Jim Wilson writes: > Between YASim, JSBsim, and the U-3A 3d-model we've got three > "origins" that represent the approximate position of the aircraft. > JSBsim is 0.2m higher than the 3D model and YASim is 0.2m lower. > It'd be nice if the two FDM's agreed with each other, at least on > the height above ground for the origin. That way I could adjust > the model to work correctly with both.
That's the hard part. The POH and the TCDS give the standard origin on the X axis (the weight and balance reference datum), and the origin on the Y axis can be assumed to be the centreline of the plane, but where do you put the Z origin? For a single, the thrustline of the propeller might be a good choice; alternatively, the cabin floor at the firewall (right in front of the rudder pedals) should work for any aircraft, and the ground sort-of works, as long as you're consistent about strut compression. I'm not big on rules and standards, but we could publish a list of friendly suggestions for all aero and 3D modellers: 1. Put the X axis origin at the published weight-and-balance reference datum. 2. Put the Y axis origin at the centreline of the plane. 3. Put the Z axis origin [where? the ground?]. All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
