Rise of the Clones (APM2.x series)



The name 3DR, 3D Robotics, and ArduPilot are trademarks of 3D Robotics.  

The design is Open Source and licensed under the Creative Commons and GPL v3 license.

A misconception is out there that cloning the Ardupilot is not liked.

This is not right, there are a few companies that make Ardupilot gear, and who give back to the community, either in support of developers, or simply adding improvements and Publishing the results for all to see.

What are not appreciated are those who take, but do not give. Who either simply take the Schematics and PCB drawings, directly use these, make equipment, and do not offer support channels or worse, those who make derivatives, and do not feed back to the community.

Recently Hobby king released the HKPilot mini, a welcome derivative to the APM series of boards, this is great news, but there is a catch.  Hobby King did not want to release the drawings.

Here is an email exchange that I have had with them regarding this issue.(please note I have been corrected, the copyright is owned by 3DRobotics)


Me Mar 11 11:47:

Where are the design files for this product? it is Open Hardware, you must publish your design files. This product is copyrighted to DIYDRONES*, and is licensed under the Open hardware licence. This requires you to publish the Eagle drawings.
Under the licence, any derived product MUST be published with the SAME open hardware licence.

Howard T., Mar 14 10:39:

Hello Philip,

Thank you for raising this matter to our attention. For us to help you with your inquiry, we will escalate this matter to our Product Specialist for further assistance. Rest assured that your concern will be addressed shortly. Thank you for your patience and understanding.


HobbyKing Support Team



Ian, Mar 14 18:20:

Hi philip , 
Thanks for contacting the HobbyKing Support Team.

You may contact DIYDRONES for the design schematics. We are not the owner therefore we cannot supply you with the design

Thanks for emailing support. 
If you have any other questions, please let me know. 
Best Regards. 
HobbyKing Product Specialist 

 After other exchanges, including posts on the product page they posted the following.


   Proficnc 11 points - 11/03/2014

   design files please


      Eagle CAD files will be uploaded shortly in compliance with the user agreement

      proficnc  11 points

      Thankyou :)

Which was great…. Except they did not post the files.

After another day of many people sending support requests, finally they sent an Altium file (Just PCB, and with exploded polygons).  This File was a modification of the Altium file I had posted on DIY Drones of an early 2.5 revision (mistakes included J ) which does appear to be the board that they have built.

But the problem? According to the licence, they MUST abide by the licence.

  • ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original.
  • Attribution — You must give appropriate credit, provide a link to the license, andindicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

So that means that Altium is OK, as that is what they used. But they MUST include the FULL design file. That is Schematic, Lib files, everything needed for others to go straight into production with this file, and it should have this license clearly marked, and it should show it is a derived work.


* The name 3DR, 3D Robotics, and ArduPilot are Trademarks of 3D Robotics.  

The design is Open Source and licensed under the Creative Commons and GPL v3 license.

The Pixhawk / PX-4 has the open Hardware licence, please see the link below for details...


1. Documentation

The hardware must be released with documentation including design files, and must allow modification and distribution of the design files. Where documentation is not furnished with the physical product, there must be a well-publicized means of obtaining this documentation for no more than a reasonable reproduction cost, preferably downloading via the Internet without charge. The documentation must include design files in the preferred format for making changes, for example the native file format of a CAD program. Deliberately obfuscated design files are not allowed. Intermediate forms analogous to compiled computer code — such as printer-ready copper artwork from a CAD program — are not allowed as substitutes. The license may require that the design files are provided in fully-documented, open format(s).


If you do not wish to release your drawings, then you must start with a clean slate, the reality is, if it is compatible with APM/PX4/Pixhawk, it is most likely a derivative. (Exceptions would be TauLabs/OpenPilot; APM code will run on their boards, but only after significant modification to the code)

Why is this important?

DIYDrones is a community where people with a common interest share their ideas, and inventiveness. It is important that the work done by those in the Development process is recognized for its worth. When someone comes along and taps into that knowledge, makes a gain from that, and does not return to the community, it takes away from why we are all here.

