Discussions

Hi guys, 

Been lurking for a few years with not much to add, but thought I might share my latest build with you. It is (yet another) folding quad, but in X8 configuration, with a few of my own ideas. This is the 4th copter I've built (all running AC code) and each one has been a learning curve, which I expect this one to be as well, although I hope I'm a bit closer to 'home'.

My application involves trekking through the bush, to eventually work on hilly, rocky areas with long grass often. So I needed a craft which would be small enough to carry easily, but then tall enough to land / takeoff in long grass. Also because there's almost nowhere level, I wanted independent legs (as opposed to helicopter type 'skids') which can adjust to uneven terrain and have a shock absorber in each, so that when it comes down if one leg touches down first it doesn't take the complete brunt of the landing. And also because I wanted redundancy I went with the X8 configuration (which doesnt lend itself to independent legs...). I also wanted it to fold up 'within itself', with no props sticking beyond the borders of the frame.

So this is what I ended up with:

Motors AX2810

ESC's Afro 30 amp

Pixhawk (a clone, unfortunately, because 3DR stopped shipping overseas as I wanted to place my order)

Prop to Prop (diag) is 770mm

Folded its 410 (L) 250 (W) and 150 (H)

AUW (with battery) is 3.3kgs

Although I have borrowed some of the folding frame ideas, the design is completely my own. I had the plates water jetted, and machined the rest (such as the gimbal) myself.

Here are some pics:

With Arms and legs opened

You cant see clearly from the pic, but the configuration is a square 'quad', I need it to fly equally forwards, backwards and sideways

Each leg has about 100mm of suspension travel

I used shock cord which I can easily adjust the tension of to get the correct balance, and the pivot point has small bearings to run on.

Folded...

The entire folding mechanism uses one 5.5mm socket to complete. All the other ends are 'captive' or can be held by hand. It takes less than 5 minutes to unfold it for flying

The gimbal retracts for transport, then moves out to clear props and legs during flight

I would appreciate your comments and advice. I've still got a fair bit of tidying up with wiring to go, and am still waiting on my 4S batteries to arrive. In the future I might change a few things (like making the legs a tad shorter), but in the mean time I need to start tuning it. I've only done one short flight in the back garden so far :)

Pete