Honey, I shrunk the world

“I just want to fly a fast plane.”

Inside today’s Diary:

• Supersonic’s dark horse

• The innovation famine

• A new chameleon jet engine

• Priced like Southwest

• Broadband for bodies

Down a dank and narrow back alley in San Francisco, Ian Brooke and a team of fewer than ten are quietly rebuilding the future of flight.

As a Rational Optimist Society member, you know all about Boom Supersonic. It’s the best known and best-funded supersonic jet startup.

Now it’s time to meet the dark horse in the supersonic race: Astro Mechanica. It just raised $27 million to build a totally different type of supersonic jet. Congrats guys.

The day I met with Astro Mechanica, a few well-pressed executives from jet engine giant Pratt & Whitney had flown in from Connecticut. In contrast, the office is a skunk works. Engineers in t-shirts and jeans, metal shavings everywhere, parts lying around.

The history of flight was meeting the future.

You board a plane in New York at 10am and land in Los Angeles at 9am.

A literal time machine.

That’s the promise of supersonic flight. It sounds so… futuristic. Yet the Concorde did it in the 1970s, ferrying business elites from New York to London in 3.5 hours. Then in 1973, the FAA banned supersonic flight over US land due to sonic boom noise. Well, that’s the official reason.

The truth is Concorde was a joint effort between the Brits and French. When Boeing couldn’t get its act together to build a supersonic jet, US regulators clipped the wings of its European competitors.

Since then we've existed in a self-imposed slow lane. We learned to fly faster than the speed of sound before we had email. Yet the metal tubes we board today fly slower than their 1970s counterparts.

Your honour, I present to you Exhibit 1 in Rational Optimists vs. The Innovation Famine. The blue X hints at our cruising speed potential. The yellow line is our slow reality.

Concorde last flew in 2003. The most advanced airliner ever built now sits in museums. That should bother you. It bothers me. It reminds us progress isn't inevitable.

Concorde was far from perfect. It burned two tons of fuel just taxiing to the runway. It was inefficient, expensive, and born more of political will than market demand. It flew for 27 years and was never once improved. But instead of iterating and solving its problems, we gave up.

Good news. The innovators are back. And this time, they’re building smarter, cleaner, quieter, and cheaper.

Meet the anti-Boeing

When I visited Astro Mechanica’s workshop, founder Ian Brooke shared a story that illustrates his philosophy of building fast machines, fast:

A pottery teacher divided his class into two groups. One would be graded on the quantity of pots they produced, the other on the quality. At the end of the term the best pots all came from the quantity group. While the quality group theorized and talked, the quantity group learned by doing.

That’s Astro Mechanica in a nutshell. It’s the antithesis of the decades-long, committee-driven process suffocating legacy aerospace. Boeing’s last major “new” plane first flew in 2009. Talk about an innovation wasteland.

Ian earned his pilot's license at 17 and admits his core motivation is simple: “I just want to fly a fast plane.” Ian is part aerospace engineer, part artist, part hacker. His small team of engineers build, test, learn, and repeat. They get more done in a month than Boeing does in 5 years.

I got to see its rapid iteration with my own eyes.

• Gen 1 engine: Proved electric compression could produce supersonic exhaust.

• Gen 2 engine: Validated efficient subsonic performance.

• Gen 3 engine: Combines both into a single system, now hot-fire testing.

Look at the improvement from Gen 1 to Gen 3:

Astro Mechanica's Gen 1 and Gen 3

All that innovation in less time than it takes Boeing to update a tray table.

Imagine Tokyo being four hours from New York. Now imagine your ticket cost no more than a seat in coach today. And you take off not from a mega-airport, but a private airfield near your home.

That’s the awesome future Astro Mechanica is building.

As my colleague David Galland explored in his excellent deep dive, The Near-Term Future of Flight, Astro Mechanica’s approach is radically different than most supersonic startups.

It’s starting with the engine because planes are built around engines. Its breakthrough: the turboelectric adaptive engine is part jet, part electric fan, part rocket.

Instead of one-speed-fits-all design like traditional jet engines, Astro’s engine is a chameleon. For takeoff and landing it behaves like an efficient turbofan, sipping fuel. When it goes supersonic it morphs into a powerful ramjet. To potentially go hypersonic (5 times the speed of sound!) in the future, it transitions into a rocket-like mode with no moving parts.

Think of it like the most sophisticated automatic transmission. “Planes are stuck in the Stone Age. We want to bring them into the future,” Ian says.

The innovation that excites me even more is how Astro makes its engine go vroom.

Today’s jets burn kerosene. When you see a fuel truck pumping into a wing, that’s kerosene.

Now picture an extremely cold, clear liquid that would instantly freeze your finger if you touched it. That's liquefied natural gas (LNG), which is cooled to about -260°F. At this temperature, the gas shrinks and becomes a liquid that can be transported.

LNG = supersonic fuel. Whether you care about flying fast or saving the planet (or both), you’ll love LNG. It:

• Offers 60% more range than Concorde had with the same amount of fuel.

• Burns 30% less CO₂ than regular jet fuel.

• Costs about one-tenth as much as kerosene.

• Can be made from sunlight, water, and air. (Not a typo. This is what my friend Casey Handmer, founder of Terraform Industries, is building.)

I asked Ian:

If LNG is so awesome, why don’t Boeing and Airbus use it?

"Because redesigning for LNG would cost tens of billions."

Unlike legacy aviation companies wedded to kerosene, Astro Mechanica is designing its engines from the get-go to run on better, cheaper, cleaner fuel.

This isn’t environmentalism for its own sake, though the planet will thank us. It’s pure, ruthless economics.

“Isn’t that just a toy for rich people?”

