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Thread: The Daedalus Project - 250 size miniquad - Light & Slim (OPEN SOURCE)

  1. #1
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    Lightbulb The Daedalus Project - 250 size miniquad - Light & Slim (OPEN SOURCE)

    Introduction
    So after buying my first quadcopter, a TBS Discovery, about 2 years ago, then building a tricopter based on David Windestalís design, I recently decided to get into miniquads. Even more: I decided to build my own frame, which I will share in this topic.


    Before designing my own 250 quad, I decided to first get a feel for this size of quad by buying and building a ZMR 250 frame. This already provided me with loads of ideas and indicated a few major problems and challenges. At least in my opinion. Those same issues also seemed to be present in many other designs.




    Problems with many existing designs
    First thing was an unnecessarily tall frame. Obviously this was necessary to accommodate the large board cams. However, I didnít like the look of those tall frames, nor did I think it was absolutely necessary. So that was the first point I wanted to change.


    Secondly, the weight of the frames and quads overall. Because frames were rather tall, multiple decks of plate material had to be used to make them somewhat rigid. This however also implied using more screws, more standoffs, more hardware in general.
    This was also something that I found troubling for two reasons: it reduces flight times and it makes the quad less durable. The more weight is slamming into a tree, the more kinetic energy there is. Contrary to what some might think: a heavy quad is sometimes more easy to break than a light one. Iíll come back on this later.



    Source: blog.oscarliang.net


    A third issue was the standard use of 3mm arms cut from plate material. Although thereís nothing inherently wrong with that design (although you could argue they increase drag somewhat), I preferred the look of a quad with sleek, tubular arms. Nowadays most ESCís can be mounted inboard anyways, so thereís no real need anymore to make the arms wide enough so they can accommodate the ESCís.



    Kind of like this one.




    Goals
    So I wanted to avoid these three problems: frames that were tall, heavy and used flat and wide arms. On top of that I also wanted to make my quad relatively portable, easy to contruct and repair, and I also wanted to make it easy to modify, either by myself or by others in the community.




    Deadalus I.O
    After 1 or 2 failed designs, I ended up with ďDaedalusĒ, version 1. Or, in full, ďDaedalus I.OĒ. This is the first prototype, which Iím still flying today:



    The first hand cut version, using square booms.



    A second, laser cut version, where I used 8mm round booms instead of 10mm square booms.



    A first carbon fibre prototype, which Iím actually still flying today.



    Incorporating various 3D-printed parts like motor mounts, camera mounts and arm clamps.



    This is the current build with slightly lighter electronics and 3D-printed parts.




    Features and specs
    - 240 size (although the booms allow for easily swapping to smaller or larger size)
    - Fits 5" props standard, but with longer booms (230mm instead of 210mm) 6" is also possible.
    - Fits up to a 4s 1800 on top, or even larger when mounting on the bottom.
    - Electronics I'm using: Naze32, DYS SN20A, Aomway 200mW, Cobra 2204, FrSky.
    - Motors can be tilted.
    - Many cheap, light, but very durable 3d-printed parts.




    The clamping parts and motor mounts
    After a general overview, Iíll give a brief overview of some particular parts, starting off with the arm clamps and the motor mounts.


    Originally the first design motor mounts were disc-shaped, 2-part mounts where the motor screws also pulled the motor mounts together over the 8mm booms, which was surprisingly durable and snug.
    The unexpected nice thing was that the clamping force was variable, allowing the mounts to rotate back or forth on impact, protecting the motors. A second advantage of this design is that motors can be angled very easily, as you can see on the previous picture. (Thatís a 5į tilt.) A third advantage is that this assembly only requires you to use 4 screws, actually saving quite some weight.





    I wasnít completely happy with the way the mounts looked though. I was wondering if I could make them more compact, primarily because that would allow me to 3D-print the parts faster when necessary. So I designed a second version of the motor mounts. This was a 4-part mount weighing only half of the first ones and which turned out to be equally durable.








    This last version of the motor mounts is basically still what Iím using today. The only difference is that Iíve adapted the holes to 2M since Iím flying an batch of Cobra motors with 2M mounting screws. A second difference is that the current versions have a slightly lower profile, bringing the motors down to the arms a little more.




    The FPV-camera and mount
    As you might have noticed, a major difference with many (not all) standard designs is that Iím only using 2 frameplates with 20mm of space in between. With regards to the flight controller, PDB, ESCís, VTX and receiver, this actually turned out to be more than spacious enough.


    The major issue was the size of the FPV camera. Up until now, I had always used a standard Sony board cam, which had very decent quality, but was way too large for my design. So I had to look for another, smaller FPV camera. I ended up using an Aomway 600 TVL, which I bought as a set together with the 200mW transmitter.





