I've been throwing around a few ideas for a hexacopter frame and have settled on a aluminum arm and fiberglass plate sandwich type frame (is there a more technical term for it?). The goal is to carry a digital SLR for aerial photography, though I'll work out the camera bits after I get past the basics of just getting it flying. From prop tip to prop tip it will be about 42 inches. The two plates in the middle are about 11.5 inches diameter and will be cut from 1/8th inch thick G10 fiberglass. The aluminum arms are 1 inch with a roughly 1/20th inch thick wall. The props will be 12 inches by 3.8 pitch.
The blue boxes under the arms are the batteries, the red boxes on the fiberglass plate are the speed controllers, the three boxes in the middle are the APM, GPS, and receiver. Bolts will hold the plates and arms together and other items will be double sided tape and probably Velcro for the batteries.
The machine to cut the fiberglass should be functional in a week or two at which point I'll be finalizing the design and cutting out the parts. If anyone is interested I'll document that process (tool selection, creating the code, etc.). Until next time everybody have a good one!
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Thanks for the heads up Jani. I've been following the Arducopter project but when I started acquiring components the official hexacopter frame wasn't out there yet (that I knew of). I already have the motors, props, batteries, and so forth which would fit a larger frame like I'm designing. The official hexacopter frame looks like a very nice setup that is well thought out. Are the design files for the official hexacopter frame publicly available? If so I might take a few design cues from it.
Alberto, I'm not familiar with CAD software in general so I'm using some computer graphics software that I use at work (Houdini). The concepts are very different but I'm able to get what I need out of it with a little tweaking in MeshLab. If starting from scratch there are much better software options that are designed for CAD use. I tried FreeCAD which seemed like a good option that I will probably come back to later when I have another project that requires CAD. I thought about folding but that'll be for a later version. I just want to get acquainted with the workflow and tooling before complicating the design too much.
Luke have you been checking out our official ArduCopter project. There are already Quad and Hexa frames ready optional additions like high rise landing gears. different bottom mounts and so on. Tri is almost ready too.
Based on your feedback I think I'll add another plate below to sandwich the batteries closer to the center. In retrospect I probably should've purchased a already built frame for my first copter but I'm too far down this path now. Thanks for the feedback!
Hi
From my days in car design the one thing that gives me cause to worry is the placement of those heavy batteries so far outboard from centre.
"The high polar moment of inertia is present when the weight concentrations are heavy and are far apart. The low polar moment of inertia is found when weight concentrations are light and are close together. In other words, it is easier to steer a vehicle with a low polar moment of inertia.
A vehicle with a low polar moment of inertia gives a quick response to steering commands. A vehicle with a high polar moment has high directional stability (meaning it resists changing its direction)."
Makes good sense to keep the heavy mass low and central.
Nice work though, keep it up!
Regards Bob
Hey,cool!! i'm trying to do something similar. Which Cad design program have you used??
Maeby the battery must go as center as you can...
Have you think about folding it??
Regards,
Nice design, in some configurations aluminium & carbon fiber touching can cause galvanic corrosion so you may want an insulator. You may also find the inertia of having a large mass on the arms impedes reaction time and hence stability.
Just thinking aloud! Best of luck. D