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mCP X Blade Micro CPx Helicopters Information and Help


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Old 07-31-2011, 01:42 AM   #1 (permalink)
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Default The double coreless tail mod guide




Many users ask me in pm help on how to make this mod, so I decided to write a short guide.

FAQ

Q: What is it?
A: Is a mod that adds a second motor on the tail.

Q: What is the purpose?
A: Its purpose is to eliminate the tail blow out and improve the accuracy of the tail.

Q: Can be used it with stock brushed main motor?
A: Yes and no. Because in some situations the current drawn by two tail motors could also be double, you may run into over-current protection of the 3 in 1 board that shut down motors and servos. This happens even with 120SR tail mod or with the 4G3 brushed main motor mod.
With a brushless converted mCP X, this possibility never occurs, because most of the current flows to the brushless controller, out of the 3 in 1 board.

Q: The stock brushed speed controller holds two stock brushed tail motors?
A: Definitely yes

Q: Why not use the 120SR tail mod, which seems much easier to achieve?
A: 120SR tail mod is a great mod, but the results are quite variable.
While the tail blow out is definitely out of the way, some people detect varying degrees of tail wag with 120SR tail mod.
Probably there are difference between board and board and, in my helicopters, the tail wag was very pronounced despite several attempts to shorten the tail boom and tail rotor blades.
Currently I have built four double coreless tail and all work wonders.

Q: What about center of gravity?
A: We have two motors instead of one, it is natural that it is moved back.
However, it is possible, even advisable, to use a tail boom as short as possible, just the length that holds the tail rotor out of the flow of the main rotor.
We have standard tail rotor (shorter than 120SR rotor) thus, the length of the tail boom is almost the same as the stock one. In addition, the total weight is about 2.5 grams less than the 120SR tail mod.
If you can put the battery well forward, the center of gravity is moved back slightly, while if you slip the battery from the front (by removing the canopy) cg can be corrected at all.



Material needed
  • Two high KV coreless 6mm motors. The stock motors are fine, but they may very well be replaced with the blade mCX2 motors. I prefer to use the type CCW due to the long shaft.
  • Two stock tail motor mount.
  • Two stock tail rotor (or two Solo Pro tail rotors).
  • 130/135mm long tail boom.
  • 120SR tail motor wires.
  • Exacto knife.
  • 2mm drill bit
  • Small shrink tube
  • Soldering station with interchangeable tips (a tip is used to melt the plastic)
[EDIT]
Currently I have used the mCX2 pair of motors, CW and CCW.
No problem at all with the tail rotor on the CW motor (which has the shortest shaft).
So I correct what I said earlier, I would say that the coupled CW / CCW is practically perfect.


The double tail motor mount

We have to cut at an angle of about 45 one of the two motor mount (the rear mount).
Do not throw away the cutted plastic. It will be used to fill the gaps during the melting of the two tail motor mounts.





Than we have to remove the flat part of the second tail motor mount (the front mount).
We use the 2mm drill bit for this.





Slide the front mount on the tail boom, well forward, enough to put the rear mount until it locks.
Finally, slide back the front mount to join and align with the rear mount as shown in this photo





Now everything is ready for melting with the solder tip. Help you with small pieces of plastic to make material where missing. Those who have already performed the mSR/120SR swashplate mod (shortened arms) are definitely an advantage.

Is very important that, throughout the melting operations, the motors are properly placed in order to prevent the motor housing may become deformed.

Melting the two tail motor mount makes the final piece removable from the tail boom.
Alternatively you can glue the two motor mounts together, but it is likely that the final piece can no longer be separated from the tail boom.
Here's the dual tail motor mount finished.





Place the motors

I think the motor with the rotor on the right side has a higher efficiency, or E-flite would put the rotor on the left.
So I decided to help the rotor with less efficiency by placing it back, so that it can take advantage of a longer lever arm.
Of course the motors are positioned in the center, making sure that there is enough space for the free rotation of the left rotor.





Soldering work

The motors are connected in parallel. Depending on the motors used, the wiring may vary.
The important thing is that, looking at their operation from side view, the rotors revolve in the same direction.


In this case I used two CCW BMCX2 motors.

[EDIT]
If you use the BMCX2 pair of motors, CW and CCW, you have to match the red wire (CCW) with white (CW), and blue (CCW) with black (CW). Some pics here.


Wiring...




... and solder to the 120SR wires





Is very important to electrically isolate the solder point to protect the mosfet against short circuits. I always prefer to secure the wires with dental floss.





Finally, I find that soldering the wires directly to the 3 in 1 is advantageous in terms of voltage drops.
This solution is not exactly easy, but for those who have no problems with solders, make a solder spot set back near the tail boom helps a lot when you need to do maintenance.

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Last edited by liftbag; 08-08-2011 at 06:31 PM..
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Old 07-31-2011, 01:57 AM   #2 (permalink)
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Beautiful work, Paolo but can it hold as good as my double tail blades?

