“I feel the need…the need for speed” — Maverick, Top Gun
Let’s face it, humans have an obsession with going fast. While the occasional adrenaline-inducing rush might be desirable, the real reason behind this obsession is that speed can save one of our most precious and finite resources: time. Throughout history, people have consistently pursued ways to move faster.
We start life crawling at .06 mph and eventually work our way up to walking speeds of 3 mph, eventually developing the ability to run between 10 and 12 mph. Bicycles open up new neighborhoods and can increase our speed by more than 50%. Cars unlock entire cities and can increase our speed of transport by a factor of 10x or more. And airplanes can ferry us anywhere in the world at speeds of 575 mph.
But despite this love for speed it’s a bit ironic that the largest “accessible” speed gains humans have made throughout history (accessible meaning the speed an average person can access — as we will mention below, certain people have been able to travel at much faster speeds than the average individual) is the 200x gain we make as humans.
The next closest speed gain we have realized is with commercial airliners with a 100x gain. But that’s a bit misleading: the Wright Flyer achieved a speed of 6.8 mph on its first flight in 1903, but early commercial airliners traveled at speeds between 100 and 200 mph, meaning modern speed gains have only been 3.5x to 7x. Trains are going 12x faster; cars only 10x.
That’s not to say humans haven’t gone much faster — we have. But these speeds have only been experienced by a rarified few. The fastest any human has ever traveled is 24,791 mph, and that record is held by just three astronauts that were inside the Apollo 10 capsule during their return from the Moon on May 26, 1969.
The world’s first scheduled commercial airline flight took place on January 1, 1914, when the St. Petersburg-Tampa Airboat Line began operating between St. Petersburg and Tampa, Florida, a distance of just over 16 miles that took 23 minutes (which coincidentally is the time it takes today to drive between the two cities).Improvements in commercial airliner technology between the 1920s and 40s (most notably the invention of the jet engine in the 1930s) allowed for higher cruising altitudes, faster speeds and larger planes.
By the 1950s we entered the jet age where long-distance travel, with transatlantic flights, became commonplace. The average speeds of commercial airliners during that era averaged just over 500 mph, essentially where air travel speeds are at today.
This stagnation in acceleration was exemplified in the 2011 essay The End of the Future written by Peter Thiel where he lamented on the overall decline of Western civilization:
“When tracked against the admittedly lofty hopes of the 1950s and 1960s, technological progress has fallen short in many domains. Consider the most literal instance of non-acceleration: We are no longer moving faster. The centuries-long acceleration of travel speeds — from ever-faster sailing ships in the 16th through 18th centuries, to the advent of ever-faster railroads in the 19th century, and ever-faster cars and airplanes in the 20th century — reversed with the decommissioning of the Concorde in 2003, to say nothing of the nightmarish delays caused by strikingly low-tech post-9/11 airport-security systems. Today’s advocates of space jets, lunar vacations, and the manned exploration of the solar system appear to hail from another planet. A faded 1964 Popular Science cover story — “Who’ll Fly You at 2,000 m.p.h.?” — barely recalls the dreams of a bygone age.”
To understand this speed stagnation and how we might reverse course, it’s helpful to look at one of the most ambitious attempts to move humanity faster.
The Concorde Era
Efforts to break the sound barrier–going faster than the speed of sound, or 767 mph, or Mach 1–began in the 1940s stemming from a combination of scientific curiosity, military advancement, and the potential for faster transportation.
On October 14, 1947 Chuck Yeager achieved that feat piloting the rocket-powered Bell X-1.
By the early 1950s, the U.S., Britain, and the Soviet Union had all developed jet fighters capable of supersonic flight.
But even before Yeager’s historic flight, people began to seriously consider the possibility of a supersonic commercial airliner — an article in Life magazine showed a design for a potential commercial supersonic transport sketched up by National Advisory Committee for Aeronautics (NASA’s predecessor) researchers.
The only supersonic commercial airliner ever to make it into active service was the Concorde. An agreement between the French and British governments to jointly develop and build the Concorde was signed in 1962. Seven years and $2B (or $19B in 2025 dollars) later, the Concorde took its maiden flight on March 2, 1969.
