ML8

To complete this project, you will need a CNC machine, 3D printer, drill, and soldering iron. More instructions to come on assembly.

I set out to build a tank of a drone. Something that would not blow away in the wind and could carry a payload equal to its own weight.

Hardware:
1 x Pixhawk 2.1
1 x 3DR GPS
1 x 915 Mhz Telemetry Receiver/Transmitter
2 x Sky III Quattro 4in1 ESC
8 x SunnySky Angel 800 KV 2820 Motor
2 x 8000 mAh 4S Zippy Battery
1 x 1000 mAh 3S Zippy Battery
1 x FPV 3 axis Gimbal (for a GoPro)
1 x X8R FrSky Receiver
1 x X9 Plus Taranis Transmitter
8 x 12x4.5 Props

Legs
8 x 8 in 6-32 threaded rod (for leg support)
32 x 6-32 lock washer
32 x 6-32 hex nut
2 x 18 in 1/2in aluminum pipe

Motor-Arms-Chassis
16 x 60mm M3 machine screw
8 x 50mm M3 machine screw

Chassis-Legs
8 x 16mm M3 machine screw

Gimbal
4 x 25mm M3 machine screw (for mounting 1000 mAh holder, battery plate, gimbal connector, and gimbal)
All of these will need a M3 nylon lock nut.

Pixhawk 2.1 Mouting
4 x 20mm M2.5 machine screw (for mounting the Pixhawk 2.1)
4 x 15mm M2.5 nylon spacer (for mounting the Pixhawk 2.1)

Other Things:
M3 8 mm washers, silicon wire (8 guage, 14 guage), 2 Mauch 200A battery sensors (these are great and have connectors for the Pixhawk 2.1), several zipties, 5.5 mm bullet connectors, 5 velcro straps (20mm wide and 1 foot long). Arms are made from cylinders 35mm pipes I took off a stacking shelf assembly I bought from Hardor Freight. I would assume 35mm carbon fiber pipes arms would be better but for $23, you get 12 arms. They are cut to 10.5".

The 3D printed objects were printed at 100% infill in PLA. This could likely be reduced to save on weight but that is not really an issue.

CNC machined parts were from 12"x12" cast acrylic (~3mm thick) with 1/8" single flute bit. All CNC cuts inside the perimeter are cut using inside the line setting. The perimeter of the piece is meant to be cut outside the line. I cut acrylic with 0.2mm depth per pass and 30 mm/s speed.

If you build one, your first thought will be, no chance this thing can fly. It weighs roughly 5kg or 11 lbs. Outweighing the DJI Phantom by 4 kilograms. But here is the math. Each motor, with a 12x4.5 prop, has 2000 g of thrust. Multiply by 8 and that is 16 kg of thrust. However, the coaxial design is not 100% efficient. The second motor just speeds up already sped up air. It does save on weight of the chassis. So say its 80% efficient and we have a max thrust of 12.5 kg. Ideally we'd like to be able to hover at half throttle and she does. At full throttle she'll soar. Careful on your first flight. If the Phantom is a Miata, then this is an H1 Hummer.

If you need assistance or have questions, don't hesitate to comment.