Recently, I began working on my model rocket to achieve the Level 1 (L1) certification through the National Association of Rocketry (NAR). The whole procedure to obtain the L1 certification is detailed here for those who are interested in pursuing the certification.
After some research, I decided to start with a beginner-friendly kit that still offered plenty of educational value: the Zephyr rocket, manufactured by Apogee Components. With a length of 143.26 cm and a weight of about 1247 g, this rocket is built to sustain high-trust motors. Furthermore, the instructions included in the kit are very easy to follow and the technical page provides also the position of the center of pressure, which is located 114.02 cm from the tip of the nose cone. The center of gravity (C.G.) will, of course, depend on the final setup with the motor installed. So, I’ll measure it once the motor is in place. However, to ensure the rocket is stable, the center of gravity should be located at least one body diameter ahead of the center of pressure.
The build process was straightforward, but still required some attention. The engine mount assembly was a particularly critical step (Figure 1 left): I followed the instructions to glue the engine mount tube and centering rings, ensuring the engine would be securely held in place during launch. I admit I used more epoxy than I probably needed, but, you know... I'm trying to stay safe :) As a side note, after realizing that the epoxy was too runny for my needs, I did some research and decided to use a thickener (hydrophilic fumed silica) to give it a more paste-like consistency. I had to experiment a bit with the ratio between epoxy and thickener, but I eventually achieved a good consistency.
With the motor mount finished, I moved on to the fins (Figure 1 right) — a step that requires both patience and precision. I used wood glue and epoxy to attach them symmetrically around the airframe. Even small deviations could affect the rocket’s trajectory, so I took extra care with the alignment. I did not use a fin alignment guide since I could see the fins were aligning quite well with the frame (great job Apogee Components!). I hope I made the right choice. I guess I will see once the rocket flies towards the sky!
For this rocket I selected the Aerotech H100W-14A which has a diameter of 38 mm and a total impulse of 234 Ns. According to Rocksim, the rocket should reach an altitude of about 609.6 m (~2000 feet), as shown in the following graph (Figure 2):
Rocksim also calculated the optimal ejection delay to be around 8.32 s. Therefore I'll need to trim the delay charge since it is 14 s by default. With the motor mounted, the center of gravity is now located 103 cm from the tip of the nose. With the center of gravity in front of the center of pressure and a distance between them of about 11 cm (which is greater than one time the diameter of the rocket), I should be able to have a stable flight!
For the painting I used a different color scheme than the original one (see Figure 3). Of course the color scheme is mostly a matter of personal preference, but I definitely like how she looks! The letters, as well as the light purple details, are made out of adhesive vinyl. The most challenging part of the paint job was the nose cone. I initially used a primer to help the paint adhere, but after doing a bit more research, I realized that an adhesion promoter would have been a better choice (primer helps with surface uniformity, but plastic nose cones often require an adhesion promoter to properly bond paint to the surface). If the paint starts peeling too easily, I’ll repaint it using the proper method.
I also wanted to play with the name and give it a new spin. So, Zephyr became... Zephyress! Why Zephyress? Well, clearly there is a reference to the original name of this kit (never forget your origins!), but I also saw it as a small personal tribute to all the amazing women in aerospace who continue to inspire me. And to add a little touch of mystery and imagination, I asked ChatGPT to come up with a short myth-style backstory for her. Here’s what it came up with:
"Most rockets are named for their power, their speed, or the celestial destinations they aim to reach. But occasionally, a name carries something more: a sense of meaning, a story, a symbol that transcends the technical. Zephyress is one such name. Zephyress, daughter of the West Wind, was born not of storm nor thunder, but of the quiet power between seasons. Unlike her father Zephyrus, who guided the winds of spring, Zephyress looked skyward — her heart drawn to the stars. Whispers say she carries messages between Earth and the heavens, riding on silver air and leaving only a purple shimmer in the clouds. Where others stir petals or bend branches, Zephyress parts the sky."
Regardless of the mystical nature, I really hope that my rocket will be able to sustain the power of an H motor and be able to touchdown safely. I am planning to launch it around mid July. So, fingers crossed for a smooth, powerful flight. I’ll report back with launch day photos and lessons learned.
Disclaimer: This post reflects my personal experience. I am not responsible for any damage, injury, or issues that may result from attempting to follow the same steps. Please do your own research and take all necessary safety precautions!