Setting up Landing Gear so the plane sits on the Tarmac

  • Hey all,


    Can someone explain the process of getting a plane to sit on the Tarmac?


    In Flight Simulator X, you have 'contact points', measured in feet from datum or CG. You could assign them a light to check their locations, or drive around in dirt and the puffs of dust would show your coordinates. (yes... it was a basic process, lol). But thats how we did it. Z, X, Y. Z was forward, X was cross ways, Z was up/down.


    How do you do this in Aerofly?


    I note the following for 'right gear' blocks in the Extra 330 TMD:


    ////////////////////////////////////////////////////////////////////////////////////////////////// BEGIN



    // right main gear
    <[string8][object][rigidbody]
    <[string8][Name][RightGear]>
    <[float64][Mass][12.75]>
    <[tmvector3d][InertiaLength][0.26 0.5 0.26]>
    <[tmvector3d][R0][0.3 -0.68 -0.87]>
    <[tmmatrix3d][B0][1.000000 0.000000 0.000000 0.000000 0.500000 0.866025 0.000000 -0.866025 0.500000]>
    >
    <[string8][object][jointmulti]
    <[string8][Name][JointFuselageRightGear]>
    <[string8][Body0][Fuselage]>
    <[string8][Body1][RightGear]>
    <[tmvector3d][Position][0.26 -0.45 -0.62]>
    <[tmvector3d][Axis][1.0 0.0 0.0]>
    <[float64][Kp][45000.0]>
    <[float64][Kd][1300.0]>
    <[float64][ZeroPosition][-0.02]>
    <[uint32][Type][0]>
    >
    <[string8][object][collisionhull]
    <[string8][Name][CollisionRightGear]>
    <[string8][Body][RightGear]>
    <[string8][Geometry][RightGear]>
    <[float64][K][500000.0]>
    <[float64][D][750.0]>
    <[float64][StaticFrictionCoefficient][2.0]>
    <[float64][KineticFrictionCoefficient][0.7]>
    <[bool][Blade][false]>
    >
    <[string8][object][wheelhull2]
    <[string8][Name][RightWheelHull]>
    <[string8][Body][RightGear]>
    <[tmvector3d][R0][ 0.440210 -0.949970 -1.196980]>
    <[tmvector3d][X0][ 1.000000 -0.00000 0.000000]>
    <[float64][Radius][0.155000]>
    <[float64][K][300000.0]>
    <[float64][D][1500.0]>
    <[float64][RollingFrictionCoefficient][0.02]>
    <[string8][BrakeControl][ServoRightBrake.Output]>
    <[float64][BrakeCoefficient][1.0]>
    <[float64][CorneringFactor][1.0]>
    >
    <[string8][object][output]
    <[string8][Name][GroundRollSpeedRight]>
    <[string8][Input][RightWheelHull.Speed]>
    >
    <[string8][object][output]
    <[string8][Name][GroundRollLoadRight]>
    <[string8][Input][RightWheelHull.Load]>
    >


    ///////////////////////////////////////////////////////////////////////////////////////// END



    * Which of these would be the tire contact point? Or, is that located somewhere else?
    * Is it measured in Meters?

  • The "contact points" a bit different in the Aerofly FS 2 and are defined in the tmc file of the aircraft. The contact points are the positions that are placed on the runway surface at initialisation, those don't have to be the wheels but they ususally are. They are just used to calibrate the orientation of the aircraft (e.g. tail down for a taildragger).


    The wheelhull2 R0 parameter is the center of the wheel, the contact point would be one "Radius" distance further down in the z-axis.
    R0 = (position vector of the wheelhull at simulation time t = 0)
    -> find the rotation pivot (e.g. from the export tm.log file), set this pivot as "R0" (location is relative to 3D model origin, x,y,z in meters)
    -> try to measure the radius of the wheels or experiment with it until you are happy... (Radius is in meters)


    Other things that repell the aircraft from the ground are the collisionhulls.
    Those take the 3D model geometry and intersect it with the ground or buildings.


    Regards,
    Jan

  • lionheart ,
    Beautiful aircraft - we are getting excited with you! Could you tell me which airport this is in the photo - looks like it has a military contingent and I assume that is a blimp hangar?


    You are learning valuable lessons and hope that you will be able to produce many new aircraft for us in the future.


    Well done


    Dave

  • Ureka!


    Still a ways to go on the landing gear. The rear gear needs to turn, the brakes need a little more zap, and the gear needs to retract up into the wings. But......! Its sitting on the landing gear, no longer leaning to one side, tailwheel has a functioning oleo... Progress, sweet sweet progress...


    As long as its nowhere near as squirrely as the Extra 330........ :D

    Devons rig

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  • I have a new issue. I have progress in that I have the landing gear moving, but they are moving up through the wings and over the fuselage, like they are hinging from inside the center of the fuselage.


