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ZERO TO HERO

Two weeks ago I decided take the plunge and build a drone. I'd been watching a heap of videos online, such as the monster drones from alishanmao as well as this impressive experiment by Raffaello D'Andrea. These guys and their creations inspired me to create something of my own (although I knew mine would be nowhere near as impressive). I challenged myself to build a drone that was as big and as versatile as I could achieve with my meagre budget (~$1000 AUD). Hardly being an RC enthusiast, and with basically zero experience with DIY RC before (I've built a flatpack RC plane and crashed quite a few cheap RTFs), I was essentially relying on my skills as an undergrad mechanical/aero engineer, but whether these would help or not I had no idea.

So I went ahead and started designing. The main deliverables were fairly basic:

1. Lots of rotors (hexacopter).
2. Bigger than 600mm diameter from rotor tip to rotor tip.
3. Fully open source, upgradeable flight controller so that I could code in different modules as I needed them (i.e. everything from GPS to telemetry to barometers, ultrasonic range finders, maybe even a seek and destroy mode with an automated nerf gun??) I didn't want to build something that would become obsolete.
4. Capable of carrying a DSLR for aerial photography.
5. Above all, it had to look cool.

Knowing only the very basics of drone building, I spent two days researching and configuring, trying to get my head around how to go about the whole thing. I scoured the Hobbyking and Ardupilot websites, as well as a bunch of drone forums for information, looking at different set ups, schematics, information on motors, props, ESCs, flight controllers, frames, prices etc.

FRAME

I decided that the frame would be the best place to start, so I ordered a Tarot FY680 from a dealer in Hong Kong (the cheapest I could find). I chose this frame because it was a) light (600g), b) big enough (>600mm diam), c) had room for a bunch of electronic equipment as well as a camera underneath the landing skids d) had lots of carbon fibre, was black, and looked totally awesome e) I had seen a few reviews of Tarot and it seemed that generally the consensus was good. Low vibration, high end performance.

PROPS, MOTORS, ESCS, BATTERY

In theory, the frame dictated the size of the props, which for the highest efficiency I figured should be as large as possible (max prop diam. size due to the constraints of the frame was 13''). The props would then dictate the type of motors that I needed to use, which would then require a certain specification of ESC. Once I knew the max consumption of the motors, I could get an overall figure for power and choose a distribution board and battery accordingly.

Overall I was a bit unsure about this whole process, getting used to electrical terminology took a bit of effort and I didn't want to go fully into the mathematics of the whole thing, so I largely just relied on looking online at other similar hexcopters to get a feel for what I needed. In the end I decided to go with these (all sourced from HobbyKing):

11 x 5 Thin Style E-Prop

NTM Prop Drive 28 Series Accessory Pack

NTM Prop Drive 28-30S 800KV / 300W Brushless Motor (short shaft version)

TURNIGY Plush 30amp Speed Controller

Hobbyking Multi-Rotor Power Distribution Board (DIY 8 x output PCB)

Turnigy nano-tech 4000mah 4S 25~50C Lipo Pack

FLIGHT CONTROLLER

Then I chose the flight controller - I decided to go with the 3DR Robotics Pixhawk (below). It looked schmick with lots of flashing lights, and all the open source functionality I could ever need. It also came with the 3DR GPS system with integrated compass (handy), and was fully compatible with the Ardupilot software and the 3DR radio telemetry system, which I was planning on implementing later on. I bought these directly from the 3DR website.

TX/RX

I wanted a 2.4 GHz system that had at least 7 channels, and the cheapest I could find for this sort of system was:

OrangeRX DSMX/DSM2 2.4Ghz Transmitter Module (JR/Turnigy compatible)
OrangeRx R710 Spektrum DSM2 Compatible 7Ch w/Failsafe
Turnigy 9XR Transmitter Mode 2 (No Module)

THE CRUNCH

So I went ahead and made the deal, and in total it ended up matching quite well with my $1000 budget. Including shipping, and a bunch of tools like a soldering iron, wire strippers, ESC programming card, and pretty much whatever else I thought I would need to get building, the whole package cost $1144.47 AUD.

The frame was the first thing to arrive, which happened today. I'm going to keep blogging throughout the build process, so if you're interested in how this project progresses, keep coming back over the next couple of weeks as I try to get this thing into the air!

Blue skies