Servers by jDrones

Synchropter project

(Pitt) #1

Just decided to show off this 2 years project.
Reasons: build a tailless helicopter because they look bad@$$ and just because I can.

I don’t take a lot of note and photo, These are all pics I have.

Project start: ‎July ‎19, ‎2015
Some line drawings (initially designed to use 4 servos)

‎September ‎3, ‎2015
Decided to start with the most difficult part, the custom bevel gears that mesh at 25 degrees.
This pair of gears proved countless people wrong about capability of 3 axis CNC

September ‎13, ‎2015
More details in

‎September ‎20, ‎2015
Made a prototype frame from acrylic

September ‎24, ‎2015
Bearing blocks

‎October ‎12, ‎2015
Came up with more practical design

‎October ‎18, ‎2015
Access to “real” CAD software

November ‎12, ‎2015

‎November ‎24, ‎2015
The finalized design

‎December ‎21, ‎2015
Getting real!

March ‎8, ‎2016
2nd most difficult part: Rotor heads
The blade grips need angled arm to avoid blade strike = custom made

Table top CNC isn’t going to make them like magic
This is Fail compilation, total of 4 failed attempts (3 are human error :stuck_out_tongue_closed_eyes: )

A pair needs to be made on the same Al block to ensure that they are identical and balanced

April ‎3, ‎2016
Finally usable grips!

April 5, ‎2016
Now, the center hub

I consider this the trickiest part to make on 3-axis machine…and they all failed

None of these hubs work,
Loose on shaft,
shaft won’t fit,
spindle not perpendicular.
no matter what tools I used to flip the work piece, there are coordinate errors
It’s impossible to make without 4th axis :weary:

August ‎22, 2016
"If you can’t flip it, mill both sides at the same time!"

//Run out of photo uploading space
continuing next reply

Chinook heli support in ArduPilot
Synchropter build need help
(Pitt) #2

What the rotor heads look like:

The curved mixing arms fix non-linearity of angled grip arms.

‎July ‎21, ‎2016
Made an upgraded version of bevel gears: “Zerol Bevel Gears” with metal bushing

August ‎28, ‎2016
"The Grand Assembly"

‎September ‎4, ‎2016
The landing skids (legs) no photo available

Til this date, I still had no idea what flight controller I could use

September 19, 2016
Joined :sparkles:
See my discussion here: Synchropter build need help

‎December ‎1, ‎2016

‎December ‎24, ‎2016
First Lift Off

Video nowhere to be found

‎January ‎24, ‎2017
Telemetry set

‎May ‎6, ‎2017
Testing Here GPS
By mounting GPS on top in Cube’s former place, Cube got moved below the frame.

This was when the magic happened
Vibration level halved

May ‎8, ‎2017
Decided to make new lower frame that allow Cube to be mounted inside.

Final Design

May ‎17, ‎2017
Start working

‎May ‎23, ‎2017

May ‎31, ‎2017
"I wanna mount a camera"

‎June ‎29, ‎2017
First Loiter

‎July 2‎4, ‎2017

To be continued

(Pitt) #3

Fail Compilation
These are either defective, outdated, incompatible or broken parts

(Nicolas Chaslot) #4

that’s an amazing job and project!

In the end, waht firmware are you running on this baby?

(Pitt) #5


I’m using modified 3.4.5 right now.
Will move to 3.5 as soon as it is stable.
I just don’t want to work with code everytime 3.5 rcxx is out.

(Olivier Brousse) #6

Outstanding and truly exceptional, thanks for sharing!
You first loiter is also amazingly stable.

Btw, 3.5 is out now :wink:

(rmackay9) #7

This is a super cool helicopter. I’ve seen the video before I think, really impressive!

(Martin Szilagyi) #8

Hi, I’m working on the same project and I have a basic questions about the software:

I’m using the PX4_2.4.6 with the APM-Copter V3.5.5 heli; frame 11; mission planner and QGround Control.
Do I need any other software?

Many thanks!


(Fnoop) #9

This is awesome! And there I was complaining to myself this morning that I have to solder wires to an ESC to get flying…

What are the upsides and downsides of this kind of copter? Why isn’t it more popular?

(James Pattison) #10

The upside is symmetric control response, and importantly, they’re basically immune to retreating blade stall (which in a normal helicopter is nasty).
The main downside is mechanical complexity.

(Andrew Rabbitt) #11

Just seen this and would like to say I think it’s AWESOME! Congratulations @PittRBM!

(Pitt) #12

Only requirements are AC 3.5 or above. So APM can’t be used.
However the official firmware only supports Tandem style (fore-aft or left-right) not intermeshing style.

The code needs small modifications to yaw mixer. Aside from that, it’s like normal heli.

(Pitt) #13

Also, obviously, no need for tail rotor and the cool look.

Complexity is not the real problem, it’s about as complex as tandem style (synced rotors) but shorter drive train and angled shafts.
The real problem IMO is lack of controller, the physics, and the dangerous look of it.
For physics part, I didn’t do much analysis or math, cascading 2 CCPM rotors just worked.

(Martin Szilagyi) #14

Many thanks! Now I’m using AC V3.6… Is it possible to get the modified code? THX

(Pitt) #15

This is my code based on 3.5.4.

There have been few changes to these files since 3.5.4 so you can’t simply copy these 2 files to 3.6.x but I believe these changes won’t conflict.
I’m no expert at coding and git thing, you may find it poorly written.

Thank you for your interest. :slightly_smiling_face: