Aerospace
3D Printed Rocket Propellant Makes Solid Fuel Competitive Again
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When it comes to propelling rockets and missiles, two different categories of propellant can be used: Liquid or solid propellants.
Solid propellants are more durable and easier to handle, but suffer from relatively poor flexibility, making direction and variation in thrust difficult.
Meanwhile, liquid propellants are more versatile, but more expensive, difficult to handle, and more prone to catastrophic explosions, or as SpaceX called it, “rapid unscheduled disassembly”.
Still, lower performance means that solid propellants have mostly been used in missiles and other military equipment that require chemicals that are safe and stable for decades in storage. And the technology used to produce the propellant for these rockets has changed very little over the past 60 years.
This is no longer true as the 3D-printing company Chromatic 3D Materials has invented a new type of 3D-printed solid propellant, which could radically change what this type of propulsion can achieve, without sacrificing any of its advantages.
Solid Vs Liquid Propellant
All rocket propellants use a mix of a reactive, energy-rich chemical and an oxidizer, letting that energy be released in a controlled manner.
Liquid propellants store fuel and oxidizer separately as liquids, pumping them into a combustion chamber. This allows the rocket to control the liquids’ flow, allowing it to throttle, stop, or restart the engine.
Most liquid propellants are cryogenic fluids like liquid oxygen and hydrogen, or liquid methane, hydrazine, etc.
In contrast, solid propellant combines fuel and oxidizer into a single, pre-mixed solid mixture. Once ignited, the propellant is progressively consumed at the speed matching the design without the possibility to throttle it, and it cannot be stopped or restarted.
Source: Drishtiias
This makes solid propellant technologies inherently less practical for many applications that require more subtle propulsion.
But they also have a few key advantages that have kept them in use to this day:
- The solid mixture is extremely stable as long as it is not ignited, and it is able to sit and stay functional for decades in simple storage conditions.
- The mechanical complexity is very low, with no plumbing, valves, or pumps, making it inherently more reliable and less prone to fail in unexpected ways.
- The design is simpler, leading to lower costs, especially for non-reusable designs.
These differences led to a split between the two propellant technologies.
Solid propellants are still used in missiles, ICBMs, and one-use rocket boosters that require little control, reducing costs and improving safety.
Liquid propellants are used in space rockets and other space missions, as well as some military applications, like, for example, Russian ICBM designs.
Reinventing Solid Propellants
Limits of Classical Solid Propellants
In building a solid propellant rocket, the fuel and oxidizer used are mixed into a thick slurry and poured directly into the prefabricated rocket’s casing. It will then be baked with heat for days to weeks to cure it into a hard, rubbery rock.
A large metal rod, called a mandrel, is typically positioned at the center of the mold before casting and then removed after solidification, leaving a hollow channel for the combustion chamber. This hole is later on filled with the ignition charge and forms the combustion chamber.
Source: L3Harris
This method has been tried and tested for more than 60 years now, but comes with severe drawbacks.
The first issue is that the mixing method still sometimes creates a tiny air bubble or crack near the casing. It can cause an explosion when the fuel is ignited, potentially mid-flight.
Another issue is that removing the mandrel can cause cracks. This also limits the shape that can be cast, reducing the options for different speeds and thrust.
Source: Additive Manufacturing Frontiers
3D Printing Solid Propellants
Chromatics 3D Materials is a company whose technology is focused on reactive extrusion additive manufacturing, or the 3D printing of material that uses chemical reactions to solidify once out of the printer’s nozzle. Notably, it started with polyurethanes and other elastomers like rubber.
Source: Chromatics 3D Materials
So this process uses no melting, lasers, or post-processing, contrary to almost all other 3D printing technologies. So the printer pumps a chemical mixture that reacts and hardens almost instantly as it is laid down.
On April 28th, 2026, the company announced it had tested its 3D printers for a new material: solid propellant.
This follows the announcement a year before that the company had achieved ITAR Certification (International Traffic Arms Regulation), which illustrate this is part of a long-term plan for the company.
“Obtaining ITAR certification marks a pivotal moment in our company’s growth. This registration not only enhances our ability to serve defense and aerospace clients but also demonstrates our dedication to maintaining the highest standards of security and quality in additive manufacturing.”
The company did not reinvent solid propellant, but tweaked its chemistry to make it 3D-printing-compatible. This radically changes what solid propellants can achieve, without the constraints imposed by the long, energy-intensive curing process and the shape of the central mandrel.
