From the beginning of our rocket motor test stand project, code named “Shepard”, our primary objective has been that the data we record with the test stand has to match the manufacturer’s data.  That seems like an obvious goal, but the temptation is always there to run on ahead to bigger and better things before you have a good foundation.  For our rocket motor/engine test stand program, Shepard is that foundation.  Once we know that we have the fundamentals down, we can progressively scale things up through sub-orbital, orbital, and even transorbital capable rocket engines.

Aaron Harper and I have recently been working overtime to get Shepard version 1.1 ready for one of our partners, the Coca-Cola Space Science Center (CCSSC), in Columbus, Georgia.  We’re quickly advancing toward version 2.0 which will be available as an open source hardware kit. Our hope is that the kit will be a tool that the CCSSC and others can use to safely teach hands-on rocket science.  Last week, for the first time Shepard satisfied it’s “vendor verification” requirement during an impromptu test firing.  I had just completed the build of some new hardware that was bound for CCSSC, and like a good little engineer, made sure that I tested it before shipping. The video below shows the actual test firing.

The data looked pretty good onscreen, but it wasn’t until I got back inside and took a closer look that I got excited.

The motor I test fired was a D12, and if you compare our curve to the D12’s curve in the official Estes documentation, you can see that they’re very similar.  Our curve has more noise in it, mainly because it’s raw data with no clean-up. The peak thrust, time to peak thrust, and the fall-off of the profile before propellant burnout all match up very well.  Keeping in mind that Shepard 1.1 is a retrofit of version 1.0 to test components for Shepard 2.0, and is not specifically designed for use with this hardware, that’s pretty remarkable.

By the time we tune and tighten things up on Shepard 2.0, we should have a very solid base to stand on when reaching towards our goal of hastening the advancement of humanity into a spacefaring civilization.

If you’re curious about exactly what it took to get to this point, have a look at our development logs on Open Design Engine.  We’d also be happy to answer questions that you have if you contact us through this blog, email, or any of our social media channels.  We look forward to hearing from you.

ad astra per civitatem