The Concorde could travel at Mach 2 (1,354 mph) with a maximum range of 4,488 miles (meaning only trans-Atlantic flights were possible), and could carry between 92 and 128 passengers.
A round-trip ticket between New York and London cost around $12,000, and the flight took three and a half hours (vs just over seven hours on a normal jet airliner).
It’s probably worth taking a moment to reflect on the kind of impact simply in terms of time saved the Concorde would have today. It is estimated that about 5M people traveled between New York and London in 2019. Cutting down flight time from seven hours to three and a half would collectively save 18.5M hours of travel time, or 2,112 years across those 5M passengers.
Over a decade that is 21,000 years in saved time. And that is just for one route. Just imagine what could be accomplished by the hundreds of thousands of years of collective time not spent on an airplane. Unfortunately, the Concorde faced many technical and economic challenges–some of which we will detail below; a full story on the Concorde’s demise can be found in this great Construction Physics article–and its final flight occurred on November 26, 2003.
Humans had figured out a way to travel, en masse, faster than we had ever gone before, but that moment was fleeting. In the 22 intervening years between that final Concorde flight and today, our collective need for speed has been denied. But there is a new hope.
A New Hope For Supersonic Travel
Today, through a confluence of technological, financial and geopolitical developments, supersonic (and even faster hypersonic) flight is back on the table. The cost to bring new jet aircraft and engines to market is astronomical — historically, something only governments or large aerospace OEMs with massive balance sheets could afford.
Part of this expense is just the engineering and capex costs related to building a new aircraft, but before planes are authorized to fly, their manufacturers must first go through the Federal Aviation Administration’s (FAA) Aircraft Certification process, also known as Type Certification that can cost hundreds of millions if not billions and take several years.
Type certification “is the approval of the design of the aircraft and all component parts (including propellers, engines, control stations, etc.). It signifies the design is in compliance with applicable airworthiness, noise, fuel venting, and exhaust emissions standards.”
As mentioned earlier, the French and British governments spent $19B developing the Concorde. Companies like Boeing and Airbus have spent $20B to $30B to develop, build, test and certify new aircraft while engine manufacturers like Pratt & Whitney, GE Aerospace and Rolls Royce spent single-digit billions to do the same for each of their new engines.
However, more recently, younger companies have found a way to finance much of their R&D and testing expenses by working directly with various U.S. government agencies like NASA and the Department of Defense (DOD).
For example, in 2008, a fledgling SpaceX won a $1.6B NASA contract for resupply missions to the International Space Station under the Commercial Resupply Services (CRS) contract. Many credit this contract win with keeping SpaceX alive by providing a funding bridge that allowed the company to continue to invest in R&D of their Falcon 9 rocket.
More recently in January 2022, Boom Supersonic won a $60M Strategic Funding Increase (STRATFI) contract from the U.S. Air Force (USAF) to continue R&D on their supersonic aircraft platform.
Another government funding opportunity for new supersonic companies is the multi-billion dollar USAF Collaborative Combat Aircraft (CCA) program, a major DOD initiative led by the USAF under its Next Generation Air Dominance (NGAD) family of systems.
The CCA is envisioned as a family of AI-enabled, uncrewed, autonomous or semi-autonomous aircraft designed to operate alongside manned fighter jets, enhancing their survivability, lethality, and operational flexibility in high-end conflicts against near-peer adversaries, especially China.
By leveraging government R&D funding, younger startups now have a chance at bringing a new supersonic aircraft to market.
In addition to more government R&D funding opportunities, VC interest in supersonic and hypersonic startups has been increasing. Over the last decade, $1.22B of VC funding has been invested into startups going after some element of supersonic or hypersonic flight.
One of the most significant fundamental challenges faced by the Concorde, and by supersonic flight generally, is that air behaves very differently above and below the sound barrier, and different kinds of aircraft work best in each domain.