Seriously, nice write up with the updated Soldering Work. You think 36AWG too much to use on these? I've never had a 120SR so I wouldn't know how thick the wire is.

Be interesting if Rakon or others adopt your design with their CNC stuff.
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Last edited by Uncle Chop Chop; 07-31-2011 at 02:43 AM.. Reason: Don't like misspelling people's names! ;)
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Old 07-31-2011, 02:33 AM   #3 (permalink)
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Quote:
Originally Posted by Uncle Chop Chop View Post
Beautiful work, Paulo but can it hold as good as my double tail blades?

Seriously, nice write up with the updated Soldering Work. You think 36AWG too much to use on these? I've never had a 120SR so I wouldn't know how thick the wire is.

Be interesting if Rakon or others adopt your design with their CNC stuff.
I'm sorry, I do not even know. Any wire barely thicker than the original is okay to me.

Yes, a cnc double motor mount it would be great, but how many they will sell?
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Old 07-31-2011, 03:16 AM   #4 (permalink)
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Quote:
Originally Posted by Uncle Chop Chop View Post
You think 36AWG too much to use on these? I've never had a 120SR so I wouldn't know how thick the wire is.
I thought about it only now!

You can use the original mCP X tail motors without desolder the original wires.
You'll have four instead of two wires that run on the tail boom.
Then you have to solder them to the tiny plug in parallel with the colors reversed or in some other way directly to the 3 in 1
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Old 07-31-2011, 09:06 AM   #5 (permalink)
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Quote:
Originally Posted by liftbag View Post

Many users ask me in pm help on how to make this mod, so I decided to write a short guide.
Wow, thank you for writing this up, liftbag. This is a really big help. Nice work! And it was a great discovery, as well! The fact that you took the time to help step everyone through it is even better.

Quote:
Originally Posted by Uncle Chop Chop View Post
Seriously, nice write up with the updated Soldering Work. You think 36AWG too much to use on these? I've never had a 120SR so I wouldn't know how thick the wire is.
If memory serves from when people were discovering the advantage of simply using 120SR wires for the mCP X tail, the 120SR wires are 26AWG. The mCP X wires are 30AWG, I think? I have the Radio Shack 3-pack of magnet wire. I know the 120SR is the middle gauge, or 26. And I think the stock wire happened to be the thin gauge, which is 30. But if you want to go to 36 AWG, that would be awfully small wire. It's half the diameter of the 30AWG.

Personally, I wouldn't go to a wire that's smaller than stock for the mCP X. You're trying to add more tail-holding ability, but with a tiny wire you'd then risk starving each motor for power. And if you're going to have a single pair of wires down the boom to feed both motors, I'd probably go thicker than stock, to 120SR / 26 AWG wire or similar. If you were to use two sets of wires down the boom, 1 set/motor, as liftbag just described, then maybe use the stock wire size. But not smaller, IMHO.
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Old 07-31-2011, 05:19 PM   #6 (permalink)
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Quote:
Originally Posted by RedOctobyr View Post
Wow, thank you for writing this up, liftbag. This is a really big help. Nice work! And it was a great discovery, as well! The fact that you took the time to help step everyone through it is even better. .
Thank you so much.

Quote:
Personally, I wouldn't go to a wire that's smaller than stock for the mCP X. You're trying to add more tail-holding ability, but with a tiny wire you'd then risk starving each motor for power. And if you're going to have a single pair of wires down the boom to feed both motors, I'd probably go thicker than stock, to 120SR / 26 AWG wire or similar. If you were to use two sets of wires down the boom, 1 set/motor, as liftbag just described, then maybe use the stock wire size. But not smaller, IMHO
I totally agree
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Old 07-31-2011, 06:57 PM   #7 (permalink)
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Curious if you have tried using just 1 mcx2 motor with the stock brushed setup?
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Old 08-01-2011, 12:01 AM   #8 (permalink)
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Quote:
Originally Posted by Spunjah413 View Post
Curious if you have tried using just 1 mcx2 motor with the stock brushed setup?
Yes. In my opinion the CCW BMCX2 motor is the same used as stock.
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Old 08-01-2011, 06:49 AM   #9 (permalink)
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Hi liftbag. Fantastic ''How to'' thread. Bravo and Grazie.
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Old 08-01-2011, 01:54 PM   #10 (permalink)
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I just broke my tail boom
Buth the motors are still oke
Buth i have the "cage "one.
Any idee how to do it with the "cage"?
Can you do this with the stock tail boom?
Or do i need a 2mm rod.
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Old 08-01-2011, 02:22 PM   #11 (permalink)
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Quote:
Originally Posted by cp Dexter View Post
I just broke my tail boom
Buth the motors are still oke
Buth i have the "cage "one.
Any idee how to do it with the "cage"?
I do not know, and frankly I'm worried about the gradual disappearance of the old tail motor mount.

