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.
I'll be sending $75 shortly for an aluminum set also. Thanks Rob.
tiggy, if you are not loaded up with money, you are perfectly free to buy somewhere else. Hobby King has Octo plates available. If you want to design your own and have them cut, go right ahead.
The exploitation thing is pretty insulting though. I've been immersed in Arducopter for the past year, spent just about every spare moment I have, and lots that weren't spare... trying to help develop the code, helping people, and learning and then sharing what I've learned. Probably over 1000 hours, if not 2000. And yes, I know how to divide 2000 by 365 and I know what that means as the outcome. Further, I've spent over $3000 crashing helicopters while developing experimental code, code that other people benefit from at no cost to them.
What have you done lately?
Risk? How about the risk of the money that I spent building the prototype, which may have not worked at all. How about that money spent on the first prototype that did not assemble at all? How about the risk that the $700 of carbon fiber I have sitting beside me gets turned into scrap?
So, you'll have to excuse me if have to draw the line somewhere. I am not a charity.
You are now perfectly free to benefit from what I have learned, and what I have shared here, and build a copy of this unit, after being inspired by it (would you have thought of it otherwise?) and knowing that it will actually fly. If your cost is $54, and you don't put any value on the time it will take you to design it and source it, knock yourself out.
And further, if your time is of no value to you, you can go ahead and manufacture them, and ship them out to people around the world.
Yes, I have actually thought of this. It's one of the reasons I decided to continue to offer the parts in Aluminum. You can mix and match as you see fit.
But, there's a few things to think about as well.
I had actually thought about removing the heat sinks completely, and thermally glue them directly to the bottom plate. But I was afraid of any electrical issues that might cause.
So barring that, you could flip them upside-down, and thermally bond the heat sinks to the bottom plate. That could work too. I just find it all starts to get a bit cludgy, and unless I saw the need, I'll go the way I have. It helps that I actually opened up the heat sink to airflow by cutting away the shrink wrap. It also helps that I left big holes in the frame for cooling air flow. I wanted to try and find the happy middle-ground between ugly ESC's strapped to the arms with a good cooling flow, and ESC's trapped under a dome.
It also helps that by my calculation I'm averaging less than 8A per 40A ESC in a hover. This will go up with more load obviously. Anyway, we'll see.
I have also thought about just offering pieces a-la carte. But right now, the volumes are so low, I get enough grumbling from the CNC shops about batch sizes as it is. If there's any volume, I'll be able to try and mix and match stock a little more.
On my big Quad that is running with 2x6s 5000ma and 60 amp speed controllers I found some computer memory fined heat sinks and cut the heat shrink tubing away from the the esc heat sink area and glued the memory heat sinks onto the esc heat sinks. The esc's are in part of the air flow from the props and just get barely warm. FYI, this is a 10lb quad with 33lb's of thrust. running 3 blade 14x7 props.
Yes, and actually Hobby King has some decent bulk heat sink for sale with nice deep fins. Not quite as good as a CPU sink, but better than the standard sinks.
You referring to this?
Rob, do you think I could receive mine by Dec 9? That is the last possible day I can receive it so it can be forwarded to me. Otherwise it will sit until 2013 which would put a damper on my holiday building plans :)
I would think that just having two kits available is the best way to go. Economy aluminum and then CF to keep it simple for you.
What country are you in?
I will do my best, it should be possible. I just gave the CF to the cutter today, he said it should be cut by end of next week. After that, it should be a pretty simple package job.
Yep. Even comes with a sheet of thermal transfer stuff.
I will stay with aluminium,
it sure will look much nicer in CF, but aluminium has so many advantages for me ... at least until I am convinced that the concept is working to my expectations. and then I might change the top plate to CF ...
BTW: do you know if there is another APM in the nearer future, or if the transcoding for the PX4 is happening soon ???