Founded in 2010, the focus of Rocket Crafters, Inc is the development and commercialization of a Hybrid Rocket Engine (HRE) technology invented by Ronald Jones, chief technologist and co-founder of the Florida based company.
In January, we reported that Jones had received a patent for 3D printed rocket fuel technology. Now, a new invention, patent number US 9,822,045, has also been granted. The method means Rocket Crafters can, safely produce feedstock and print rocket fuel from a blend of thermoplastic and high-energy nanoscale aluminum particles.
Safely is the operative word here.
The rocket fuel uses nanoscale particles of pure aluminum. A material that anyone familiar with additive manufacturing respects as highly reactive.
Aluminum as a fuel source
Another project, this time at the US Army Research Laboratory at Aberdeen Proving Ground, Maryland, discovered that a novel aluminum alloy reacts with water to produce hydrogen. Producing hydrogen in this manner could remove one of the barriers to the use of the material as a fuel source, making it easily transportable.
The pure aluminum used by Rocket Crafters, when in nanoscale particles, will spontaneously ignite on contact with the atmosphere.
This is obviously problematic and Rocket Crafters notes their process is “mechanically simple and immune to accidental detonation – a desirable characteristic and one that traditional rocket engines do not have.”
The Jones patent demonstrates, by using additive manufacturing, “how to safely process and integrate the material so that it can be compounded, 3D printed, transported, stored, and used to fuel a hybrid rocket engine.”
This means the high-energy, but highly hazardous material can be used as a fuel additive in a rocket engine.
“With this latest invention, we now have the technology to design and manufacture hybrid rocket engines that can effectively compete with more expensive, less reliable and less safe liquid bi-propellant and solid rockets,” Jones said.
How to 3D print rocket fuel
The newly granted Rocket Crafters patent was filed in September 2016. A visit to the website of the US Patent and Trademark Office provides more detail on how to 3D print rocket fuel.
The introduction to US Patent 9,822,045 “Additive manufactured thermoplastic-aluminum nanocomposite hybrid rocket fuel grain and method of manufacturing same” describes how the fuel grain is made from a stack of fused layers, “each formed as a plurality of fused abutting concentric circular beaded structures of different radii arrayed defining a center port.”
The material is a compound of hybrid rocket fuel and the nanoscale metallic material, in this case aluminum. When mixed accorded to a particular ratio, a 3D printable feedstock can be made. This feedstock is then used with an FDM 3D printer to create the fuel grains.
Multiple layers are 3D printed, creating a “bonded and concentric substantially circular ring-shaped beads of different radii and defining a center combustion port.”
Putting the 3D printed rocket fuel to the test is also the subject of considerable activity. In July, Rocket Crafters won a $542,600 research contract from DARPA. The eight-month project for Rocket Crafters’ Direct-Digital Advanced Rocket Technology (D-DART), will see a 5,000 lbf peak thrust, throttle-capable rocket engine built for the U.S. agency.
A partnership with Coastal Steel Manufacturing, LLC, located in Cocoa, Florida will see a regular series of Hybrid Rocket Engine (HRE) D-DART test firing.
Let us know if this use of 3D printing should be recognized in the 2018 3D Printing Industry Awards. Make your nominations here.
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Featured image shows the Intrepid-1. Image via Rocket Crafters.