Jon Berndt wrote:
We have always used the "empty weight" CG of the given aircraft in the developmentJim wrote:Before we get too worked up about this... It has absolutely nothing to do with modeling the aircraft. It is only a reference point for positioning the 3D model in the scene. All the nose is, sans pitot tubes and other items that are not centered, is a location easy to identify on almost all aircraft.With this in mind, now, we go back to the stated problem. Let's say we (FDM/JSBSim) are reporting the lat/lon of the nose of the aircraft to FlightGear's visual subsystem. We know where our CG is in lat/lon, and we know where the nose is relative to that. So we report in lat/lon/alt coordinates the position of the nose. Now, let's say we drop a payload and the CG shifts. In the FDM, the position in lat/lon/alt is still the same. However, the location of the nose has now shifted with relation to the CG, because the CG has shifted. If we report the new nose position to the FlightGear visual subsystem, there will be an instantansous shift in the visual position of the aircraft.
of our Weapons Systems Trainers (WST), Part Task Trainers (PTT) for military,
as well as Flight Training Devices (FTD) for commercial. It doesn't move, and it is
significant with respect to the flight dynamics... The visual systems we use have
the ability to offset the eyepoint from the control point so with a little up front math,
the graphic artist can use any origin for the 3D model...
--
Russ
Conway's Law: "The structure of a system tends to mirror the
structure of the group producing it."
-- Mel Conway Datamation (1968)
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