Carbon Cub

    Is your cockpit instrumentation actually working as its hard to tell from the video? If not display the inflight data display ribbon ("I" shortcut key) so we can see what your vertical velocity is on touch down. Also with the VVI from the data ribbon display enabled, using a chase view for landing that gives a view of the landing gear would show (if the landing gear animation graphics are already setup) if it is collapsing or not. For conventional (taildragger) landing gear doing a two point touchdown (two front wheels contact first) is normally prone to a couple of bounces if you are descending too fast, normally a three point landing (both front wheels and tail wheel contact simultaneously) is less likely to bounce. Also, using a chase camera view allows you to see how the landing gear shock absorber is working as long as your gear graphics is working correctly.

    Quote from jayeye2011

    Is your cockpit instrumentation actually working as its hard to tell from the video? If not display the inflight data display ribbon ("I" shortcut key) so we can see what your vertical velocity is on touch down. Also with the VVI from the data ribbon display enabled, using a chase view for landing that gives a view of the landing gear would show (if the landing gear animation graphics are already setup) if it is collapsing or not. For conventional (taildragger) landing gear doing a two point touchdown (two front wheels contact first) is normally prone to a couple of bounces if you are descending too fast, normally a three point landing (both front wheels and tail wheel contact simultaneously) is less likely to bounce. Also, using a chase camera view allows you to see how the landing gear shock absorber is working as long as your gear graphics is working correctly.

    I can make another video with a chase view and data ribbon on. The cockpit is not yet implemented, this is the original one still.

    Actually, looking at the video at 0.25x slow motion, it looks more like your propeller hit the tarmac and disintegrated. You could do a in game playback using an external camera view to see what part of the plane hit the tarmac. So could have been just a bad landing with too much down pitch attitude on the aircraft. If you have sound activated you should hear a sound (balloon popping or firecracker?) that indicates you crashed.

    I am not a real life pilot so I don't know how the aircraft is supposed to fly in terms of its takeoff and landing pitch attitude characteristics and how easy it is to be in a nose up attitude when landing. I know that Kaniewski's PA-11 Cub Special is configured so it's natural flight pitch attitude is nose up (not sure if that is real-life accurate) so that it is easier to make a 3 point landing. In contrast, Kaniewski's Stearman Model 75 Kaydet is currently setup more for a nose down attitude characteristic making a 3 point tough to achieve so you end up easily doing 2 point bouncing ball landings which if done incorrectly resulting in a nose down propeller hits the tarmac landing.

    Quote from jayeye2011

    I am not a real life pilot so I don't know how the aircraft is supposed to fly in terms of its takeoff and landing pitch attitude characteristics and how easy it is to be in a nose up attitude when landing. I know that Kaniewski's PA-11 Cub Special is configured so it's natural flight pitch attitude is nose up (not sure if that is real-life accurate) so that it is easier to make a 3 point landing. In contrast, Kaniewski's Stearman Model 75 Kaydet is currently setup more for a nose down attitude characteristic making a 3 point tough to achieve so you end up easily doing 2 point bouncing ball landings which if done incorrectly resulting in a nose down propeller hits the tarmac landing.

    Well it could be the prop that hit tarmac as well, this was most for checking the gears stuff. Not much of a proper landing and touchdown. With the panel it might be easier to see the different values at touchdown time. At the moment the plane has no sounds activated at all.

    Unlike X-Plane you cannot specify the aircraft CG. It would be nice to be able easily and arbritrarily redefine the lateral CG position but unfortunately you cannot do this in Aerofly FS 2 or 4. All that you can do is either adjust the mass values of the different rigidbody objects or change the R0 X (lateral) coordinate of the most massey part, the fuselage to alter the CG point. Who knows where the actual lift datum point is in the model. Also, only the person who has the 3D model file knows where the 0 datum point is on the aircraft to which all the rigidbody R0 points are referenced.

