Hi Gérard, gerard robin schrieb am 13.11.2007 12:59: > On mar 13 novembre 2007, Georg Vollnhals wrote: > > > >> Hi Gérard, >> >> although your H 21 flies very nice (and has an exellent 3D-model, >> eye-candy!) I have the same "yaw"-problem - reaction is very slow and >> damped. This makes procedures nearly impossible like going down to >> your selected landing-area against the wind, then turning >> (yaw-axis) the helo at very low height (very low speed or >> hovering) to "fit" your landing-place. >> Once again, I do know not so much about real-life tandem-rotor >> helicopter flight behaviour, it is just "common sense" that this >> "low-yaw-reaction/low-yaw-power" is somehow noticeable. >> >> Georg >> >> > Hello Georg, > > Thanks for your feedback. > I conclude that i have to do more and more tuning. > > May be with that existing great helicopter yasim code source from Maik we > have reach the limit. > > no, I am sure that don't reached any limit here. > My previous mail was mainly to say that i could notice some actions (good or > bad) from the ballast definition to the fly quality. > My first tests were crazy (helicopter sliding on the side, and a huge yaw > problem), the helicopter was unable to fly straight ahead. > May be the yaw problem is only due to that ballast definition, may be there > is > some more complex interactions. > The yaw problem is rather complex. It is the result of tilting one rotor to one side and the other to the opposite direction. This results in a yaw-moment on the fuselage. The resulting yaw rotation depends on many parameters: - the tilt angle of the rotors (which depends on the CYCLICAIL control input and min-, maxcyclicail, on delta3, rellenflaphinge, relbladecenter, weightperblade, the airfoil parameters, delta, cyclic-factor, and the blade geometry; most of these parameters we do not know.) - the interaction of the downwash (and remaining air) with the (rotating) fuselage, gears and stabs (downwashfactor, yasimdragfactor, yasimliftfactor, geometry of fuselage, gears and stabs) - the weight distribution (the gravity tensor) of the whole helicopter.
Unfortunately these parameters are not independent of each other and some of them are not linear (and for some the derivation changes the sign....) And we even do not know, which is the maximum yaw-rate of the real helicopter. Conclusion: The yaw rate is one of the complexest values simulating a tandem helicopter. > Could be an open Question :) > > Cheers > > > Regards, Maik > > ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
