Otto (RD-8) Tear down rebuild.

Published: Sun Nov 11 2012

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In this rebuild, we tear down Otto, which is a small 25cm class UAV with an ArdupilotMega w/GPS navigation and turn it into an OpenPilot sport quad!
We start by removing the top protector plate and exposing the GPS module.

I carefully remove the flight controller, the GPS assembly, the Xbee telemetry socket and the Sonar sensor.

 

We are left with the basic drive train, which is a mess as I built Otto as a AP/AV drone in a drastic hurry after the ARDi Crash. It served well to fulfill the Cowboy Way Mission and many others.

I decided since I was tearing it all the way down, I might as well optimize the ESC configuration, and install the SimonK ESC firmware and the Amtel Bootloader so I can update the ESC via the Servo lead at a later date.

The biog issue here was the spagettii like power distribution (PD) harness. We get rid of that in this rebuild.

I started by pealing off the ESCs and flashing the custom firmware.

 

Next I remove the old PD Harness

Nexy I soldered femail 4mm bullets on an HT-60 battey lead and hobbyking 4-1 bullet adapters, then heat shrink.

Next I cut the bullets off each of the motors, and tin the ends.

Next I remove the motor leads with female bullets of each of the ESCs

I then solder each ESC directly to each motor, eliminating much wire and bullet weight. I test rotation direction on each one as I solder to ensure it is correct, but in case I mess up, I can reflash the ESC with a reverse direction firmware, but this was not needed. 

Next I connected all the ESCs up to the new PD harness.  The result is simple elegant and very light in comparison.

Now we are ready to put it all back together.

Another round of heat shring to prevent the bullets from vibrating out of the PD harness.

With the PD heatshrunk we are ready to reassemble and replace the main plate.

After installing standoffs that fit the typical MK/KK FC spacing, I put the main plate back on and begin putting the hex bolts back in. I added a good yellow velco battery strap.

Notice that I insert some recever foam on top and below each face of the ESC as I have learned the ahrd way that Carbon Fiber parts conduct elctricity.

With everything in place, I use colored PVC tape to secure the ESC inside the arm, while giving a sense of front and rear arms.

TO make the Open Pilot CC3D fit my adopted KK/MK spacing standard, an array of adapters are required.

To ensure I can hide my FrSky RX beneath the FC I add another level of Standoffs.

I place the RX and connect the CC3D RX wireing harness and put a pice of RX foam to help hold the RX in place.

I sandwich teh RX between the main plate and the bottom of the RX stack.

Some protective nylon wire mesh around the RX and ESC leads prevent the sharp edges of the CF frame from cutting the wires.

Using a new adopted standard of using slices of pool noodles as landing gear and orientation aids, this little guy may be ready for props and a flight test.

As I am preparing to install som GAUI 8inch style props, "Murphy"'s Law kicks in and I realize I have soldered the WRONG ht-60 plug on the PD harness so I cannot put attach a lipo pack. This rebuild is complete, but Props, Test flights and PiD tuning with the GCS will have to wait for another day.

Happy quadding!
Franco