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Old Jul 29, 2015, 07:40 AM
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Build Log
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 Windestal’s 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 didn’t 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. I’ll come back on this later.


Source: blog.oscarliang.net

A third issue was the standard use of 3mm arms cut from plate material. Although there’s 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 ESC’s can be mounted inboard anyways, so there’s no real need anymore to make the arms wide enough so they can accommodate the ESC’s.


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 “Daedalus”, version 1. Or, in full, “Daedalus I.O”. This is the first prototype, which I’m 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 I’m 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.

EDIT (August 10 2015): The frameplates have been updated to version 2. http://www.rcgroups.com/forums/showp...2&postcount=19

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, I’ll 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. (That’s a 5 tilt.) A third advantage is that this assembly only requires you to use 4 screws, actually saving quite some weight.



I wasn’t 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 I’m using today. The only difference is that I’ve adapted the holes to 2M since I’m 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 I’m only using 2 frameplates with 20mm of space in between. With regards to the flight controller, PDB, ESC’s, 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 I’m 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.



I’m still waiting for the camera to arrive in the mail, but it sports a decent Sony sensor, so I can’t imagine it would be of lesser image quality than the Aomway anyways.
When it arrives, I’ll 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 “column” in the centre of the frame, also incorporating the PDB and Naze32 board I’m using. This module basically provides most of the structural integrity for the middle part of the frame.


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

As of now, this configuration has worked surprisingly well. I haven’t 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 it’s not indestructible, but it has taken quite a few beating without breaking anything… I’m 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 you’re crashing. (EDIT: With the v2 plates I've somehow managed to lower the AUW to 460 grams. Including Mobius.)


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. There’s 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, …? I don’t know, some aspects might be, some aspects definitely are not. I’ll let you guys decide, although I don’t believe it’s 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: I’m 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 don’t 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 you’re interested, leave a message and I will upload the .DWG files as well.
However, there’s 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. I’m 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 – oh, so dreadful – taller version.
Anyways, it would be nice to hear your input, re-designs and modifications. It might even be useful for me as well.


The individual part links
In order to make it more convenient for you guys to download the individual parts, I'll link them here directly. These will always be the most recent iterations of every part, so you don't have to look for them every time. The other parts are still available in my Thingiverse account directly though.

- Frameplates v2: http://www.thingiverse.com/thing:953480
- Arm clamps: http://www.thingiverse.com/thing:944456
- Motor mounts v3: http://www.thingiverse.com/thing:944436
- Camera clamp v2: http://www.thingiverse.com/thing:944449
- XT60 Bracket: http://www.thingiverse.com/thing:944428


Future plans and modifications
Currently I’m looking at making a second prototype which incorporates some changes I wanted to make after flying this first version for a few months:
- Shorter “wheelbase”: I would like to decrease the distance between the arms with about 5mm. Not sure if this would improve handling. We’ll see. (EDIT: done! See post #19.)
- 8mm booms with a 4mm inner diameter instead of 6mm. I have noticed that the carbon booms I’m 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!
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Last edited by Daedalus_BE; Aug 10, 2015 at 08:43 AM.
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Old Jul 29, 2015, 04:41 PM
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Not sure what I have to add since I'm still struggling getting my first build right. I'm in agreement though about the tall double plates and would prefer to keep it nice and compact. I have the KK board and while it's lcd screen is considered convenient in the field, I'd prefer the fc tucked away, with the usb connector on the side. I may have to switch out the board, plus the led blew on it anyway. I have about 80mm by 180mm on the deck, doesn't seem like a lot of space. Nice motor mounts by the way.

Thanks for the posting. Keep us updated.
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Old Jul 30, 2015, 03:45 AM
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I believe the KK's with LCD's do still have their use. However, if you're running a Naze32 with Cleanflight, you can tune rates and PID's through your transmitter directly, more or less like with Naza. So you could do without the buttons and LCD.

That's a point worth addressing overal in this build though: it really helps if you have a small and versatile flight controller, small ESC's, small Vtx and Frsky telemetry. It is possible to go with other electronics, but you will lose a lot of space and wiring might be more complicated. So that might be one of the disadvantages of a small design like this.

Also: feel free to use the motor mounts by themselves on your own design. They are all in my Thingiverse account.
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Old Jul 30, 2015, 10:33 AM
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I really like the look of your build and I'd be interested in trying it out but till I get my own 3D printer it's just not worth it to me, I fly hard so the 3D printed parts don't hold up and having to buy replacements over and over again makes it not worth it vs. something like a fiberglass / CF frame that holds up to acro flying.

