Minnesota-based Chromatic 3D Materials has developed a novel way to build solid fuel for booster rocket designs: 3D printing it. This could enable novel rocket shapes and sizes, as well as more precise control over the production process, leading to more stable and predictable solid-fuel rockets.
The process for producing solid rocket fuel and solid-fuel rockets has changed little over the decades. The fuel and oxidizer are mixed with a binder into a slurry, which is then poured into the rocket shell and left to harden with a metal rod at its center. This metal rod is then removed, leaving a gap for the combustion chamber. When the fuel is ignited, it burns from the inside out, giving some control over the burn rate, fuel quantity, and eventual burn time.
But this process is still rather imprecise. Cracks and fissures can form during curing due to air bubbles in the mixture, and the shape of solid rocket boosters is largely determined by the curing process.
A static fire test of the 3D solid rocket fuel.
Credit: Chromatic 3D Materials
Chromatic 3D Materials is looking to do things differently. First, it made a printable rocket fuel material. It tweaked the chemistry of existing binders, allowing them to remain in a liquid state in the printer but to harden after printing. Now, when combined with fuel and oxidizer, it can be printed in liquid form, hardens and cures once printed, allowing it to be printed into a wider array of shapes and configurations, Tom’s Hardware reports.
In theory, this could allow for fuel shapes that would be impossible with traditional molding techniques. That could allow the creation of uniquely shaped solid rocket boosters and speed up the curing process in general. What used to take days or weeks to harden now takes almost no time at all.
To confirm that the 3D printed fuel can withstand the extreme pressures of a real combustion chamber, Chromatic recently conducted a high-pressure, high-temperature test and found it more than capable.
The propellant “achieves energetic loading levels comparable to top-performing conventional propellants while delivering the structural integrity required to withstand high-pressure combustion environment,” Chromatic said following a recent static fire test.
Chromatic also said it was working with government and industry bodies to prove the capabilities of 3D printed fuel and to encourage adoption, highlighting the fuel’s potential importance to strategic readiness for the rapid scaling of rocket (and missile) production. Considering how modern conflicts like Russia’s invasion of Ukraine and the US-Iran war have shown a demand for mass missile attacks and manufacturing them at scale, 3D printed solid rocket fuel could aid dramatically in improving readiness for such conflicts.
