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Thread: Open Source Aircraft Design for CNC?

  1. #11

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    Both J and Eric are right.

    If some tyro builder (me for instance) had ready access to a CNC mill, then plans start to look more appealing as opposed to kits. For instance I can hand build a couple representative ribs, then get the mill to make the rest, all exactly right, in far less time than I'd spend screwing them up. I'd only need to pay for (some portion of) the mill, the raw parts, and cleanup. OTOH, I'm never going to financially compete with some factory's economies of scale. Nor expertise.

    ------

    The "open source" part of this is ready availability of plans for well-known, proven, approved, parts that we could make ourselves rather than purchase. As we build up a body of items and parts useful for all airplanes, then more and more opportunities arise for totally new and/or custom aircraft design. It's not so much about making a complete OS airplane ... yet.

    For example, suppose we make good wire harnesses, axles, struts, ribs, antenna ground planes, engine mounts, control horns, etc. with CNC and make the plans available? Once proven and approved, that makes the FAA examiner's job easier too. All kinds of things we can now reliably make ourselves.

    While not everything can become open and/or automated, we don't have to stop with hardware parts. How about an avionics stack built on reliable solid-state sensor and an android tablet? Or software-defined radio? We probably can't do open-source looms for carbon fiber, but our local club might be able to do some kind community vacuum bagging tool.

    3-d CAD? I will look into it a bit. I have not played with any of it so don't know much. Google has something free. Autodesk just released a crippled free version of Inventor. (It will do components but not assemblies.) No idea what SolidWorks might or might not have, nor what's on FOSS software places.

    The second big starting issue is "repository." Do we know where and/or how we want to store and distribute the designs?
    Richard Johnson, EAA #395588

  2. #12

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    Thumbs Up

    Greetings,

    The idea of building and having my own CNC shop is very appealing and its use in homebuilding certainly has many benefits.

    I would agree with several of the comments that CNC makes a much more appreciable difference in the building of metal aircraft over wood, just from a parts-per-material-piece perspective.

    As for OS, I am a huge supporter of OS as a general rule, but in this instance I am not sure if that is the best starting point for some of the same reasons previously mentioned. IMHO the best starting point would be to get a working group together to define the goals/direction of the over-all idea you have in mind first. After things are a bit more defined, begin building the interest group network, followed by growing geographically oriented "workshop groups" to start building the CNC equipment as well as promoting local training in the computer skills and how-to seminars while building the OS library as Richard suggested.

    With all of the resources in play, thinking about a large, massive really, project like development of CNC versions of public domain designs would be the next logical step. After coordinating and executing at least one public domain design project, including the build and test flying, moving into a OS original design would seem a lot more likely.

    As I said, I fully support the idea of OS and have thought of similar groups myself. What has always killed the idea for me has been the back-office end of a project like this. I have managed non-profit organizations and been a/the lead on projects with hundreds of volunteers, both technical and "unskilled" (I hate that term), and it is the administrative end that is the truly daunting part of the process.

    Due to a relatively recent negative experience, I have not been inclined to be the originator of any such projects. But I am interested in participating in something like this.

    If you (John) or anyone else is interested in taking this idea beyond the "boards", I would like to participate. My contact info is below.
    Blue skies and tailwinds,
    ~FlyBoyJon

    Jonathan Wanzer
    Pilot, Mechanic, Instructor, Student
    Email | Website | Facebook | Google+ | Twitter | Tumblr | LinkedIn

  3. #13

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    Hi Jonathan,

    Thank you for your thoughts on this topic. I am interested in taking this further, so will make contact separately. I too have had a negative experience and mine was with a museum not-for-profit aircraft restoration project a few years ago. I bailed early on because it was so poorly organized, with no thought about how to effectively manage the talented volunteers they had.

    In any case, agree with a strawman approach first to validate the concept. Might not work, but it might too, so a solid plan at the start is the foundation to build on.

    Richard,

    You read my mind on taking it further with avionics and other systems. I think that is a logical step down the road and I think that we should take advantage of new manufacturing methods and new directions in mobile computing technologies. Probably a whole other thing there.

    (BTW, my day job is a Principle Engineer (Software) with Lockheed Martin.)

    I think that just having 2-3 people to figure out some high-level details and objectives and then throw it open for comment is probably the way to go at this early stage.

    Thanks for the discussion and well, lets see what happens.