    In order to mount this camera, I originally designed and printed a press-fit type mount. Although this worked rather well, the camera recently started vibrating as the mount was subjected to wear and tear.



    Although the mount appears to be massive and heavy, it was printed with about 15% infill, keeping the weight below 5 grams.


    A second version of the camera mount was designed and printed, using a two-part clamping design.





    This is the mount Iím currently still using. However, I must say that I was not particularly impressed with the video quality of the camera itself. For outdoor flying, in perfect lighting conditions, it performed well. However, I also fly indoors from time to time and with less than perfect lighting, the dynamic range was simply not good enough (which was to be expected when buying a CMOS camera of course).


    So basically I had to look for a new FPV camera, preferably a CCD camera, which was able to fit in the 20mm space in between the frameplates. After some research, I decided to order the Turnigy IC-120SHS from Hobbyking, which is a tiny 20x20mm camera.





    Iím still waiting for the camera to arrive in the mail, but it sports a decent Sony sensor, so I canít imagine it would be of lesser image quality than the Aomway anyways.
    When it arrives, Iíll have to come up with a new camera mount anyways, so I will post that design over here as well.




    Flight controller and PDB configuration
    As I stated earlier I wanted this quadcopter to remain as flat, light and simple as possible. Instead of using a second set of middle posts/spacers between the frameplates, I decided to make a ďcolumnĒ in the centre of the frame, also incorporating the PDB and Naze32 board Iím using. This module basically provides most of the structural integrity for the middle part of the frame.



    Also note that the frameplates Iím using are only 1mm carbon fibre. This keeps everything light, yet very stiff.


    As of now, this configuration has worked surprisingly well. I havenít really had the need to come up with something different here. The advantage of this way of mounting is that you save some space and weight, which would otherwise be taken up by extra posts and hardware.




    All-up weight, ready to fly, with Mobius
    One of the most important factors in designing a quadcopter, was the weight. At least for me personally. I wanted to see how light I could make the frame, without sacrificing structural integrity and durability. The current weight of the quad is 470 grams. That includes a 3s 1400, FPV-setup and a Mobius.





    The most surprising thing was that this light weight actually made this quad very robust. Obviously itís not indestructible, but it has taken quite a few beating without breaking anythingÖ Iím thinking the lower weight also reduces the amount of energy it endures upon impact. 470 grams versus 570 grams (on a typical similar sized quad) might not seem like an awful lot, but I can imagine it has quite an influence when youíre crashing.




    Originality(?), Open source & Thingiverse
    Although I have come up with a lot of the features on this quad by myself, I have recently come to the conclusion that some aspects have already been incorporated in other designs as well. Thereís in fact nothing new about using carbon booms for arms, designing a less tall quadcopter or making clamp-style connecting parts. So is this design original, novel, inventive, Ö? I donít know, some aspects might be, some aspects definitely are not. Iíll let you guys decide, although I donít believe itís that important of a question.


    I do however want to make this project open source. (Basically a Creative Commons licence model, without commercial use.) In other words: Iím sharing all Sketchup files and .STL files, necessary for printing the parts, on Thingiverse. Do note however that this is a work in progress. The files on Thingiverse are not yet complete. Some files need some tuning. You should be able to print all plastic parts at this point however. Just donít forget to read the instructions.


    The Thingiverse link: http://www.thingiverse.com/Daedalus_BE/designs


    The exact dimensions of the frameplates are not yet available. I have drawn the original frame in Autocad, so if youíre interested, leave a message and I will upload the .DWG files as well.
    However, thereís a larger files on my Thingiverse, where you can find the Sketchup file of the complete, assembled quad. The frameplates are in there as well. Iím currently learning to use Solidworks, so I hope to have the .SVG files of the frameplates very soon.


    Why am I sharing all parts and designs? Because I hope some people out there might want to experiment with this type of frame as well. The possibilities are endless. You could even build a hexacopter or a tricopter using the clamps and motor mounts. It should leave room for a lot of creativity. You should even be able to convert the frame to a Ė oh, so dreadful Ė taller version.
    Anyways, it would be nice to hear your input, re-designs and modifications. It might even be useful for me as well.




    Future plans and modifications
    Currently Iím looking at making a second prototype which incorporates some changes I wanted to make after flying this first version for a few months:
    - Shorter ďwheelbaseĒ: I would like to decrease the distance between the arms with about 5mm. Not sure if this would improve handling. Weíll see.
    - 8mm booms with a 4mm inner diameter instead of 6mm. I have noticed that the carbon booms Iím using right now become more flexible after some (serious) crashes. I want to see if I can glue a second 6mm carbon boom inside the larger 8mm boom so I can increase the thickness of the walls. Another option would be to switch to 9mm booms, but those are far less easy to find. (Larger booms would be impossible since the space between the 16x19 motor mounting pattern would not allow it.)
    - A better FPV-camera (as stated above).




