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Apr 08, 2014, 12:31 AM
Vids: YouTube.com/FyreSG
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Mini-Review

CX-20 Auto-Pathfinder RTF - A Beginnerís Perspective





Introduction

I enjoy flying my Skyartec Butterfly but I needed something more powerful, more stable for aerial videography or even FPV. I knew it would be a matter of time before the other Chinese manufacturers release their version of brushless quads, given the great popularity of toy-grade brushed quads. Needless to say, I was extremely pleased when Banggood.com asked if I was interested to review the CX-20 along with the Mobius Action Cam.

I believe many multicopter beginners - existing pilots of micro brushed quads - are interested in getting a “next step up” multicopter, and have set sights on CX-20. Therefore, I hope this review can provide basic knowledge of the quadcopter as well as answering the following questions:

1. Is this suitable for a beginner? Is it a good idea for someone with no experience in quads or helis to learn flying one with the CX-20?
2. Is this a worthy upgrade for someone who has experience in flying micro brushed quad?
3. Will an experienced multicopter pilot like CX-20?






Package Contents

The contents were neatly packed in several boxes. The props appear to be quite balanced with my highly-inaccurate prop balancer.





For more details, check out my unboxing video:

Cheerson CX-20 Auto-Pathfinder GPS RTF - Unboxing (3 min 26 sec)





Up close with CX-20

I would be blind if I didn’t notice its resemblance to DJI Phantom.

I like its sci-fi looks but worried about poor visibility of the front of the quadcopter when it is far away. The props are all white and each of the front arms has a thin red stripe.



If I were to compare to the Butterfly, which is made of CF-lookalike material, CX-20 feels less rigid and gives me the impression that it is less durable. I suspect a hard landing will break the landing gear, and the arms would not withstand hard knocks. Are there any support structures inside the plastic? We need to remove the cover to find out.

To remove the cover, I used the hex screw driver. However, the hex head was “rounded” after the fourth screw. Good thing I have a set of hex screw drivers to the rescue! Off goes the cover...



The big white box seems to be the flight controller. It has a tiny button on top. I suspect it is used to reset the FC. There is a (micro?) USB port on one of the sides of the FC. We may be able to fine-tune its P, I, Ds or even update its firmware via that port. The receiver is on the left of the FC. Many of you have already read that the GPS plastic piece on the top of the cover is fake, as the GPS module is that square piece at the top-left portion of the FC. Is the manufacturer worried that customer wouldn’t know there is a built-in GPS unit?



Each arm has an ESC and a brushless motor. The arm looks pretty fragile to me.





Battery

The package comes with a 3S 11.1V 2700mAh LiPo battery. It is so fat that it hardly fits into the battery compartment. I had to use a great deal of force to push it in, and removing it is very difficult. Pulling the power and/or balance cables is not a good idea. I can’t imagine how to fit the battery if it is bloated. We may have to remove the friction foam strips at the bottom of the compartment.

I made a loop / handle for pulling the battery out of the compartment, with duct tape.



It certainly makes removing the fat battery easier, but the additional tape makes closing the battery compartment cover harder.





Transmitter

It’s not programmable, it has no LCD; just two sticks, two switches and a set of trims.



I pasted a copy of the flight modes on the transmitter, just in case I need to use them.

Let’s see what’s inside the transmitter.



I hope the photo is useful to those who wishes to convert it from Mode 2 to other Modes.



Flight Experience

I have a problem with this quad - I could not arm it when I wanted. I kept trying, and trying, until it disarms. This is extremely annoying! I am waiting for the manufacturer to reply. Update: I resolved the issue. Refer here.

I started off in manual mode, indoors (no wind). As it lifts off the ground, corrections are needed to ensure it lifts off vertically. While in the air, CX-20 achieves a stable hover as it hardly drifts forward/backwards or sideways. However, it intermittently exhibits a very slight right-yaw drift.

At outdoors, I enjoyed trying out Position Hold and Altitude Hold modes because I had never tried these modes before. However, I’m not impressed as there seems to be a lack in precision as the quad drifted in all directions.

I made a video to illustrate the stability of different flight modes. Check it out at the videos section.

The quad flies really well, even in windy conditions. It cuts through winds that would have blown micro quads away. As CX-20 transits from forward flight to banked turn, the amount of throttle compensation is minimal. Banked turns and figure-8s are easy to do. Piros are pretty fast (high yaw rate) and at night, piroing produces UFO-like effects.

