Here Comes the Boom: Supersonic Startups

Starring Exosonic, Aerion, Boom, and Hermeus

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In 2011, NASA flew the Space Shuttle for the last time, and for a decade, the United States lost the ability to launch astronauts from American soil.

In 2020, SpaceX regained that ability for America, launching astronauts to the International Space Station from Cape Canaveral, Florida, and earned an astronomical $100 billion valuation in the months that followed.

I got irrationally excited a few weeks ago when I realized that the same pattern might be playing out in the supersonic aircraft space.

In 2003, the Concorde made its final flight, and for nearly two decades, the world has had no active commercial supersonic jets.

But now, in 2021, there is a flurry of activity in supersonic travel: four companies with four very different approaches to the market are vying for dominance. All four have impressive investors and experienced teams. Which one will win? And might they become the next SpaceX?

I decided to dive into the industry to try to find out — and to show you what markets look like in the early innings, before winners are chosen, and when venture capital investors in Silicon Valley have to make their bets.

Challenger #1: Supersonic, Hold the Boom

To understand what makes this first startup so cool, we’ll need to start with Supersonic Physics for Dummies. (Written by a Dummy.)

Any object moving faster than the speed of sound creates a shockwave known as a “sonic boom.” You know that these booms are loud — about ten times louder than thunder — but you might not know what they look like.

Sonic booms are not one time events, so supersonic planes drag a “carpet” of boom-ness over the ground wherever they go. Regulators realized this while the Concorde was in development back in the ‘60s, and banned supersonic travel over land to protect the eardrums of the general public. Those bans are still in place today, which means that supersonic flight was, and still is, only allowed over the ocean.

A loophole, however, might be found in “low-boom,” the ability to fly supersonic while generating a quieter “thump” on the ground.

Starting in 2018, NASA kicked off the X-59 Quiet Supersonic Technology program with Lockheed Martin to smooth out the edges of booms by meticulously shaping a supersonic aircraft. The program hopes to prove that low-boom is possible, and to kick the regulators’ butts into gear. (Luckily, the latter effort seems to be working!)

Another positive externality of the program has been the creation of Exosonic, a startup building a low-boom passenger jet.

Exosonic was founded in 2019 and funded by Y Combinator. They’re still in the “a team and a dream” phase of their startup journey, but their traction to date has been impressive. Exosonic secured one of three awards from the U.S. Air Force (alongside Boom Supersonic and Hermeus, both covered below) as a potential vendor for “executive transport” aircraft.

Their team is also quite impressive. Norris Tie, the Founder and CEO of Exosonic, is the perfect guy to start a low-boom supersonic startup: a propulsion engineer, a life-long lover of high-speed vehicles, an MBA, and an alum of the X-59 program at Lockheed.

I had a chance to talk to Norris while writing this piece, and asked him what made him leave Lockheed to start Exosonic. His answer was great:

Well, I had already applied to business school when I started at Lockheed Martin, and when I got accepted, I wasn’t going to say no to Stanford.

Near the end of my tenure at Lockheed, I got invited to a happy hour. Most folks already knew I was leaving, and one of the Business Development guys said, “Hey, Norris, I hear you’re thinking of starting your own company.”

I replied yes, I really want to help bring about commercial supersonic transportation, and the guy responded, “isn’t that what we’re doing here?”

I said, “Well, let me ask you this: do you think I could be a Program Manager here at age 28?” And he said, “Well, you’d probably have to wait until you’re at least 35…”

And I said that gave him his answer right there.

(Talk about being impatient about building the future!)

Challenger #2: Business Jet, Boomless Cruise

Aerion Supersonic is the OG. Funded by the Bass family, Aerion has been pursuing the supersonic dream since 2003, and they’re now gearing up to massively expand their production capabilities to churn out aircraft. They haven’t yet flown a jet — none of these companies have — but they are debatably the furthest along of the bunch. They also recently solidified a partnership with Boeing, which gives them resources (people, cash, relationships) to pursue their unique strategy:

  1. They are building business jets, not passenger jets: think Gulfstream, not 747. This is a non-trivial difference, as Aerion will presumably sell these jets directly to rich people and enterprises, rather than to airlines. It also means their planes need to fit just 8-10 passengers, rather than the 50+ necessary for a passenger plane.

