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Nov 10, 2004, 04:07 AM
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Thread OP

MicroHeli4: a servoless micro heli DIY project

Hi all!
This is my new project of micro indoor heli. This is the first prototype of this microheli (See attached photos)

Itīs a servoless multirotor heli that measure only 32cm (12.5")

Here are the specs:
Lenght : 32cm (12.5")
Width : 32cm (12.5")
Weight : 162g (126g w.o. batt)
Motors : 4x GWS EDP50 (CN12RXC motor)
Props : GWS 3x2
Body : Carbon rods (4mm)
Electronics : Home made Mixer & 4 Esc & BEC module
Gyros : 3 Murata ENC-03 sensors (same as GWS PG-03 Gyro)
Battery : LiPo 2S700 or 2S880
Battery life : about 8 min. with E-Tec 2S700

It has all functions : Throttle, Pitch, Roll and Yaw

It flies well and quite stable (better out of ground effect). Itīs really tiny for indoor flying (I usuaslly fly on my tv room) and I can land it in many places (tables, chairs...) When I have more time I will post some videos... and more photos.

I had constructed other multirotor helis (bigger) but they have the disadvantage that I need to make CW and CCW propellers to correct and control the torque effect. This micro heli use standard and cheap motors and props (no CW and CCW props) and I correct the torque effect with a twist in the two ailerons motors, so I have yaw control (If I increase rpm in the pitch motors it start to yaw to the right and If I increase rpm in the ailerons motors it start to yaw to the left).

The electronics and software were developed for this project. There are 2 modules :
- Main module : It has the main procesor (16F876 PIC) that make the channel mix, 2 Esc, battery monitor and gyro software (I implemented three variable gain proportional control gyros). And two 16F627 for the other 2 Esc's. 4 FETīs (IRF7456) and BEC.
- Gyro module : 3 ENC-03J sensors and an OP amp with low pass filter (72Hz) to help eliminate vibration noise in the gyro sensors.

Thanks to chichi for his colaboration on this project.

I like to know what do you think about this project and new ideas are welcome. If someone wants I could post more info.

I am now working trying to make it more stable.

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Nov 10, 2004, 06:09 AM
Site Aspie
Lynxman's Avatar
Very cool! How much does the mixer weigh, and how did you make it? I imagine you can also make the mixer by using three on-board V-tail mixers.

Have you tried without gyros? I guess it would be almost uncontrollable twithout them.
Latest blog entry: EL-39 compilation video
Nov 10, 2004, 08:28 AM
My member is not
Zlatko's Avatar
Very nicely done
I have been thinking about the same thing. I have a "few" EDP-50s, ESCs, PG-03 etc
I was planing on 5 motors, 4 like yours but straight up, the 5th one like on a helicopter at 90 degrees for the rudder. Using 2 V-tail/elevon mixers ( like Lynxmans idea ) for the oposing lift motors for horizontal control through 2 gyros. 3rd gyro for the rudder.
The other idea was to use the 120degree servo mixing on the TX for 3 lift motors ( 4th motor for rudder ) this would eliminate the V-tail mixers, 1 lift motor and ESC but each motor would need its own gyro
I even have "some" EDF-40H to play with for this project.
Unfortunately, I don't have much "play" time.... to finish it.
Nov 10, 2004, 08:30 AM
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Lynxman's Avatar
The problem with using a TX CCPM-mixer is you can't use gyros.
Latest blog entry: EL-39 compilation video
Nov 10, 2004, 12:38 PM
Registered User
Dr Honda's Avatar
Hey Linxman...

If I'm understanding Zlatko corectly... you wouldn't need the gyros on all the axies. (unless you want it stabe) the Tx would mix 120 deg lift and cyclic (like it would driveing the 3 120 ccpm servos) then you would use one basic gyro to to control a tail motor like a conventinal heli.

hummmm.... I think I just thought of my next project after I finish my T-rex.
Nov 10, 2004, 12:44 PM
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Lynxman's Avatar
I don't think you'll be able to fly it without gyros. I think it will be extremely unstable. JoseJ probably has experience with this.
Latest blog entry: EL-39 compilation video
Nov 10, 2004, 02:57 PM
hi Jose,
welcome to r/c thread

thats very nice job,well done.

i like build i think such as this one day (but need to learn for pic programing).

i have some of motors such as yours in the pic but they have not any numbers on them so please do you know any link for these motors or any advice?

i hope another friends help here and keep this thread on for learning more about these four or more rotors heli's.

it is not possible control these heli'd with no any gyro and only with transmitter so why?

how we can instal a gyro on these kind of heli's?

best regards, Mohammad
Last edited by mohammad_sa39; Nov 10, 2004 at 03:00 PM.
Nov 10, 2004, 03:01 PM
Registered User
Mr.RC-CAM's Avatar
Amazing stuff. Have you thought of publishing the full details so that others could attempt to build it?

