Intro: Modular Multicopter, Quads, Hex, Oct, Y4, Y6, OCT X4, Up to 16 Motors!
Welcome to the build of my latest and greatest multicopter.
I have decided to try something a bit different on this build, so this multicopter can be configured to what you want. It starts as a quad (either + or X), and then can be changed into a Y4 (by removing one arm and have the 4 motor underneath one arm), add another couple of motors and change to a Y6. Then add two more arms (and the original 4) and you have a true HEX6 in either + or X. Then if you want you would add another two arms and make it into an OCT again in either + or X. and if you don’t want to make the extra arms you could just double the motors on the quad. OR if you really want to go to extremes how about doubling up the motors on the HEX for 12 motors, or double up the Oct for 16 motors!!!!!!
I spent quite a long time designing the centre hub to allow for all the configurations and the first test fit seems to look good. All the arms are held in place using a long tie wrap thread though all the arms.
Step 1: Sequence of Build.
Sequence of Build
So I have used my tied and trusted method of:
1) designing using QCAD on my Raspberry PI.
2) Printing out and sticking the paper to 3mm Plywood
3) Cut out using my fret saw. (I really need a laser cutter!)
4) Stick bits together.
5) Add some motors and ESC.
6) Add a flight controller and receiver.
7) Test fly and crash badly.
8) Go back to step 4 and try again.
Step 2: The ARMS.
This design if for 10” propellers, you could use smaller ones, but not bigger (if you are going for the OCT option).
The arms themselves are cut from 3mm 1/8” ply and are designed so the sides and top and bottom are cut out in pairs.
If you look at the plan for the arms each A4 print will make 2 complete arms. The pieces should be cut with consideration to the grain and flex of the ply wood. and the motor double piece of ply has the grain in the opposite direction to give the best strength in this area.
The arms can be mounted either way up and if you are going for a HEX or OCT then you will have to alternate each arm as the propellers over lap considerably. The difference between mounted either way up is 15mm so you should see it’s a good safe distance, and the same applies if you also mount motors on the bottom.
Step 3: The Central HUB.
The Central Hub.
Again the central hub is made from 2 pieces of 3mm or 1/8” ply and cut out together, you will notice on the plan there is an extra random hole in the middle of one of the arm slots, this is to help realign the two bits if you lose track of which way up and around they go.
The holes for the flight control board are drilled for 45mm hole spacing and will suit the full sized KK2.1.5 and All in one pro multiwii boards.
Step 4: Motor Mounts.
So the motor mounts are designed to use the aluminium cross mount, this brings the holes to outside the diameter of the motor and more importantly allows a motor to be mounted on the top and bottom.
A long M3 screw and lock nut is used in each hole, and if only one motor is used then its best to put a washer on the underneath wood side.
Step 5: Wiring.
Flight control board.
I have decided to stick with the KK2.1.5 board as it will allow me to change configuration quickly and without the need to connect to a computer. You could use another board, but you will have to work out how to set it up.
The power wiringI decided to wire the motors in pairs with one motor running clockwise and the other running anti-clockwise. This will work fine for the quads, hex and Oct, but when you want to put a motor on the underside it needs to run in the opposite direction from the one on the top, and because it is mounted upside down it needs to run in the same direction as the top. (i think that makes sense)
Step 6: Configurations.
Their are loads of possibilities. The obvious ones are the quad hex and oct in either X or +.
But then you have the Y4 which is basically a tricopter without a servo. It uses a motor on the top and bottom on one of the arms. You can choose to put the arms where you want (see note at bottom). but you must make sure that two motors spin one way and two spin the other.
Then you have the Y6 which is a tricopter with a motor on the top and bottom. Where you place the arms is up to you (see note at bottom), but you should make sure that all the motors on the top spin clockwise and all the motors on the bottom spin anti-clockwise, which means all the motors are turning the same direction but the ones on the bottom are upside down so turn the opposite direction when viewed from the top.
Next we have a X8 or +8, which is a quad with motors on both the top and bottom. like the Y6 the top motors spin clockwise and the bottom ones spin anti-clockwise. Again you can play around with where you put the arms. (see note below)
You can place the arms where you want but if they are not in standard angles then you will need to change the mix via the mix editor. This isn't hard to do and i have included a picture of the pitch and roll values for all the positions around the circle in 15degs increments.
AND once you place the arms any closer than 90 degs then you will need to alternate the arms from high motor mount to low motor mount and so on.