Where did Aerospike Bullets come from?

So I mentioned on a few forum posts that I have been working on Aerospike Bullets for over 20 years and more than once I have been asked where did the idea come from.

I graduated from the University of South Alabama in 2001 with an undergraduate degree in mechanical engineering and and my first job out of school was as a research engineer at the American Cast Iron Company in Birmingham, AL. It really was a great job for a new engineer. Lots of cool projects. One of the projects I was handed was to decrease the “cold spot” at the center of a copula furnace by increasing the speed of the oxygen injectors around the edges.

I remembered a class I took called “fluid dynamics” and there was a very short section on what we refer to as “compressible flow”. It included a section on rocket nozzles. I tried making some to speed up the oxygen and it failed miserably. That lead me to first studying aerodynamic theory and I fell in love with it.

As I was studying how to make injector nozzles, I came across the idea of aerospike rocket nozzles. You just take a rocket nozzle shape and turn it inside out. They are not used due to the weight issues for rockets but I first wondered what would happen if I put one on the back of a bullet.

I was studying for a masters in engineering and ready to jump in when 9/11 happened and I still had about 6 months left of involuntary reserve time from my enlistment. The USCG found out about my engineering work and I was slapped with a direct commission and sent on a five year detour.

When I left the USCG for the second time, I took a job in Huntsville, AL and started working toward a PhD. What to study? Of course I picked ballistics! I finally learned the math I needed but it wasn’t until Covid that I had the free time and money to really jump into the research.

I worked with a couple of undergraduate students last summer (shout out to Kobie and Julia!) but the results were all over the place in live fire testing. It wasn’t until this January that I finally had the breakthrough and got the designs working!