It is clearly not a sporty aircraft as it takes time to gain speed, and it has to slow down considerably before making a turn. I wish it could have a steeper bank angle so I can get it to dash forward faster and stop with a shorter “braking distance”. In my video showing fast circuits around the field, I constantly applied full forward elevator to keep it going at max speed. Banked turns were executed with the application of full aileron inputs. There were times that it was moving too fast and the bank angle was not sufficient, causing the quad to make an unexpected huge turn.

CX-20 is a gentle flyer, built for stability instead of for speed. While this quad does not excite thrill-seeking pilots, its great stability will useful to those who use it as a video recording platform.





Aerial Videography

It comes with a nice GoPro mount with 4 rubber vibration isolation “things”. As I have a Mobius, II simply tied it to the plate with 2 rubber bands.



It works really well as there are hardly any jellos in my videos.



The quad has takes little effort to lift the light-weight Mobius camera. It flies the exactly same way with or without Mobius.

I recorded a 360-degree panning video with the quad set to Position Hold. It wasn’t fixed to the same spot but it was good enough to remain above my head for a good 30 seconds. Pos Hold is especially useful for a 360-degree panning shot of the area. Without the feature, it would be a difficult to manually keep the quadcopter at the same spot. With Pos Hold, I did not need to worry about the quadcopter drifting away as it yaws. All my attention can be focused on getting the right shot.



The Mobius Action Cam, I feel, is a great companion to CX-20. Both are nicely-priced yet perform rather well. Together, they make an attractive package to the budget-conscious pilots who want a decent aerial video platform.





Key Questions

1. Is this suitable for a beginner? Is it a good idea for someone with no experience in quads or helis to learn flying one with CX-20?

Given its fragile structure, I don’t think it is a good learning platform for a total beginner. You’re better off learning with a durable toy quad, or get a more durable brushless quad.


2. Is this a worthy upgrade for someone who has experience in flying brushed quad?

Absolutely! The power boost will surely be appreciated and you’ll be amazed at how much more stable it is as compared to the toy quads. The flight modes can be useful for recording aerial videos as well as flying smooth circuits.


3. Will an experienced multicopter pilot like CX-20?

As I’m not an experienced multicopter pilot, I can’t give a good answer here. The inability to finetune the quad may annoy pilots who seek perfection. The lack of D/R and expo adjustments may also be an issue to some. Pilots seeking for high-speed action would need a Sports Mode - steeper bank angles - but that’s lacking. Then again, experience pilots are likely not the intended audience of this quad, and they are also likely to have already built better multicopters.



Conclusion

To me, CX-20 is an excellent brushless multicopter. It requires minimal effort to install, no confusing programming of the FC or TX are needed, just charge the battery and fly. The various flight modes makes it more interesting to fly, and may also help improve aerial videography.



Pros

+ Highly stable platform for casual flights or aerial videography
+ Requires no complicated assembly or configuration; Ready-To-Fly!
+ Fancy flight modes
+ Attractively priced


Cons

- Not easy to distinguish front vs back; easy to lose orientation
- May be fragile; parts susceptible to breaking



Links

- Photo Gallery: http://www.flickr.com/photos/fyresg/...7643621139864/
- CX-20 RTF: http://www.banggood.com/Cheerson-CX-...-p-916733.html
- Mobius Action Cam (with wide-angle lens): http://www.banggood.com/Mobius-Actio...-p-917817.html
Last edited by FyreSG; Apr 11, 2014 at 08:49 PM. Reason: Added disarming / arming link; updates to flight experiences.
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Apr 08, 2014, 01:01 AM
Registered User
Maybe I missed it in your great review but does it have lights? My buddies Phantom has all white props but even in the day its easy to see the red/green leds.
Apr 08, 2014, 01:11 AM
Vids: YouTube.com/FyreSG
FyreSG's Avatar
Sorry I didn't write anything about the lights! Yes, there are lights! Underneath each arm there is a light strip (red or green), and at the rear of quad, there is a red (motors disarmed) and green (GPS lock acquired) status indicator lights. When flying outdoors, both lights up.

I'm not used to looking at the lights of the quad so I didn't realize they were there. All along, I tell my quad orientation by the colored props and colored arms.
Apr 08, 2014, 05:17 AM
Registered User
ars1968's Avatar
thank you very much for the review, it has served me very helpful
Apr 08, 2014, 06:48 AM
WHAT U LOOKIN AT!
jaskel's Avatar
awesome review mate thank you!!!!
Apr 08, 2014, 06:50 AM
Registered User
What's with the constant beeping. I'd smash it into a building if it does that all the time. ....god awful.

Nice review.