I have heard people say “I do not want to open source my product based on APM, because people will copy it…..” the reality is, without the open nature of the project, this person would be unable to economically design their project in the first place, so feeding back to the community is a small price to pay.

For those interested, have a look at the git-hub repositories, there are a number of hardware suppliers supported by the code base, and the development team, these manufacturers get direct support from the whole team, because they are OPEN with their code additions, and also with their hardware.

When purchasing hardware, consider this,

  1. does the company you are purchasing from directly support the product?
  2. does the company seek to improve on the product, and release this information for the community to use?
  3. do profits from the sale of the product go towards creating better outcomes for the community in the longer term?
  4. does the company have quality control?
  5. does the company have engineering on hand to help with your log analysis?

This Blog will be moderated. All posts will require approval. 

Views: 5283

Comment by Philip on March 23, 2014 at 1:43pm

@Bertold  PCB's are artwork, they are based on artwork, the schematic, laying the parts out, it is all works of art.  please be careful with quoting Copyright law as an excuse to commit Fraud.  Without complying with the licence requirements, any sales of these boards into Australia (where I am) or the US at least is not strictly legal.  why risk it, when all that is required for compliance is so simple?

Comment by Philip on March 23, 2014 at 1:49pm

Clarification to All.

The main sentence missed is that derivatives and improvements on the design are encouraged,  Clones are tolerated as they add no value to the project.

The catch is that if you wish to make a derivative or clone, you MUST obey the license.

The original designer of the ardupilot series (APM 1, APM 2, APM 2.5) is Jordi Munoz who formed 3D Robotics.    The others are clones, or derivatives,
Craig Elder pointed me to even earlier work
This all started with the Ardu-IMU https://code.google.com/p/ardu-imu/
and then the Ardupilot https://code.google.com/p/ardupilot/
If you note, all of those sites say this is a  DIY Drones project and the development of the autopilot came out of this community.  
FlyMaple is  original work.  It is not a clone or a derivative. 
VRBrain, is original work by Virtual Robotix.  It is not a clone or a derivative. 
ArduFlyer, is a direct copy or clone of APM 2.5.  RC Timer has respected the copyright on the name and has removed APM and 3D Robotics from the board but does not adhere to the Open Source Hardware license by publishing the schematic and the PCB files.
HKPilot, is a direct copy or clone of APM 2.5.  HobbyKing has respected the copyright on the name and has removed APM and 3D Robotics from the board but does not adhere to the Open Source Hardware license by publishing the schematic and the PCB files.
HKPILOT MINI, is a derivative of the APM 2.5.  It is based on the schematic of the APM 2.5 but the PCB is different.  Again Hobbyking has not adhered to the Open Source Hardware license by publishing the schematic and the PCB files.  
AUAV-X1 is a derivative of the Pixhawk / PX4.  It is based on the schematic of the Pixhawk but PCB is different.  Arsov UAV has not adhered to the Open Source Hardware license by publishing the schematic and the PCB files.  
The whole idea of Open Source Hardware is that is a community effort and everybody benefits from the innovation.  When companies take an open source community effort and don't publish their changes, the community that created the project in the first place does not benefit. 
Comment by hal on March 23, 2014 at 2:06pm

When companies take open source and make it closed source and violate the license it is stealing.  What they are doing is stealing the time and resources everyone put into the product in order to profit.  With zero R&D costs the profit margins change dramatically.  The companies know this.  It is just a calculated risk reward that they feel is in their favor.  Who knows the same plant that makes 3dr hardware may very well be the same ones rebranding it for another company.  Wouldn't be surprising at all since the have everything already paid for, supply chains in motion, and the pre production work already done.  The only cost they would incur is that of actual supplies and manufacture.    So for them every extra board produced is almost entirely pure profit. 

Comment by James on March 23, 2014 at 3:17pm

since discussion about copyright is involved.. I'd like to quote oshwa faq about it. (http://www.oshwa.org/faq/

Under U.S. law, and law in many other places, copyright does not apply to electronic or physical designs. Patents do. The result is that an Open Hardware license can in general be used to restrict the plans but not the manufactured devices or even restatements of the same design that are not textual copies of the original.