Put more simply, engines that can provide the propulsion needed to get to, and maintain supersonic speeds are very good at operating efficiently at high speeds, but burn a lot of fuel (or are inefficient) at lower speeds, and because much of a supersonic flight is spent at subsonic speeds (like during taxiing, takeoff and landing), the planes end up burning a lot of excess fuel.
Using a bicycle analogy: supersonic jets essentially use a higher gear when starting from a dead stop or operating below cruising speeds. They have to do much more work than they need to, wasting precious fuel. The Concorde used most of its fuel during subsonic operations and was 10x more expensive to operate than a 747.
To understand how new engine technology can change the equation for supersonic flight, it’s first helpful to give a brief primer on the two main types of commercial jet engines historically used. The Concorde was powered by four Rolls-Royce/Snecma Olympus 593 turbojet engines.
The turbojet engine was once widely used in military fighter jets because it can produce high-velocity thrust. However, as mentioned before, while it was efficient at high speeds, it burned a lot of fuel at low speeds. For military applications, where cost matters less, this wasn’t a major issue, but for commercial air travel where costs matter a lot, this was a big problem.
Most modern airliners today use turbofan engines, which can be considered a cousin to the turbojet engine, but they make less noise, are more efficient at lower airspeeds, and use less fuel on a relative basis.
Both types of engines have similar mechanics: air flows into the front of the engine, is compressed into high-pressure air that is then mixed with jet fuel and ignited creating hot expanding gas that is expelled out of the back of the engine providing thrust.
That hot gas flowing through the back of the engine also passes through a turbine, causing it to spin. This spinning turbine powers the compressors via a connecting shaft, causing them to spin (and in the case of a turbofan, that turbine also spins a large fan at the front of the engine that essentially acts as a propeller sucking in, and passing through, excess air).
The main difference between the two engine types is that in a turbojet, all of the air entering the engine is focused into the combustion chamber, whereas in a turbofan, much of the air being pushed into the engine by the large fan at the front flows around the combustion chamber and out the back of the engine.
This is known as bypass air, and the ratio of air flowing around the combustion chamber to air flowing into it is called the bypass ratio.
The reason that turbojets can produce higher speeds is due to their low bypass ratio: focusing all the air into the combustion chamber increases the flow rate of that air (the amount of air moving past a specific point over a given period).
Using a standard garden hose as an example: normally water flows out of hose at a standard rate when turned on, but if you use your thumb to block part of the mouth of the hose, the water suddenly starts spraying out at a faster speed.
Turbojets focus the air, causing it to move faster and at a higher pressure into the combustion chamber, which then produces more exhaust velocity upon combustion, and thus more thrust and more speed.
While a high bypass ratio doesn’t allow for supersonic speeds, all that air flowing around the combustion chamber and out the back of the engine (a process that requires minimal fuel) does provide enough thrust to hit and maintain cruising speeds of around 500–600 mph.
Modern commercial airliner turbofans have a bypass ratio of 12:1 meaning that 12x the amount of air going into the combustion chamber actually flows around the engine and out the back, and this air (which again, requires only the fuel used to power the turbine that turns the fan at the front) provides 80% of the thrust the aircraft needs. In aircraft using turbojets, all of the thrust comes from the fuel-induced combustion.
In a perfect world you could have an engine that could perform at optimal efficiency at both low and high speeds: at low speeds thrust would be mostly provided by bypass air, requiring less fuel, and at high speeds air could be focused into the combustion chamber to provide high-exhaust gas thrust, requiring more fuel.
The challenge here is that in a turbojet, a single shaft connects the turbine to the compressor. This means the turbine and compressor must rotate at the same speed, and this speed is typically high to maximize thrust.
Turbofans often have multiple spools (e.g., a high-pressure spool and a low-pressure spool). This allows the fan, which is driven by the low-pressure turbine, to rotate at a much lower speed than the core turbine.
If you could decouple the turbine from the propulsion unit in a turbojet, you could spin the turbine slower at slower speeds (saving fuel) and faster at faster speeds (where more fuel would be required).
But this would require a way to spin the turbines at different speeds using an external power source as you wouldn’t be able to use the exhaust gas to power the turbine.
