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?