    Examples:

    PA-11 Club Special tmd

    // airframe

    // mass: 409.9 ( -0.079 0.000 -0.273 )

    <[rigidbody][Fuselage][]

    <[float64][Mass][215.0]>

    <[tmvector3d][InertiaLength][ 3.20 0.49 0.667 ]>

    <[tmvector3d][R0][ 0.0 0.0 -0.432677 ]>

    <[tmmatrix3d][B0][ 1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0 ]>

    >

    <[rigidbody][LeftWing][]

    <[float64][Mass][30.0]>

    <[tmvector3d][InertiaLength][ 1.30 4.79 0.19 ]>

    <[tmvector3d][R0][ -0.024769 2.1 0.449867 ]>

    <[tmmatrix3d][B0][ 1.0 0.0 0.0 0.0 0.99963 0.02727 0.0 -0.02727 0.99963 ]>

    >

    Compare to

    Stearman tmd

    <[rigidbody][Fuselage][]

    <[float64][Mass][884.2]>

    <[tmvector3d][InertiaLength][4.302037 1.107473 1.186110]>

    <[tmvector3d][R0][0.262640 0.0 -0.018969]> // 0.254 meters = 1 inch

    <[tmmatrix3d][B0][1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]>

    >

    <[rigidbody][UpperWing][]

    <[float64][Mass][83.6]>

    <[tmvector3d][InertiaLength][ 1.65 8.95832 0.20 ]>

    <[tmvector3d][R0][0.216920 0 1.088677]>

    <[tmmatrix3d][B0][1.0 0.0 0.0 0.0 1.0 0.0 0.0 0.0 1.0]>

    >


    For R0 X coordinate, 0.0 is the aircraft reference datum, and positive value means location is forward of it and negative value means location is aft of it.

    Again where the 0 datum reference point is actually located on the aircraft is up to the 3D model author. Logically it should either be the known aircraft specified CG or the know aircraft's center of lift point. But only the 3D model author knows what it is.

    Yes it has been quite some investigation to figure out everything, Jet-Pack (IPACS) support has been invaluable. I have the original model in Blender, and I have tried to verify the different R0s for the gears and multibody against this (and as you said, they are relative to model origin).

    If you didn't have to consider some kind of divide by zero error from improper coordinate values, I would normally try to have a softer shock absorber like in cars rather than a stiffer one if you want a less bouncy landing. But I don't know if that is more influenced by the Kp (spring constant) term or if it is the Kd (damper) term.

    In regards to more forum threads on aircraft creation, these ones exist for Aerofly FS 2


    Thread
    Brewster B339 Buffalo and Spitfire Mk1a Project
    I thought you might like to see a couple of models I've been working on in AC3D that hopefully will one day find their way into Aerofly FS2. Let me say at the outset they will in all likelyhood be payware as I'm not retired and its difficult to justify the amount of time these creations take otherwise. Other than that my plans are fluid at this stage. I work on them as and when I can. External meshes are done and I'm now working on textures and materials. After that Pilot and VC are then on the…
    MDIvey


    Thread
    Aircraft TMD Self Help Group
    I know a handful of people other than IPACS staff have successfully created aircraft for AF2 (Sylvain, Steve, Kai, Dino and Krystoff come readily to mind). The most challenging area seems to be the creation of the necessary config files and most of us will readily admit that any headway that is made is in no small measure facilitated by help from IPACS' Jet-pack (Jan). He is heavily involved with a master's thesis at the moment and will no doubt not have as much time to help us out. What I was…
    MDIvey

    Regarding the videos, they are very interesting to see and I am glad you have a Youtube channel. If you don't mind my asking, when you get to the point of creating your instrument graphics and animation in Blender, could you post a video showing how you make a steam gauge instrument in Blender, like maybe an example of doing either the RPM or VVI instrument and how you tie that into the aircraft tmd file?

    Quote from jayeye2011

    If you didn't have to consider some kind of divide by zero error from improper coordinate values, I would normally try to have a softer shock absorber like in cars rather than a stiffer one if you want a less bouncy landing. But I don't know if that is more influenced by the Kp (spring constant) term or if it is the Kd (damper) term.

    Yes I have been testing with multiple Kp/Kd values for the joints. Now front gears uses Kp around 150000 and Kd 500.

    Strange, I wonder if a good Kp value depends on aircraft weight, seems to vary a whole lot.

