Hi, OK a little about what I am doing, I had an idea about an alternative way to produce lift, being that it doesn’t rely so much on an airfoil. I actually got the idea from studying insects and I can’t go into much more than that before I know it works (or not). so anyway, I’m new to CFD and I have a few questions. I feel a little embarrassed to ask this but how do you model the drag direction on the (x,y,z) coordinate system for a rotating propeller, in the force and moment coefficients tab under result control using a transient LES Spalart-Allmara simulation. My question also applies to the lift axis and pitch axis

Any help on this would be greatly appreciated.

# Force and moment coefficients for rotating propeller

**afowler**#1

**kcontractor**#2

Hi @afowler,

I assume you might be modelling a single blade of your propeller, since you want to calculate Lift?

If this is the case, you can simply orient your blade geometry such that the inflow direction is in, lets say, the [X+] direction. The Lift would now be the Forces in the [Z+] direction, i.e. **Pressure Force Z + Viscous Force Z** and the drag would be **Pressure Force X + Viscous Force X**.

The values of Pressure and Viscous forces can be derived by setting up a force plot in **Result Control**.

Please let me know if this helps

Best,

Krishna