A Little Background
Soon after I got my Level 1 high-power certification in March of 2011, I started planning for my Level 2. I knew it was a good idea to just keep logging flights and gaining experience. But a few months later, at my first flight with Tripoli Central CA, I experienced my first CATO on the same rocket I used for my L1 certification. It was a total bummer, but I learned some important lessons (o-ring hygiene) as I pieced together what happened in that flight.
While I was still trying to figure out if I could salvage my L1 rocket (I did), I bought a kit for my L2 certification. I chose a Binder Designs Excel because it offered a dual-deployment option and kraft tube construction, which kept the price lower than any fiberglass or carbon fiber option. Then the kit sat around in a box for a couple of years as we settled into a new home and became parents of two. I started construction of the rocket in 2014 and built the fin can, which came out beautifully. Somewhere along the way, I wrote a few posts about the build on this site.
And then…I put the hobby on hold. My attention was elsewhere – family, work, buying our first house, other hobbies. I didn’t get to a single high-power launch from 2011 to 2023. I always planned to get back to rocketry, and in the spring of 2023, I finally did. At this point, my son Carson was interested in rocketry himself and was a helpful partner in the construction and planning. We had also moved to a larger home and I had space for a small workshop, which meant no more epoxy work at the dining table!
First Flight
We finished up the rocket in early 2023. Because I had completed the fin can over a decade prior, the rest of the work was just assembly of the avionics bay, fit-tuning the couplers, installing rail guides, and painting the rocket. Because my L1 rocket was named Forte, I decided to name this (larger) L2 rocket Fortissimo.
In May of 2023 we drove out to the Tripoli Central CA launch site for the maiden flight of Fortissimo. The plan was to fly on a CTI I195 motor using a 38mm to 54mm adapter. We used motor ejection to deploy the entire recovery system, starting with a drogue chute at apogee. The main chute was wrapped in a chute release which deployed at 800 feet.
The flight was a success. The airframe was in great shape. We reached a max altitude of 589 meters (1,931 ft) AGL and a velocity of 126 m/s (281 mph) under 7.9 Gs of max acceleration load – measured on an Jolly Logic Altimeter2. The ejection charge fired several seconds after apogee (after falling 70 meters). In retrospect we should have drilled out a few seconds on the delay grain, but there was no damage done. It was a good test flight and we started planning for the next flight.
Second Flight
I wanted another test flight before making an L2 attempt, and used the opportunity to gain experience with some new tools and techniques. We added a Blue Raven altimeter to the avionics bay to fire the separation charge at apogee and added shear pins to all airframe couplings to keep everything together during flight.
It was my first time using shear pins and preparing a black powder charge. I did the calculations to determine the size of the charge and knew it would be a good idea to run a pop test to confirm separation. Unfortunately, we’ve found the new Featherweight Altimeters app pretty buggy and weren’t able to successfully run a pop test via the altimeter. Running short on time, we decided to just add a little extra black powder (about 20% more) to the charge and keep the motor ejection charge in place (with full delay) as a backup. That way, if the the altimeter failed or the apogee charge wasn’t sufficient for separation, we had a second charge that would fire a few seconds later and hopefully finish the job. And if the apogee charge did work as planned, the secondary charge would just vent out of the (now open) airframe.
The altimeter, black powder charge, and shear pins added many more steps to our pre-flight checklist, but we felt pretty confident we had thought through all of the critical parts of flight prep. In July of 2024, we again joined the Tripoli Central CA club for a brutally hot launch in the summer sun. Hanging out in a dirt field with zero shade in 100° heat is not awesome, so we were eager to get in and out pretty quickly. We were also doing a test flight of Carson’s new custom built rocket, Red Shift, which is a super lightweight and designed for a long, slow burn on F10 motors. Given its small size and long, steady burn, we knew some help would be needed for recovery, so we were also testing a new Featherweight GPS tracker, for which Carson designed a custom nose cone mount.
