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Old Sep 29, 2014, 08:47 PM
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Cheerson CX-20 Bigshark

The main CX-20 thread mostly deals with the "open source" and "Quanum Nova" models.

I am starting this thread to discuss issues more specific to the Bigshark (BigFlyShark) model.
To begin, I ordered the open source model and got the Bigshark model by mistake.
After getting some help from Banggood support I was able to calibrate the compass.
Since then I'm glad I got the Bigshark model.
It makes an excellent aerial video platform.

Here is the compass calibration demo from Banggood support:
CX-20 Bigshark Compass Calibration (1 min 9 sec)
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Old Sep 29, 2014, 09:06 PM
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CX-20 Bigshark - USB connection to a PC

First, this connection works on my XP portable, but not on my XP desktop.
I think my desktop is missing some C++ dll's?
Anyway, on the portable, it works.
When I made this demo, the CX-20 had a Mobius camera strapped on the GoPro mount.
CX 20, Bigshark version, FC to PC connect. (revised) (7 min 6 sec)


The software and manual may be downloaded at:
http://www.bigflyshark.com/Home/Product/SharkX8#
Select the support tab.
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Old Sep 29, 2014, 09:20 PM
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A little reverse engineering & testing

When RTL is selected, or is triggered by lost TX signal:
1) The CX-20 will climb if it is below the return altitude,
2) Then yaw to the heading it remembers from when it was armed,
3) Then it flies backwards to its armed location,
4) Then it descends rapidly if it was above the return altitude,
5) Then it lands slowly from the return altitude.

If you keep flying after the low voltage alarm blinks & beeps, the blink & beep frequency will get faster.
Then at the next (landing) voltage point, it will land at where it is.
I have switched on RTL at that point and it looked as if it were going to try to climb & RTL.
This seemed too risky on an almost dead battery, so I switched back to GPS loiter & let it land.

The Safety zone altitude and range work as advertised.
In the US and many other countries, the legal max altitude is 400 feet (122m).
I currently have my max range set to 350m. I have not tested the TX that far yet.
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Old Sep 29, 2014, 09:37 PM
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So - After 3 months of flights, some crashes and repairs, some mods and accessories, I currently am flying:
CX-20 Bigshark
9443 props
accessory jacks relocated
skid rubbers relocated
Mobius w/lens A
Modified 2-axis gimbal
5.8Ghz FPV downlink
7" screen ground station
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Old Sep 29, 2014, 09:42 PM
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Has anyone been able to slow the yaw rate so video pans look smoother?

I have tried yaw sensitivity settings of 100, 50, and 20, and I can't see much difference.

16 The Lodge at Westmore aerial views (5 min 42 sec)
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Old Sep 30, 2014, 11:51 AM
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Thanks for starting this thread. I am very interested in this version of CX-20.
The other thread has turned into a tinkerers dream while this one hopefully will be more of a RTF/stable option.
I am looking at this and other quads for a stable video platform.
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Old Sep 30, 2014, 11:57 AM
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I will follow this thread since the Flying3D X6 & X8 have also a BC FC....

Software is probably identical ...
Flying3D X8 ground station software demo (7 min 35 sec)
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Old Sep 30, 2014, 04:49 PM
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Quote:
Originally Posted by SeByDocKy View Post
I will follow this thread since the Flying3D X6 & X8 have also a BC FC....

Software is probably identical ...
https://www.youtube.com/watch?v=F7_D58cb-6Q
Other than the window size, the screens look identical.
I posted a comment on your video asking about yaw rate.
Maybe post a link back to here from your youtube video.

If I was shopping for a quad, the X8 looks very good.
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Old Sep 30, 2014, 06:01 PM
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I'm glad I found this thread, I too was supposed to get the open version and ended up with the BigShark. At first I was upset, but since I'm only interested in aerial video and photography maybe it's not such a bad thing after all.

So my question is where do I get the software to upgrade the FC?

I actually just unboxed the CX20 today, but it was windy so I didn't want to risk a maiden flight and crashing it. I'm kind of nervous, this is my first quad and I've read about the fly aways, my plan is to get comfortable with it before I strap on a $400 GoPro.

