Discussion Submicro Walkera 4#3 FP - >> BRUSHLESS CONVERSIONS.

[Minibichus]

This is the non-brushless mods thread. General questions and such.
http://www.rcgroups.com/forums/showthread.php?t=830247

This is the original thread from which one branched.
http://www.rcgroups.com/forums/showthread.php?t=726698

Please, post any brushless conversion comments in here. To try to separate the gigantic 4#3 thread from the small portion of people working on brushless conversions.

We'll see if this one sticks. I'll start moving my own posts from the big 4#3 thread onto this one so they all are in 1 place.

I'll transfer all the pictures from the gigantic 4#3 thread to my own blog.

[Minibichus]

post #1

Originally Posted by Minibichus

Alright, this is it... I've been lurking this thread for almost two months now and I can finally jump in with something to add.

First of, I am an avid RC car person and I've never flown RC helis before so this, I must say, was an interesting way of getting into them... usually you buy an easy RTF stuff and get on with it, unfortunately I decided to make it quite a difficult experience to learn... but well worth it.

Long story short:

It all started when I got a picooz back in x-mas, loved the thing, tweaked it, modded it, flew it... awesome toy. best 25.99 bucks I've spent in a loong time. Unfortunately, the picooz did woke up the RC giant inside me.

So, while looking for a micro heli for a friend 3 weeks ago, I came across the 4#3 and I'll just say that the rest is history. Ordered one and once I got it , went out and flew it, well, heh, tried to fly it at least, dunno if you coud call my 1st ever attempt a flight...
I was hooked man, the heli dropped the gauntlet and it was on...so, what do I do next? instead of learning the basic heli skills, I just take the heli back inside and tear the whole thing down to bare frame and while I am doing that, I am writing a list of things I needed to get:

Amongst these are:
-Spektrum DX7
-Spektrum AR6300
-BlueArrow 3n1 mixerboard
-Hacker X5 BL controller
-Team Losi 8750kV BL motor
-Some small 7.4 LiPo pack
-Lots of prayers. (I discovered they had no prayers at the hobby store)
-Lots of luck. (same for luck...)

This was two weeks ago, today I am proud to anounce that my 4#3 is fully spektrumized and brushless converted. I can hover the thing for almost 1 minute with the DX7 now vs. the P.O.S. radio that came with it.
Flight time is hard to tell yet b/c I am not able to hover it for very long before pilot error forces emergency landing.
It is currently running 1 flightpower EVO20 300 mAh 7.4v cell. Its got so much power that it can lift a 49 grams 1000 mAh 7.4 lipo that I use sometimes while testing on the stand. However, most of the mixing test and tune was done using one of my Team Orion 4800mAh Lipo packs for my RC cars. With this pack I was able to keep the thing on the ball bearing turn table I built for at least 1 hour @ max travel stick. (The maximum throttle is actually limited to 50 percent in the D/R of the radio simply because more than ~50% percent gas on the main rotor the helicopter just goes up into the skies like a rocket propelled spinning pirouette
Current combat weight, RTF is ~69 grams with a 300mAh battery. That puts it ~20 grams over what it weighted stock.

I've already found ways to get it lower than this weight, but it will get expensive fast so I am gonna sit back and enjoy it, and learn, yeah, I forgot I don't know how to fly helis... yet... and now, nothing better than my own 'creation' to learn...

Cheers.

MB.

EDIT: I just finished my 2nd flight. I measured the time in/out and I got about 9 1/2 minutes of pretty much hover the thing around the backyard. Time was measured until the cutoff of the 3n1. The 3n1 controls the tail rotor and gyro. (kinda sucked b/c the main hacker X-5 still was going strong...oh well)
I only have 1 pack sitting around, but the beauty of this thing is that I could stick another 300mah pack and fly the thing all day long...
As for the main motor, the Losi gets hot, I'll measure the temp it with my nitro temp gun after the third flight but its hot enough not to touch it.

[Minibichus]

post#2

Originally Posted by Minibichus

I'll have a few high quality pics later tonight b/c yesterday I did my test flights at 1:30 am US eastern time and I went straight to bed after that.

