How do you figure the area for a rotor? In order to figure loading on a micro-autogyro.

Is it the area of the rotor blades themselves, or the entire area of the circle created when they spin?....or some combination?

From : Don Stackhouse

In general, we refer to "disk loading" of a rotor as being analogous to the wing loading of a wing. Disk loading is based on the total area of the circle swept out by the blades.

There are other parameters that address blade area. In some cases you might hear of a "solidity ratio", which is the ratio of the blade area to the total disk area; i.e.: how much of the disk area is "solid". Another term that's typically used in propellers is something called the "activity factor" of the individual blades. It's something like the aspect ratio of a wing, but it's weighted to take into account the fact that an inch of blade chord at the tip is more important than that same inch would be if it was further inboard, because the airspeed is higher at the tip.

Don Stackhouse
DJ Aerotech