Backpack-able Anycopter

Hello !

These are my instructions for scratch-building the Flitetest: Anycopter. I live in a small flat with no outdoor space so I do everything in my front room. I use things I can find around the house as tools/rulers and everything in between. This proves that anyone can build multirotors and that you do not need a garage/workshop in order to-do so!

I have designed this so that it will fit into my backpack (Targus), I probably won’t fold this quad all that often, but something that I wanted to try for redundancies sake. I frequently travel 250 miles home to see family via train and would like to be able to take it with me on occasion.

Assumptions

For this, I need to make some assumptions of equipment and processes you have already completed. These are as below:

You have your parts – I have used:

4x Turnigy Multistar 20A ESCs,
4x Turnigy Multistar 2213 980KV motors,
4x 10×45 props (2CW and 2CCW),
HK V2.1 control board (flashed with Kapteinkuk xcopter V4.7),
300 x 10.5 x 10.5 booms (pine from B&Q),
3.6mm plywood,
2x Turnigy 3000mah 3S batteries – 22 minutes flight time,
Quadcopter power harness,
Receiver and radio,
10cm servo leads,
BEC (for OPTO ESCs only),
Velcro and zip-ties,
M5 bolts.

I have pre-programmed my ESCs individually using my Turnigy programming card.

You have some tools such as jigsaw, sandpaper, drill, pliers etc.

Marking up the circle

First of all I drew around a square placemat on my 3.6mm exterior plywood (my local DIY store has no aircraft grade plywood), then drew an X from each corner to find the centre. I then used my waste paper bin to draw a circle inside the square, this was great as the bin has a centre point from its manufacturing process. I drilled this out and used it to find the centre. However I strongly suggest using the proper method which can be found here: http://www.instructables.com/id/How-to-find-the-center-of-a-circle/ but the basics of it is; draw chords and perpendicular lines (90 degrees from chord) all around the outside of the circle, where the lines meet in the centre is the middle!

I used this tutorial http://www.popularwoodworking.com/woodworking-blogs/editors-blog/dividing-a-circle-into-three-without-a-protractor to help me find the thirds of that circle, its super easy and worked well. Once you have found the centre, draw a radius line, exactly half way (on your radius) between the centre and the edge, draw a perpendicular chord. Where the chord meets the edges of the circle, draw lines into the centre. You now have thirds!

To divide the circle up into quarters, just use a long edge and draw a line from edge to edge through the centre. Then, at the centre mark, draw another perpendicular line edge to edge.

I’m using these third lines for the tricopter boom holes, quarter lines for quad (for a hex just use the third lines, but extend them edge to edge). I measured 6x300mm booms (two extra for crashes!) and simply sanded off the corners to make them smooth, to cut everything out I used my 3-in-one drill/jigsaw/sander.

Fitting the flight controller

For my build I am using a HobbyKing quadcopter control board V2.1 -FC (I've read that the only difference between the V2.1 and V3 was that it has less RAM, so I went with the V2.1 and saved a few pounds).

Using the lid of the packaging that comes with the FC (just as David recommends) I found the centre by drawing an X from each corner and poked a small hole with a pen, this allows me to centralise the foam onto the centre-plate. While fitting ensure the direction is correct (corner forwards for Xcopter) and hot glue it into place. I then hot glued the FC onto the foam.

The idea here is to dampen the FC from any vibrations, so if you have something better then be sure to use that. The more stable your FC is the better it will perform.

Drilling all the holes

I clamped both circles together and drilled 5mm holes for the M5 bolts I have, (I only drilled the quad holes at this time) drill about 5cm from the edge of the frame. I also greyed out the areas where the booms turn on the bottom plate to ensure I wouldn’t mount/glue anything in its way.

Now in order for the quad to fold up and fit into a backpack, I need to ensure that the booms can be quickly fixed securely into place, but then undo when required. I originally screwed through the top plate and into the boom, but on impact this splits the wood thus breaking the boom.

So in order to get around this problem, drill 3mm holes either side of where the boom sits, as close to the edge of the frame as possible. Then use a small zip-ties to lock it into place. This trick works great as on impact it will snap the zip-ties and you won’t split your boom, it holds it great and can be quickly cut to fold the quad.

Getting the wires all neat, for me, is important so I drilled a 5mm hole to feed the ESC leads up from inside the frame to the FC.

Fitting all the pieces together

Now that we have all of the holes drilled, it’s time to put all the bits together!

Grab your power harness and solder the power leads to the +- of your BEC to the harness, triple check you have the red+ to red+ and black- to black-.
Zip-tie your motors to the end of your booms, get them nice and tight!
Connect up your ESCs to the motors and zip-tie them onto the booms too.
Take the top plate of the frame and the booms and put the bolts though the holes of the frame into the booms so it starts taking shape, use a flat surface here to help.
Connect the power from each ESC to the harness, try to ensure that the wires are central and will not get in the way of any moving booms, also make sure the connector reaches the outer edges of the frame. Triple check again that you have the +- correct!
Run all of the motor 3-pin leads into the hole drilled on the top plate up towards the FC.
Hot glue the BSC to the frame and run the wire up through the same hole as the 3-pin ESC leads.
Bolt on the bottom plate, and tighten everything up.
Connect the motors to the correct pins on the FC, ensure that the signal wire, orange, faces inwards, and the brown (ground) wire faces outwards, for Kapteinkuk V4.7 you need it connected as follows:
Motor 1: front left, CW
Motor 2: back left, CCW
Motor 3: Front right, CCW
Motor 4: Back right, CW
Then connect the Aileron, Elevator, throttle and rudder from your FC to your receiver. Check your manual to see which goes in what channel, for my Futaba R2006GS it is:
1-Aileron
2-Elevator
3-Throttle
4-Rudder
Connect the BEC to the receiver in the correct place, for me it was the last pins, B.
Place zip-ties through the drilled holes to secure the booms in place.

Moment of truth

Now that everything is connected, it’s time to check that the motors are spinning and the quad functions OK, do this now.

Check that the motors are spinning the correct way and calibrate your throttle range. The motors should spin as follows:
Motor 1: front left, CW (right)
Motor 2: back left, CCW (left)
Motor 3: Front right, CCW (left)
Motor 4: Back right, CW (right)

If one is spinning the incorrect way then simply change two wires between the motor and the ESC.

To calibrate your throttle range I have written a post on my blog here:
http://alexwhowhat.wordpress.com/2014/03/31/calibrate-your-hk-v2-1-kapteinkuk-v4-7-throttle-range/
Or David has it written up on his website here:
http://rcexplorer.se/educational/2011/02/kk-quad-x-setup-guide/
Or watch the Flitetest video on the control board here:
http://youtu.be/c9MNRT19yp4

For my quad, my pots are setup as follows:
Roll- 10 o’clock
Pitch- 9 o’clock
Yaw- 10 o’clock
This should give a nice smooth flight, but if you are struggling and it is tipping/wobbling, turn down the roll pot first, then adjust the others to suit your flying style.

Propellers and fly

Go ahead and put your propellers on the motors, ensuring that you have R propellers on motors 1&4 and L propellers on 2&3. I used some Velcro to fasten my battery onto the bottom of the frame which works great. Design your feet of choice, I personally don’t use any as I only fly over long grass.

Go fourth and fly your very own creation!