Spring 2019

My first year of grad school has now come to an end. I’m halfway through and still on track to graduate in May 2020. This spring semester went better than the fall, largely because I had more rockets to work on!

As far as the rocketry team is concerned, we participated in the third annual Argonia Cup in late March. We built a minimalistic rocket – 3” in diameter, 5’ tall, basic dual deploy to recover our golf ball payload that we flew on a CTI K740 as opposed to the L1000 motors we’ve done in years past in larger, heavier rockets. Dual deploy recovery has won the competition two years in a row, and as it would turn out, that same method would prove itself again this year.

I led recovery operations for this rocket and pulled off a flawless test flight a week before the competition. At the competition itself, we were the 3^rd or 4^th flight early Sunday morning (Saturday was too windy for anyone to fly). The up part went great, but for some still unknown reason, there was no separation at apogee. Both charges fired, just no separation. The main charges separated the nosecone, but due to high downward velocity, it couldn’t pull out the chute enough (too much drag). The rocket hit hard and destroyed everything but the motor hardware. This is the first all-out failure I’ve directly been responsible for, but what still frustrates me is that I don’t know what I’d do differently next time. I ground tested it, flight tested it, and it still failed. While hard to come to terms with, the rest of that launch day was awesome. There were multistage flights and many more university team competition flights. OSU’s other team, the senior design capstone team, ended up winning on a second flight that used dual deploy. They developed an autonomous glider, but that wasn’t what won the competition for them. With that, OSU has now won all 3 of the Argonia Cups. 

The (only successful) flight on an I284

CTI K740 Boost

Argonia Cup 2019

We are not attending the Spaceport America Cup this summer. Several of our most committed members, myself included, are staying in Stillwater for the summer, so we hope to work on research motors and a new 4-axis fiber winder Dr. Arena purchased in February.

Outside of the rocketry team, I was enrolled in the first rocket propulsion course to be taught at OSU. Our class project involved studying 3D printed, liquid-cooled rocket nozzles. To complete this, our class was split into two teams: one to work on the nozzles, and one to develop potassium nitrate-sorbitol (KNSB) propellant rocket motors. KNSB is a poor propellant compared to commercial-grade composite propellant, but the materials are readily available, easy to manufacture, and very affordable. By the end of the semester, we were able to fire a rocket motor for $6 a pop, whereas a commercial motor of equivalent size would cost $30. It was tremendously exciting to be manufacturing our own propellant, something I’ve dreamed of doing for three years. The motors themselves were quite small, only 4 ounces of propellant in each, but they let us test lots of nozzles affordably. 

Cold flowing of our final nozzle design, producing a total annulus of water around the nozzle

Capture showing the water near the nozzle surrounding the white KNSB exhaust.

The project was successful. We can quickly and safely make KNSB propellant grains at OSU, and we fired ten 3D printed rocket nozzles, some regular, uncooled plastic, some with an integrated coolant feed system to circulate water throughout the nozzle itself. This is usually known as regenerative cooling, but regenerative implies the coolant fluid is injected into the combustion chamber, which we did not do in this project. Injecting water into a solid propellant motor wouldn’t make for very effective combustion.

We mostly used PLA plastic for our prints, and we determined that PLA is not a suitable material for rocket nozzles. Even cooled, the entire nozzle geometry was effectively destroyed. Cooling did however reduce some of that ablation.

The most interesting finding of the project was a unique nozzle material printed for us almost as a gift by a student researcher. The nozzle was uncooled and made of selective laser sintering (SLS) nylon that can withstand heat better than PLA. This nozzle outperformed all our PLA nozzles by a long shot, so this is a material I want to test more often going forward. Unfortunately, we only got the one nozzle for this semester’s project, but I expect to use it more in my thesis work later this year.

All in all, great project. I appreciate Dr. Rouser funding the materials to get us going in making research motors. This is an area the rocketry team wants to build on this summer.

With the summer now having gotten started, I’m deciding how to proceed with the cooled nozzle project, working on my own personal rockets, and should start rocketry team work soon. While I’m working part-time research jobs over the next few months, this is the first summer in 6 years that I am not working full time. Because of how much I hate being bored, especially during the hot summer months, I have a long list of personal projects I want to work on, mostly rocketry-related. I also want to improve my soldering skills, make sourdough bread, and read more.

Ever since starting college, I’ve read significantly less than I did in high school, but that changed last fall when I started reading George RR Martin’s A Song of Ice and Fire series. Since finishing those in March, I’ve also read It by Stephen King, and reread childhood favorites like Rocket Boys, The City of Ember, and The Mysterious Benedict Society. That’s been a major plus of grad school: that I not only make more time to read, but that it has returned as a source of enjoyment like it was when I was growing up.