SexieHexie (Hexacopter With 8520 Motors)

This project is dedicated to the Belgian artist Panamarenco (link) who passed away december last year . He combined art with technics , especially flying objects . He will be missed ...

The supplies for this Hexa may look a bit strange but we're living special times , all model shops are closed due to the Covid-19 shit ... During the nineties I scratch-built many balsa R/C planes so there's still some WoodStock (:-) ) left . This brings us to the supplies :

Supplies

For the airframe :

- 2mm light aircraft plywood ( we need a 60 by 60mm part )

-3mm plywood or paint mixing sticks for the motor mounts

-Carbon fiber rods , 4.8mm or smaller ( but check for decent stiffness )

-scrap Depron , balsa for battery holder , canopy ...

-lots of imagination and patience , work slowly and carefully :-)

Avionics :

Transmitter and receiver ( I use FlySky I6 and FS-RX2A Pro V1 receiver )

Flight controller board : F3 Evo brushed ( or any 6 motor board )

1S Lipo battery , approx 600mAh (25C or better )

6 8520 1S motors ( 3CW and 3 CCW ) with props (55mm)

Tools :

woodworking tools , dremel , drill , all you can get your hands on :-)

Step 1: Draw Plans ( or Print Them )

First we need building plans , they will simplify your work as you can build the airframe on them .

I made several drawings as they got dirty during the job . They can be drawn in a couple of minutes , if you use millimetric paper it's much easier :-)

Step 2: Building the Motor Mounts

Mine are made of paint mixing sticks , appox 3mm thick ( and very cheap ) . We pick the best one out of the pack ( verify if it's staight , weight , quality ) and size it to 16mm with a Proxxon circular saw . Sand it , draw a nice line in the middle and mark the holes for drilling with a hand tool .Draw the external lines . Take your artwork to the drill stand , put a 8.5mm drill into the machine and drill all holes ( it's wise to make some extra motor mounts , some holes will be out of center even if you work carefully ).Cut the parts apart with the circular saw if you have one ( borrow one , it'll save you lots of time ) . Sand all parts , carefully try if the motors fit ( they won't , so sand the hole very carefully until the motors fit snugly) .

Et voila , motor mounts : Check !

Step 3: Building the Baseplate , Mark CF Rod Positions

Very easy ! Start by cutting a 60 by 60mm plate from 2mm aircraft plywood , cut off the corners (see drawings ) , sand , and put it on top of the building plan . Draw the lines for the CF rods using the lines on the building plan ( I used 4.8mm rods so adjust to the size of your stuff ) and it's done !

Step 4: Assemble the Frame

Make sure your working surface is completely flat and equal , use a fuselage builder jig or balsa building plank if possible . If you're working on the kitchen table cover it because we'll use glue and we will spill :-)

Put two motor holders on the plan and cut a CF rod . Use Cyano glue ( superglue ) and glue the motor holders to the rod . Put the baseplate on the plan ( put some scrap balsa under it if the motor mounts are 4mm) and line the whole thing up with the plan , glue with Cyano .

Let dry , even superglue needs some time . Now you can assemble all the motor mounts , CF rods to the baseplate with Cyano . Take your time and work precisely , you'll have to adjust the CF rods (cut with a certain angle) to have a good fit .

Six motors will produce a fair amount of vibrations so we need to reinforce the CF-motor mount connection point . This is done by soft balsa strips (3mm thick) glued with white wood glue next to the CF rods . It will add some weight but losing a motor in flight is much worse !

At this point , the AUW ( All Up Weight ) is about 14 grams , quite acceptable .

Congrats , you have made yourself a nice airframe !

Step 5: Installing the Motors

This is an easy job . Because the motor mounts are ( or should be ) almost straight in all axes just put in the motors ( it's a good idea to test them first ) . Make sure to put the motors ( (CW and CCW) in the correct positions . I used a triangular tool to verify my job . If it's all OK fix the motors with a tiny drop of Superglue .

All up weight is now about 50 grams .

Step 6: Installing Avionics

I had to repair my Flight controller , the step-up converter was dead .

I removed/replaced this part : MT3608 booster

Found lots of info here :-)

Fix your Rx and flight controller to the baseplate with double tape or the sticky things that fix your GoPro to your motorcycle helmet ( I used these 3M things , they are great because they also absorb shocks to the flight controller ) . Make sure the FC is placed in the right direction ( arrow marking on the pcb ) .Take the drawing and F3_EVOmanual and solder the motor wires to the correct motor outputs .

The CW motors are on the left , the CCW on the right if the flight controller is facing forwards .

Take your time and check , check and doublecheck :-) . A short motor connection may ruin the FC ...

If you wish you can also install a buzzer for low batt warnings etc ...

Now it is time for a few tests . I assume the Rx is already bound to the transmitter and the FC has Betaflight 3.1.0 or more recent on board . Here's how I configured my flight controller :Speedy Bee configurator

Configure for X-hexacopter . When configuration is done check motor rotation direction , NO PROPS YET !

Step 7: Prepare for a Test Flight

Use rubber bands and a few pieces of wire to fix the battery . I made a "testing landing gear" with 6mm depron fixed to the motor mounts . Use UHU POR or the Depron will melt !

Almost done :-)

Step 8: Here We Go !

Make all necessary preflight checks , install a fresh charged battery and take off ! She flies like a quad but because of the 2 extra motors you should ease on the throttle :-)

When your hands are no longer trembling go for another battery and another battery and ...

Have lots of fun !

If any questions drop me a line , always at your service !

Bob

Step 9: Modifications , Corrections Etc ...

Despite the correct diameter of the holes in the motor mounts the CCW motors came loose , seems they are a little thinner than the red CW motors . Solution : reposition the motors , take som wire or wool or whatever and glue it at the underside of the motor mounts with cyano . Replace the depron test LG by one in medium 2,5mm balsa . She made several flights after these mod's , no problems so far !

Stay safe , and most of all : have great Fun !