I would like to share with you my latest project. Currently I am at the crossroads and would appreciate any feedback.
The main goal was to design a truly portable drone that fits into a backpack. I was unhappy with the foldable frames on the market, as they were all too large. The ones which fold in horizontal plane still have a problem with landing gear, and in umbrella-type frames you need to sacrifice the space for electronics. I ended up with such requirements:
Compactly folding core
Arms fixed with a screw (no plastic clips)
I've decided to use two 16 mm tubes as a frame core in order to make it strong and flexible. I've made two modules for front and rear arms. PMMA plastic is used to reduce the prototype costs (however, 3mm plates are surprisingly strong), later I am planning to switch to carbon fiber. The most compact folding is achieved when arms are above each other.
Firstly I was attaching legs to the core tubes (PVC plastic). But then I realized that they can be fixed with the same screw as arms. And this shortens the assembly time. Legs can have different length, mine are short just because I ran out of tubes.
Following the modern trend I added a vibration isolated plate. The number of damping balls can vary depending on the load. Some balls have flexible position in order to fit to different core sizes.
My current frame size is 710mm and it folds into ~ 370x170x120 mm, which is less than 8L volume.
While the weather was not good for flying I decided to collect my thoughts. The frame is portable and also turned out to be quite flexible. Several holes can be drilled for the arm-fixing screw -> several square frames can be build from the same parts.
I started to dream about "Lego" for drones. The main point about "Lego" is that from the same parts one can build various things. There are some plastic analogues like RotorBits, however I was considering only carbon fiber and aluminum parts. Currently with my friends we are working on such set of universal parts for multirotors. Here are the characteristics we implemented in the kit:
Personally I am really happy with the result.
Even my large 710 mm drone fits into a backpack. The frame is easily customizable: in order to change the size one simply slides the arm-modules, also variable parts can be attached to core tubes or to the center plate.
At this point I would like to hear your opinion. Did you also think about a truly portable DIY drone? Which characteristics would be the most important?