Not begging for anything here (and I have plenty of stuff to keep me busy) but if you'd like some feedback I'd be happy to build (using my electronics / parts) a frame you send me parts for and do a blog post / review of it to help get the word out. I have a set of motors / ESC's and several FC's, I could throw one together quick and get it in the air.

If that's something you're interested in awesome, if not well then just keep up the great work! I'll be getting a 3D printer sometime this year (tho it may not be till Xmas) and I'm definitely interested in this thing once I'm setup!
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Old Jul 31, 2015, 03:29 PM
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Cereal killer, I was already thinking of sending out a few frames really! I'll have to look into that though. The carbon fiber frameplates werd very labour intensive since I routes them by hand. :-) I should be able to hook you up though. Give me a few weeks. I'll contact you again!

Thanks again for the kind words everyone. I have gotten many Nice comments via PM as well, which is really motivating. :-)
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Old Aug 01, 2015, 11:22 AM
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Something I just thought of... How much are you paying for the arm carbon rods? Have you considered replacement carbon arrow shafts? Not sure the size difference but around here you can buy a 5pk for <$30 (and each one is long enough to cut in half and make both arms). I use them as spars in planes and stuff.
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Old Aug 02, 2015, 07:36 AM
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Hmm, that's a great idea! I just looked into it though, and it turns out that there's a few issues with carbon fiber arrows:

1. They are all pulltruded tubes. They are only strong in the longitudinal direction.
2. While they are available in 8.8mm OD, which could be made to fit, the wall thickness is usually very low.
3. Some arrows are in fact aluminum with a very thin outer layer of carbon fiber.

However, that still got me thinking if there aren't any other products out there that use carbon rods with 8mm OD and which are actual woven carbon. I have looked into kite rods and fishing rods as well, but they all seem to be pultruded rods.
If anyone happens to know about a different source of cheap, easy to buy carbon rods, don't hesitate to give me a heads up!

Currently I'm buying standard carbon tubes from eBay now and then. They usually end up costing 20 euros/dollars per meter. So I can cut 4 arms for that price, which is not too steep, especially considering I have only broken one arm so far, during a very hard crash.
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Old Aug 02, 2015, 07:43 AM
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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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Old Aug 02, 2015, 10:45 AM
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Quote:
Originally Posted by Daedalus_BE View Post
Currently I'm buying standard carbon tubes from eBay now and then. They usually end up costing 20 euros/dollars per meter. So I can cut 4 arms for that price, which is not too steep, especially considering I have only broken one arm so far, during a very hard crash.
Not sure if this place has what your looking for but you can check them out
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Old Aug 02, 2015, 04:36 PM
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They only seem to carry pultruded tubes as well. I have actually used those in the past, but quickly realized they were only very strong in the longitudinal direction. Once I bolted down the clamps and motor mounts, the arms cracked. The "woven" carbon fibre arms solved those problems the second time around, fortunately.

I do appreciate the heads up though! They still do look like a good source for carbon alltogether. I might have a look there for carbon plates in the future!
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Old Aug 02, 2015, 06:04 PM
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and Dragonplate is a good source for CF though I've yet to dive in , still working out my stuff with wood.
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Old Aug 03, 2015, 10:15 AM
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What's the general opinion on implementing rubber damping balls for Mobius/Gopro these days? Are they still necessary/trendy or do people prefer to go without them?

I'm thinking about making holes in the new frame to accomodate those rubber balls since I'm still having some minor jello.

Or are there currently more advanced/easy/compact ways of tackling the problem?
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Old Aug 03, 2015, 11:01 AM
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I have been thinking of how to make a 'foldable' version of this by removing the arms.

Perhaps using a horizontal pressure mount for the rear arm. Then the rear plate could be removed and the motor arm slips out the back. Would likely want to have quick releases for the ESC leads then.

Further more, if the bottom plate could be made shorter, ending before the forward boom. The a similar mechanism could be used, but keeping the vertical pressure mount. Not sure this would be structurally sound.

I wonder how much weight would be added by using 'U' bars with 3d printed shrouds...
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Old Aug 06, 2015, 07:32 PM
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I like your low profile design but you need some way to add tilt to the cameras otherwise you'll be staring at the ground.

Keep up the great work though!
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Old Aug 07, 2015, 07:44 AM
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I'm not sure if tilting the camera is necessary. I much prefer tilting the whole frame really. In other words: by tilting the motors! :-) There is actually no real disadvantage to tilting the whole frame instead of only the cameras. There's even an extra advantage IMO: the quad generates less drag in forward flight.

Let me know if you agree though. I might be missing something!
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