Jump to content


This topic is now archived and is closed to further replies.


Lift and trim moment in REC 1101

Recommended Posts

Hi guys.I've done a quick search for this but I didn't really find anything. If there's a older post someplace, just point it out and I'll go read.I'm trying to get some stuff straight in my research. Firstly, Pitching Coefficients: According to Etkin/Reid's Dynamics of Flight, Positively cambered airfoils create a negative (Nose Down) pitching moment and Negatively cambered ones, naturally create a positive (nose up) moment. So side question here: since REC1101 says + = Nose down, if I'm modeling a positively cambered airfoil (main wing), the moment coefficient in Real Life would be negative resulting in a nose down moment. So to correctly model this in REC1101, i should invert the sign and multiply by 2048 and enter that... correct?But the real question kind of relates to pitching moment. Acording to how I'm reading some other text books, if the CG is ahead of the AC, the H. Tail requires a lift vector downward (while, conversly, if the CG is behind the AC, the lift vector is upward on the H. Tail). Is that correct? Hypothetically saying that is correct, would I model that as a negative number in 1101:Cl_dh ?Then I have a question about the Cm_dt - Trim Moment entry, are there any formulas to calculate this, or is there some aspect of dynamics that I'm looking to adjust as I go trial-and-error on the entry?Thanks in advance and, like I said, if this is covered elsewhere, just point me in the right direction.Scott B.

Share this post

Link to post
Share on other sites

  • Create New...