early stage modeling we did, which actually allowed us to quit our jobs, was can we do this for reasonable prices? And we feel like we are driving towards that. At the end of the day, Venus does not plan on being an airline operator. Really, we want to be more the vehicle seller and then sell or lease a vehicle to an operator that then at the end of the day they get to kind of pick their prices.

Joe:       

And how many seats do you envision in the cabin? Have you looked at that?

Sassie:  

Absolutely. So the current design is about 12 passengers. As we continue to get more engine testing and get more efficiencies and learn more, we might be able to expand that a little bit. I think one of the biggest questions we always get is there going to be a bathroom on the plane? And Andrew and I have-

Andrew:   

No.

Sassie:    

 Yes. Andrew and I have arguments about that all the time. And we'll see, I think I'm going to win in the long run.

Graham:    

I'm 68. I need a bathroom even on an hour long flight.

Sassie:      

Exactly. Exactly.

Graham:   

So here's the thing, I mean I'm fascinated by rotating detonation engine technology, rocket engines, ramjet engines, and it really appears to be coming to the point where people are really beginning to pay attention. It seems like a great idea. Why not just be an engine developer? Why do you want a... A vehicle is going to present a whole host of challenges in its own right. As you've pointed out, waverider flight, cooling those leading edges, passenger safety, all that sort of stuff. Huge challenges. Why not just be an engine developer?

Anfrew: 

It's a question we get all the time. And the answer is right now as we're trying to mature this technology, you have to fly. You got to show it in action. And so what we absolutely are committed to right now is building our own vehicles so we can go demonstrate it. In the end, do we want to build engines and partner? We're open to finding the right partners that want to join us on this journey. But the one thing that's absolutely going to be true is engine-vehicle integrations are the game. And we actually were talking to aircraft manufacturer executive and we're kind of talking through this and the answer is no. I know the aircraft will look like these engines just get bolted on, but they don't. If an aircraft wanted to switch an engine, it's something on the order of a billion dollars effort. If you have a car and you want to change the engine in your car, you can't just go down to the engine mart and bolt a new one in your car.

There's all of these integrations and they all matter. And the biggest one that might surprise people, it's really all the vibrations. You might think that makes sense in your car. But no, it is absolutely true. Even in the rocket industry. You can have an engine that will wiggle in a certain way that completely destroys the rocket. You can have a rocket when it's flying through the air, wiggle in a certain way that completely destroys the engine. And so the amount of work to iron those two things out sometimes can be more expensive than just developing the engine itself. So we knew in order to show the engine, in order to show its value, we had to own all of that part. So at least all the way into the prototyping phase, we knew we wanted to go do this. And then the good news, we mentioned the front of defense work is on the way. If you have something that's small, but it's going Mach 5, it's going Mach 7, there's absolutely already value working with the Department of Defense for some of the missions they care about.

Joe:           

Andrew, you said “we”. Give us a sense of who “we” is. I know Jim Bridenstein, the former NASA administrator, is one of your advisors, but how many engineers and scientists do you have working on this project?

Andrew:    

Yeah, there was about a hundred people in terms of full-time employees and contractors working on the project right now. And yeah, as you mentioned, got a strong team of advisors helping us along the way and I think our engineers always get surprised how many people it takes to keep a business running. Yes, we have engineers, technicians, operators, pilots, but we also have accountants, purchasers and HR and all the rest of the things. Right.

Sassie       

Absolutely.

Graham:   

You've done pretty well in raising money in what is not an easy environment for a very, very long range idea, i.e. long horizon. It sounds like the idea is resonating. I mean, what's the reaction are you getting when you go out? Are you actually seeing that people see the potential and think this is something that really could work?

Sassie:        

Absolutely. I mean, I'll be honest, fundraising is hard. It's pretty much a full-time job. It's about all I do. I feel like I tell the Venus story over and over and over again. Thankfully, I had some early coaching that even when you're fundraising, it only takes one yes. So you might pitch a hundred times, but if one person says yes and they are believers and excited about what you're doing, that's how you can grow and scale. And so I have seen the market be a lot tougher. This last year has been one of the worst markets in venture capital history, and so it's been more of a challenge to raise, but thankfully because of the technology we have and because of the team we have and because of the culture of how we're running and operating a company, we've been able to find some of the world's best investors to join us on this journey.

