ArduRocket first flight
The very beginning of the flight had a bit of a twist to it, but the rocket stabilized quickly. Here is the kmz file of the flight. The flight profile was generated with uav_log_to_kml using the ArduRocket data stream.
The biggest challenge was getting everything mounted solidly. The xBee RPSMA connector is threaded, which provided a good way to mount that, but nothing else even had mounting holes. I built a custom mount from G10 (aka FRP) fiberglass board, and then secured things with zip ties. I was concerned that something was going to come loose, especially as the descent was a bit quick (over 20 ft/s), but it worked well.
As I analyzed the data, I discovered a couple things that would really make this a quality telemetry system suitable for high power rocketry.
- The velocity is reported as ground speed only. The ArduPilot code does not take the mainly vertical nature of a rocket flight into account. Thus my use above of average fps during ascent. As ArduPilot was created for planes, this is not an issue with the code, just the application. This is calculable using the provided data, and is likely the first major modification to the base ArduPilot code.
- Data is not recorded on board. As long as you maintain radio contact, this is not a major issue. Thankfully this flight did maintain contact throughout. However, if it had not, valuable data would have been lost. This is a harder fix, as the ATMega processor has limited serial i/o capacity. While possible to resolve, additional hardware will be needed. In the short term, higher gain antennas will work. I do not currently have a real-life measurement of the max range with the antennas used (3.1 dBi).
As a first attempt, this project proved to be quite promising. Adding flight event capabilities should happen sooner rather than later. Combining this unit with the ability to perform various flight events would be very powerful. This is a great platform for a DIY flight computer.