I've successfully built a little RC/robot car and while working on it, I've been tempted to also work on a 'simple' quadcopter; or at least, to determine feasibility.
One problem I keep bumping my head up against is .. how do you know what motor/props you can get away with? On the one hand, there are some existing projects that work so one can just crib those parts .. for instance, get some 7A brushless DC motors, and some Turnigy 10-18A ESC's to drive them, and build or buy a flight controller, and away you go; those are fairly sizable motors, and I'm not sure what props you'd put on there, but you could likely get it all to work.
For my project, I'd like to entertain the idea of using cemented lego (or perhaps balsa wood if weight is a huge issue) for the X-frame, and then put small motors and props on there (maybe some foam circles to avoid damaging anyone/thing it crashes into). As 'small as I can get away with', and still buildable without many mechanical skills. Maybe try to have a framer thats 6" or 8" across, with some little 2-3" props on there... as opposed to big 6" props on a 24" frame or whatever. Essentially, I'd like to create a flying box .. just a little quad that cna lift off, putter around, and land; no high speed needed, no high performance. I've picked up a gyro chip and some bits, so I Can try to have some fun with it, keep it balanced etc, but msotly I want to be able to fly up, and point a camera down to take a short clip or do live streaming flying (like in my car.)
I assume you start with a rough weight calculation; given the frame, pcb's, guess at motor weights etc, you can get a full weight of X poudns/kg.
Given weifght X, how do you determine what sort of motor and amperage you need? and what props to get the necessary lift to get off the ground for a *copter?
I've experience with brushed motors, but resources seem to suggest brushless is the way to go for these projects; to keep my life easy, I may go with these $10-$13 Turnigy ESC's (can get them at Hobby King.) Given 4 of them, and say $50 + shipping, thats pretty good and greatly simplifies the design of the flight controller.
The ESC family I'm looking at it:
hobbyking.com/hobbyking/stor ... aff=588847
Other options are welcome! But if it helps to have a ESC to narrow in on motors, theres somethign to work with.