hello

I am trying to validate one UAV which I have design.

as increase in angle of attack lift force is increasing but drag force is constant which is idealy wrong, can some one help me out.

below is my project link

Hi kasd,

thanks for reaching out to us here in the forum.

It seems like the drag direction is wrongly assigned. As airflow is in the y direction the Drag direction should be the same. Please switch these or compare the pressure force y to compare the drag forces.

Best regards

Sebastian

ignore the force coefficient folder.

If suppose I have not assign the force coefficient,

still the drag force will remain same . because the drag force not required the direction.

Hello @kasd ,

Based on my understanding of your results, it seems that you are measuring the tangential force acting on the aircraft, rather than the drag force. To calculate the drag force accurately, it should be based on the freestream and the angle of attack, so that it is parallel to the flow direction.

If you only consider the tangential forces, it is not surprising to observe a lack of variation in the force values. However, a significant portion of the drag coefficient comes from the normal forces that arise at higher angles of attack due to flow separation. By aligning the drag force direction with the flow direction for each analysis, you should be able to detect the expected logarithmic changes in the drag forces.

I hope this is helpful,

Best regards!