Nov 10, 2004, 03:10 PM
Frame Design Engineer
superdave42's Avatar

I always wanted a dragonflyer but there jsut is not $900 worth of parts on that thing to justify the high price.

I want details. hell I'd like to buy one from you.

I don't have lots of time to experiment and make my own. but I could assemble my own if you sold me the completed circuits
Nov 10, 2004, 03:31 PM
Registered User
Thread OP
Thanks to all...

Lynxman, you are right, I tried it without gyros (gain=0) and I think you couldnt fly it for more than 1 or 2 seconds .Really this is an electronically stable machine.

The mixer board weights 12.5g and the gyro board weight 13g. The main board (mixer & more...) is constructed using SMD electronics (PICs, FETs and BEC)

I think you can try to make it with mixers and standard gyros but I prefer to have all the control.

Here is a photo of the main board... and yes! I dont make a PCB for this prototype, I use an standard stripped board (I sanded it to save weight).
When I have more photos I try to explain it in more detail...

I am taking more photos and some videos that i am planning to post tomorrow...
Nov 10, 2004, 03:43 PM
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Lynxman's Avatar
I'm very impressed! Good job!
Latest blog entry: EL-39 compilation video
Nov 10, 2004, 05:49 PM
Registered User
I can certify the flying of that machine.I had already fly it and itīs amazing at least.
For history and to answer a few questions.

All began past year when we see the tribelle, thinking on them we realize it can be done cheaper.
The equipment was 3 ips on 15 inches self made "cuffed" props 2 CW and 1 CCW, the
motors driven by Kontronic micro 10 , to make it stable we use a GWS gyro in elevator(rear motor) and an ACT gyro for two servos (wing gyro that allows the use of flaperons) .Mixing in the radio was motor to elevator , motor to ailerons .
The thing flys with 6 700 ni-mh.
The hover was very controlled but sometimes ,total loss of contol of the elev.
Trying to solve the problems was not sucessful and I pass the project to jose alone
I was tired.
Jose made a wonderfull mixer to use with inexpensive four channel radio and use 3 gws gyros with some problems . Afterthat he improves gyro work by processing the signal direct from gyro sensor to the pic .This happens to be the solution to a lot of
Problems with the last "batch" of propellers (being too soft) leds to the third part.
Using 3 ips with normal props + an direct edp for yaw control, another winner.
Jose try to make it smaller with same components and fail to have enough stability.
Next is this project ,the result of hard work .

This reply is not trying to disencourage anybody is only showing our fails so you can learn from it.
I think this project can be made with two wing gyros that allow flaperons 4 motor controllers and a TX capable of butterfly mixing (crow brakes) plus elev to flap 1 , elev to flap 2 ,rudder to flaps .
A lot of mixing that maybe encounters some problems but I will try using servos to see if it can be done . Remember yaw control has to be done by increasing and decreasing aileron and elev motors.

Juan Enrique
Nov 10, 2004, 05:52 PM
Frame Design Engineer
superdave42's Avatar
very interesting...

any ideas why the tribelle and dragonflyer cost soooo mcuh??
Nov 10, 2004, 06:17 PM
Registered User
I donīt know about the dragonflyer but the tribelle is pure carbon and uses coreless motors with planetary gears and 100 khz controllers , not to talk about gyros and the
fact is made in germany(labor hour is not cheap) on an almost one men factory.
Also the impact of his stubenfliege gives him the credit to sell expensive things without needing explanation of the efforts involved.
A person who buys a Ferrari donīt know why is so expensive but is a Ferrari.
Trying to find wing gyros I found. Futaba gy 351; wing gyro by Ikarus,fuzzy from acteurope , surely there is many more.

Juan Enrique.
Juan Enrique.
Nov 10, 2004, 08:49 PM
My member is not
Zlatko's Avatar
Juan and Jose,
Your advice and help is greatly appreciated. It is wonderfull that you have succeded with this project.

Jose, I have been trying to locate the Murata gyros for a long time without luck. I am trying to locate some ENC-03M. Can you help with a contact?

This one
Same as ENC-3J but only 0.4gm

Cheers and thanks again
Last edited by Zlatko; Nov 10, 2004 at 08:53 PM.

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