The 2s lipo battery is just longer than the stock one, not wider (or taller), I originally test fitted it on the stock battery holder and it works okay, but to answer your question I did fabricated my own battery holder, I'll show pics of that too. Its a very simple holder that keeps the battery stuck wherever you set it when you take off.

The tail motor is still the stock coreless motor. (amazingly enough) I must say that this little unit is pretty darn awesome so I had to find a way to keep it in. This was indeed a bit tricky to keep it in, but armed with ohm's law and an amp-meter I "fabricated" a custon current regulator using high wattage resistors.
My findings are that the tail coreless motor will run farily cool with ~2.4 ohms from an 8.4 power source (a lipo fully charged). There is still room left to go down up to 1.66 ohms. With the current 2.4ohms the tail authority is pretty good up to about 49 percent of the losi power curve, the last 5 percent (54 percent power) is when the losi starts to overpower the tail by a little bit, not too much but you can feel it. Today I'll try 2 ohms flat on the tail and report my findings. The 7mm coreless motor draws a ton of current, finding its limits is what's hard.

As for wiring the stuff together. This was probably the trickiest part of all, but after is done the amout of tunning possibilities I have now was overwhelming at first. (specially for a helicoter noob like me!)
There is two motor ESCs on the chopper: the X-5 and the 3n1 mixer board.
The main rotor X-5 is hooked up to the THROTTLE channel of the AR6300 receiver. (not the mixer board)
Then, the two 3n1 channel inputs (main and tail) are hooked up as follows: main is plugged into the PITCH channel on the AR6300, and the tail plugs into the RUDDER channel. The 3n1 board has also two motor outputs, 1 for main, 1 for tail. The main is soldered out, that is, there is no output cables for the main in the mixer board. The tail rotor plugs to the coreless motor thru a 2.4 ohm resistor in series. (to avoid frying the motor)
So here is how it works. Since the DX7 does pitch mixing with a nice 5 point curve, *all* I had to do fine tune the pitch curve (b/c its actually the throttle input for the mixeron board) to match the primary throttle for the main X-5 ESC.

Cheers.

MB.

[Minibichus]

post#3

Originally Posted by Minibichus

As per somebody's PM request, I'd figured I'll share with everyone what parts are involved in doing this "mod".
It is by no means a cheap mod, but it sure works and it requires mininal soldering skills. (mostly cable splicing/resoldering cables together)

-Spektrum DX7 radio: $149.95 at LHS bucks without RX and no servos.
-Spektrum AR6300 nanolite RX: $49.95 at Local Hobby Store.
-BlueArrow 3n1 mixerboard: $48 bucks at BPHobbies.com
-Hacker X-5 brushless speed controller: $26.99 bucks at LHS.
(you can use the YGBE4L super light ESC if you prefer, any lightweight ESC will work. I bought the X-5 b/c the LHS carried it and it was cheap, thats all)
-Losi 8750 kV motor: $25.99 at LHS. Suggestions have been made about the 5000kV mini Feigao, at 2S it should be good to go, maybe even increaed flight time due to it being a less of a "hot rod" motor...)
-x5 10 ohm 1watt resistors: ~$2 bucks at local radioshack. (for tail)
-Dean's Micro 2R plugs for battery pack and hel: $1.65 a pair.
-Flightpower EVO20 300mAh: $22.99 at LHS ea.
-Several JST plastic plugs and cables to replace the walkera 4#3 non JST plugs and to change the large futaba style Hacker X-5 connector. $8.99 at LHS for all of them.
-Tons of heat shrink tubing. (blue and black) 1.99 at radioshack. Use it, better than smoking electronics.

As for gyro, I am using the one that is built in the mixer 3n1 board. Seems to work decently and on top of that I want/need to learn how to keep the tail pointed right.

Hope this helps.

MB.

[Minibichus]

post#4

Originally Posted by Minibichus

Well, it all sounds good in theory and it really did sound good to me back when I was researching but the truth of the matter is that Blue Arrow 3n1 won't run on single cell so don't make the same mistake I made buying it and now I am sort of "stuck" with it. It is a good unit but I think that the small Esky HH gyro and perhaps two good micro brushed ESCs like the pixie-7 from Castle Creations or maybe smaller ones are probably a much better route if you're going to stay brushed but going with Spektrum. The AR6300 unmodded weights 1.9 grams on my scale and it is a really good receiver IMO. (there is not much else in there left to take out: Horizon did a really good job with it. As for HH vs. the 3n1 get the HH no questions asked, otherwise you'll have to build a test stand where to setup the revo mixing and it is a really tedious and time consuming process...

