> Note that JSBSim would get all of this for free simply by allowing > coefficients to be (optionally) specified for individual surfaces, > each with its own orientation. All JSBSim would have to do is sum up > the moments and forces (mostly forces) for the collection of surfaces.
I think we all agree on this and I'll go on record as saying that we will do this. Hopefully sooner rather than later. I want to chew on it for a little while longer, and hear Tony's impressions on how it should or should not be implemented, and then provide access to that approach (i.e. implement it). There are some nuances to that approach. For example, does it work *with* the existing approach, or would it be an entirely new and separate way to define the aero characteristics of an aircraft? If it was to augment the current way of doing things, would it provide any aero force or moment that was *already* provided by another set of coefficients? We would not want to duplicate aero coefficients anywhere. Initially, I think the piecewise approach would be to augment the full-coefficient approach. For instance, the wing could be broken up into at least a couple 2 or 3 spanwise segments per side. Each would have its own portion of the total area assigned to it. Each would have its own alpha and velocity vector (and perhaps each would bias its own velocity vector as in the case of a wing with twist towards the tip). This single case is probably most worthwhile to model in a piecewise method, and the benefits seem apparent right off the bat. If propeller swirl modeling is included with this, stall and spin characteristics would be vastly improved. However, in the above approach, there would perhaps be a component of roll damping that would then be modeled by this piecewise approach. So, would we remove the Clp (roll damping) coefficient? The H.tail and rudder might also provide some roll damping, but removing the coefficient approach in favor of the piecewise approach would result in an insufficient modeling. It's a tradeoff. I still think that, with care, the piecewise approach could nicely augment our current approach. Perhaps the piecewise approach would be blended in only in particular regimes. Jon
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