Quote:
Can you do this with the stock tail boom?
Or do i need a 2mm rod.
You can try to do it with stock tail boom.
I think one of the two rotors will feel the influence of the main rotor, but maybe it works fine.
If you want to try with the stock tail boom, I'm curious to know the result.
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Old 08-02-2011, 04:45 AM   #12 (permalink)
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Quote:
Originally Posted by liftbag View Post
I do not know, and frankly I'm worried about the gradual disappearance of the old tail motor mount.


You can try to do it with stock tail boom.
I think one of the two rotors will feel the influence of the main rotor, but maybe it works fine.
If you want to try with the stock tail boom, I'm curious to know the result.
I just did the double tail mod using the "cage" style motor mounts. I just cut the cage off (and used the material for filling). Unfortunately this style of mount is not as tight a fit for the motors as the non caged variety. I CAREFULLY heated the mount and squeezed it together slightly. Just be carefull not to go too far.
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Old 08-02-2011, 05:43 AM   #13 (permalink)
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I can push the motor out of it's cage .
And then cut the cage of.
Buth i was looking at some other small motor and found a x-twin motor that is between the size of the stock motor and the 120 sr tail motor.
Did whane of you tested them?
So not i will.
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Old 08-02-2011, 06:05 AM   #14 (permalink)
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Quote:
Originally Posted by cp Dexter View Post
I can push the motor out of it's cage .
And then cut the cage of.
Buth i was looking at some other small motor and found a x-twin motor that is between the size of the stock motor and the 120 sr tail motor.
Did whane of you tested them?
So not i will.
Yes, I tried some 7mm motors (single, not double), the measure used on the Walkera 4G3.
It was the next step after I've used the 120SR tail motor.
I was quite pleased, because the tail wag was much more acceptable, but occasionally run into the tail blow out.
This is why I tried the way of doubling the stock tail motor which in my case it was an absolute success, to the point that I consider my final solution to get rid of tbo and tail wag.

Currently I have no interest in the tail brushless conversion
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Old 08-02-2011, 06:50 AM   #15 (permalink)
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Mine is also 7 mm in diameter.
I think we are talking about the same motor.
Did you try it with the stock tail fin?
With the x-twin prop it my preform beter.
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Old 08-02-2011, 07:08 AM   #16 (permalink)
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Quote:
Originally Posted by cp Dexter View Post
Mine is also 7 mm in diameter.
I think we are talking about the same motor.
Did you try it with the stock tail fin?
With the x-twin prop it my preform beter.
I have used the Astroid design tail fin, modded tail motor mount and shortened blades 120SR rotor.
Some pics







What's the x-twin prop?
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Old 08-02-2011, 09:36 AM   #17 (permalink)
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Its the prop that comes with the airplane where is I've got the motor from.
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Old 08-03-2011, 04:20 AM   #18 (permalink)
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I've just tried this double tail motor mod and found the run time on nano-tech 300's to be unacceptably reduced. About 2 mins of flight time and they're starting to run out of enough grunt for inverted flight.


This is on a stock rig with dual mcp x tail motors.

Did you try it on a stock rig first Liftbag?
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Old 08-03-2011, 04:58 AM   #19 (permalink)
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Quote:
Originally Posted by Lunar View Post
I've just tried this double tail motor mod and found the run time on nano-tech 300's to be unacceptably reduced. About 2 mins of flight time and they're starting to run out of enough grunt for inverted flight.


This is on a stock rig with dual mcp x tail motors.

Did you try it on a stock rig first Liftbag?
Not me. Others have tried your setup here in Italy, but no one has reported such a dramatic decrease in flight time.
Some reported over-current protection events during some extreme maneuvers, and I mentioned in the guide.

Your flight time indicates an over-current problem, but it's hard to say, maybe a defective motor or scratched insulated wires that are shorted on the carbon rod.

My flight time with HP05s / XP-7A is four minute, where the nanotech reach 3,75V and they are charged with 220 mAh.

Actually I fly with a new brushless setup that consists in a HP08 11800KV motor, 9T pinion and XP-12A esc.
This bird is heavy, weighing 58 grams with nanotech lipo and flies in a similar way to a sports model rather than a pro model (extreme 3D capable).
I have setup the tx timer to 3' 30" and after flight the lipo measure 3,80V and is recharged with 190 mAh.

So I think you have some kind of electrical problem that needs to be investigated.

Paolo
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Old 08-03-2011, 05:30 AM   #20 (permalink)
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The batteries didn't seem to be any hotter than normal but yes it could be a voltage leak somewhere. I am still using the stock battery chargers which are also probably a bit ambiguous in their final result but I will remedy this shortly.


Today I finally received the remaining parts for a brushless rebuild so I'll investigate these problems as I go.
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