On Fri, 15 Mar 2002 12:11:59 -0800 Andy Ross <[EMAIL PROTECTED]> wrote:
>Ski jumps are an immediate counter example. Modeling ski jumps are the one example I can think of - the single special case - where this is important. [How many terrain polygons will it take to accurately model a ski jump, anyhow?] I'm not sure I want to do a complicated gear model with fidelity solely for this case. >The point to doing per-gear collision detection is to account >for non-flatness of the ground plane. That gets defeated if you treat >the gear compression configuration as a flat space normal to the >earth. :) Not really. A long time ago (maybe a couple of years) we discussed how to account for sloped runways. I think most runways slope little enough that for the purpose of forces and moments due to gear we can assume the compression occurs only in the vertical plane. For instance, even if the runways slopes (side to side) 10 degrees (I think this is pretty severe) the vertical component of stroke only differs by 1.5%. However, when the aircraft comes to equilibrium, it will still be slanted (rolled) 10 degrees. Among the problems we run into with any proposed "right" approach, is that the aircraft may straddle polygons and the movement from one polygon to the next may result in discontinuous jumps with the surface normal. I think there needs to be some smoothing there. >Really, we have a perfectly acceptable gear model for many situations >right now. We're already getting complicated by considering per-gear >collisionn. If we're going to do it, I'd rather we do it right. Per-gear collision gives us enough "bang" for little effort. Doing it "right" would entail much more than we are willing to give (much more than we _need_ to give): tire wind up at touchdown and energy release at 70% ground-sychronous rotation; multiple strut articulated gear (such as the F-18), etc. Jon _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