Astro Mechanica and the Turboelectric Adaptive Engine
Astro Mechanica is a San Francisco-based company formed in 2022 that is building out the future of supersonic flight. Their unique approach has focused on a foundational innovation in supersonic propulsion which tackles this Achilles’ heel of supersonic transport — fuel efficiency — head-on.
MaC is excited to announce our investment into this amazing company, joining investors United Airline Ventures, Andreessen Horowitz, Giant Step, Lowercarbon Capital, Voyager, Neo, Alumni Ventures, Dolby Family Ventures, Eli Dourado, Julian Capital, Rogue, Industrious Ventures, Myelin VC, Not Boring, Wayfinder, Y Combinator, and Astera.
Astro Mechanica was formed by Ian Brooke, a certified pilot who started building model planes at the age of 13 and later ran a successful company machining motorcycle parts of his own design. In 2003, Ian met an American Airlines captain and aircraft mechanic.
The experienced aviator took a bright and curious teenager under his wing, launching a mentorship that still endures today.
Being uncredentialed in the area of aerospace engineering freed Ian up to come up with a first-principled, fresh approach to supersonic flight. He has surrounded himself with experts in the fields of aerospace, electrical and software engineering, manufacturing, propulsion, aircraft development, finance and operations and government relations.
This team brings experience from companies that include SpaceX, Boom Aerospace, Astra, Neuralink, Astranis, Northrup Grumman, Bridgewater and Anduril.
Astro Mechanica’s novel breakthrough is their turboelectric adaptive engine (TAE) that decouples speed (engine propulsion) from efficiency (turbine/compressor speed). They achieve this through the use of an external turbogenerator which provides electrical power to electric motors that spin the compressors, removing the turbine altogether.
In turbofans and turbojets, the only purpose of the turbine is to spin the compressors (and the fan in the case of the turbofan). But since Astro Mechanica’s TAE has electrically-powered motors that spin the compressors, no turbine is needed.
When their jet is moving at subsonic speeds, the turbogenerator provides enough power to the motors so that they can spin the compressor fans at an optimal speed to flow enough high-pressure air through their propulsor to create fuel-efficient thrust via a higher bypass ratio.
To achieve supersonic speeds, more power can be supplied to the motors, spinning the compressors faster, driving higher speed, higher pressure air through to the combustion chamber, where additional fuel is injected to create that high-velocity gas exhaust required for supersonic speeds.
Upon approaching Mach 3 (2,301 mph), the jet is moving fast enough where the engine can then act as a ramjet, a type of air-breathing jet engine that relies on the vehicle’s forward motion to compress incoming air for combustion.
At this point, the turbogenerator is turned off and thrust is maintained through the combustion of the high-pressure and fast-moving air flowing naturally through the combustion chamber.
Leveraging this novel engine breakthrough, Astro Mechanica plans to build out a vertically-integrated aerospace company. It will first use its engine to field autonomous jets for the previously-mentioned CCA program (which will buy down technical risk through government R&D funding), then private planes, then commercial planes, all of which the company will manufacture, maintain, and operate.
This vertically-integrated approach fueled by a novel technological breakthrough is the path followed by SpaceX, Tesla, MaC portfolio company Stoke Space, and a few others.
Innovations in engine efficiency and speed have propelled Boeing and Airbus into the two main players in the commercial aviation space owning more than 95% of the market with a combined market cap of $319B.
But innovation at these two primes have stalled out and the focus for the last several decades have been around financial engineering, not innovative R&D. What SpaceX has been to the launch industry or Tesla to the automotive industry, Astro Mechanica could be to the jet industry.
We have stagnated on speed for far too long. Our need for speed must be met. We can combine lessons learned from the past with new technologies to shrink the world once again and give humanity back millions of years of time to spend exploring the world with friends and loved ones.
Easier access to new places and cultures, with more time to explore them might just lead us to a deeper understanding of each other and a realization that we all have more in common than previously thought. This is the kind of world we deserve, and one in which Astro Mechanica will help unlock.