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Speedbyrd

Moving the "C of G"

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if I want to move the 'center of gravity' on one of my planes, what is it I have to change? I want to move it backwards. thanks

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This can be done in the aircraft's aircraft.cfg file in the section under [WEIGHT_AND_BALANCE]. It looks like this:[WEIGHT_AND_BALANCE]max_gross_weight = 2450.000empty_weight = 1452.000reference_datum_position = 0.000, 0.000, 0.000 empty_weight_CG_position = 0.000, 0.000, 0.000max_number_of_stations = 5station_load.0 =158, 0,0.820210,-0.961286,Pilotstation_load.1 =158, 0, 0.820210, -0.961286, CoPilotstation_load.2 =0, -3.015092, -0.820210, -0.961286, Pax 1station_load.3 =0, 3.015092, -0.820210, -0.961286, Pax 2station_load.4 =0, -5.725066, 0.000000, -0.961286, Cargo empty_weight_pitch_MOI = 1400.000empty_weight_roll_MOI = 1137.000empty_weight_yaw_MOI = 2360.000empty_weight_coupled_MOI= 0.000CG_forward_limit= 0.000CG_aft_limit= 1.000----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satellite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004, MIDCON P-401"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

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Hi,to move the CoG back or forward you need to adjust the "wing_pos_apex_lon" value in the aircraft.cfg(airplane_geometry).you can then check the new position of the CoG in FS9 under fuel and payload section (the black and white circle on the airplane picture)cheers,harald

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Be careful on doing both. The wing apex position is exactly what it says: the position of the wing apex relative to the ref. datum; it does NOT affect the CG directly. However, it DOES affect the placement of the CG relative to the ideal position of 1/4 MAC, and thus flight characteristics. The CG placement line in the weight and balance section DOES move the CG relative to the ref. datum. Both changes can radically alter flight characteristics, and even ground stability.... when I was first learning about this I moved the CG too much and the plane would load up sitting on its tail :-) Is there something in particular that is troublesome about this CG? Mike

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probably not, I was just back on the DC-10 again, but I've put that behind me since I have all the same liveries available for my SMS MD-11's that I had for the DC-10's and the flight dynamics on the MD-11 are quite satisfactory. I just had problems getting the D-10 off the ground unless I really fought with it and put the elevator trim way up. Since I'm not that knowledgeable in aircraft design, I decided it's best to stay out of that. The MD-11 more than serves my purpose regarding tri-engine aircraft.

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Your warning is important. The wing_pos_apex_lon does only what it says - it changes only the position of the wing relative to the reference datum - it leave the tailplane/horizontal stabilisr in the same position so changes the geometry of the aircraft. This is not what is wanted. The attached figure shows the relationship.The correct way to change the cg is the obvious one - change empty_weight_CG_position.

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