# CONTACTS POINTS

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Can anyone direct me to a source of advice on setting contact points particularly for tail-draggers.What I don't understand are:- Relationship between "Vertical Position" and "Static Compression". - Effect of "Wheel Radius" - Effect of "static_pitch" and "static_cg_height" On the ground, is the actual distance the Vertical Postion minus the Static Compression?What are the effects on the geometry when the Static_Pitch" is about 12 deg, typical for a tail-dragger?Why can't FS calculate the "static_pitch" and "static_cg_height" from the contact point settings?Although I get there in the end by trial and error, I've had aircraft dropping on to the runway with a crash, leaping up from beneath the runway and tipping onto its nose. I still can't find a consistent way to set accurate values at the beginning.

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Yes, it's an exercise in frustration almost every time, but it gets better eventually. First, have you had a look at the Contact Points section of the Aircraft Container SDK?There's also a utility called Aircraft Container Manager (ACM) which eases much of the pain, and actually helps you understand the relationships. http://www.aircraftmanager.com/ It's not exactly updated or, as far as I can tell, oficially supported, but it does a very good job for contact points and lighting.static_cg_height , static_pitch: The height and pitch of the aircraft when at rest on the surface. The program uses these values when placing the aircraft on the ground at startup, when slewing, and any other time the simulation is not determining aircraft position.Wheel Radius: The radius of the wheel, in feet. This is used to correctly animate wheel rotationStatic Compression: The amount the wheel's strut is compressed when at rest, in feet. This term defines the strength of the strut. A smaller number will increase the "stiffness" of the strut.Ratio of Maximum Compression to Static Compression: Used primarily for landing gear strut animation to determine the relative amount that the strut compresses.--Jon

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Thanks, I'm glad I'm not alone. I've read the Aircraft Container Manager which you quote from, but it doesn't answer my questions which arise when the reference.Figure 3 suggests the distance from the vertical datum to a wheel contact point is Vertical Position + Wheel Radius. But should this be Vertical Position - Static Compression + Wheel Radius?Figure 3 shows the Reference Datum parallel to the ground. For a taildragger the static_pitch can be about 12 deg so is the vertical disance between the reference datum and contact point (Vertical Position - Static Compression) * cos(static_pitch) + Wheel Radius?I'm going to try to work out the geometry from first principles. Watch this space!

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