The applicable section of U.S. copyright law is 17.102(b), which says: “In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.”

There are similar statements in the laws of other nations.

The effect of this is that the license restricts the publication of a schematic or a laser-cutting plan, rather than the use of the schematic to make devices that are sold. You can control how people sell the plans with your license, but you can’t keep them from commercially manufacturing and selling the devices with your non-commercial license, unless you have a patent.

base on the quotation, may I suggest the "violation of copyright" might not have a stand? Therefore no one is violating copyright, but just being unfaithful to open source spirit. 

again, i'm no advocating manufacturing and selling it with no return to community is right. 

Comment by James on March 23, 2014 at 3:30pm


btw.. about this part. 

AUAV-X1 is a derivative of the Pixhawk / PX4.  It is based on the schematic of the Pixhawk but PCB is different.  Arsov UAV has not adhered to the Open Source Hardware license by publishing the schematic and the PCB files.  

I used to send oshwa an email about such kind of derivative..  and the follow is the answer.. which will probably put them in disadvantage as well

Dear Oshwa Committee:

May I ask for some clarification on oshwa license about recreation of a current open source project? We are working on recreating pcb design from a known open source project. We are using the schematics from the project to recreate pcb layout as an improvement. We wonder, under Oshwa license, is the recreated pcb design required to also be under oshwa and published along the product. Or can we reserve the recreation as private property?


The license is viral, so you must publish all your files as open source hardware as well. You cannot have the recreation be reserved as private property. Hope that clears things up!


that means, if the derivative is based on an oshwa licensed schematics, it shall still be made public and agree on the same oshwa license

Comment by Philip on March 23, 2014 at 4:27pm

I think the thing here is intent.  if the community can be taught the intent of the law, then the pressure can be put on people who with no real effort of their own, take ready to run designs, and directly profit without contributing back.  these people are like mosquitoes, they take, and only leave disease in places they have been.  the problem is, consumers who are short sighted, only want to have the immediate benefit of a cheep product, and cannot see past their wallets to the effort that has gone into the product by those that developed them. 

The intent of open Hardware is not to make money off other people effort with nothing in return, it is to facilitate knowledge growth for the whole community.

Comment by Phillip Kocmoud on March 23, 2014 at 5:26pm

Philip, Publishing the X1 schematics and PCB files has never been in doubt for Nick and I. We are choosing to wait until we have the actual working product in hand to do so. The AUAV-X1 is technically a derivative (we did in fact use the PX4 as a starting point) and we acknowledge the effort and license of Lorenz. Thank you Lorenz!

I personally find this topic complicated. I feel this and all knowledge should be for the free benefit of humankind and attaching any limits on that seems self-serving. There will always be contributors and leaches. No legal-eze will ever change that. What strikes me as odd is we all learned from someone or something. Certainly the APM or the PX4 were not the first autopilots, yet the fact that there is a license on them places a burden on everything after.

I believe anyone may take any features of the AUAV-X1 that are not a “derivative” and feel free to use then without acknowledging Nick and I.

That is "open source" to me but I am sure that violates some other license!

Comment by Philip on March 23, 2014 at 5:54pm

@ Phillip Kocmoud   Thank you for the Acknowledgment to Lorenz and that it is a derived Product.  will edit the main blog when the files are posted. 

Thank you

Comment by Craig Elder on March 23, 2014 at 6:14pm

@ Phillip Kocmoud   I would like to add my thanks as well.

Comment by Andrew Rabbitt on March 23, 2014 at 6:57pm

One legal curiosity for open-source hardware and software is how it relates to potential patent claims of third parties.  It's worth noting that in producing any embedded hardware or software product, patent infringement at some level is almost guaranteed.  It's only that most patent holders have limited ability to investigate potential infringements and file claims.

With OS, everything is out in the open for easy investigation, however ownership and infringement is much harder to pinpoint.  In my opinion, especially for software, releasing source code under a GPL is a significant protection against potential infringement claims.  Hardware less so, since someone has to manufacture it for some profit.


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