Andrew:      

Absolutely. And the other key thing I'll add to that is I mentioned how small our engine is and how much thrust it's already making. Well what's really cool about that, it sounds really small, but actually means we can piece together a vehicle and we can go have it go Mach 5 and it maybe is only 12 ft., so it's not a massive vehicle. So we're talking about getting all the way to a full-on tech demonstration with a small vehicle so it doesn't cost nearly as much as you might think. Like yes, eventually maybe you want to go build a bigger vehicle. And of course Stargazer eventually is enough for passengers, but it's actually a real advantage for us of just how small we can build that first real prototype.

Joe:           

 I’ve got to ask the one question. There's so much concern in aviation today about sustainability. How does this fly in the face of that? I don't assume that you're basing this in sustainable aviation fuel.

Andrew:    

 Well, what's really great about this engine, I mentioned we're using hydrogen peroxide. Our fuel, most of our vehicle is actually hydrogen peroxide and not jet fuel. And so if you actually compare how much jet fuel we use and you compare that to say a Gulfstream with 12 passengers going across the Pacific, we use half the jet fuel, right?

Sassie:     

 So there is a sustainability angle

Andrew:      

Already.

Graham:    

What's hydrogen peroxide like? It doesn't sound like the nicest of chemicals, but is it emissions free when it burns or?

Andrew:       

So in the end, yeah, what's actually happening with hydrogen peroxide is it splits thermally. So once it's inside the rocket chamber and it's hot, it actually splits into steam and oxygen. What you're going to end up using is that oxygen reacts with jet fuel and then the extra steam just comes out as water.

Graham:   

 What's hydrogen peroxide like to handle on the ground?

Andrew:     

Yeah, that's a great question. So it is sort of metastable, not the best thing to handle on the ground, but that's where one of our exciting innovations happened this year. And so because we actually push it into the engine directly. What they would do in rocket uses in the past is push it over a catalyst bed. We're actually able to go increase the safety of the hydrogen peroxide on the ground by adding some extra stabilizers into the system. And so that actually means it'll be really easy to handle. It'll be very similar to handling jet fuel.

Graham:        

Interesting. The other question I had, this is purely my interest, so you need jet engines to take off and to do the initial climb and then you light the RDRE up. You don't have common flow path or anything like that. So you just close the jet engines off at some point, do you?

Andrew:    

That's right. Yeah. The technical term is cocooning, which I love because you'd have to protect the jet engine in the end. You're flying in an altitude where all the oils would boil, pieces would freeze. So yeah, you kind of cocoon off the jet engine, you make sure you're protecting it with some blankets, nitrogen, something like that. And then you got to keep it... You can't let it get too hot either, so whether part of the vehicle so-

Graham:     

Yeah. Because when you shut it down, it's hot. So you've got to be able to let it cool to a certain point and then-

Andrew:        

Let it cool. And then make sure if the outside of the vehicle is 800 Fahrenheit, you've got to make sure that the jet engine can handle that, all parts of it can handle it or make sure it stays in its comfort zone. That's right.

Graham:       

Cool. And one technical question, just my own interest. How does the nozzle work... You don't have a rocket bell at the back there. How does the nozzle work?

Andrew:     

Yeah, so you're right, you called it earlier. It is an aerospike. So what's interesting, the rocket industry has always had a sort of fascination with the aerospike. It is a system that whether you're at sea level or whether you're at really high altitudes, that your plume is able to grow in size since you're always having that optimal thrust coming out of the rocket. In the end though, when you start thinking about it from a rocket point of view, any of the performance gain in the payload to orbit was almost always offset by the extra mass in the system. So no one's ever built one. Our engine is burning in a ring of fire, right? So we actually need one anyways. This is what we end up needing to use. And so for us, it's actually then exciting that we'll get that sort of pressure matching. As we're going from sea level to 150,000 ft, we should have a rocket nozzle that adjusts to the atmosphere and absolutely will take credit and advantage from that performance and also will become the first system to really have flown in aerospike.

Joe:          

Cool. Well, I have to say, you mentioned the X-15 at the beginning and those were the days when this industry dreamed big, and it's nice to see us starting to dream big again. So thanks to both of you for joining and let's give you a quick moment to give an advertisement. You want to give our listeners your website to find out more?

Sassie:       

Sure. You can find us at www.venusaero.com and aero is A-E-R-O and also find us on Twitter or LinkedIn or all the other standard social media places.

Joe:          

Sassy, Andrew, thanks so much for taking the time to share your views and tell us a little bit about your project. That is a wrap for this week's Check 6 Podcast. A special thanks to our podcast editor in Ohio, Andrea Copley Smith. Have a great day and see you again next week for another Check 6.