Paul Surgeon writes: > I don't know about everyone else's experience but I haven't found > one aircraft in FG that wants to sit still on the ground even with > the engine off. I've never seen a stationary aircraft "weather > vane" into a 10 knot wind in real life.
It might be that the problem is not ground reactions but aerodynamics. Even if the ground reactions are accurate, the aerodynamic solver (YASim) or coefficients (JSBSim) may be producing *far* too strong forces and moments for low relative wind speeds and/or extreme values of alpha and beta. That's just a guess, though. In real life, my Warrior II (which weighs about the same as a 172) will sit perfectly still in a 30 kt wind from any direction, with no tie-downs and the brakes off. I wouldn't leave it unattended that way, of course, but it never moves during a walkaround in those conditions (even yesterday, when the 30 kt wind was hitting it from 90 deg). The control surfaces move in the wind, though, and sometimes hurl the yoke into my stomach if I'm not holding it. For a further example, the Ottawa Flying Club never leaves parking brakes on and ties down only at night, unless the winds are very strong. Planes -- even light ones like Cessna 150's -- simply don't roll around in sub-gale-force winds. In FlightGear, on the other hand, a JSBSim or YASim plane will happily start rolling, pitching, and yawing on the ground with sometimes only a 5-10 kt wind. > Last time I flew in a PA28 she required a fair bit of throttle to > get her rolling even on a hard surface. Check the tire pressure -- unlike Cessnas, Cherokees are notoriously hard to move on the ground if the nosewheel or mains are only a few pounds flat (i.e. too little to see). I actually keep a bicycle handpump and tire gauge in my plane for that purpose. All the best, David _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
