How one rocket startup is developing 3D-printed rocket engines for testing

Tom Cross

I had a rare opportunity to visit Rocket Crafters, a small rocket company located in Cocoa, Florida, just 10 miles from the Kennedy Space Center, that is developing and testing what is known as ‘hybrid rocket engines’. These 3D printed engines are born in Colorado from a custom-made printer because none exist on the market that’s large enough to print these rocket engines that DARPA contracts them to build, with a $600,000 investment.

Press gathered inside Rocket Crafters control room to speak to the team. (Tom Cross)

After the hybrid fuel grains are printed, they’re shipped to Rocket Crafters in Florida where they are further processed by wrapping them in carbon for additional strengthening and then test fired. The company is testing three engines per week at an industrial location in the city of Cocoa. The only requirement the City has for testing these engines is to keep the noise level below a certain decibel, over concerns of disruption to neighboring residential.

Multiple small unwrapped 10-second burning test-engines on a shelf for future testing. (Tom Cross)

The engines, called fuel grains, are tubes made of ABS plastic, the same material LEGO are made of. The fuel grains are so safe, in fact, they can fly with them on airplanes as a carry on. They are specially shaped for the use of burning smoothly as a rocket engine, something only a printing process could form, which is a patented invention by Ronald Jones. The fuel grain needs an oxidizer in order to burn through, and without that, there’s really not much you can do with them because they’re just a tube of plastic.

When I arrived at Rocket Crafters the day of the test, I asked if I could set up my launchpad cameras to capture the flame of the engine during the test fire. Due to safety concerns over their oxidizer tanks that were already full, the team kindly advised against doing so. The oxidizer is nitrous oxide, also known as laughing gas at the dentist. Needless to say, it probably would have been incredibly funny had it sprung a leak while I was setting up my camera. The whole test stand sits on the back of a flat-bed trailer that’s ratcheted down to the concrete and protected by mobile steel walls on three sides.

CEO Sid Gutierrez, a former Space Shuttle Pilot, and Shuttle Commander touted the safety aspects of their rocket engine. “What you won’t see are cryogenics, bi-propellant liquid fuel engines, no signs saying explosives,” he said during the video conference. Rocket Crafters are carving their slice into the new wave of affordable launches for small-scale cube satellites and have grand plans of creating their own rocket called Intrepid consisting of multiple hybrid rocket engines burning simultaneously.

They brought me into their testing facility to showcase their fuel grains, carbon wrapping process, and most importantly a 10-second test fire of one of the engines from inside their control room. During the test, the engine could be heard through multiple block walls and doors as if it was just 10 feet away. The building didn’t shake, the sound was intense, though. The video on the screen doesn’t do it justice. The whole experience was pretty awesome.

Rocket Crafters still has a bit of work to do trying and testing new components before they’re ready to launch but they’ve already begun making prototypes of their full-scale engine. The day I was there, engineers were testing a nozzle made of a material they hadn’t tried before. “You don’t see many 15-person companies developing a rocket,” said Robert Fabian, SVP of Propulsion.

SVP of Propulsion explains the components inside the test-tube. (Tom Cross)

I’m no rocket expert, I’d be a rocket scientist instead of a photographer if so, but I learn a lot by doing this. I think this particular hybrid rocket engine would be perfectly suited for a prosumer market of amateur rocketry, especially considering how safe they are and non-toxic to the environment. The few amateur rocket enthusiasts I’ve asked about hybrid engines said they’d be great to have after they fix the flaws of hybrid engines.

Here’s a video of one of their engine tests:

Tom Cross

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