So, to answer your question, no, don't buy the bluearrow 3n1 unless you plan on going 2cells with a brushed setup. (which is probably not worth it)

MB.

[Minibichus]

post #5

Originally Posted by Minibichus

Sorry for taking this long... (thanks spainman)

This is correct, the receiver AR6300 has 6 channels. The main X-5 hacker controller plugs to the AR6300 THROTTLE channel and then on the 3n1 mixerboard the throttle plugs to the AR6300's PITCH channel and the rudder plugs to the AR6300's RUDDER channel. This way you can do whatever revo mix you need based on the pitch curve. Much more control (and things that can go wrong... heh) than just the simple 'pot' to change the single rate revo mixing on the 3n1 mixerboard.
I desoldered the cable for the main motor on the 3n1 mixer board. The tail and main battery cables are still there.

MB.

EDIT:
Note1: If you install a hacker X-5 (or any other BL speed controller) make sure that you turn off the BEC of one of the 2 speed controllers in the chopper.
Note2: Remember that the 3n1 mixerboard is a 2-3 cell ONLY board, you won't be able to use the single cell lipo that came with your 4#3.

[Minibichus]

post#6

Originally Posted by Minibichus

Thanks, greatly appreciated Jonathan.

The stock Walkera 4#3 has a 4-in-1 main&tail revo mixer/gyro/receiver circuit board. It is not a 3-in-1 mixer board like I have.
The BlueArrow 3-in-1 mixeron board that I am using has a main&tail revo mixer and a gyro but no receiver. All of them adjustable (gain and threshold adjustable for gyro, and single rate for the revo mixer) Additionally, it provides a crude D/R (dual rate) adjustable knob to limit the amount of tail rotation that acts similar to a current limiter. (mine is set to max D/R, but I limited the tail motor current draw thru the resistors b/c the gyro will not respect the D/R set limit and send full power to the tail motor and if not protected, then another fried tail motor under 8.4 volts)

This is the board that I used on my conversion:
http://www.bphobbies.com/view.asp?id...4&pid=B0548273
I purchased it from them as well, I hope I don't break any rules by showing here the link to the store item.
This 3-in-1 board without the plastic case, trimmed wires and removed of any unecessary wires weighted ~4.9 grams. It suited perfect for my space needs, and it has JST connectors already installed with the correct polarity for the Spektrum AR6300 receiver.

As for the tail motor/servo question. All the AR6300 does is interpret the radio signals back into PPM signals that it sends to each of its 6 channels. The tail motor speed controller in the 3-in-1 mixer board converts this PPM signals coming from the AR6300 rx into the appropiate motor RPMs. It works the same way as an RC car speed controller plugged into a car recevier. A servo also reads the PPM signals, but it interprets its meaning in a different way. Say that the PPM signal carries a value of 0, when a servo reads this zero, it interprets it has to center to angular position zero. Similarly, when a speed controller reading this PPM signal of zero it interprets that it has to stop the motor.
When the PPM signal reads 30, the servo interprets this signal as I have to move to position 30, and it swivels accordingly until it hits position 30 in the arm travel. A speed controller will interpret this signal as I have to give the motor juice to go 30 percent of max power. When radio sends a -17, servo will move to position -17 and a speed controller if not reversible, it will simply ignore this command by cllamping the value to zero. (on RC cars, going negative position on the PPM signal means that you want to hit reverse, so the speed controller set the motor to spin backwards)

Hope this helps.

Cheers.
MB.

[johnIn2SonAZ]

hey MB,
got my order from HH and they messed up and doubled my order for the Losi motors.
now i have 4- of the 8750Kv motors and 3- of the 10250Kv motors!
what the hell am i going to do with all these Brushless motors??
guess i'll have to start selling Microns with full Brushless conversions!..... lol.
-johnw

[Minibichus]

Originally Posted by johnIn2SonAZ

hey MB,
got my order from HH and they messed up and doubled my order for the Losi motors.
now i have 4- of the 8750Kv motors and 3- of the 10250Kv motors!
what the hell am i going to do with all these Brushless motors??
guess i'll have to start selling Microns with full Brushless conversions!..... lol.
-johnw

Nah... just trade me one of the 10k Losi ones for the nice battery holder tray that I made heh...

