January - March 2024

Dev Log 18

Project Update - January 2024

There were still a couple of small things with Air MK1 that needed to be done, so in January I did just that. First up was installing the rail buttons on the vehicle (figs 1, 2). These rail buttons are 3D printed and fit in a 3030 aluminum extrusion.

fig 1 - Rail buttons

fig 2 - vehicle mounted on launch rail

I also put together another TFAC r3 board, and finally got the GNSS radio working (fig 3)! The issue is what I thought it was - a bad GPS antenna.

fig 3 - Working GNSS radio!

Another cool thing I did this month is a make a PCB assembly montage of TFAC. It was my first time doing something like this, and I learned a lot about recording your projects and editing videos. Here's the link to the video - https://youtu.be/mceE_PpdT4M

After all that hardware stuff, it was time to work on TFAC's flight software. I was having some issues with transmitting packets; what I did to fix this is increase the Air Data Rate, and change my data packetizing library (fig 5, 6).

fig 4 - TFAC connected to the tlm radio

fig 5 - Ground Control UI

Rocket -> Receiver -> GCS

I really wanted two-way comms, so I could remotely control when the cameras turned on and have a Ground-Locked state so I could perform pre-flight tests on the vehicle while it was turned on. I already got two-way comms working in the back end, now I had to write the code for the GCS to reflect that. I included a vehicle command section where I could turn the cameras on or off, command the pyro channels, and change the avionics' states (fig 7).

fig 7 - Updated GCS software

Project Update - February 2024

Sooooooooo I messed up soldering the new TFAC r3 board (figs 8, 9). I didn't inspect the board well enough after soldering and so I didn't catch the fact that one of the load cells was bridged. When I powered the board with a 3s LiPo and commanded that load cell to turn ON, I heard a loud pop and was greeted with the unpleasent site of a hole in my load cell :/

fig 8 - One good load cell, one very stressed load cell

fig 9 - Load Cell "Popped", Circa Feb '24

After that unpleasent event, I was met with another unpleasent event! This time my barometer started acting up (fig 10), or rather down. Whenever a telemetry packet is sent there's a change in the read interval for the baro which causes a change in the measured pressure. To fix this I played around with the ADR and UART rate until it was resolved.

fig 10 - Raw Baro Readings

Pleasent event alert - The camera commands work well (fig 11)

fig 11 - Runcam arming from GCS

Well this is sad. I broke another TFAC board (fig 12). This was extremely stupid. I had the switch wire right up against the 5V and GND lines of the servo, when I plugged in the battery it looks like I fried the Teensy's VREG. I think it should be salvageable, and then only think I need to do is replace the VREG.

fig 12 - Broken TFAC r3

With all that done it was time to launch Air MK1. I packed up the rocket (fig 13) and sent it to my mentor who has a motor and will be launching the rocket. I can't go launch the rocket because I have my 10th Grade finals.

fig 13 - Air MK1 packed

Next up Air MK2 (fig 14). This is going to fly higher, faster, and I'm going to implement everything I learned from Air MK1 into this. This will be a dual deploy rocket, meaning it has a drogue parachute deploy at apogee and a main that deploys closer to the ground, controlled by TFAC. The forward section of Air MK2 holds the nosecone, eyebolt bulkhead and main parachute. The aft section holds the 54mm motor mount tube, thru-the-wall fins, eyebolt bulkhead and drogue parachute. Both sections of airframe are attached by a coupler which doubles as the avionics bay with avionics and cameras.

fig 14 - Air MK2 3D Model

I also designed the avionics bay (figs 15, 16). The av-bay holds TFAC, 3s LiPo, Telemetry radio and antenna, GNSS antenna, and a pull pin switch for arming the stack. The av-bay has three physical parts - the sled, forward and aft bulkhead. The sled is fully 3D printed. The forward and aft bulkheads are 3D printed out of PETG at a high infill and have 5mm plywood plates epoxied on them. The whole bay maintains structural integrity by two 6mm threaded rods that run through the whole bay.

fig 15 - Av-bay front

fig 16 - Av-bay back

Project Update - March 2024

Lot of Air MK2 progress this month. The vehicle is almost fully done. Cut the tubes, got the fins cut, fin slots cut, motor mount epoxied in, inner fillets, outer fillets, sanding, beveling, painting (figs 17 - 24)

fig 17 - Tubes cut out

fig 18 - Fins, bulkheads, jigs

fig 19 - MMT epoxied

fig 20 - Av Bay

fig 21 - fin slots cut, MMT epoxied in airframe

fig 22 - Inner fillets done

fig 23 - Outer fillets sanded + beveled

fig 24 - First coat of paint on the aft airframe

Also finished up the av-bay (figs 25, 26).

fig 25 - Avbay front