Looking around for an inexpensive, almost-ready-to-fly brushless-motor quadcopter to use a basis for indoor flight-control research, I was delighted to come across the Altair Aerial Blackhawk. With its extra-long extension legs and GoPro mount (which I plan use for additional sensors), the Blackhawk really fit the bill.
As soon my Blackhawk arrived, I removed the cowl covering the fuselage, revealing the custom flight controller / receiver board shown below. I unplugged the LED leads for the headlight and four arm lights, carefully snipped the soldered-on wires with a diagonal cutter, and unscrewed the board from its mount, leaving me with the ESCs and battery leads shown in the second picture below.
The Blackhawk with its original flight controller
Original flight controller removed
As you can see, the inside bottom of the Blackhawk didn't provide a flat surface on which to mount a new controller. So I used Tinkercad to design a 3D-printable mount that I attached with E6000 adhesive. The mount has the standard hole spacing for a 36x36mm flight controller and power distribution board (PDB).
Once I'd printed out the board on my Lulzbot Mini, I added some M3 nylon machine screws and spacers:
Then I glued the mount to the Blackhawk with a bit of E6000:
Next I secured the PDB to the mount with another set of spacers, soldered a new pair of heavy-gauge wires from the power supply to the PDB, soldered some female jumper leads onto the control wires going into the ESCs, soldered a pair of female jumper wires to the auxiliary power supply, and soldered the ESC power wires to the PDB. Double-sided VHB tape helped re-secure the ESCs firmly in place:
For the flight controller, I chose the inexpensive Flip32 Ominbus F3. Its onboard battery-elimination circuit (BEC) allowed me to connect the power wires directly from the PDB, and its DSM connector made it easy to plug in my favorite receiver.
For the flight-control firmware, I decided to with my own C++ Hackflight system (which also works on Arduino-based flight controllers, as well as a flight simulator I built with UnrealEngine4.) After testing the IMU, receiver, and motors, I attached the propellers and was ready for the maiden flight:
As you can see, the LemonRX receiver fits nicely into the front of the fuselage, leaving plenty of space to attach a "companion board" like the Raspberry Pi Zero W, NanoPi, etc. – as I hope to show in a future post!