Quad RCX250 Mini quad Build thread

Lee

Well-Known Member
Here is my write up on the RCX250 mini quad from Myrcmart.
Heres what I bought.
RCX Carbon 250 quad
The new RCX H1806 2400kv motors
The package I got, was with four motors and 16 gem fan 5040 props.
RCX 12A ESC (SK)

I will be using an OpenPilot board I had lying around, and I have ordered some Zippy Compact 1500mah 35C batteries.

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First the frame.
Well I was very nicely surprised to see the quality. The carbon is well woven and the finish is slightly satin like, similar to the QAV250.
All the CNC cuts are clean. No burring. Meaning I either got lucky and they had just changed the tool, or the QC is better than the other companies frames of this type.
The pieces had a light oil over them. Not sure if this is from the manufacturing, or to stop them scratching each other in the bag.
The arms look very strong. The seems to be more material around the motor mounts. Something lacking in other companies versions.
Here comes the kicker.
This frame is only $17 !!!!! Although the price is ment to go up later.
I have thought to build my own frames, but at this price, why bother.

Only one thing let the frame down. A coupe of the metal posts had too large a thread for the screws to grip.
I had to swap the screws around a few times, but eventually got a combination that worked.

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The reason I had to wait so long for my quad to arrive, was the new 2400KV H1806 motors. These are hot out of the factory.
They are and upgraded version of there popular 2300KV motors.
Bearings feel very smooth, and the windings look very carefully assembled.
They come with two prop mounts, one for standard style props, and one for Tiger style.
The standard version come with a 5mm shaft. This negates the need for a prop adapter to shim the Gem fan props.
Warning about the screws supplied with the motors, they are too short to go through the arms.
Lucky I had some longer ones from an old 450 heli. Just be careful not to make them too long as to touch the windings.

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The ESCs are Simon K flashed 12A. I removed the ESC motor wires, and solder the wires from the motor straight to the board.
One downside to these ESCs, is the battery wires are too short for the mini copter without adding extensions to allow all wires to be soldered together.
I have opted to replace the wire completely with longer ones. I have informed myrcmart to suggest lengthening them by 20mm.

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When cutting the motor wires, I found the enamel coating goes all the way up the wire. So when you cut them to length, you will need to scrape the coating off, before they can be soldered.
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Next I will wire up the power distribution. I did start this, but got annoyed with the short ESC wires, so I'm waiting for some 18AUW wire to arrive with my batteries.
 
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Stambo

Well-Known Member
Looking good Lee, I am sure you will love it. :)

Something I have done differently is put the nicely rounded arm bolt heads at the bottom.
My theory is less sticking down to get caught on anything if I am really going low and if I ever have to replace an arm it is easier to put the hex driver from the bottom and get a small spanner on the nuts. :)
 

Stambo

Well-Known Member
Be interesting to see what you think of the 2400 motors, I have the older 2300 versions and they are ok but I would love more power.:)
Might build another aimed at 4s. :biggrin1:

I started with 3 blade Gemfan 5030.
Now I have 2 blade HQ prop 5030, they are definitely stiffer but I have not noticed a huge difference in performance.
 
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Tasajara

Active Member
Looking good Lee, I have the older RCX motors , but I really like look of the new ones. I like the fact that they have a way to mount the higher end Lumenier 5x3 Carbon Fiber Props
I have been wanting to stick a pair on one of my 2 Mini's. Looks like I need to order a set.
 
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cml001

Well-Known Member
So when building this, or a small mini like this.. Esc, battery, receiver.. How do u run the wires? Battery to ESCs( soldered together or to a distribution board)... Throttle leads to the controller from the ESCs.. Do you remove the power lead on 3 of them and run the 4th on to the board(or bec) with the power lead?
 

Lee

Well-Known Member
So when building this, or a small mini like this.. Esc, battery, receiver.. How do u run the wires? Battery to ESCs( soldered together or to a distribution board)... Throttle leads to the controller from the ESCs.. Do you remove the power lead on 3 of them and run the 4th on to the board(or bec) with the power lead?

On bigger frames you will use a Distribution board, and some small frames have one too.
On mine, I'm just soldering all the wires together.
ESC + and ESC - soldered together then to the battery lead.
Throttle leads going to the FC board. If they have switching BECs in them, then its best to remove all bt one red lead, or all of them and use a separate BEC.
If they are Linear BECs, then you can leave them all in.
 

Lee

Well-Known Member
No, the FPV cam is tucked inside. The Mobius on top is set back enough that in a head on crash, the frame would take the brunt.
But i'm working on an idea to use my Gopro as the FPV and recording cam, with an added platform to the front.
 

Lee

Well-Known Member
So I'm going with the single Gopro as my Recording and FPV cam.
The is zero lag when testing on the bench, so it should work fine as FPV.

I had a spare piece of carbon, the same width as the arms.
It came from my Goblin 570, used for a separate Gyro sensor, if you have one, which I don't.

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Lee

Well-Known Member
The frame kit comes with some useless flimsy landing skids, that nobody uses.So I made my own.
These are standoffs from a Trex 600 tail boom case.
I cut them in half and screwed them to the legs.

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Stambo

Well-Known Member
I don't use landing skids on mine, I just land on the base.
I figure anything like that hanging down gives you more to catch on the ground when low flying. :)
It means you have to have somewhere to take off from, I carry a piece of plywood around.
 
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Lee

Well-Known Member
From experience with my QAV500, having no legs has caused more damage then having legs would.
If you think about it, unless you are just hovering around, the lowest part of the quad will be the tips of the props.
Or in my case the gopro mount, because the quad is tipped forward all the time.
Even if i do catch one, they are plastic, and will bend :D

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Stambo

Well-Known Member
I see your point.
I was thinking more along the lines of reaching something really low at speed then levelling off to glide under.
I intend to fly under my truck one day. :)
 
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