So, after successfully finishing wiring up the receiver, video transmitter, and OSD (On-Screen Display) for my Blackout Mini hexacopter (it came to me mostly-assembled), getting it bound and programmed and calibrated to the transmitter, the thrill of actually plugging it in and turning it on was a blast.
It flies! I'm hoping to get it to do more than hover at waist height this weekend if the weather is good.
So, since the Hex came to me used and almost ready to fly, I wanted to build one myself from parts. Just like I wanted to build my own pedals and guitars, I wanted to put together my own quad. The hex is going to be fast, very powerful, and is not a lightweight; I wouldn't mind having something a bit smaller, lighter, and more agile so I can get more comfortable with flying close around trees and other obstacles.
Having had success with the Blackout products, which come with their own power distribution board (PDB) that makes wiring everything up much cleaner and simpler, I wanted to build one of those for my first "real" build. Unfortunately, they're highly in demand, so when ReadyMadeRC got some in stock, I jumped on one (and I'm glad I did; they sold out the rest of the 40+ units in stock within 24 hours). I'm still waiting for many of the parts, but here's what I've done so far:
The PDB is integral to the frame, and avoids the rat's nest of power wiring that many other frames end up being. After all, you need to run two wires per motor, plus power to the flight controller, camera, transmitter, LEDs, etc. The PDB makes that much simpler, and is the only plate not made of carbon fiber.
3mm thick carbon fiber arms. I opted for the smaller ones for 5" propellers (220mm motor-to-motor dimensions), but you can swap them out for slightly longer arms that let you run 6" propellers (260mm motor-to-motor).
With a SunnySky motor attached.
I'm using SunnySky's 2204 2300KV motors (2204 = 22mm diameter, 2300KV = 2300 revolutions per minute at 1v with no load). They're lightweight and efficient, but if you run them at higher voltage with bigger props you can get a lot of thrust out of them. It's a setup that gives me room to grow.
Currently the motors only attach with two screws, as the motor mounting holes are in a "diamond" pattern that doesn't quite match the slots in the arms. While others in the forums say that it's fine for mounting, I may decide to widen the slots to fit all four screws in down the line (although widening eight slots in 3mm carbon fiber might be a bit trying).
Those propeller spinners look nice, but they don't lock down super well and can spin off midflight. I have some M5-threaded Nylock locking nuts on the way to help prevent that.
1mm carbon fiber plates on the top and bottom.
The carbon fiber plates are secured together with nylon screws, spacers, and posts. In a crash, the nylon screws absorb the impact and shear.
I sanded the edges of all the carbon fiber plates with 600 grit sandpaper to keep them from scraping wiring. Some guys coat the edges with CA glue, but I'm not sure if I'm going to be doing that.
Also took the opportunity to tin all the solder pads I would be using on the PDB. Yay industrial soldering gun!
This teeny little Pololu 5v step-down UBEC will be used to turn some of the power from the battery (either 11.1 volts or 14.8 volts) into a clean 5 volt power supply to run the receiver and flight controller.
Speaking of the receiver, I'm using the FrSky D4R-II. It's small, lightweight, binds to my FrSky Taranis transmitter, and has another benefit as well: it can output PPM control.
I popped the jumper on two pins to set it in PPM mode. This means that, instead of running a half-dozen wires to my flight controller (one per channel) I only need to run three wires and that will cover up to eight channels. Much cleaner and simpler.
The three cables will plug in right here.
The flight controller is the Naze32 Acro. This is the stripped-down Naze32, without GPS or barometer or altitude hold support. It's still pretty full-featured and very programmable through USB. It will do a variety of flight modes, including self-leveling, and control the motors, and that's all I really need.
It's also pretty tiny at 36mm square.
Here's all the pins that can be soldered to it. The more full-featured boards take even more. I'll actually be using fewer pins than this; there's some tricks you can do to make things a bit simpler and smaller.
I couldn't really assemble it tonight (waiting on stuff like the battery plugs, electronic speed controllers (ESCs) and some other bits) but I wanted to see generally how it went together and how small it was assembled.
Nylon screws in the bottom, unthreaded spacers between the bottom plate and the PDB.
These weird-shaped spacers hold the flight controller in place. It will eventually be locked down with tiny Nylock locking nuts.
With the arms inserted but not bolted in, it looks like a quad!
My ESCs are shipping in from Germany, my first-person video camera is shipping from somewhere in the US, a bunch of odds and ends and the video transmitter is in transit from Florida, and flight batteries and more things will hopefully arrive tomorrow. Will update more when I can actually start to get this thing wired up.