Rattan V-Tail Quadcopter!

Here are some test flights of my latest home-made multi-rotor creation: a V-Tail Quadcopter, built from rattan, wood, and zip ties, mostly. I was inspired by David Windestål's recent V-Tail build video on the Flite Test channel to make one of my own.

My Approach

I decided to construct my first V-Tail quad using cheap and mostly natural materials, patterned after some of what I've learned from some of my previous "bamboo" tricopter designs. The hope was that a V-Tail configuration could offer similar handling to a tricopter, without the additional parts and complexity of having to set up vectored thrust on the rear rotor.

So Why Rattan?

 It's cheap, light, extremely tough, and easy to work with! You can heat up rattan and reshape it however you like, and when it cools down, it will keep it's new shape. One of the problems I've run into with rigid 'prefab' frame designs has been that the more rigid a frame, the more likely it will shatter or get hopelessly deformed upon the first heavy impact. Aluminum, CF, and FG just won't give. And once they do, they're pretty much totalled.

I decided to approach the problem of crash tolerance by designing a frame to help absorb and release shearing forces. I've experimented with a lot of different multirotor frames, and one of the things I've realized is that a frame doesn't need to be completely rigid to perform well--at least not with the kind of casual flying that I do. That being the case, very rigid materials may not be the best choice. I tend to crash a lot. And zip ties are so cheap and plentiful! 

Crash Proofing

In a crash situation the foam bumpers, rattan, and wood will help protect the rotors and electronics, absorb lots of shock, and either twist or 'break-away' at the root--which is held together entirely by zip tie tension and the friction of wood and rattan against rubber. 

My Rattan V-Tail Quadcopter - For the front arms I recycled a length of 3/4" square length of wood and foam bumpers salvaged from a previous frame. The wood and foam are covered with fiberglass tape. The cowling is also from an older design, and is just corrogated plastic folded in 2 places. 

Under the hood: I'm using two spare DT750 motors for the front rotors, and on the rear I have two 2213N motors, with 30Amp Plush ESCs throughout. The thrust developed by these motors is a little different, though not an issue because the flight controller manages how much each rotor needs to stay in balance (mostly). I still need to find the ideal mix for better pitch control...  

Some thoughts on thrust angles

To be honest, I didn't even measure a precise angle on the V-Tail. I just shaped it to be a symetrical and roughly around 40 degrees. I don't think it matters so much. There seems to be plenty of angle on the V rotors for yaw authority. 

Notice that the orientation of my V-rotors is opposite from how David designed his V-Tail. His rotors thrust inward across the center line, while mine thrust outwards from it. As as result, I reversed the rudder values for channels 3 & 4 in the Mixer Editor. So instead of using:

Ch.3 Rudder: 100 and Ch.4 Rudder: -100

I reversed it like so:

Ch.3 Rudder: -100 and Ch.4 Rudder: 100

Keeping things 'Tight'

I carved a flat space along the top of the rattan spine, and covered with a strip of bicycle tube rubber. Then secured the front arms to the spine with zip ties, lashing the pieces together through holes drilled into the plywood. To tighten up the frame a bit more, I used 2 short pieces of rattan as shims, kept under tension with the zip ties and strips of bicycle rubber inner tubing.

Bamboo skewer also used to tighten things up a bit further under the zip ties.

The KK2 board foam case is used to protect the board. It can be detached easily by sliding off the fastening zip ties.

The perch for the KK2 board is made of 1/8" plywood. There are holes drilled through at either side of the spine and cross member, zip ties lash everything secure. 

To get a desired 'supple strength' on the V-tail, I heated up a few lengths of rattan and shaped it to the degree I wanted, drove in a couple woodscrews to anchor the "V" to the spine, and for good measure squirted a little hot glue into the gaps to make sure things want to stay put. Here I used vinyl tubing and zip ties to provide additional strength and shock absorption.

With the vinyl tubing I lashed it all together and then looped in zip ties to 'rachet' it all down even further. 

The V-Tail stands up on its own! I installed a new Flite Test battery/camera tray--which I can't wait to see how well it works to absorb vibrations... I think it goes perfectly with my frame design!

 Dry Weight = 1300g.