See my comment after quotation... > 2. I think what you are saying is: > > epsilon = f( alpha, flap, slat ) > > I don't think that you were advocating using two 2-D table > > epsilon(slat=0) = f ( alpha, flap ) > epsilon(slat=20) = f ( alpha, flap ) > > If you were, there would have to be an interpolation done between these two > tables in order to get the effects during transitions. Yes, that is > important, because the dynamics of the aircraft during a surface change like > that is examined by the FAA during qualification. I'm just guessing that we > could cobble something together in the existing JSBSim structure to do an > interpolation between these two tables. >
Indeed, I was talking about two 2-D tables, "wrongly" guessing that JSBSim would interpolate the data in case, let's say, the current slat position is not any of the specific slat for which the tables are defined. Such an interpolation would be quite accurate, being better the more 2-D tables we define. This would be a very useful feature, and although I am not a programmer, I guess (hopefully right this time...) that it wouldn't be hard to implement (Jon?). You are right with the failure cases of the flaps/slats logics; that complicate things, but maybe interpolations could still help. > Now, if you add in thrust effects, you end up with: > > epsilon = f( alpha, flap, slat, thrust ) > > We are now at a 4-D table. In this example, the thrust effects on downwash could be evaluated in DATCOM+ for a clean configuration, once with zero thrust, then with an array of thrust coefficients, and finally calculating the difference relative to the zero thrust downwash. A table of delta_epsilon vs. Thrust_coeff could then be built. What is needed is just the thrust effect, without having to worry about flaps or slats. This difference in Epsilon should be added to the overall epsilon. I understand this can be done in JSBSim by using "Functions" (although I am still not sure I already know how to do it); is that right? Jon, if you are still here...regarding the horizontal stabilizer property I was indeed talking about JSBSim. I know there is a property for elevator deflection, but in many cases also the stabilizer moves to different angles for trimming the aircraft. Well, meanwhile I see there are two new replies in this thread, I hope my long story is still relevant... :) Fabian > Bill > > p.s. You really have to stop paying me by the word ;-} > > > ------------------------------------------------------------------------- > 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 > ------------------------------------------------------------------------- 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
