While SpaceX and its ilk in the commercial rocket launch market have changed the economics of space and ushered in an era of small satellite entrepreneurship, the actual rocket engine technology they use isn't that different from what was in use 50 years ago when NASA was making its first forays into outer space.
Firehawk Aerospace, a new startup founded by CEO Will Edwards and Chairman and Chief Scientists Ron Jones, wants to change that with a stable, cost-effective hybrid rocket fuel that employs additive manufacturing (industrial-scale 3D printing) to overcome the hurdles and limitations of previous hybrid fuel engine designs.
Hybrid rockets themselves – ones that use a combination of solid fuel and liquid oxidizer – aren't new, but they have always faced significant limitations in terms of their performance metrics and maximum thrust power. Jones, a longtime rocket propulsion researcher and aerospace structures and advanced composite engineer, has been fascinated with engine technology and how to overcome the limits of past hybrid engine designs, while also retaining the benefits – including safety and cost.
Jones had been very interested in physics and engineering through high school and college, but ultimately joined the Navy and became an aviator before later coming back around to working in the aerospace industry. Meanwhile, he took advantage of the advent of the internet in its early days to begin diving deeper into his early love of rocketry, specifically researching hybrid engine technology and trading notes with experts all around the world.
"Ultimately, I came up with two concepts together," Jones told me in an interview. "One is that they were using the wrong fuel – the fuel they were using was too elastic. Once you put it under pressure, it's going to reverberate, and it's not very strong so as it gets thinner, it will essentially break off chunks, and you lose a lot of fuel. So I switched that to a structurally very hard polymer. And second, I could see that they're molding in casting just wasn't a good idea. I switched that out to additive manufacturing."
With additive manufacturing, which builds up a structure over time by extruding material, instead of pouring a liquid into a form and allowing it to harden, you can do things that are impossible with molding, including building up intentional, very structured internals. If you've ever seen at-home consumer 3D printing, it's like the criss-cross patter you see in larger solids to provide rigidity or support to the external surfaces. That turned out to unlock a lot of potential for solid rocket fuel pellets.
"With additive manufacturing, I was able to do something no one else had done before. And that is to create a highly engineered internal structure that you can't do with molding," he said. "With those internal structures, we've been able to greatly improve the performance of the rocket engine, making it very reliable and also very safe, and these were the primary attributes that I was going after."
Firehawk now holds five patents related to its 3D printing of rocket fuel, and it has already conducted 32 engine hot fire tests at both 200 lbs and 500 lbs of thrust to verify that its design actually works. The startup is also working on an engine capable of 5,000 lbs of thrust (roughly equivalent to Rocket Lab Electron's second stage), which it plans to begin testing later this year at a new facility it's building for the purpose.
As mentioned, current launch companies are already operating using much older, but still effective, rocket technology. So why bother with a new type of hybrid engine design? For a number of reasons, but efficiency and safety are chief among them.
Firehawk's fuel can be stored, transported and handled much more safely, since it's not susceptible to accidental detonation when the fuel and oxidizer are separate. It's also non-toxic, and only produces exhaust that Firehawk says is "environmentally benign." Safe handling of existing rocket fuel options for large launch vehicles requires a lot of special care and safety, as well as training, all of which adds up to time and expense.
Firehawk can also provide custom engine designs in between 4 to 6 months, it says, whereas typical new rocket engine development based on existing technology usually takes between 5 to 7 years. That time savings also adds up to significant budget savings – on the order of hundreds of millions of dollars – meaning new and better rockets can be iterated more quickly, without long useful lifetimes required between generations to recoup initial R&D costs.
The fuel can also be stored and transported over long durations, and even potentially stopped and restarted mid-flight, all of which means that longer and more complex missions can be accomplished at far lower costs than ever before. Obviously, the potential has sparked a lot of interest from both potential commercial and government customers, according to CEO Edwards.
Earlier this year, Firehawk Aerospace closed a $2 million seed round, from investors including Victorum Capital, Achieve Capital, and Harlow Capital Management, and they're currently looking to grow the team, particular with driven engineers looking to work on the future of rocket propulsion. It's also in process with a number of potential partners and letters of intent for commercialization of its technology.