    I'd love to hear your suggestions and comments!

  2. #2
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    Hello Daedalus_BE,
    I love your 250 quad, coupled with being very well assembled, it is an extremely clean design.
    I will be very interested in following your progress and would really appreciate the chance to have a look at the layouts for the frame plates.
    Would it be possible for you to send me a copy of the DWG's (or if you have already got to grips with Solidworks then the .SVG) as I don't have sketch up.

    It a beautiful little piece of kit, you should be proud of what you have achieved so far, but I am sure I will have a few thoughts and comments once I've found some time to look over the files.
    Thanks mate

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    Thanks for the nice words! I sent you a PM a few minutes ago.

  4. #4
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    Another thing you might consider to trim some more weight is making an integrated board that contains all the electronics. You will save some weight in wires connecters etc.

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    An integrated board (basically like David Windestal did on his last version of the Tricopter) would definitely be something I'd want to see on this quad. That would make it much cleaner indeed. However, that seems like something I could only have manufactured by specialized companies, right? Up until now I've basically made every part of this quad at home, but an integrated board would be somewhat more difficult. Or are there cheap places to have prototypes manufactured these days?


    Anyways, I just added a .SVG and .PDF file of the frameplates to my Thingiverse account. They are ready for download and can be cut by hand using the PDF or with a laser cutter using the SVG. Should be easier than the CAD files I sent out to some of you before!


    - Frameplates: http://www.thingiverse.com/thing:952102
    - Arm clamps: http://www.thingiverse.com/thing:944456
    - Motor mounts: http://www.thingiverse.com/thing:944436
    - Camera clamp: http://www.thingiverse.com/thing:944449
    - XT60 Bracket: http://www.thingiverse.com/thing:944428





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    If you want to collaborate, i can design a PDB for this. I have been wanting to design something, and was thinking of doing it for the zmr250 frame but someone already beat me to it.

    Advanced Circuits near where i live will do 2 layer boards under 60 square inches for 33 bucks each. Minimum order is 4.
    http://www.4pcb.com/33-each-pcbs/

    Leo

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    Hmm, that sounds really cool! I didn't know it was possible to have them manufactured in such low numbers. I'll keep in touch with you.

    I'm currently designing a slightly shorter frame (5mm shorter), so I'd prefer having a PDB version of that. I'll have to cut that frame first, test it, and then have a PDB manufactured for it.
    However, feel free to make a mock up using my PDF or SVG file though! I don't mind at all.

    Many thanks for the link, I'll keep in touch!

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    The PDB i have in mind is something that everything solderes to (ESC, Flight Controller, OSD, etc.) This way there are very few wires, and you get some weight savings. For components i was thinking NAZE32, Kiss ESC's 18A, MiniM-OSD.

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    The Daedalus v2 frameplates are done! I have managed to improve my Solidworks skills somewhat over the past few days (read: weeks), so that barely allowed me to make a decent file. I have uploaded it to my Thingiverse account in PDF and SVG: http://www.thingiverse.com/thing:953480


    You can use the SVG file in a laser cutter and it will come out looking like this:







    Although the frame is shorter by 5mm, 6 inch props still fit. You will have to use 230mm long booms instead of 210mm though.





    Changes since v1:
    - 5mm shorter. This improved the handling and reduced torsional flex in the frame.
    - 4 extra center post holes. This discards the previous tower style mounting of the FC. The problem was that the screws on top of the v1 plates were directly under the battery. The new plates allow more space for the battery to sit. This also increased the rigidity of the frame somewhat. (Although: if you cut the frame plates from 3mm plywood, you could do without these center posts as the wood is already rather stiff.)
    - 3 holes for rubber damping balls for the camera to sit on. I haven't tried this out just yet, but it should work. I will provide an actual camera plate later on. (Unless someone here wants to have a go at it! ;-) )


    A final advantage of these plates seems to be that they made the quad a little lighter once again. I still cannot get my head around how 5mm shorter plates made for a 10gr difference, but hey the quad now sits at 460 grams AUW (Mobius included):



    (You can also see the v2 carbon plates I've cut in this picture.)


    I have only flown a few packs with the new frameplates, but I had the impression the handling was a little better. A little faster responding. However, that might also be some kind of placebo effect. The main benefit for me is that I've made the quad 5mm shorter so it's a "little" easier to transport.


    If you've got any questions don't hesitate to leave a message here or via PM!

  10. #10
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    We've found the you don't need the dampening for the camera on a 250-ish size quad. (running sunny skies). We've been just velcro-ing them to the battery tray. Ours has the battery on the bottom.

    Keep up the good work! I really like how you're knocking out the weight. Also like getting away from the flat arms. I'm betting your round tubes would work a lot better as your speed increases.

    -jim lee

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