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Arducopter frame design: Where to learn/read?

Posted by Ground Loop on February 26, 2011 at 11:26am

I'm scratch-building a new Octocopter, in the style of the Hashcopter, using square aluminum tube, and eight motors ganged as pairs with (Quad) Arducopter software.

 

Where is a good place to learn the factors and trade-offs in Quadcopter frame design?  How long should the arms be, and what are the pros/cons of different lengths?

 

Should the craft be as tight/small as possible (props near, spaced evenly), or is there a benefit to having the motors out further from center?

 

Any tips for optimizing arm length?

 

Thanks!

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Tags: frame, hashcopter, octocopter, scratch
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Replies

  • Michel Dias Arouca de Souza October 13, 2012 at 11:22am

    I need a diagram on autocad dwg to cut the machine plasma, need a scheme octocopter.se Would anyone can help me thank.

  • Ground Loop March 16, 2011 at 9:41am
    Aside from spacing, I still haven't found any pro/con comparison of the Hashcopter "paired motors" Quadcopter control, vs the more traditional Octocopter (eight motor control).  I'm still looking for the catch, since it seems Hashcopter is simpler and more fault tolerant.
  • Squalish March 15, 2011 at 8:57pm

    I've been looking at this recently - the Hashcopter design is alluring.  There are two variables here on a symmetrical hashcopter: motor to motor, and crossbar to crossbar.  Making c2c about 40% of m2m allows you to maximize prop diameter by equalizing the spacing between diagonal props with the spacing between adjacent props.  Coincidentally, 40% of m2m is about the maximum prop diameter that is physically possible.

     

    I wouldn't advise spacing the props *too* closely though, I would expect all sorts of adverse vibrations and drag to develop.  What is the optimal spacing?  Nobody knows.  Unlike fixed wing planes with their wind tunnels though, this *is* something you could test using an accurate digital scale, and a pair of ESC/motor/prop/watt meters on an adjustable jig.

     

  • Ground Loop February 26, 2011 at 12:31pm

    More directly, is there a preferred ratio for prop diameter to motor spacing?

     

    If I'm swinging a 10" prop, how much space needs to be between prop tips?  I've read that tight (close) motor spacing gives superior yaw control.  Is there a limit to this?

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