    Examples:

    C172

    <[multibody_joint][JointFuselageRightGear][]

    <[string8][Body0][Fuselage]>

    <[string8][Body1][RightGear]>

    <[tmvector3d][R0][ 0.1 -0.5 -0.5 ]>

    <[tmvector3d][X0][ 1.0 0.0 0.0 ]>

    <[float64][Kp][70000.0]>

    <[float64][Kd][1500.0]>

    <[uint32][Type][0]>

    >

    Jungmeister

    <[multibody_joint][JointFuselageRightGear][]

    <[string8][Body0][Fuselage]>

    <[string8][Body1][RightGear]>

    <[tmvector3d][X0][0.930765 0.000004 0.365618]>

    <[tmvector3d][R0][0.442420 -0.025636 -0.927850]>

    <[float64][Kp][20000.0]>

    <[float64][Kd][2000.0]>

    <[uint32][Type][0]>

    <[string8][InputPosition][0.1]>

    >

    DR400

    <[multibody_joint][JointFuselageFrontGearUpper][]

    <[string8][Body0][Fuselage]>

    <[string8][Body1][FrontGearUpper]>

    <[tmvector3d][X0][-0.1276 0.0 0.9918]>

    <[tmvector3d][R0][1.25972 -0.07824 0.03]>

    <[float64][Kp][50000.0]>

    <[float64][Kd][1000.0]>

    <[uint32][Type][0]>

    <[string8][InputPosition][ServoSteering.Output]>

    >

    F4U

    <[multibody_joint][JointRightGear2RightGear3][]

    <[string8][Body0][RightGear2]>

    <[string8][Body1][RightGear3]>

    <[tmvector3d][X0][0.000000 0.000000 1.000000]>

    <[tmvector3d][R0][ 1.8290 -1.6403 -1.5134 ]>

    <[float64][Kp][100000.0]>

    <[float64][Kd][50000.0]>

    <[uint32][Type][1]>

    >

    Camel

    <[multibody_joint][JointFuselageRightGear][]

    <[string8][Body0][Fuselage]>

    <[string8][Body1][RightGear]>

    <[tmvector3d][X0][1.0 0.0 0.0]>

    <[tmvector3d][R0][ 0.17619 -0.3 -0.572081 ]>

    <[float64][Kp][200000.0]>

    <[float64][Kd][800.0]>

    <[uint32][Type][0]>

    >

    I think the landing speed can be a huge impact here, touching down with 90-100 knots will probably break something. I have some issue getting the throttle reduced.

    • Official Post

    In the video the reason for the crash reset is a propeller collision with the ground. The gear was probably too soft to stop the velocity and deflected enough for the prop to hit the ground.


    Regarding the airfoils: If I recall correctly the Carbon Cub tmd is based on Krzysk's Piper Cub and I already set up the airfoils for that. So the airfoils should be all good in theory. You can of course adjust it for flaps lift and moment coefficients, etc.

    Quote from Jet-Pack (IPACS)

    In the video the reason for the crash reset is a propeller collision with the ground. The gear was probably too soft to stop the velocity and deflected enough for the prop to hit the ground.


    Regarding the airfoils: If I recall correctly the Carbon Cub tmd is based on Krzysk's Piper Cub and I already set up the airfoils for that. So the airfoils should be all good in theory. You can of course adjust it for flaps lift and moment coefficients, etc.

    I guess touchdown speed impacts this too. So it is the multijoint Kps that might need to be adjusted?

    Kaniewski also had a PA-18 Super Cub model for FS 2 which had a different tmd file configuration. Might be worth looking at although it was never converted to FS 4. The PA-18 would be a closer match for a Carbon Cub than the PA-11 since it had flaps and the PA-11 does not, more powerful engine, and looks to be a different airfoil setup in the tmd file which is questionable since they both are supposed to use the USA 35B airfoil. However Kaniewski's PA-18 seems to have used a fixed pitch propeller whereas I would assume the Carbon Cub being more modern setup might use a constant speed propeller setup?


    GitHub - krzysk1/pa18: Piper PA-18 for Aerofly FS2
    Piper PA-18 for Aerofly FS2. Contribute to krzysk1/pa18 development by creating an account on GitHub.
    github.com


    Here is a sometimes useful listing of aircraft vs airfoil used

    The Incomplete Guide to Airfoil Usage

    Should the following elements be correct for getting the throttle input to work correctly (if I have some controls mapped to the Throttle command)?


    Quote from jayeye2011

    Regarding the videos, they are very interesting to see and I am glad you have a Youtube channel. If you don't mind my asking, when you get to the point of creating your instrument graphics and animation in Blender, could you post a video showing how you make a steam gauge instrument in Blender, like maybe an example of doing either the RPM or VVI instrument and how you tie that into the aircraft tmd file?

    Yes I have been trying to add some videos from different sims there. Will see if some videos can be added concerning instrument development, once I get to that point. I try to get the model to a state in which is somewhat stable in the sim, and then start looking at the details.