MB.

[ikonosphere]

Hi all,

I'm new to all this, but have enjoyed all 420+ pages of the prior 4#3 thread from the very beginning.

I've had a 4#3 from the moment it was available, but have been very unhappy with it because all kinds of things went wrong.

Finally, after many mods and much soldering this thing flies great now, especially since I converted it to a dual main motor setup (using two stock main motors) and fitted stronger rotor blades tailored from 5#5 blades.

My BL question now:

Can ONE BL ESC run TWO BL motors simultaneously?

I know there is no obvious benefit from using two main motors instead of one, but I'm so much in love with the dual motor setup that I'd love to use two 3.5g BL motors for the main rotor, once I go BL

Any idea if this would work?

Thanks for sharing your ideas!

[johnIn2SonAZ]

Originally Posted by Minibichus

Nah... just trade me one of the 10k Losi ones for the nice battery holder tray that I made heh...

MB.

ahh alright!....he..he
e-mail me your address.
-johnw

[johnIn2SonAZ]

Originally Posted by ikonosphere

Hi all,

I'm new to all this, but have enjoyed all 420+ pages of the prior 4#3 thread from the very beginning.

I've had a 4#3 from the moment it was available, but have been very unhappy with it because all kinds of things went wrong.

Finally, after many mods and much soldering this thing flies great now, especially since I converted it to a dual main motor setup (using two stock main motors) and fitted stronger rotor blades tailored from 5#5 blades.

My BL question now:

Can ONE BL ESC run TWO BL motors simultaneously?

I know there is no obvious benefit from using two main motors instead of one, but I'm so much in love with the dual motor setup that I'd love to use two 3.5g BL motors for the main rotor, once I go BL

Any idea if this would work?

Thanks for sharing your ideas!

why?? trust me one of the losi motors is way way too much power.
two just would kill the lipo too much current drain.
you will be very happy with one losi 8750Kv BL and one 3.5g outrunner in the tail like i have in my micron v2.
-johnw

[Minibichus]

Unfortunately no,
1 BL ESC will only run 1 BL motor. Commutation has to be done at the ESC level instead of that the motor (in brushed motor the commutator takes care of swapping the polarity) B/c of this, you can't use the same ESC to drive both motors b/c they are not at the same physical location.
Additionally, most sensorless ESCs use the 3 wires to "read" the rotor position so 2 motors will completely confuse the ESC.

MB.

Originally Posted by ikonosphere

Hi all,

I'm new to all this, but have enjoyed all 420+ pages of the prior 4#3 thread from the very beginning.

I've had a 4#3 from the moment it was available, but have been very unhappy with it because all kinds of things went wrong.

Finally, after many mods and much soldering this thing flies great now, especially since I converted it to a dual main motor setup (using two stock main motors) and fitted stronger rotor blades tailored from 5#5 blades.

My BL question now:

Can ONE BL ESC run TWO BL motors simultaneously?

I know there is no obvious benefit from using two main motors instead of one, but I'm so much in love with the dual motor setup that I'd love to use two 3.5g BL motors for the main rotor, once I go BL

Any idea if this would work?

Thanks for sharing your ideas!

[ikonosphere]

Originally Posted by Minibichus

Unfortunately no,
1 BL ESC will only run 1 BL motor. Commutation has to be done at the ESC level instead of that the motor (in brushed motor the commutator takes care of swapping the polarity) B/c of this, you can't use the same ESC to drive both motors b/c they are not at the same physical location.
Additionally, most sensorless ESCs use the 3 wires to "read" the rotor position so 2 motors will completely confuse the ESC.

MB.

MB,
johnw,

thanks for your replies.

johnw: I was asking because with the two stock motor the bird has so much more power and nearly the same flying time as with only one motor. I can fly incredibly banked turns with two new stock motors, if you promise me your single BL setup has the same power, I will bury my dream and go for the single BL.

MB: thanks for sharing your knowledge!

Regards

dm

[Lutin]

I'm in thanks for the info....