Here are some close-ups of the arms and legs. They are made from DuPont Zytel®, very strong and resilient in a wide range of temperatures.
Guillermo had some break force testing done, the results were impressive:
In the center it takes 204 lb (92.5 kg), and at the tip 772 lb (350 kg).
Sliding dovetail and set-screw retains the legs, allowing for easy replacement if needed. Picatinny rail mounting system integrated into the bottom of the arms provides endless mounting options for accessories.
Motor wires are protected, but not buried. Quick release clips keep things tidy.
Comments
The rail system is brilliant. Motor protection is a great idea.(assuming adequate cooling) Channels for wiring. Worth every penny. Agreed. Provided they stand up to our abuse.
And worth ever penny! These things are very, very hard to break.
$96 for four arms?
Veikko, I think you need to keep that bottom material in the holes to provide support for the Picatinny rail.
@Gary/Robert we will be selling these arms separately. If you want to get a head start designing frames with these, the hole spacing for the threaded inserts is a 20mmx14mm square (center to center). The bottom inserts line up with the ones on top :)
@Jethro the max motor diameter for these arms is 30mm.
I think opening up those holes would result in DJI arm syndrome.
John, I got hands on with those plastic arms at AVC. When I initially saw the arms, my heart sunk... another crappy plastic armed quad. But then when I got the arm in my hands, I was surprised and very impressed. It is quite stiff. I don't have any objective data, but subjectively, I think the arms are a really good design and will serve well.
I'd really like to get one of these things as a knock-around quad and development machine.
They are not nearly as stiff as a pure CF tube. But they feel stiffer than many CF-TubeClamp assemblies. Particularly if those tube clamps are plastic. The only thing stiffer would be a 20+mm CF tube in a wide aluminum clamp. That's the thing about CF tube... everybody loves sexy carbon fiber, but the devil is in the details, and anybody clamping CF tubes into plastic clamps has lost the plot.
Still nothing holds a candle to my welded aluminum frames, but I digress.... :D
Gary, I'm also interested in using these arms and ESC's in an Octo design. I've asked but not gotten an answer.
What are the motor mounting hole dimensions and maximum width motor we can use?
Hi Joshua, these arms seem very well designed, Zytel is an extremely tough plastic and these should definitely not be a significant failure point on your new copter.
Personally I wish the propeller thrust flat plate interference could have been a bit less, but given the need for torsional and longitudinal rigidity I understand why it isn't.
Given the cellular structural design I doubt that excess arm flex is likely to be a problem with these inside the maximum weight carrying potential of this copter.
I love the rail mount and think these are an exceptionally versatile and rugged design.
I think you definitely outdid the DJI Flamewheel with these.
Being that we are really a DIY community at heart, I also would like to know if these arms and your 4 in one ESC for that matter are going to be made cost effectively available for our own design uses.
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