Following the calibration of the motors and the flight controller, yesterday’s job was to clean up the megahexactoper and get it physically ready for a first flight.

Hexacopter joins us for breakfast…

I’ve read dozens of stories about builds like this where the builder was not sure to tighten all screws and disaster happens as a result.   So last night’s activity was to level all motors, and tighten all screws along with adding thread locker to them.  This way they hopefully do not loosen.

This week I hope to launch the megahexa on her maiden flight.  This is a big, symbolic step in the process of getting this bird doing its thing, aerial photos and video.

A couple of posts ago I mentioned that I’d solved some problems with calibrating my ESC’s.  ESC’s are little electronic devices which control the speed of the motors.  I had a bad wire on one of them.

That meant I was able to move to the next phase of the build on the Tarot T960 hexactopter, getting the flight controller (the brain of the unit), the transmitter/receiver, and motor/ESC’s to all work together.    Things did not go smooth and for two weeks I was trying to find a solution. Needless to say, I’ve been getting pretty mad and frustrated.

The Problem

The process is supposed to go like this:

1. Establish communication between the transmitter and receiver.
2. Calibrate sticks on transmitter
3. Attach each motor/ESC to receiver and calibrate throttle range (let the motor/ESC know what the full range is, example -100 to +100)
4. Attach flight controller
5. Calibrate flight controller to sticks and stick ranges

At that point I should be able to arm the motors and move to the next step.  Unfortunately once I completed the process, all or some of the motors would beep constantly.  The other motors which did not beep would arm.  The beeping indicated that the low throttle range was not low enough and for safety the motors would not start up.

Each time I powered up the bird, the motors which would beep would be different.  Once only one beeped and five motors armed.  The next time only two motors would arm, and the other four beeped.  This would change all the time, despite my not changing anything.

Since my remote’s range for the throttle is typically -100 to +100, I could not make the throttle’s -100 go any lower.  I tried dozens of configurations.  I recalibrated the ESC’s about 20 times.  I redid everything many times.

I had read that there’s a compatibility issue between the SuperX controller and the Hobby Wing ESC’s, and one person online said he replaced the ESC’s with another brand and that worked.  So I ordered some different ESC’s from a Denver area hobby shop.

Yesterday I had gotten to the final straw, giving myself one more chance to configure the setup before I cut the 48 total wires involved in connecting the ESC/motors, and started to solder the new ESC’s on.  Out of random desperation I decided to pick a “random” page in a forum thread which did have some posts about similar issues.  The thread had hundreds of pages and I’d scoured much of it for hours.  I chose page 187.  The first paragraph had a guy who was successfully flying with a similar setup to mine, but one day two motors started to beep and not arm.  His solution was to calibrate the ESC’s at -90 and +100 on the transmitter, then change it back to -100 and +100 when hooked up to the full system.

BINGO

That solution worked, and yesterday I had NO unwanted beeping.  I was able to arm all six motors on all of the numerous startup tests I ran.

I don’t want to be overly confident and jinx myself, but it would “appear” that I’m back in business.

Next up is tightening down and thread locking all of the screws on the bird, cleaning up the wiring, and starting the throttle tests with the propellers attached.

The maiden flight will hopefully be coming soon.

For a few day’s I’ve been stumped on getting my motors/esc’s “throttle calibrated.” This is a process where you basically need to allow the motors to “know” what the throttle range is, from 0 to 100%.

In perhaps one of the most boneheaded parts of my build I was trying to calibrate motor one, which is on the front right of the hexacopter. No matter what I tried the ESC just beeped forever. To confirm that I had my transmitter and receiver actually set up right, I bought a cheap servo at a local hobby shop and hooked it up to the receiver’s throttle output. Sure enough, the servo woked. That eliminated the radio/receiver as the issue.

I started thinking perhaps my ESC wires were mixed up, but I put numbers on all of them when I installed them to avoid mixing them up. At that point I looked under the bird and saw the #1 on the front LEFT arm. What an idiot! I had the bird upside down so the front left was motor #1! OMG!!!

After that I was quickly able to calibrate 5 of the 6 motors. Motor #3 would not receive any signal. So I got a multi-meter out to test continuity of the cables. The signal wire (white) on #3 was bad. No connection from one end to the other. This is a total pain as I would have to pull out the ESC wires from the arms and re-feed a replacement through. Then in a brilliant revelation, I tied some string to the old wires. I pulled the string through the arm as I pulled out the old wiring. Then I attached the new wires to the string and threaded it through again. Voila. Save myself the mega-hassle of trying to fish wires through.

Re-wired ESC

I then soldered the new wire to the ESC (photo), and put a servo plug on the other end. Once that was done motor #3 recognized the receiver and I was able to do the final calibration.

On to motor configuration!