New Octo Copter Design/Build Thread

Starting a new thread to show what I'm working on.  I'm building a new Octocopter of my own design.  The goal is to use it for Aerial Photography, lifting a mid-weight camera such as a Sony Nex5.  It will of course be using Arducopter for control.  ;)

I started off researching the various kits on the market, and starting getting analysis paralysis.  I looked at all the options such as Droidworx AD8, Cinestar, CarbonCore, and SteadiDrone.  But I just wasn't happy with the design on them, particularly for the price they ask.  Combined with the fact that I can be pretty frugal, and have a strong DIY ethic, I decided to just design my own.

The basis of the design relies on many of the Hobby King quadcopter parts.  I liked the design of the motor mounts, they are very professional looking, even compared to some of the high end machines.  And I liked that the boom mounts are blocks of aluminum instead of plastic.  Very rigid.  I also liked the look of the dome on their H.A.L. quad, but since they don't sell it seperately, I bought the whole kit, it's only $34, amazing!  I might end up using the rest of it someday, who knows?  So, I basically emptied out their stock of Talon parts, so if you need to fix your Talon quad and the parts are backordered... sorry!

Once that was settled, I set about designing the center frame.  My design required a few things, namely I want all the wiring hidden.  I don't want any spaghetti showing.  Particularly with the ESC's, while still allowing cooling airflow.  This required the center hub to be larger than is typical.  I then needed a smaller subframe to house the avionics.

You can see these plates below.  The larger one houses the HAL dome. You will notice the 3 blue anti-vibration grommets in the middle.  This is the APM1 pattern.  I did that just because.  Maybe I'll use an APM1 as a stand along gimbal controller.  The second plate had grommet mounting for an APM2.  The final plate is the top plate, and has bolt patterns for the Ublox GPS and the magnetometer.


This next photos shows the avionics frame built up with an APM2 mounted.  25mm aluminum standoffs are used. I don't like the plastic standoffs typically used.  They get loose, and lead to vibration.  They also break easily.  This structure ends up being quite rigid.


Here is the avionics frame mounted on top of the main frame.  Yes, the main frame is HUGE.  I actually don't see the point in having a tiny center frame, and then long arms.  This seems like it just leads to flex, and doesn't leave you with any real estate to mount your avionics.  


This photo shows one of my design features.  I put some cutouts on the bottom frame for weight savings, and then made matching cutouts on the top frames.  This creates some nice conduits to run wires neatly.


Here it is with the HAL dome mounted and one of the Talon arm mounts bolted in.  I'm really happy with how stiff the assembly is already.


Here it is with one of the arms mounted.  These are the short 220mm arms, I also got some of the 320mm arms.  One may wonder how I'm going to get away with such short arms and 13" props....  Astute readers will know what I'm planning already. ;)


This last photo shows one of the ESC's in position. This is a Hobby King F-40A, it's somewhat larger than typical 20A units which is partially why the frame is so big.


That's it for now.  I had the plates cut out of aluminum to start with because it's cost effective.  If it all works out, I'll probably have it redone in carbon fiber plate for the weight savings.  I was a little uncertain about the weight, but it looks like the frame will come in at 1070g all in aluminum.  That's about 300g heavier than a Droidworx AD8, but not too bad. It will drop about 1-200g if redone in CF.

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  • Received my CF kit the other day. Everything looks great! I hope to have some pictures up of the build soon. Thanks Rob!

  • Rob,

    I have been reading this thread with great interest.  I am thinking of reproducing your design with some tweaks, so I have to thank you for all of the hard work you have put in to this design.

    I have a question about props.  I can't seem to find any 12x4.7 APC Pushers.  I am not sure they even exist. In the absence of APCs, what do you recommend?  It sounded like you were not super happy with the 12x3.8.  Just curious about what you are planning on using.

  • Hi Rob, I just sent you an email about the shipping. Maybe my first message got caught by a spam filter? Just want to know if you have a tracking number so I can see where it's at.

  • Hi  Rob

    I know you are very busy with the CF parts.

    But could you PLEASE send me the aluminum parts in whatever condition next week ?

    I would really like to have them here before the end of the year .

     Everything else is already sitting here,  complete new set of avionics including new APM 2.5 etc …. Plus I have 6 days allocated for the project …wouldn`t like to see them going to waste


  • Here is a drawing that I created to show everybody the different layouts you can use to assemble this. It's pretty self explanatory, it shows 3 prop sizes and 3 arm lengths, to help you decided how you want to build it.


    I have to caution that I did assemble it with the longer arm lengths, and I wasn't as happy with the overall stiffness.  It would help if you actually glued the arm mounting blocks to the frame plate.  The issue is that it's possible to torque the mounts and make them twist unless you have the screws REALLY tight.

  • Doug PM'd me asking for a list the HK parts you need to buy to complete this.  I'll just post the response here so everyone can see.

    The motor mounts, for you get these:

    Or these:

    Obviously the HAL parts are about half the price.  But the little carbon fiber landing legs on the Talon mounts are useable as landing gear.  That's what I'm doing right now in fact.  Buy extras when you get these.  They bend VERY easy.  I've actually been brainstorming better replacements for these that eliminate the need for risers as well.

    Don't bother with the HAL landing gear, it's junk.

    Then there's the HAL dome:

    This is obviously subject to your personal feelings.  I like it, particularly with the black G-10 avionics plates.  

    I used these spacers on my prototype, but they're also pretty soft and junky, so I have included stronger ones with the kits.  So you won't need these.

    For the booms, take your pick of these:

    I bought all of them actually, so I have extras of the short ones if anybody wants to buy them from me.  I used the long ones, cut in half to 160mm with my 12" props.

    And finally, these boom mounts:

    Unfortunately it looks like all the mounts are backordered right now. :(

  • Hi Rob, I just sent the balance on the paypal.

  • If you have the time, can you post a picture here of what you will be sending. Since it will be forwarded to me, I want to make sure some small piece doesn't get misplaced. You have an idea when it will be sent and how much $ I need to send. If you have an aluminum kit (with or without hardware) I might want that also.

  • Hi Rob

    Can you please tell me when the Aluminium parts will be mailed ?

  • Rob, how much would it be to add an aluminum kit to my CF order?

This reply was deleted.


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