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Hey Peeps! Introduction to the site and Gremlin build details.

#1
Hi All!

Greg from Texas coming through to say hi and give some (hopefully helpful) details of my recent Gremlin build! It is kind of long, but hopefully someone gets something out of it!

I'm relatively new to multi-rotors. I picked up an Inductrix along with a Dx6e few months ago and was immediately hooked! I've been watching FT for a few years now and have always wanted to get into the hobby. I've had a bunch or RC cars and trucks in the past, currently have a Losi Mini8ight with a Traxxas VXL and some metal gears, and an Associated Mini Apex touring car to rip around with, but was getting the itch for some FPV action!

Once I got the inductrix, I pretty much immediately went out and bought the FPV Pro and the Spektrum Focal V2's, Then a few days later picked up a Torrent. I've been spending more hours than I should in Liftoff and have been ripping around the fields by my house with the torrent and inside with the Indy's, so I figured it was time to get a Gremlin as well!

Picked up TJ's CF kit, and it came with all the components just a few days later, with free shipping I might add! Thanks Flite Test!:applause: I got to building along with the video (which I may have watched like 5 times while I was waiting for shipment) and got everything together in maybe 5ish hrs. I took my time by my eyes aren't as good as they used to be and that tiny board was just that, so once I got everything together just right, I plugged in my board to BetaFlight to set up the transmitter, and unfortunately wasn't getting it to connect. I had flashed the board and verified it was working before the build, but must have overheated it or something because there was no usb connection whatsoever. The board powered on just fine, there were no shorts according to the Fluke meter. Camera and RX powered up and worked fine, but the blue and red LEDs were just solid no matter what. After I felt like I had checked and double checked everything sufficiently, I went ahead and ordered another F3, and started disassembly. After desoldering, I went back and tried reconnecting, and still no luck, so now I have a neat looking F3 stuck to my things drawer set!

About 3 days later (thanks again FT!) my new board came, so I dove right back in! Luckily the motors and ESC's were already together, everything was pre-tinned and ready to go, so I started with re-assembly! Little side note, I ordered a really fine tip for my Hakko iron, and I actually think that with that super fine point, I was having trouble getting enough heat just in the right spot and may have been part of the reason I cooked the board, so I switched back to the standard chisel tip it came with which is pretty fine to begin with, and that seemed to work much better for me. Anyhoo, got everything back together and this time checked for USB connectivity after every component installation to try to pinpoint any potential issues as they arose. Second time was the charm, and got it connected to BF no problem.

Another thing to note, my second Femto F3 flight controller came with all of the wires for the esc's pre installed, which were super thin wires, much smaller than the stock esc wires, so I had to remove those before I started assembly. It also came with a 3 pin header in the RX pads on the board which I wasn't really sure how to remove since I couldn't figure out how to heat up all 3 connection points to be able to pull the header out, so I snipped the 5v pin since I'm running Spektrum (you wanna fight about it?) and needed 3.5v, and soldered the ground and signal wires directly to the pins on the header, which were bent away from center, and put some heat shrink around them. JUST LIKE FROM THE FACTORY he he he. Hey, it works! Another thing I noticed right away is that the arrow orienting the board was pointing a different way from the stock board, but I figured that you can just clock that later in BF so I stuck with my original layout with the USB facing out the side instead of out the back like the 2nd board would have been from the factory.

So...got everything wrapped up and connected to my Tx and got it registering in Betaflight. Set my modes and Arm, and I noticed that the arrow pointing towards the front of the quad was pointing at the side of my gremlin. I figured that would be the case, so I went into the configurations tab of BF and set my yaw axis by -90 degrees and that corrected the image and orientation of the quad. Easy Peasy! Once I got the motors spinning the right way, and felt like all my preflights were done, I threw on some props, double checking the correct ones were on the right motors, and set off for my maiden hover.

As soon as I started to throttle up, I noticed a massive twitch and it was NOT looking like anything that could take flight. The dang thing was having a seizure on my floor. I'M LOSING IT!!! CLEAR!!! CLEAR!!! So I held it by the battery and rev'd it up a teeny bit, and sure enough, the thing looked like it was trying to wag it's tail. Neat little dance, Gremlin, but NOT what I was expecting. It seemed like the gyro was freaking out trying to correct something that wasn't happening. I hooked it back up to BF, and found that I could rev the motors up in the motor test function and everything was smooth as silk! What was happening??

Then I realized that the motor was spinning when I tried to rev just motor number 1 in the motor test, was not the same motor that was marked number one in the diagram in BF. After some more testing , the MOTORS were also clocked 90 degrees, not just the gyro set up according to the arrow on the quad model in BF. So OK! Now I'm getting somewhere. So how the heck do I fix that?

Thanks to Josh Bardwell's Youtube video on remapping Resources (https://www.youtube.com/watch?v=z5aO-3_n-Hs), I was able to get the motors in sync with what the quad model was showing and like magic! No spastic tail wagging!!!

I'm happy to say that I'm that talk of the nerds with my shiny new Gremlin that I built myself! It's flying like an angel and taking a beating like Rocky Balboa! Just a slight deviation to the butter like build of the MAN himself TJ on the video, but definitely a fun project that required knocking some dust off the old noodle to figure out. I can't wait to get another set up so I can have one for my buddies to crash.

Sorry for the long post. I'm sure most of you have fallen asleep or clicked away by now but hopefully this was a little help to someone! If anyone has any questions on their build I'll be happy to share what little I know!


PS
Does anyone get in a full flight suit like Maverick to fly their Gremlin, or is that just me? I BUZZIN THE TOWER GOOSE!!:cool::rolleyes:
 
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