I was always fascinated by model rockets when I was younger which led to my re-obsession with the hobby at the start of the pandemic. After assembling my first few rockets (with remarkably better attention to detail than I remember as a child) I knew I wanted a rocket that did more than pop a chute. This led to the design and development of a modified model rocket payload capable of carrying electronic devices including an altimeter, recovery buzzer, and eventually a tiny video camera. I also refined my finishing techniques and even started sewing my own parachutes.
Phase 1 – The “Simple” Payload
This was my first attempt at modifying a “kit” model rocket. I used the base model as a starting point, purchased a bunch of craft materials and extra rocket body tubes and got to work. The goal for this phase was to develop an “auxiliary” payload section that could be added to the base rocket, while still maintaining aerodynamic stability. Although the payload is extremely simple it allowed me to explore techniques for mounting electronics within a rocket body.
The “Simple” payload (Simple Payload) consists of a power switch, battery, Estes altimeter, buzzer, and a couple leaf switches for arming and deployment sensing. For simplicity, the buzzer and altimeter were designed to use the same power source. I originally thought of hacking apart the altimeter and rewiring the power leads to a common battery but to my surprise the altimeter uses a rather unique tiny 6V battery. Turns out it is very hard to find a 6V battery clip/holder. Instead I chopped up the altimeter, preserving the tiny battery compartment, and re-routed the power leads.
The main reason for separating the battery compartment/holder from the rest of the altimeter was for ease of access. The altimeter screen is designed to be viewed by removing the payload from the rocket (or recovering the rocket after successful deployment). With the altimeter installed in the rocket body in this orientation, the battery compartment on the back becomes difficult to access. I relocated the battery compartment under the nose cone and mounted the nose cone with 3 tiny screws. This allows for easy access to the battery compartment in the field using only a screw driver, if necessary. (Turns out it was necessary as the battery popped out of its compartment on the first launch and reset the altimeter!)
In addition to the altimeter, the simple payload also includes a deployment activated buzzer. A simple series circuit powers the buzzer when both the Remove Before Flight (RBF) switch (tag removed) and the deployment switch are activated (this switch is just visible on the top edge of the coupler in the image above).
A simple slide switch in the body of the payload acts as a master on/off and powers the altimeter. The RBF switch allows for the payload to be powered on while removed from the rocket without the buzzer activating. This is helpful when reviewing previous flight data on the altimeter. Plus it looks awesome!
Launch Pad and Controller
My D-size rocket kit did not come with its own launch stand and I decided to construct my own. This was an incredibly rewarding experience and let me add my own fun features such as a camera “blast-shield” and “launch tower” camera mount. The base is a 20″ pre-cut round panel available at most hardware stores. I drilled a hole in the center and inserted a 3/16″ 4 foot long steel rod. To protect the wood, I covered the entire base in a couple coats of heat resistant paint. I also epoxied a section of heavy duty foil in the center that would, theoretically, protect the wood from the rocket exhaust. It looked very cool until it was absolutely obliterated during the first launch.
I also fashioned a small but powerful launch controller using a small plastic project box, a lighted switch, a couple 9V batteries and, of course, a red launch button. To keep it portable I chopped up a long RCA audio cable I had so that the launch cable could be disconnected from the box and wrapped up. The rocket end of the launch cable also includes an RCA jack that terminates in a pair of alligator clips for connecting the igniter. This configuration has reliably ignited the standard Estes igniters I have been using so far.
Phase 2 – A “Smarter” Payload
Phase 1 was ultimately a prototype for bigger and better things. I was able to modify a kit rocket and add my own payload. The simple payload was constructed of form board and card stock and turned out really well, however, I have since acquired a 3D printer. Phase 2 includes the development of a more advanced payload (Camera Payload) that includes a LiPo battery, micro-camera, and onboard charging circuitry using a 3D printed sub structure.
The camera payload makes use of a tiny camera I found online. I hacked apart the internals and wired in my own power cables. Design of the sub-structure took many iterations due to several constraints. The camera must be pointed in a direction that makes sense (slightly downward), the buttons must be accessible “in the field” to start/stop recording without disassembling the whole payload, and the SD card must be removed with relative ease. The camera circuit is incredibly fragile so disassembling the entire payload to access the SD card is not an option. These constraints resulted in the final sub-structure design. Buttons are activated by push rods that extend through the side of the payload, and the SD card is somewhat accessible after removing the nose cone (I still need to use tweezers to actually insert/remove the card easily).
This payload is designed to operate separately from the simple payload allowing for modularity in payload configuration.
During this project I also edited a couple videos for Youtube. Editing took so long for such a short video but I had a blast putting it together and am quite pleased with the result. Even got to learn a little motion tracking in After Effects!