On vendredi 05 décembre 2008, gerard robin wrote: > On vendredi 05 décembre 2008, gerard robin wrote: > > On vendredi 05 décembre 2008, gerard robin wrote: > > > On vendredi 05 décembre 2008, dave perry wrote: > > > > dave perry wrote: > > > > > Hi All, > > > > > > > > snip > > > > > > > > > Would it not be more realistic to rotate the 3D model about -3 or > > > > > -4 degrees about the ac3d z-axis. > > > > > > > > I did not make myself clear in the initial questiion. The video link > > > > only detracted from my point. The model in the .ac file is just a > > > > rigid body that gets displayed when the fdm says the pitch is zero > > > > degrees (or perhaps zero incidence). The fdm then rotates this rigid > > > > model for other flight conditions. So if the model starts 3 or 4 > > > > degrees too nose high for realistic cruise, it will remain 3 or 4 > > > > degrees too high in pitch for all other rotations from the fdm. In > > > > particular, it will be 3 or 4 degrees higher than a realistic stall > > > > at touch down, burying the tail cone in the runway. > > > > > > > > To make this clear, I opened the c172p.ac in ac3d, made a screen > > > > capture of the side view, then rotated the model by - 4 degrees and > > > > made a 2nd screen capture of the side view and then scaled and > > > > combined these into one small .png which is attached. > > > > > > > > My only point is that I think the rotated side view pitch (bottom > > > > image) looks like a c172p at cruise and the original side view (top > > > > image) looks like a c172p in level no flap slow flight. Compare the > > > > wing and horizontal stab incidence angles in the two images. In the > > > > rotated side view, the horizontal stab is at zero incidence while the > > > > non rotated side view shows a noticeable positive incidence for the > > > > horizontal stab which would normally require significant up elevator > > > > to maintain. > > > > > > > > Making this change will be a lot of work since the panel will be > > > > messed up. I know because I made a similar rigid rotation > > > > correction about a month after I first submitted the pa24-250. > > > > > > No if that was necessary , their is nothing else than modification of > > > the offset in the c172p.xml model. The panel should follow > > > > > > However i noticed that with the actual position the model has the nose > > > gear up above the ground. > > > An offset of -2 deg would be nice > > > > > > <path>c172p.ac</path> > > > <offsets> > > > <pitch-deg>-0</pitch-deg> > > > </offsets> > > > > oups err > > <offsets> > > <pitch-deg>-2.0</pitch-deg> > > </offsets> > > > > may be more > > > > > > Dave P. > > Just tried with -3 deg it is right > sorry no snapshots. > May be the pilot position must be upper , since it has moved
and again before leaving may be <z-m> -0.05 </z-m> -- Gérard http://pagesperso-orange.fr/GRTux/ J'ai décidé d'être heureux parce que c'est bon pour la santé. Voltaire ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