That’s what J.P. Morgan reportedly said to Henry Ford when Ford showed him the first Model T. It’s also the main pushback people give me when I pitch them, like an overfriendly golden retriever wanting to play ball, on supersonic flight.

Ian emphasizes supersonic “is not interesting if it’s not affordable.” The goal is: "Everyone gets to fly supersonic, priced like Southwest. San Francisco to Tokyo, Mach 2+, for under a thousand bucks.”

The specific numbers will evolve. But this is pure rational optimism in action: Leveraging innovation to turn elite toys into mass flourishing.

How will Astro Mechanica achieve this? Cheap LNG is one pillar. Efficient engines are another. The third pillar is blowing up the entire 1950s airline model and reimagining how we fly. Ian’s vision is basically Uber, for the skies.

That means:

On-Demand Flights: Forget fixed schedules. Book flights when you need them like you’d hail a ride.

Smaller Airports: Utilize thousands of underused regional and private airfields, bypassing the cattle-call congestion of major hubs. Closer to home, faster ground time.

More Jets: Small, private-jet sized supersonic aircraft dispatched dynamically based on demand. No more flying empty seats across oceans. Ian says: “There aren’t that many planes in the world today.”

Suddenly, the economics work. Small planes, cheap fuel, efficient engines, point-to-point travel, anywhere on Earth. It’s faster, cleaner, cheaper, and more human.

I’m going to fix it

Many great business ideas, and trillions in wealth, have been born from thinking, “That sucks, I’m going to fix it.”

Redeye flights really suck. I’ve lost track of the sleep I’ve missed squished into a metal tube flying home from America. Stumbling off red-eyes feeling like a zombie, arriving home to three kids jumping all over you. Fun!

I just want a world where you can fly anywhere in single digit hours. Is that too much to ask? Thankfully Astro Mechanica is working to make my dreams a reality. Ian says,“We can go everywhere three times faster and at the same price.”

Supersonic flight might be the most underrated innovation of our time. Change the speed of travel and you reshape the world.

Humans consistently spend about an hour traveling daily (see Marchetti's Constant). When speed increases, we travel farther. Draw a circle that defines where you can go in one hour. Now imagine expanding it to continents. Sydney in 4 hours, not 15, makes your world radically bigger.

Supersonic travel is broadband for bodies. Faster travel, just like faster internet, unlocks whole new industries and opportunities we can't even fathom yet.

Pop quiz: When Uber first launched in San Francisco what share of the black cab market did it control within a year? Answer…

300%.

By making it easier to book a limo (Uber’s initial business model), Uber didn’t just steal market share. It tripled the market! Supersonic will do the same for travel.

Where will you go when you can fly anywhere twice as fast? New York for a meeting, back in London to tuck your kids in. Sign me up!

Jets transformed Hawaii from a distant paradise to a vacation hotspot, multiplying tourism six-fold in the 1960s by cutting travel time in half. Supersonic travel could create the same revolution for farther destinations.

Imagine a buddy texting you on a Friday morning: “Sydney for the weekend?” Seriously.

66 years separate these two photos

The Wright Brothers first sputtered into the air in 1903. Concorde took flight in 1969. From Kitty Hawk to Mach 2 in a lifetime.

We are now over 50 years removed from Concorde's debut. Imagine where we could be if ambition hadn't stalled. Zipping around the world many times faster than the speed of sound? Likely.

In an era where America’s former industrial champions like Boeing are mired in bureaucratic decline (doors falling off mid-air!), Astro Mechanica is reviving the golden age of aviation. Founder-led vision. Hands-on building. Audacious goals. This is the innovation feast we've been starved for.

I keep thinking back to visiting Ian and seeing the three “suits” from Pratt & Whitney. To be clear, Pratt & Whitney makes unbelievably good jet engines. Guys I’m very grateful for all your hard work so I don’t have to worry about dying on an airplane!

But they’re optimizers, not innovators. Same deal with Boeing. A once great company now run by accountants. Boeing doesn’t even build airplanes anymore. It pretty much buys parts off dozens of companies and stitches them together. It’s less aircraft manufacturer and more coordinator with a logo.

The Rational Optimist Society exists because we believe our best days are ahead.

Astro Mechanica is making it happen. Build the engine. Launch the plane. Shrink the world.

Ian and his team have successfully demoed their full size turboelectric adaptive engine. Now they’ve raised $27 million to go build a supersonic jet.

As Ian said to me:

“It’s airplane time.”

I can’t wait to see it fly.

Did you hear the good climate news?

By Dan Steinhart

The New York Post published a surprising story this week. After ~20 years of shrinkage, the Antarctic ice sheet expanded by 108 gigatons/year from 2021-2023. The study was derived from NASA satellite data and performed by Chinese scientists. No one disputes the finding as far as I can tell.

Instead, they ignore it. The Post was the only paper to cover this story. This is a pattern.

Try asking a random adult: Do you think US carbon emissions are up, down, or about the same in the last 20 years? As an ROS member, you know the answer: down 20%, thanks mostly to cheap natural gas from fracking.

Seems important! Yet most people have no clue… giving cover for states like New York to keep its inexplicable ban on fracking.

Note this does not mean global warming isn’t real. The Antarctic ice sheet lost 142 gigatons a year from 2011 to 2020. The recent rebound recoups less than 2 ½ years’ worth of losses. The researchers attribute the rebound to unusual increases in precipitation, which probably won’t persist.

But it’s important to rationally consider all evidence, especially when evaluating doomsday predictions, which have always been wrong.

Share the future with your friends by clicking the “Like” and “Restack” buttons below.

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Stephen McBride and Dan Steinhart are co-founders of the Rational Optimist Society.

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