    Regards,
    John Nicol

  4. #14

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    John,
    Please add me to your off-list discussion. richard@ytivarg.com

    Jonathan,
    Thanks for joining up. However, I too am leery of "let's get organized and steer" rhetoric. The fear of chaos--rather than self-organization--emerging is natural, but I think misplaced. Some organization makes sense. Do we, should we, and how would we provide CNC machines or services to our local chapters for instance? Too many times I've been burned like John by well-meaning people who wanted to help but knew only how to meddle. It sounds like you too have had some bad medicine here. If we can work through that then I'm game.

    John (again),
    I knew I was reading a kindred spirit. Sr. Software and Systems Engineer (in Portland.) :-) I'm working with cars though, more's the pity. I agree. An OS avionics stack can and probably should be sidelined for now, but certainly not forgotten.

    now back to work
    Richard Johnson, EAA #395588

  5. #15
    rwanttaja's Avatar
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    For something like this, your best bet will be a small (offline) team. Otherwise, you'll be inundated with "It should be tandem seating" "Design it to use a Subaru" "It should be high wing instead" "What about floats" "Pushrod ailerons would be better" "Why not make it a taildragger" sorts of interference. Get 2-3 guys together, decide on an approach, and go with it.

    Ron Wanttaja

  6. #16

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    Agreed, thanks for your thoughts Ron.

    I did find a neat aircraft being built using CNC methods as a kit. It is the JDT Aeromax here: http://www.jdtmini-max.com/AMax.pdf

    Definitely along the lines of what I was thinking. CNC built, in this case with a CNC laser. But the principle is the same as what I was thinking of in terms of manufactured parts, easy assembly, labeled parts etc. I was thinking a bit more extreme, with a newer construction technique and providing the CNC files for people to do it themselves. In any case, I think we have a small initial team assembled and will resurface if all goes well with more points for discussion and wider input. As I said, might not work, but won't know until we investigate further and figure out if it is doable.

    John

  7. #17

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    When we designed the HoneyBee G2 one of our design goals was to take maximum advantage of CNC and Cad. I agree that this is the way to get precision in low production numbers while keeping cost affordable.
    The biggest single cost is the powerplant. The lighter the better but if one goes too small then engine choices are reduced. From my experience it would be about as easy to start clean as to try to adapt an existing design. Also one should look at other materials and assembly techniques. Look at the Cricket for example of different building materials that could fit with CNC methods.

  8. #18
    I registered just to participate in this discussion.

    I agree with many of Eric's points here: http://eaaforums.org/showthread.php?484-Open-Source-Aircraft-Design-for-CNC&p=3724&viewfull=1#post3724

    In fact, you only have to look at Zenith's designs to see how all metal aircraft can be reasonably made with CNC.

    As a point of intrest, there are already people using this general approach using existing, closed-source designs.

    Robert Haines designed his own CNC that he sells plans for here: http://www.hainesengineering.com/cnc/

    He subsequently used this CNC to begin scratch-building a Zenith CH650, as Zenith provides a plans-only option for this aircraft.

    This approach requires first digitizing the plans, and generating g-code or similar. Robert has stated on zenith.aero that the time required to do this is roughly equivalent to the time required to manually lay out cuts on aluminum sheet. Real time gains are apparently only made on the second airframe. I suppose that spare parts are easily come by though.

    The OS approach would mean that these steps would not be required to be done by the builder; instead the efforts of the contributors would be amortized over every plane built.

    I think that many of the CH750 design elements would lend themselves to this sort of project. IE. All Metal Construction, 'squared' fuselage, etc.

  9. #19

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    Bill, please contact John off-list and ask to join our working group. Our initial thoughts were leaning toward wood. It looks like you have a lot of value to add to our discussion.
    Richard Johnson, EAA #395588

  10. #20
    Quote Originally Posted by JNicol View Post
    Agreed, thanks for your thoughts Ron.

    I did find a neat aircraft being built using CNC methods as a kit. It is the JDT Aeromax here: http://www.jdtmini-max.com/AMax.pdf

    Definitely along the lines of what I was thinking. CNC built, in this case with a CNC laser. But the principle is the same as what I was thinking of in terms of manufactured parts, easy assembly, labeled parts etc. I was thinking a bit more extreme, with a newer construction technique and providing the CNC files for people to do it themselves. In any case, I think we have a small initial team assembled and will resurface if all goes well with more points for discussion and wider input. As I said, might not work, but won't know until we investigate further and figure out if it is doable.

    John
    John,

    I strongly agree with you and would like to join the group. I left private message to you on the forum. Please reply, so I can join. I am a SolidWorks user, so I am sure, I can contribute.

    Thanks in advance, jim.bo12345

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