The second flight was mostly successful, and we learned a couple of lessons. We flew on a CTI I175 motor this time. We reached a max altitude 570 meters (1,869 ft) AGL and a velocity of 114 m/s (255 mph) under 7 Gs of max acceleration load – measured on the Blue Raven altimeter. The apogee charge fired successfully, but I’m not sure we achieved full separation. The backup ejection charge from the motor might have completed the job. (I think this because we didn’t actually shear the pins, they just bent out of the way and there was a noticeable kink in the av bay coupler.) The more interesting failure was on the chute release. I was using an older rubber band to hold the parachute bundle and it snapped before the release pin popped at the expected altitude. So, we came down under the main chute for much longer than planned. We had some additional drift because of it, but it was fine. It was a good lesson to use fresh elastic to wrap the parachute bundle. Otherwise, we had a clean flight and full recovery.
Certification Flight
With two successful launches (and some good lessons) under our belt, we prepared for a certification flight a few months later at TCC’s October Skies launch event. I studied for the L2 written exam and we made a few modifications to Fortissimo ahead of the launch. We added a new avionics bay sled that was capable of carrying both the Blue Raven altimeter and the Featherweight GPS tracker. At some point during the first two flights we created a soft spot in the airframe – either from a hard landing or careless handling between flights. It was unlikely cause any problems, but I was a little nervous about potential buckling under the axial load of a J-class motor. We 3D-printed a coupler and epoxied it inside the airframe at the soft spot just to stiffen things up a bit. Finally, we repainted the rocket white, which helps a little to prevent radiant heat absorption when we’re waiting on the launch pad under the intense Central Valley sun. Otherwise, the rocket was flown as-is, with a similar flight profile to our previous flights.
The plan was to fly on a CTI J250 motor in a 2-grain 54mm case. Getting ahold of CTI reload hardware was actually pretty tricky – cases and closures seemed to be in short supply as CTI works through a production backlog. Apogee deployment would again be handled by the BlueRaven, with the motor ejection charge as a backup. The full recovery bundle would be released at apogee with a drogue chute to start and the main chute wrapped in a Chute Release set to open at 600 feet. Our simulations showed an expected apogee at 1,104 meters (3,622 ft) AGL.
After a missed exit and some creative navigation, we still got to the launch site with plenty of time to get setup. I found the prefect, and took my written exam, which I passed. We prepped the rocket for flight and brought it back to the prefect for inspection. He gave us the green light and we got ready for flight. Our preflight checklist is a little more involved than it used to be with arming an altimeter and connecting the GPS tracker to the ground station. But we took our time and were soon ready for flight.
Fortissimo soared off the launch rail and had a clean flight. We were slightly off vertical, but nothing too concerning. We reached a max altitude of 1,086 meters (3,563 ft) AGL with a max velocity of 179 m/s (399 mph) under 9.8 Gs of max acceleration load. That was a new max altitude record for me and my first flight over 1 kilometer. The simulations were pretty much spot on. On recovery, we again couldn’t tell if the apogee charge fully separated the rocket or if the backup motor ejection charge finished the job. But the recovery system worked as expected and we came down for a soft-ish (27 ft/s) landing. Everything was intact and could’ve flown again. After inspection from the prefect, he congratulated me on achieving Level 2 certification from Tripoli. It felt great to finally reach this milestone after so many years of planning.
What’s Next
Now that I have my L2 certification, I’ve been thinking about what’s next. L3 certification is out there, but I’m not interested in chasing that any time soon – I will get there eventually. I think the power range for L2 motors unlocks some really interesting possibilities. In the near term, I want to start exploring some new design and construction techniques, including composite airframes, 38mm and 54mm minimum diameter designs, and true dual deployment. I’m looking forward to my first supersonic flight with all the thoughtful design and precise fabrication that demands. And I’m really excited to help Carson prepare for his Junior L1 certification some time in 2025.
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