A long long time since I published last time, I'm drawing something fun and I thought you would like to see it!
It is a small frame all cnc machined from delrin sheet for 5" propellers. It seems a crazy project but i have a friend flying this kind of multicopters and it is really fun!
It is not originally thought for Arducopter but I recently purchased some Ardupilot 2.6 and i am seriously thinking to install one of them here.
Dimensions (center to center)
right to left = 165mm
front to back = 145mm
HD camera: Mobius
Ipad size comparison:
Comments
http://youtu.be/EI1I0UsC5l8
Hi Jose,
Here's the result of borrowing you top tray idea! many thanks!
Looks great, congrats...but the (integrated) compass is mounted far too close to the battery which will affect GPS modes badly.
Nice design!
Just to make you aware:
The ArduPilot's stabilization and navigation is built on DCM model which relies on Kinematics and does not take into account the Dynamics model (such as air drag due to propellors and adaptation to winds) and uses minimum DOF as required by flight (about 6-8 parameters). With Dynamics model it can go up to 12 or more.
For a smaller craft, we need dynamics model to be present to perform robustly with a fast processor; however, for larger flights (such as 80cm motor-motor distance as in 3DR, DCM does a very good job). Yes, of course, you can use the same APM or PX4 board to write a dynamics based stabilization algorithm (its an area of research and already implemented by ETH Zurich, Standford, Georgia Tech. Univ, and available online)..
weight is 112 for this proto because thickness of delrin is near 9mm and not 8mm.
it will weight 93gr when i get correct delrin sheets
i have machinned a first prototype this afternoom:
I made a mistake about the CoG issue. John is right - the height from the propeller plane to the CoG does not affect the pitch and roll moments, and, since unfixed bodies rotate about their center of gravity, the CoG location does not directly give any pendulum effect. In the later stages of design, there may be some effect on response to winds, but that's a much more complicated issue.
Delrin warps a lot when machining deep, wide pockets (relative to the wall thickness). I'd recommend machining it from polycarbonate. Printing it is a good (but more expensive) option as well. I agree that you should try for narrower, faired arms.
This is a common problem with modern digital video cameras. GoPro for example has the same issues with reduced GPS performance.
First of GPS signals are very weak so they are easily affected by other RF sources. And secondly, a typical digital camera like this has image processing chips running in the 1Ghz+ range. And take a guess what frequency range GPS operates in?
And more importantly, I really like the frame design in this thread btw. Looks very well thought out, robust and functional. Only problem is as mentioned, the flat arms reducing lift efficiency.
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