Hi so, for my physics project, I decided to find the effect of dihedral angle on the longitudinal stability of the aircraft, and I decided to go with NACA 0012. I found that when the dihedral angle is 0 degrees, the neutral point was somewhere about 0.0442 m away from the leading edge, whereas the CoG was at -2.034 m away from the leading edge (meaning its in the opposite direction and its 2.034 m from the wing). This was the point when XFLR5 gave a line that made a 45 degree angle between the axes. 45 degree was taken in as the angle, since this was the angle that would make the wing not too stable (too jerky of a ride) and not too unstable. The MAC of the wing was 0.180 m (from XFLR5) and the static margin that I computed (I was shocked) was 11.5455555556 or (11545.5 %). I don't know what I did wrong.
If youre at neutral point, we still have a constant moment at CG (which is at neutral point). So why does the aircraft continue in the same trajectory as the disturbance? Should it not always either pitch up or down due to the constant moment acting on it?
About which point are the pitching, rolling and yawing moment (Cl, Cm and Cn) calculated? The guidelines says it is about a point XCmRef however there is no definition for that point in there.
Hello. Unfortunately in every analysis so far, even with the simplest NACA airfoils I cannot obtain Cm vs. Alpha with negative slope. Do you maybe have a tip or any clue on what I could've done wrong? Thanks in advance.
Thank you for these outstanding tutorials.
I don't know who disliked this, it's a great video. XFLR5 is very good, unfortunately documentation is almost nil, we rely on gifts like this one
Incredibly useful info! Thanks, André!
What a nice video. Thanks for the info
Hi so, for my physics project, I decided to find the effect of dihedral angle on the longitudinal stability of the aircraft, and I decided to go with NACA 0012. I found that when the dihedral angle is 0 degrees, the neutral point was somewhere about 0.0442 m away from the leading edge, whereas the CoG was at -2.034 m away from the leading edge (meaning its in the opposite direction and its 2.034 m from the wing). This was the point when XFLR5 gave a line that made a 45 degree angle between the axes. 45 degree was taken in as the angle, since this was the angle that would make the wing not too stable (too jerky of a ride) and not too unstable. The MAC of the wing was 0.180 m (from XFLR5) and the static margin that I computed (I was shocked) was 11.5455555556 or (11545.5 %). I don't know what I did wrong.
Thanks for your tutorials
thanks. very well explained
If youre at neutral point, we still have a constant moment at CG (which is at neutral point). So why does the aircraft continue in the same trajectory as the disturbance? Should it not always either pitch up or down due to the constant moment acting on it?
guys my cm/alpha line has curve but he has linear why it is different and how it effects?
About which point are the pitching, rolling and yawing moment (Cl, Cm and Cn) calculated? The guidelines says it is about a point XCmRef however there is no definition for that point in there.
How can ve solve if we have two error in same reynolds
hello, i have some issues which is when im doing an Analysis the lift indicator(the green one) is not normal, do you know why?
which profile have u been using?
Hello. Unfortunately in every analysis so far, even with the simplest NACA airfoils I cannot obtain Cm vs. Alpha with negative slope. Do you maybe have a tip or any clue on what I could've done wrong? Thanks in advance.
HI, It 's usually a matter of moving the CoG forward, by adding nose lead for instance.
techwinder thank you very much. Will try it out :)