Also, there is no mention of flight times.
Ty.
Last edited by EhnTeePee; Apr 08, 2014 at 06:57 AM.
Apr 08, 2014, 09:56 AM
Vids: YouTube.com/FyreSG
FyreSG's Avatar
Glad that the review was useful!

The beeping is to remind you that you must keep the throttle stick is at the required position for GPS Position Hold and that beep cannot be disabled. While flying about (obviously not in Pos. Hold), it beeps, how annoying! It sounds awfully like an error beep, but it is not.
Apr 08, 2014, 10:10 AM
Plus Pilot
Jumanoc's Avatar
Great review. Could you use discharged batteries on TX for testing if a different beep alerts about low voltage on it. Thanks.
And could you ask your dealer...:
1) About how to use the 2 trim controls
2) Any option for gimbal tilt control ?
3) Where to connect Tilt wire in Flight Controller ?
Apr 08, 2014, 10:18 AM
Registered User
Quote:
Originally Posted by FyreSG
Glad that the review was useful!

The beeping is to remind you that you must keep the throttle stick is at the required position for GPS Position Hold and that beep cannot be disabled. While flying about (obviously not in Pos. Hold), it beeps, how annoying! It sounds awfully like an error beep, but it is not.
Indeed.
The GPS hold on my MultiWii holds independent of throttle position.
I can still climb or descend while it is holding.

Is it me, or is it "Twitchy" when attempting to hold position?(perhaps Accel/Gyro Calib?) (PIDs ?)


Keep the info coming Fyre.
Apr 08, 2014, 12:30 PM
Vids: YouTube.com/FyreSG
FyreSG's Avatar
Quote:
Originally Posted by Jumanoc
Great review. Could you use discharged batteries on TX for testing if a different beep alerts about low voltage on it. Thanks.
And could you ask your dealer...:
1) About how to use the 2 trim controls
2) Any option for gimbal tilt control ?
3) Where to connect Tilt wire in Flight Controller ?
I don't have discharged batteries. I'll have to drain the current ones before I could test that out.

1. I don't understand the question on using the 2 trim controls? Are you referring to the AUX knobs?

2. I'm guessing that can be done via the (unused?) channels on the RX, and controlled via the two AUX knobs: one for panning left/right and the other for tilting up/down. Could you tell from the photo showing the internals? If you need the full resolution photo, please visit my gallery.

3. Sorry, I'm new to multicopters. I don't understand what you mean.

The dealer is not well-versed RC stuff; they sell all sorts of stuff, from clothes to tablets to RC toys. They simply forward my questions to the factory. We get frequent miscommunication despite me communicating with them in their native language because information has to be relayed via a middleman. We may get better answers from the experienced pilots who happen to own this quad.
Quote:
Originally Posted by EhnTeePee
Indeed.
The GPS hold on my MultiWii holds independent of throttle position.
I can still climb or descend while it is holding.

Is it me, or is it "Twitchy" when attempting to hold position?(perhaps Accel/Gyro Calib?) (PIDs ?)

Keep the info coming Fyre.
I'd love to have that GPS position hold allowing altitude changes. But I don't think it's there on CX-20.

I don't think it's twitchy. It's more like slowly drifting about in all axes. If you saw my video, when in Manual mode, I tried to hover the quad at the same spot, that is twitchy. As I have limited experience in multicopters, I can't comment if this is acceptable.

One thing I realize is when I switch on Pos Hold, the motors power down for a brief moment, before powering up again. When that happened for the first time, it scared the crap out of me, as the quad was really high up and losing power means a completely destroyed CX-20.
Apr 08, 2014, 07:36 PM
WHAT U LOOKIN AT!
jaskel's Avatar
I would be interested in seeing how the RTH works and how close it lands to the take off spot!
Apr 08, 2014, 08:47 PM
Multirotor Builder!!!!!
Nice review. this is a pretty good little copter. I have 3 flights on mine. and in high winds and it handled pretty well. I tried the RTH today and it worked good. it landed about a foot from the landing spot.
Apr 08, 2014, 08:56 PM
WHAT U LOOKIN AT!
jaskel's Avatar
Quote:
Originally Posted by tc3wins
Nice review. this is a pretty good little copter. I have 3 flights on mine. and in high winds and it handled pretty well. I tried the RTH today and it worked good. it landed about a foot from the landing spot.
Nice, id be interested to fly it out of range and see how it goes then

I also heard it has auto landing on low voltage, have you flown it to the LVC and see if it lands?

What sort of flight times are you getting?
Apr 08, 2014, 09:01 PM
Multirotor Builder!!!!!
I have only flown it for about 5 minutes each time. it has been super windy and a lot of rain the past few days.


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