“In a solid rocket, the shape of the hollow core in the middle of the fuel determines how it burns and how much thrust it creates. 3D printing enables “impossible” internal shapes that can’t be made with a mold, potentially leading to rockets that fly farther or more efficiently.”
Potential of 3D-Printed Solid Propellants
Stellar Initial Results
During the April 2026 tests at the Integrated Solutions for Systems (IS4S) test range in Opekia, Alabama, the propellant demonstrated excellent combustion and propulsion potential. Most importantly, it could withstand over 1800 psi of combustion pressures without structural failure.
Based on current results, Chromatic’s material has the capability to propel approximately 90% of the U.S. rocket arsenal with equivalent speed and range, while creating opportunities to further enhance both.
“The propellant achieves energetic loading levels comparable to top-performing conventional propellants while delivering the structural integrity required to withstand high-pressure combustion environment.”
New Design Possibilities
The direct integration of propellants into structural components allows the company to reduce unnecessary mass, create more efficient internal geometries, and precisely tailor thrust behavior.
This makes this manufacturing method an inherently superior one to the traditional method.
It is also investigated by other major powers, notably at the State Key Laboratory for Manufacturing Systems Engineering in China, which also published an article titled “Additive manufacturing of solid propellants: Exploring the frontier of solid propulsion systems”.
Another potential is that 3D printing solid propellant can allow for the mixing of different types of fuel in the same rocket. So while still not as flexible as the pumping of a variable amount of liquid propellants, it could make it possible to vary speed and thrust at different stages of flight.
The result of these possibilities could be lighter propulsion systems with higher performance, longer range, and greater operational flexibility for future missions.
3D Printed Solid Propellant Applications
So far, Chromatics 3D Materials is clearly eyeing a defense contract for building missiles propelled with fuel printed by the company. As the US arsenal is depleting from wars in Ukraine and Iran, this could be an answer to strained supply chains that limit the production rate of these missiles.
The method is compatible with existing systems and chemicals, so the initial contracts would likely be with known designs. But in the long run, innovative design choices that fly farther, hit harder, and can be produced faster would be the main contribution of this technology.
As the US defense budget is expected to quickly grow to $1.5T, this is potentially very lucrative for the company.
Another option could be to integrate such fuel into space systems, like, for example, emergency evacuation pods in space stations or future Moon bases, as the durability of the material makes it a superior option to the unstable liquid fuels favored today.
Investing In Solid Propellant Rockets
L3Harris Technologies Inc
(LHX )
Lately, most of the attention of financial markets regarding rocketry has been focused on reusable rockets, notably Rocket Labs (RKLB ) (follow the link for our investment report) and the upcoming IPO of SpaceX.
But new technologies like 3D-printed solid propellant might make these designs more valuable and more widely used in the future.
Since the July 2023 acquisition of the missile reactor developer Aerojet Rocketdyne for $4.7B, L3 Harris added a 4th department to the company centered on missile production.
Besides this, L3 Harris is a leader in military communications, integrating “missions systems” for military command, as well as satellite and space sensors.
Source: L3Harris
This puts the company in a perfect position to benefit from a boom in demand for missiles using solid fuel.
To respond to the recent urgent surge in demand, L3Harris has announced a first-of-its-kind proposed partnership with the Department of War (DoW). The DoW will invest $1B L3Harris’ Missile Solutions business through convertible preferred security.
Then L3Harris will IPO its Missile Solutions business in the second half of 2026, to some extent recreating Aerodyne Rocketdyne, but with other extra technologies from L3Harris attached as well. After the IPO, L3Harris will retain a controlling interest in the Missile Solutions business.
Source: L3Harris
L3Harris also unveiled in the summer of 2025 its Red Wolf missile concept. This design should cost as little as cost around $300,000 to $400,000 per unit, versus well over $1M a piece for existing standoff cruise missiles, moving in the right direction of more numerous and lower cost ammunition.
Here, too, improved fuel design could go a long way in boosting production speed and reducing costs while improving performance.
Source: The War Zone
The upcoming IPO of the missile segment could unlock further value as a direct way to invest in this theme, if not just the US, but also all its allies move on to build a massive inventory of air defense against future threats, while still benefiting L3Harris stock price as well.
L3Harris should also benefit from rising orders to other defense companies or armed forces growing in size, as it will be providing them with increased volume of secure radio, network capacities, drones, and other sensors, taking a little piece of every pie, almost no matter what the weapon system is finally picked.
(You can read more about L3 Harris in our investment report dedicated to the company.)
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