I am interested in building a quadcopter from scratch.
Because I like to err on the side of caution, I'm considering adding "safety cages" around each propeller/rotor, to hopefully prevent (at least minimize) the chance of the spinning rotor blades coming into contact with someone. Without knowing much about the physics behind how "lift" works, I would have to imagine that cages present two main problems for rotors:
- They add weight to the copter making it harder to lift the same payload; and
- They're sheer presence/surface area makes it harder for the spinning rotor to generate lift and push down away from the ground
The former problem should be obvious and self-evident. For the latter problem, what I mean by "surface area" is that I imagine that the more caging around a spinning rotor, the more difficult it will be to lift effectively. For instance, a spinning rotor might have the ability to generate enough power to lift, say, 2kg. But if we were to construct an entire box (not cage) around the entire rotors, with 6 sides and no openings, I would imagine its lift capability would drop to 0kg.
So obviously, what I'm interested in is a cage design that provides adequate safety but doesn't "box in" the rotor so much that it causes the rotor to be ineffective or incapable of providing lift. So I'm looking for that optimal tradeoff of safety (boxing/caging around the spinning rotor) and lift performance.
I would imagine calculating and designing this is a pretty huge undertaking with a lot of math behind it. I'm just wondering if anyone has already figured all this stuff out, or if anyone knows of a way to model this safety-vs-lift-performance trade off in some way.