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Bert Pieke

Question on wheel motion

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Does anyone know how I can adjust the front wheel on my Dreamfleet Archer, to keep it from burrowing into the ground on braking?See attached picture..The Dreamfleet Cardinal does not exhibit this kind of behavior..I've looked at the aircraft.cfg file and can find no obvious differences, but then again, I'm not really sure what I should be looking for either..

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I don't have this aircraft so I can't give you exact figures but you probably need to lower (make more negative) the contact point for the center gear in the aircraft.cfg file. First make a back-up of the file you are going to modify.Example from the stock B737-400:-------------////------------[contact_points] //0 Class <0=none,1=wheel, 2=scrape, 3=float> //1 Longitudinal Position (feet) //2 Lateral Position (feet) //3 Vertical Position (feet)-------------////------------point.0 = 1, -25.0, 0.0, -17.5, 1000.0, 0, 2.0, 70.0, 0.5, 3.5, 0.900, 9.0, 8.0, 0, 220, 250point.1 = 1, -114.0, -18.0, -21.3, 2000.0, 1, 2.0, 13.0, 3.0, 2.5, 0.900, 11.0, 9.0, 2, 220, 250point.2 = 1, -114.0, 18.0, -21.3, 2000.0, 2, 2.0, 13.0, 3.0, 2.5, 0.900, 11.0, 9.0, 3, 220, 250-------------////------------In this case, on point.0, you would make the the -17.5 more negative. This number is in decimal feet so I would look at the position of the nose gear axle. If it appears to be at ground level, change the value to -18.5. Make fine adjustments, 0.1' at a time, till it sits properly.You can make the adjustments to the aircraft.cfg file using notepad even while the sim is running, but you will need to re-select the aircraft after each adjustment and save so the aircraft.cfg file will be re-read.When all of the points, as well as the static_cg_height and static_pitch are set properly, the aircraft will barely move verticaly when switching between normal and slew node. Maybe just the distance of the suspension's movement.Lou

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Hello,There is something wrong with the amount of travel of the front suspension. If the figures in the cfg are off your compression will be too small, thus resulting in the wheel getting burried. The correct values can only be supplied by the modeler, since he can get the amount of suspension travel from the model in the design program. Say for example in Gmax the nose wheel would travel 1 feet from fully uncompressed to fully compressed. That is the total amount, and from this amount he would decide the percentage the gear would compress when the aircraft is sitting still on the ground.One thing that may help is adjusting the stiffness of the suspension. Try different values, and see what happens. If it would be for example 0.8 try 0.6 to see what happens.When I make my models I spend a lot of time testing to make sure this does not occur on my AC.Hope it helps.Udo.

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Thanks to both the previous posters! Based on your advice, I fiddled around with the suspension settings enough so that the wheel no longer goes down into the pavement.. but is this ever finicky! I admire the folks who do this kind of design for a living!Thanks again!

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