Discussions

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.