I found some of my notes regarding the changes I made to the c172p.xml and c172p-set.xml files back in 2007. The changes that seemed to work the best for me are in the -set.xml file:
1) Change the <aileron-trim> value from the default 0.027 to a value between 0.030 and 0.032. 2) Change the <rudder-trim> value from the default 0.00 to a value between 0.05 and 0.10. I am still experimenting with changes to various values in the c172p.xml files, as there are ample opportunities to further refine the flight characteristics in several areas there. But maybe John and Ron would be willing to test these rudder/aileron trim numbers a bit and give me some feedback? Not surprisingly, I found that the rudder trim value has the greatest impact on the effect of P-factor. And indeed, on the real aircraft there is a ground-adjustable trim tab on the back of the 172's rudder--and this is always bent slightly in order to offset the need for right rudder in the climb. So setting a positive value for rudder trim seems to emulate this effect, and results in a less impressive left-turning tendency in the FG C172P. As for the aileron trim, I found that a very small change seems to also help the situation. My current settings are 0.05 for the rudder trim, and 0.030 for the aileron trim--but I am not sure these are the best values, and thus would like some input from other 172 pilots out there. It make take retesting with a proper set of 3-axis flight controls to make this determination; as it stands now, these have been tested using an inexpensive joystick with auto-coordination turned 'on' to control the degree of rudder input needed from the pilot. If it's not too much to ask, I would also like someone to change the name of the engine file to "eng_o320.xml." It seems like a small (nit-picky) issue I realize, but the 172 never came equipped with an Injected, Opposed (IO-320) engine. There were a couple of later models with the Lycoming IO-360 engine, but the 172P had the non-injected opposed (O-320) Lycoming engine. Again, it's a small point, but it helps resolve confusion for those new to FG and trying to sort out the way things work. And it only takes about 30 seconds to fix. I am significantly impressed with the level of understanding shown by people like Ron Jensen and John Denker, regarding the piston-engine issues we are experiencing in the 172 model. I think that these guys are really getting close to further improving the fidelity of the model, and this will only make a great emulation that much better. Thanks in advance. TB ------------------------------------------------------------------------------ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
