Calculating Darg of Propeller for Micro Air Vehicle

"propeller darg for a 5x3 gws propeller"

Please explain "darq?" Do you mean drag or thrust?

Please explain 5x3 gws propeller?

it's drag... the prop is a 5" diameter by 3" pitch electric r/c prop manufactured by Grand Wing Servo.

In response to the original poster, in referencing drag, are you referring to the aerodynamic drag created by the prop on the airframe when the motor and prop are in a 'freewheeling' state, i.e. no power applied to the motor while the aircraft is underway, Or are you referring to the load placed on the motor by the prop at a given RPM. Search around on the electric R/C model forums, lots of information on prop / motor combinations there. BTW, GWS makes a horrible prop... Go with an APC instead. Yeah, I fly r/c... have since about '67

Ordinarily, you would calculate the drag of wings and airframe at the desired speed and load, and from that, calculate the desired thrust. Then, HP required to propel the plane can be determined, and a propeller can be selected to match the engine. The propeller efficiency will tell you how much of the engine's horsepower is converted to thrust. So, although a propeller blade experiences drag as it rotates through the air, that drag is typically not measured directly -- it shows us as a factor in propeller efficiency.

If you want to analyze the propeller as a series of airfoils (wings) with the angle of attack (β) twisted so the output velocity (V) is constant over the radius(r) (per β = ArcTan(V/ωr), then there is a very good program called "DesignFOIL Release 6" available here:

http://www.designfoil.com/

You can download a trial version that can run the "Virtual Wind Tunnel" on airfoils of your choosing. That will give you the coefficients of Lift and Drag. You type in each (β) and rerun. There is a drawback with the trial version in that you are limited to a fixed Reynolds Number (which you get from the airspeed and wing width).

The official version is only $95.

The Tutorial and Helps are very good reading too!

This program should put you in the ballpark. Ultimately, you will need to do testing of the actual performance.