Author: Jacob Smith -
I am really pleased with my progress so far. I now have a working tracker system and in this post will describe the additional components I have added to my circuit, and the cameras I will use in my payload.
Just how cold will it get?
It will be interesting to know the outside air temperature during the flight, and also to compare it to the temperature inside the payload box. The electronics will probably do a good job at keeping themselves warm so this comparison will indicate how good the polystyrene box is as an insulator. Some people recommend using hand warmers but the risk of overheating the components then becomes greater than them getting too cold. One wire temperature sensors, meaning they only require one pin on the Arduino, are handy for measuring temperatures.
After checking the sensor datasheet for how to connect it to my Arduino, I was quickly able to print the temperature of my room to the Arduino serial monitor. During the flight, this data needs to be saved to an SD card. I also plan to write the GPS data to the SD card to act as a 'black box'. So I got myself an SD card module for the Arduino and after some basic testing was able to save the temperature data to the card.
______________ (Left) The temperature sensor is the small three-legged black thing, and the SD card is the big vertical component. (Right) Reading and saving the temperature to the SD card…pretty toasty!
Eye in the sky
Taking pictures of the earth as the payload soars to altitudes of around 30km is the main reason why I wanted to do this project. Therefore it is important to use a good camera that will perform in the extreme cold and not run out of space or battery before the highest point has been reached. I was also inspired by a video I watched from on-board a HAB flight, so I will definitely be using a video camera on my flight.
GoPros are by far the most popular video cameras to use due to their proven reliability in extreme conditions amongst other things. They are, however, well outside of my price range. So I went about researching cheaper alternatives that would perform nearly as well. Many action cams claimed to operate in the extreme cold, have a long battery life and great video quality, but it wasn’t until I found out that a fellow HAB enthusiast had used the Lightdow LD4000 that I had proof of a cheap video camera performing well on a HAB flight. I got one as a birthday present and will add an SD card and power bank to make sure I capture the whole flight.
My Lightdow LD4000 action camera
For taking stills, Canon cameras are widely used as they can be combined with the open source Canon Hack Development Kit. The CHDK is a firmware extension that allows the camera to automatically take photos at set intervals – very useful for HAB flights. I managed to bag an unused Canon Powershot A1100 IS for £30 on eBay. This has been recommended as a good camera for beginners in High Altitude Ballooning. I will talk more about the cameras once I get around to testing them.
Next on the list
Now I have figured out the circuit connections I will create a permanent circuit on a stripboard which I will be able to simply plug in to the Arduino. This makes for a more robust circuit as the wires and components are soldered onto the stripboard rather than just plugged into a breadboard from which they could easily come loose in the violent vibrations of a HAB flight.
I need to buy a power bank for the action cam, and batteries for the camera and Arduino. I can then start looking for a suitably sized polystyrene box as I will have all the components in the payload. Providing all the testing goes well, I will then know my final payload mass so will be able to buy the right sized balloon and parachute.
Thank you for reading this post, check back for more updates soon!