    Can someone figure out what I have done wrong? It took me a while to get to this point. I have been trying out many versions of top landing gear, trying to get one to animate. The Pivot points are proper, but it appears to hinge from the center of the plane.


    This is the RigidBody section at the top of the TMD file;




    This is the Graphics Section of the TMD;




    These should be the controllers?




    This is the control section just before Graphics;







    I have been copy/pasting and experimenting, then redoing it, over and over, trying to find a section that works. When I try adding a pivot and axis point to a rigid body, it crashes the sim. Makes sense, but when I do a hinged body, it doesnt work.


    I also tried 'MapRightGear' (same for left) and it hinges in the same spot.

  • The MapLeftGear/ MapRightGear is just the deflection angle, it can't change the pivot. Do change the hinging point of your gear you need to adjust the Position parameter of the jointmulti that is connecting the two parts. This position depends on your 3D model but you should be able to steal it from the tm.log file. Find the suggested hingedbodygraphics object there, take its Pivot values and paste those three values in your jointmulti "Position" value.


    And no the controllers are not the flaps, its the "GearInput" which is then taken in by "ServoLeftGearSequence" and then used by "MapLeftGearDoor" which then feeds into the joint.


    1st the gear input reads your hardware inputs and interprets their commands as 0.0 or 1.0. The Sequence then moves slowly to that position. You could directly use that sequence position but then the gear starts moving right away, no time for any gear doors to open before the gear starts moving. So we use the "MapLeftGearDoor" to say: start moving at 0.05 (5%) of the sequence, that delays the movement of the Gear.

  • Thank you Jan.


    So Mapping is on/off positions in a animation track. Nice. I remember now you talking on this a while back.


    I cant believe I posted the flaps section instead of gear, lol... I think it was 4AM. bad me.


    I did use the pivot point from the TM log. It should be correct. I have tripple checked it to the power of 5. I have the main gear linked to the wings. I wonder if these are also messed up in the TM log. One of my tires had faulty height. Maybe these main gear have a bad gizmo location. That would explain why they are hinging from odd points. I'll check them in Max.


    Thanks again,



    Bill
    LHC

  • Ok, I did find one issue. My hydraulic cylinder I had rerouted to Fuselage from the wings. I have my landing gear mounted to the wings and I had changed it with hydraulic cyl. to link with the fuselage as I got animation movement. I changed it back so that hydraulic cylinder R0 coordinate is back to left wing, (which kills any animation movement). Also, the gear pivot point is proper. Its copied from the TM.log.


    So that is fixed and now the gear no longer animates. Now, when I hit G to raise the gear, nothing happens, and then 'blip' the plane resets on the ground. So I am wondering if its my hydraulic cylinder setting? Could I possibly need to change a setting to get it to work? Like lowering the movement or something?


    This is the Left Main Gear (top primary that should hinge into the wing).



    Also, the pivot for the wing is right on also. Double checked.

  • First you will have to "unlock" the jointmulti. Currenlty 100000.0 Nm are created when you rotate the joint about 60degrees, so thats not good. Set Kp and Kd of the jointmulti to 0.0, freely pivoting.


    Then I'd go on by changing the hydraulic_cylinder. Attach the R0 to some logical place on the wing, a direction to where to pull the gear when it is retracting. Then attach the R1 to a plausible location on the gear. Reduce the K and D parameter for now to something like 1000.0 and 100.0. Just test that.


    The rigidbody "InertiaLength" does not really change the speed of the servo, it describes the inertia of the body. Higher values represent a larger body, a body that is more resistant when you want to accelerate the rotation. That is just a physical constant that comes from the dimensions of your gear, once set you don't have to adjust that. To change the speed of the servo find the gear sequence and change its speed value.


    This is not "magic", there are no keywords that will make your gear work all of the sudden. For a retractable gear to work properly you will need to find the right parameter for your aircraft geometry. You can copy paste over parts from another aircraft but if you want the gear to retract correctly you will need to adjust the R0 of the rigidbodies, joint Positions as well as the hydraulic_cylinders R0 and R1, and of course the wheelhulls. I'm afraid it's not that easy but if you try to understand all of the connections using a pen and paper you might get there faster than by just swapping blocks of code hoping that it will just suddenly work. Try a 3D drawing of your R0, R1 of the hydraulic cylinder and jointmulti and rigidbody... or add small parts into your 3Ds Max model to visualize things in 3D... You'll get there, I'm sure!


    (sorry for the bad english language, it's late here)


    Regards,
    Jan

  • Ok. I tried that. My little yellow dart fell into the ground on the left gear.


    I wondered if that information was in the Wiki, but the Wiki shows base, unsetup, blank code blocks.


    I then thought about how far I have come in 30 days and that my plane is once again back in the ground. I am firing shots in the dark. I have no concrete settings to go by. This is, for me, all guess work. I need to go on vacation from this for a while. Maybe in the future, the SDK will have information on exactly how this works. For now, I have to walk away. I still love this simulator. I just cannot make my plane to properly work in it.