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Build and review of $73 ZMR250 racing quad

ZMR250 racing quad review

image of assembled ZMR250 aliexpress kit

The dramatic popularity increase in FPV drone racing has led to a wide variety of frames, kits and parts to buy. Choosing a 250 racing quad to buy can be a daunting task depending on what you are after. If you are looking for a starter racing quad, budget, just for tossing around or as a spare backup then the Aliexpress ZMR250 is the perfect deal. At the price of 73$ it leaves you well under the 100$ mark. You should note that this kit doesn’t include radio, battery, charger or FPV gear. You’ll have to buy those things separately if you don’t already own them. I prefer it that way because then you can decide yourself which radio to use as well as charger and lipos. If you do look for a ZMR250 kit including a radio and receiver then Banggood has one for around 166$. I personally haven’t tested it but by the looks of it it seems like a solid choice!

One late night I stumbled upon a post on Rcgroups about a this super cheap ZMR250 kit for at Aliexpress. It’s a 250 fpv racing quadcopter. I ordered one because I was interested in how a cheap 250 fpv racer would perform in terms of quality and flight characteristics.

In this post I will show you how I built this kit and modified it to fit my taste and needs.

When doing builds like this I always use my iron soldering clamp stand. I can’t stress this enough how easier it makes all the soldering jobs because lets face it – sometimes your two hands just isn’t enough. Especially when dealing with these small components and wires where good soldering bonds means everything. I bought mine at a local hardware store but Banggood have a similar one. It really becomes your third and fourth arm.

Whats included in the package:

– Mini 250 3K Carbon Fiber Quadcopter Frame
CC3D Flight Controller Mini Power Distribution Board PCB
1806 2280kv Brushless Motor x 4
12A Simonk ESC x 4
5030 Propeller CW&CCW x 8
– CC3D Flight Controller x 1
– Led Strips x 2

Frame specs:

– Materials: 3k Weave Carbon Fiber
– Maximum Propeller: 5″
– Motor Mount: M2 12mm – 16mm
– Flight Controller Mount: 30.5mm x 30.5mm
– Board Camera Mount: 32mm x 32mm
– Weight : 140g

Motor specs:

1806 2280kv Brushless Motor 
– KV: 2280
– Max Trust: 460g
– No. of cell: 2-3S
– Framework: 12N14P
– Propeller: 5″ ~ 6″
– Length: 26.7mm
– Shaft: 2mm
– Diameter: 23mm
– Weight: 18g

Esc specs:

12A Simonk esc x 4
– Max continuous load: ~11 amps
– Burst Current: 16A/10sec
– BEC: 5v/1amp max
– Lipo Cells: 2 to 3 cells
– Weight: 10g
– Dimensions: 24mm L x 18mm W x 7mm H (29mm in length including capacitor)

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I started working on the arms and motors because I wanted to get the esc/motor soldering and wiring done first.

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I decided that I wanted to solder the motor wires directly to the ESCs to have minimal wires. I first tested the motor direction by hooking up the wires with crocodile clips. This allowed me to reverse the direction without soldering anything. Make sure which directions the motors are supposed to run and that the exposed wires/clips doesn’t short out. Two of them are clockwise and two are counter-clockwise.
After getting the polarization right I put bits of tape on the arms and drew how to wire the motors to the escs. You can see this in the above picture. It saved me alot of trouble and I didnt need to resolder anything.

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I wrapped the ESCs tight with electrical tape.

Photo of motors and escs soldered and mounted to the ZMR250 arms
Arms almost done!

Make sure you test the ESCs individually before wrapping them up.

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Test fitting the arms to the bottom plate

I wanted to keep the wiring and power distribution board sandwiched between the two bottom plates to reduce the rats nest-look of the finished quad. To do this I had to add spacers and longer m3 screws for attaching the arms. The spacers I used is the plastic adapters you get when buying propellers. They are pretty weak and therefore only a temporarly solution until I find something better.

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Next step was to solder all the components to the included power distribution board. That includes the ESCs power wires, JST plug and wires for powering the FPV system, the included LED lights and the main lipo cables with XT60 plug. This is pertty straight forward and most of the job is stripping the wires. When stripping your wires I really recommend this wire stripping tool.

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IMPORTANT! Always test your Power Distribution Board for shorts before plugging in your battery. I recommend using a voltmeter with a beeper such as this one. It has a setting which will make a beep when current is flowing between the two terminals. This way you can make sure that there is no short between the + and – pads and that all the ESCs are fed with power. This is also a good time to mark the ESCs servo wires if you plan on routing them between the bottom plates as I did. This way you know which ESC goes where on your control board.

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Next step is to prepare the second bottom plate. Depending on how you want to place things and which equipment you plan on using this step could be different when you build it yourself. I am putting the CC3D on nylon spacers as I plan on placing my 6ch receiver underneath it to save some space. I’m using the Eachine 700tvl ET200 5.8G 32CH 200mW transmitter for this frame as it’s small and very lightweight. I’m powering the transmitter from my PDB via a LC filter that is shown in the image below. I will be making a post of how to build one as it’s really simple and you should really consider building one as it’s filtering the power from your lipo which could be polluted by interference from your motors and ESCs.

Image of LC filter
LC-filter mounted
image of lc-filter
LC-filter

My FPV camera (which I don’t remember where I bought it, probably Hobbyking) is mounted to the camera holder with rubber bands. This was first a temporary solution but then I figured that it’s a pretty good way to secure it since it’s flexible and more crash resilient. I rather change out some rubber bands instead of a camera anyways. This way you can also slide some foam in in the top to make it tilted upwards. The camera mounting sheet have two tabs in the bottom and top which slides into the top and bottom frame plates to secure it.

image of FPV camera

image of parts mounted

 

In the above image you can see that I’ve switched out two of the “quick lock” nuts to normal ones as the cones were slightly unbalanced. I will swap out the remaining two as soon as I find some counter rotating ones.

Summary

Being such a cheap kit one can imagine it being a nightmare to assemble. This is actually not the case, I found it really fun to build and easy to customize to your own needs. Sure you might have to use other screws or special parts but most of the time you have these things lying around somewhere. The frame parts and holes aligned which made it easy to fit together. I would recommend buying nylon spacers to use when building this kit. There is no manual or instructions included but most of the parts are easy to tell where they should be attached. If you are struggling with any parts feel free to contact me or look at images. I would totally recommend this kit if you are looking for a cheap 250 racing quad kit. As I wrote earlier you need your own transmitter/receiver, battery, FPV gear and charger to get this quad flying.

Pros:

– Easy to build
– Cheap!
– Looks good
– Good fit
– Most things included
– Powerful motors

Cons:

– Unbalanced lock nuts for the propellers.
– No manual

Order it at Aliexpress or Banggood with transmitter and receiver combo!