  2. Aerion is developing a “boomless cruise” technology to fly supersonic over land. This is different from “low boom,” as it’s more of a concept of operations than a change to the shape of the vehicle. Aerion jets will fly higher and slower, around Mach 1 to 1.2, to avoid creating a loud boom. (Apparently, this is only possible if weather conditions create a deflector shield, off of which the boom can bounce before it gets to the ground. Yeah, I don’t really get it either.)

Challenger #3: The Hype Machine

Boom Supersonic’s meteoric rise has been both unbelievable and inspiring.

Blake Scholl was the founder of Kiva Labs, an eCommerce startup that was acquired by Groupon in 2012. After two years in his new, post-acquisition role, he took the logical next step: founding a supersonic jet company.

The inspiring part is that it worked. Through sheer will, intelligence, and his undeniable skill for building hype, Blake has grown Boom from an idea to a billion-dollar company in seven years. Boom was part of the Winter 2016 class of Y Combinator, and has now secured 30 pre-orders for its aircraft: 10 from Virgin Group, and 20 from Japan Airlines (the latter of which invested $10 million in Boom alongside their order).

If you want to understand what a Silicon Valley Hype Machine looks like when operating in full force, look no further than Boom’s unveiling of their XB-1 demonstrator vehicle. It has everything: sexy hardware, a noble mission, and a ridiculously-high-production-value video.

Challenger #4: Super-Supersonic

Hermeus has a lot in common with the other names on this list. They’re building speedy passenger jets and they won the Air Force award. But there’s one big difference: Hermeus wants to go hypersonic, not supersonic.

Hermeus is targeting Mach 5. That’s five times the speed of sound (~6,100 kilometers per hour), or roughly one mile per second, about twice as fast as the world’s next-fastest operational aircraft (the SR-71 Blackbird, the top-right dot below). You certainly can’t fault the team for lacking ambition!

The wild part is that the Hermeus team might just be able to make it happen. In nine months, they built a Mach 5 demonstrator engine — which is a lightspeed development timeline in the aero world — and after a fresh round of fundraising, they’re building a full-scale engine.

I had a chance to talk to their Founder and Chief Product Officer, Mike Smayda, while preparing this piece, and he said:

At this point, it’s a lot of engineering. Not science. We don’t need to invent anything new.

The component technologies are sufficiently mature to build hypersonic aircraft. High-temperature materials are commercially available. Ramjets have been flying since the 1950s.

Last year we demonstrated that we can design and build such an engine.

🔮 What happens from here?

Imagine, for a second, that you’re a venture capital investor diving deep into the supersonic space. In which of the four teams above would you invest?

Do you prefer the long history of the Aerion team, or the hype machine that Boom has built? How fast is fast enough? Will low-boom work? How will the FAA regulate supersonic aircraft? Which of these teams will actually succeed in building a supersonic jet? If they do, how big will the market be?

In researching this piece, I’ve only barely scratched the surface of the complex dynamics of the airline industry — if I was still a VC Associate, I’d plot the schedule performance of these companies over time (meaning, checking that their years-to-launch have actually gone down over time, far from given in a hardware schedule!), and dig into the economics of the pitches they’re all making to their end customers.

For now, all I feel comfortable predicting is that every company that makes it to market with a working, safe, supersonic aircraft before 2030 will become a $5+ billion company.

Yes, this is an easy prediction, considering Boom is a billion-dollar company and still 4-6 years from flying a jet — but the fact that it’s easy to make is illustrative of why investors love the supersonic jet industry!

That said, making it to market will be incredibly challenging. Building something nobody has ever built before is hard. Employing highly-talented and highly-compensated engineers for a decade without revenue is hard. Keeping the hype train going without obvious interim milestones is hard.

It’ll be exciting to watch these companies do battle over the next decade. I’m rooting for all of them.