I also bought a Arris CM2000 Gimbal, is there a place to just directly plug it into the FC for control and power?
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Old Sep 30, 2014, 10:56 PM
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Quote:
Originally Posted by dronenewb View Post
I'm glad I found this thread, I too was supposed to get the open version and ended up with the BigShark. At first I was upset, but since I'm only interested in aerial video and photography maybe it's not such a bad thing after all.

So my question is where do I get the software to upgrade the FC?

I actually just unboxed the CX20 today, but it was windy so I didn't want to risk a maiden flight and crashing it. I'm kind of nervous, this is my first quad and I've read about the fly aways, my plan is to get comfortable with it before I strap on a $400 GoPro.

I also bought a Arris CM2000 Gimbal, is there a place to just directly plug it into the FC for control and power?
Yes, this model makes a great aerial video platform.
For me, the GoPro was too expensive and had too much barrel distortion.
The normal lens Mobius camera makes stunning images fo $80.
Even after slightly lossy post-processing with "ProDRENALIN" to straighten barrel distortion, I'm happy with the results.
Play the video in post #5 at full screen, and you will see what I mean.

The software link is under the demo video in post #3.

The accessory jacks on the bottom will supply 12v for the gimbal and 5v servo for the tilt.
Initially I mounted the gimbal base on 12mm stand-offs to clear the jacks.
I since have relocated the jacks to the side, and the gimbal base directly on the bottom. (see post #4)

I mostly fly in GPS mode.
If I make a mistake, I center the sticks and it just hangs there, even in the wind.
Other than testing, I have only used RTL twice.
Once, I lost sight of it in the sun.
The other time, I was framing a shot in the FPV screen, and the quad was behind a tree.
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Old Oct 01, 2014, 09:21 AM
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I already have a GoPro Black Edition, maybe I would be better off selling it and getting the Mobius since I don't ever use it anyway.

I missed the software link the first time I visited the page, I thought they were all pdf files, got it installed now though! For whatever reason the update button does nothing when I click on it.

Thanks for the info on the gimbal, after a few flights (hopefully today) I'll get that installed and working.

I plan on only flying in GPS mode as well, I'm don't have any desire to become aerial acrobat and don't care about speed at all, actually would rather have it go slow so it's easier to control. Luckily I have a huge grass field to practice in...away from people and animals!

I also tried the compass calibration like in the video to no avail, the red blinking light never turned yellow on my mine, has anybody got this to work?
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Old Oct 01, 2014, 09:25 AM
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Might be nice to add a version history to the top of this thread since there doesn't appear to be one on BigFlyShark's website. I'm on 1.29 and the latest is 1.31 and it says it added 6S battery support and OSD.
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Old Oct 01, 2014, 09:50 AM
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Quote:
Originally Posted by sureshot__ View Post
Other than the window size, the screens look identical.
I posted a comment on your video asking about yaw rate.
Maybe post a link back to here from your youtube video.

If I was shopping for a quad, the X8 looks very good.

I will try to reduce yaw rate and make a test ASAP. The FY-X8 is not bad at all too... but not the perfect quad . I like it anyway
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Old Oct 01, 2014, 12:49 PM
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Yaw rate tests 150, 200, 250

I do not see much difference.
The results vary only by my ability to keep the stick close to null.
CX-20 Bigshark - Yaw comparason (1 min 9 sec)
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Old Oct 01, 2014, 01:00 PM
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Quote:
Originally Posted by dronenewb View Post
I already have a GoPro Black Edition, maybe I would be better off selling it and getting the Mobius since I don't ever use it anyway.

I missed the software link the first time I visited the page, I thought they were all pdf files, got it installed now though! For whatever reason the update button does nothing when I click on it.

Thanks for the info on the gimbal, after a few flights (hopefully today) I'll get that installed and working.

I plan on only flying in GPS mode as well, I'm don't have any desire to become aerial acrobat and don't care about speed at all, actually would rather have it go slow so it's easier to control. Luckily I have a huge grass field to practice in...away from people and animals!

I also tried the compass calibration like in the video to no avail, the red blinking light never turned yellow on my mine, has anybody got this to work?
The settings change in real time. The bottom left button turns back to green as they complete
The update button is only for future firmware updates.

I had to watch the demo video very closely at first before I saw that SWA was being toggled just 0-1-0-1-0-1 until the LED changed.
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