Review in progress Cheerson CX20

Also known as the Quantum Nova, and various other names. This is one of the most successful Phantom clones on the market in its various forms. There are more people rebranding this with slight variations than you can shake a stick at.

This is a GPS equipped full featured unit that can do almost anything including autopilot flight. You can use the Mission Planner software and  use it for automated areal surveying, searching, air photography and video. It's really a great budget platform to do almost anything.  It is based on the open source system so although you can fly it right out of the box, some tinkering can and should be done to get the most out of it.

It's a true 350mm + size unit and can be kitted with telemetry, GoPro type cameras, GoPro type cameras on Gimbals, FPV Camera & transmitters. You can even have a gimbal mounted GoPro camera AND a fixed FPV camera. It will readily carry that. There are just so many addons that this one can take that it boggles the mind.

Price as tested: $ 289.99 (watch prices, it's cost changes frequently)
There are several versions out there. I opted for the Open source MX + GPS version listed as the Auto Pathfinder. Is's pretty complete.
There are versions that come without the radio set for less money but they involve a lot more tinkering and if this is your first bigger quad, or your very first one quad at all, then you should avoid that version. 

We just got this one and a few of the addon components should be here next week so this will be an ongoing review as we add things and tweak them so stay tuned.



This is what we can report so far:


The following is what we called a "Acceptance inspection". In the Air Force, whenever an aircraft was delivered to another unit. it is inspected thoroughly.
If you are not comfortable performing this level of disassembly on your quad, or if you don't have the skills to do so safely, i urge you to find someone that can help or do this inspection for you.
For optimum use of time. Attach your battery to the provided (or an upgraded aftermarket charger).
Once the battery is attached, then plug the charger in.

Important:  Follow safe handling procedures for LiPo batteries.

Initial Acceptance Inspection:

If you pop the cover off of the GPS mast (the GPS is actually inside the main body) You will find the Magnetometer. It's the drones onboard compass. By putting it up here, it is not influenced by the rest of the onboard electronics. If you are going to open the body (and I insist on doing so for a detailed inspection when any new drones arrive) you must unplug the magnetometer. Make sure the actual sensor is VERY secure, it is one of the parts that if it comes loose in flight, you could end up in trouble. This was secured with double sided foam tape AND hot glue. This is GOOD.

Opening the body:

There is an included tool, a multitip screwdriver. One double ended part is the Allen key. The smaller tip is for the small screw at the very end of each arm. the tool is rather soft metal and easily damaged. I opted to leave the tip screws out.
The middle of the round part are the motor mount screws. They are the larger of the Allen key sizes. You do not need to remove them. Just make sure they are not loose. Avoid excess force. 'Finger tight' is the ideal level of torque.  The next 2 screws just before the round part of the arm and the one near the main body are the next to come out. Make sure that the clear lenses covering the LEDs is fully snapped in place.



The inside components:

Flip the CX20 back onto it's belly and gently remove the upper half, being especially careful of the wires for the magnetometer. You can now see the interior.

In each arm is the ESC (Electronic Speed Control) for each motor. They are the long skinny circuit board. It also holds the arm LEDs.
The silvery square in the main body is the GPS sensor. This location is actually quite good. I got satellite lock in seconds where you can actually end up waiting up to 2 minutes.
The white box under the GPS module is the radio control receiver. Both GPS and RX are held in place with double sided foam tape and a small zip tie (This is GOOD.
The rectangular box is the APM (Auto Pilot Module) and runs the whole craft. make sure it is very secure as well. Mine is held with double sided foam tape and a small zip tie (This is GOOD).
The foam tape absorbs some of the vibrations as well as secures the components. On the far side of the APM is a mini USB cable. It runs to a small board at the belly. It has the connections for the camera and gimbal and whatever other accessories you decide to add.

Here is a closeup of the interior.
Make sure all plugs are secure, Inspect all solder joints to make sure they are in good shape. Sometimes a poor joint can occur and the few minutes inspection here could prevent a lot of damage and frustration.

You should also make note of the numbers on the ESCs (the green circuit boards in the arms, close to the motors). Write this down somewhere and make sure the model and version numbers all match. If they are at all different, that may make it difficult to get them calibrated. This may not be necessary so I suggest you only perform this calibration if you really think you need to or if there are problems;

http://copter.ardupilot.com/wiki/initial-setup/esc-motor/

Tip:
You can also see the transmitter. I have added a 'cheat sheet' guide to the switches. I did not use the wording in the manual but terms that I personally consider easier to remember. 
Radial means that no matter what direction the quad is pointed, operated based on radial directions from the transmitter. If  I push the stick forward, it flies away from me, no matter where the front is aimed. This can be a good setting for less experienced pilots and it really is pretty easy. You don't have to worry about orientation on a craft that looks the same at every angle. 
Military members will know that RTB means 'Return To Base'.

Now that I am satisfied that everything is secure, the body is reassembled. Making sure that the wires for the Magnetometer are fed into the mast (carefully). All screws redone, but again ONLY finger tight. If you overtighten, then things will break or pull out of where they go. Make sure you reconnect the magnetometer (MAG for short) and snap the cover back on.

Note there are 2 antennae. This has a diversity receiver. If there is a better signal from one over the other, it will select that signal for control. This is a much safer system than just one. It can also give you better control if you are at the limits of range (try to avoid being in that situation though).

This is a little better view of the plugs on the belly of the CX20

The landing struts are attached with simple thumbscrews, Make sure to route the antennae into the grooves and notches provided. do NOT overtighten the thumbscrews.

The propellers go on to specific motors. there is a little arrow on each arm. The clockwise arrows are on the arms with the black acorn nut on the motor The correct propeller for this is the 'A' on them. For ease of identification, I marked the bub of the propellers with black permanent marker. The Motor shafts are keyed (they have a flat section) so the props can only go on one way. Make sure to tighten with the wrench, but again, only finger tight. You will notice that the black nuts are left hand threaded so you can't really mix them up. When all is said and done, you should have the black at opposite arms. 

The transmitter (Tx) is a 6 channel model. 4 channels are the sticks and the two knobs between the sticks and the antenna are for whatever you add. Most typically they are used for the camera gimbal. If installed (look for an upcoming entry), you can tilt the camera side to side plus up and down by adjusting the knobs.
There are also 2 switches  one at each upper corner of the transmitter. The combination of their settings can perform several functions. for example: if you set the left switch up and the right one all the way down, the CX20 will automatically return to where you took off. This can literally save the unit in many circumstances. I made up a simple reminder chart that I have taped onto my transmitter.

I suggest you look at the Mission Planner software at this point. This is just a few of the many excellent tutorials on YouTube that explain how to set it up.

Note: if your APM is made by Fatshark, the software and procedure is a little different.

http://diydrones.com/profiles/blogs/successful-test-of-the-cheerson-cx-20-apm-arducoper-firmware

https://www.youtube.com/watch?v=JMSwDUrns2Q




More to come. Please check back later.