So I totally dropped the ball on this. It's been an absurd time since I opened this forum but I guess I should do something with it. lol
Right now I'm going to go through the various resources I've found on the CX-20/Nova and post them all here. I have links, drawings, photos, and other such things. Hopefully we can all add to this and maybe have provide a good source of data to new owners.
One thing that drove me nuts at the beginning was understanding what I had and then trying to get the thing off the ground. These are common issues with people so I'll start there.
The CX-20 comes in two distinct versions. Those are the "Auto Pathfinder" version and the BigShark or BigFlyShark version.
From what I've been able to tell, the manufacturer has a general design but anyone wanting to sell it as a product can have things done in a number of ways. So there are minor differences between various units based on the sales channel and/or plants they came through.
The BigFly Shark version has a different flight controller that isn't open source. Here we're entirely focused on the Auto-Pathfinder which is equipped with a flight controller mostly based on the Arducopter controller.
That controller is open-source and you can load it with the copter firmware, but make no mistake about it, it's not an APM flight controller or even a good clone. The pinouts are completely different. If you aren't careful when hooking up additional hardware, you could easily hurt the car,
Well, that's all for tonight. It's 1am and I'm exhausted. More to come tomorrow after work.
Replies
BEFORE YOU FLY!
So you get your CX-20/Nova and you are eager to fly it. You plug the battery in and wait patiently and finally run out to fly it....and it crashes horribly or flies away....
This happens a lot more than it should. Quality control is crap on these. Consensus seems to be that the Nova is better in this regard because Hobby King might check them first since the Nova is just Hobby King's own white labeling of of the CX20.
Instead, what you want to do is take it apart and inspect EVERYTHING. Inspect your solder joints, make sure everything is plugged in tightly and neatly. Make sure nothing can move around or shift - particularly the GPS and Flight controller.
Check that the screws are all tight. And if you want to do a little extra work, move the GPS to the dome and foil over it as you see in the 6 mile flight video above.
Also, you may want to go ahead and order a set of props. I highly recommend the props from the DJI Phantom. Just the standard OEM Phantom props. They are self-tightening. You no longer have to deal with those nuts. And I suspect that's how I lost a prop on mine at 300 ft.
The landing gear are incredibly fragile. Before they break, I recommend a nice tight wrap with white electrical tape. Otherwise you may find that after your first landing you no longer have landing gear and you have to put it up until the new gear come in. Reinforcing it with a piece of 12 gauge housing wire helps even more. It adds a tiny bit of weight but worth it in my opinion and the more efficient design of the phantom props off-sets it in my opinion.
Here's a site that's already started the aggregation of the information on the CX-20. LOTS of into here.
http://www.rcgroups.com/forums/showthread.php?t=2206138
I made a sheet with the flight modes and taped it to my transmitter. I was going to attach it here except it was customized because I moved some things around. Here's someone who made one for the default modes to download and tape to your transmitter.
http://api.viglink.com/api/click?format=go&jsonp=vglnk_14605574...
After my first crash where where it just lost a prop, flipped over and flew into the ground, this site was EXTREMELY valuable getting humpty dumpty back together again.
http://quadcopter-robotics.blogspot.com/2015/01/nova-rebuild-apm-in...
Also, he answers questions often. I "donated" to the cause. If you find the site as useful as I did, I encourage you to do so as well.
This is an inspiring video. Mods done to the CX20 to allow 6 mile flights. :-)
https://www.youtube.com/watch?v=TmmT7dlaTh4&ebc=ANyPxKqaUb4PnDe...
FACTORY PARAMETERS!
In case you've got your parameters all screwed up, this can be invaluable. Just unzip it and then in the advanced parameters section of Mission Planner you can click on "upload" and write all of the factory parameters to the file and it will be right back where it was when you got it.
TIP: Once you initially get any problems fixed and calibration done, then export your parameters. Then if you screw something up you aren't starting from scratch. it's incredibly easy to render your copter unflyable in Mission Planner as it has no guards against doing so. And if it was something you tweaked that you didn't understand you won't even know where to look to fix it. There are no "defaults" to go back to because each time MP starts, it gets the existing parameters from the copter.
CX-20_Factory_Parameters.param
Here's some information from BangGood that solves something I've seen a lot of people puzzled over.
Cheerson CX20 CX-20 Open-source Flight Controller Auto-Pathfinder RC Quadcopter With GPS RTF
If it can't be connected with PC please click here to dowload the program: dotNetFx40_Full_x86.exe and MissionPlanner-1.2.55.msi
Default Parameter
Notice: DO NOT use the WiFi camera, the receiver of quadcopter will be interfered by that and lost control. DO NOT upgraded the firmware, or it will show something error, such as"no dataflash" or no log written.
Both of them are Open Source version, the position of GPS and compass are changed. Left one is GPS installed inside the quadcotepr, its compass is in the dome; Right one is the GPS installed in dome, its compass is inside the quadcoter. They are delivered randomly.
Good idea Kevin. Hopefully these can help and I'd like your thoughts on them if you have a better way around these issues.
Here are some of the problems I encountered and the fixes I found. You must know the basics I guess and be able to connect your aircraft to Mission Planner.
(A) The aircraft tilts to one side/front or rear as it takes off, often resulting in an aborted takeoff. The solution was found here.
https://www.youtube.com/watch?v=-5b0Xeps4cM
(B) The aircraft wobbles and jerks around a bit when in loiter (like it is over correcting to wind gusts and the like) The FC needs to be "auto tuned". I watched and followed this video and it sorted things out. Note: Once the procedure is completed, you MUST land while in AltHold mode and then disarm to save the corrected PIDS.
(C) Aircraft doesn't face towards the waypoint it is enreute to.
WP_YAW_BEHAVIOR - This determines which way the craft points when flying a mission in auto mode (or RTL). The factory setting of 0 doesn't yaw the craft when moving from waypoint to waypoint. I changed it to 1 so that it points the front of the craft in the direction of the next waypoint. It just (to me anyhow) looks cooler in a video to see in the direction you're headed.
Change this in Mission Planner
Yeah. I have some links on that I'm going to post on that shortly.
As to the specific questions, that tilting at takeoff is definitely a known problem and that video often fixes it assuming the problem isn't with something being loose on the inside. The adjustment it makes I believe is a shortcut version of ESC calibration. it knows you are attempting to hold it in one spot so as it veers when there is no input from you it can adjust each ESC to get to stable and it makes these adjustments until it gets settled enough to know what it should be at and uses the light to let you know. But I'm not sure if it's actually calibrating the ESCs or if it's using the flight controller to make adjustments to the signal before it hits them. A full ESC calibration might be better and certainly wouldn't hurt but after doing so I would do the calibration on that video again. Here's a video on that:
CHEERSON CX-20 ESC CALIBRATION
https://www.youtube.com/watch?v=3I4oDG9qMlQ
The YAW mode was one I planned to look into but hadn't had time to. Thanks for answering that one for me!