Simviation Forums

I followed Miltons excelent advice on setting up my landing gear and it worked well. Problem is that when my aircraft gets low on fuel and when I land the gear become unstable again because of the lack of the fuel weight. I added the cargo weight to the aircraft weight to comppensate because for some reason when I put station load points in to try to balance the aircraft it becomes more unstable. I've tried to change the compression in the airfile that does'nt seem to help. So it is nearly impossible to taxi without having a gear crash when the fuel is low. Can anyone provide some insight? Thanks Greg.

Can you post your contact points, you gross weight, your empty weight and where your CoG is right now?

Did you perform the needed calculations for the compression ratio? First, you measure the distance the gear compresses on normal parking to get the "Static Compression distance". Then measure the distance the gear compresses the most to get the "Maximum compression distance". I think you take the Static compression and divide it by the maximum compression to get the actual "Compression Ratio". Or is it the other way around?

This is as far as I can remember from the top of my head. I'm not that good at math.

Thanks guys. Following is the info requested.                                                                                          reference_datum_position     =  0.0, 0.0, 0.0       // (feet) distance from FlightSim Reference position: (1/4 chord, centerline, waterline)
empty_weight_CG_position     = 0.0, 0.0, 0.0    // (feet) longitudinal, lateral, vertical distance from specified datum


[WEIGHT_AND_BALANCE]
max_gross_weight = 2323880                      // (pounds)
empty_weight = 1292200                           // (pounds)

;Moments of Inertia
empty_weight_roll_MOI    = 30000000.0000
empty_weight_pitch_MOI   = 50000000.0000
empty_weight_yaw_MOI     = 50000000.0000
empty_weight_coupled_MOI = 0
reference_datum_position=0.000000,0.000000,0.000000
empty_weight_CG_position=0.000000,0.000000,0.000000
max_number_of_stations=50
station_load.0=0.000000,0.000000,0.000000,0.000000
                                                                                                                                                                                    [contact_points]

       //0  Class                        <0=none,1=wheel, 2=scrape, 3=float>
       //1  Longitudinal Position        (feet)
       //2  Lateral Position             (feet)
       //3  Vertical Position            (feet)
       //4  Impact Damage Threshold      (Feet Per Minute)
       //5  Brake Map                    (0=None, 1=Left, 2=Right)
       //6  Wheel Radius                 (feet)
       //7  Steer Angle                  (degrees)
       //8  Static Compression           (feet)  (0 if rigid)
       //9  Max/Static Compression Ratio
       //10 Damping Ratio / Water Rudder Effectiveness  (0=Undamped, 1=Critically Damped) / 1.0 = normal
       //11 Extension Time               (seconds)
       //12 Retraction Time              (seconds)
       //13 Sound Type
       //14 Airspeed limit for retraction     (KIAS)
       //15 Airspeed that gear gets damage at (KIAS)

point.0 =   1, 120.5, 20.0,   -19.0, 2000.0, 0, 3.0, 70.0, 1.4,  2.5,  0.7,  10.0, 11.0, 1, 220, 300
point.1 =   1, 120.5, -20.0,  -18.0, 2000.0, 0, 3.0, 70.0, 1.4,  2.5,  0.7,  10.0, 11.0, 1, 220, 300
point.2 =   1, -16.5, -11.0,  -18.5, 2000.0, 1, 3.0, 20.0, 1.4,  2.5,  1.00, 10.0, 11.0, 1, 220, 300
point.3 =   1, -62.0, 23.0,   -18.5, 2000.0, 1, 3.0, 0.0,  1.25, 2.0,  1.00, 10.0, 11.0, 1, 220, 300
point.4 =   1, -62.0, -23.0,  -18.5, 2000.0, 2, 3.0, 0.0,  1.25, 2.0,  1.00, 10.0, 11.0, 1, 220, 300
point.5 =   4, 44.5,  149.5,  1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  0,   0,   0
point.6 =   4, 44.5,  -149.5, 1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  1,   0,   0
point.7 =   4, 147.0, -25.0,  1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  2,   0,   0
point.8 =   4, 147.0, 25.0,   1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  2,   0,   0
point.9 =   4, -23.5, -25.0,  1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  5,   0,   0
point.10 =  4, -23.5, 25.0,   1.0,   2000.0, 0, 0.0, 0.0,  0.85, 2.5,  0.30, 0.0,  0.0,  5,   0,   0
point.11 =  5, -79.5, 5.5,    -1.5,  2000.0, 0, 0.0, 50.0, 0.0,  0.0,  0.1,  10.0, 11.0, 0,   0,   0
point.12 =  5, -79.5, -5.5,   -1.5,  2000.0, 0, 0.0, 50.0, 0.0,  0.0,  0.1,  10.0, 11.0, 0,   0,   0


max_number_of_points = 21

static_pitch = 0.0
static_cg_height = 18.7
                                                                                          The pink box in the gmax scene is where the current flightsim reference point is located. Its not at the recomended position because of the length of the aircraft 450 ft. approx. Sliding it forward created an unaturel flight charecteristic when pitching the aircraft. (Tail movement)The grid is -18.7 ft. to the bottom of frame 100 close approx. Thanks for the reply. Greg      

Here is a shot of the gear config. on the ground.      

[quote]Thanks guys. Following is the info requested.

Thanks once again for the bail out Milton. I'll try all that you suggest. Is there anything you do'nt know about Sim design? I ca'nt say thanks enough for all that you do here at the forum. Greg