Released Labrador Beaver 8x8 1.2

Amphibious 8x8

  1. TrackpadUser

    TrackpadUser
    Expand Collapse
    Documentation support
    BeamNG Team

    Joined:
    Aug 24, 2019
    Messages:
    336
    Yeah, my last experience driving a vehicle driven by one of those CVTs was more than 5 years ago, so I don't exactly remember how they behave :p

    But TBH, I think this mod works fine as-is, and I'd prefer to spend more time working on other stuff. This update was mostly to fix an issue that had been on my WIP for a while, and to fix the material issues resulting from the pigeon update. PBR paint materials was just a nice bonus :cool:
     
    • Like Like x 1
  2. Damian Bower

    Damian Bower
    Expand Collapse

    Joined:
    Sep 27, 2021
    Messages:
    1
    i love this mod! could you make a rxr or a 4x4 in some of your next mods?
     
  3. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    Another problem is the buggy drivetrain. Too many differential means the drivetrain friction is too high, accelerating from 1km/h to 36km/h is slower than coasting down from 36km/h to 1km/h. Also the wheel torque often fluctuates violently between positive and negative, sometimes the vehicle creeps backward in D and creeps forward in R.
    BeamNGdrive-0235212939-RELEASE-x649_28_202112_41_12PM.png BeamNGdrive-0235212939-RELEASE-x649_28_202112_44_24PM.png BeamNGdrive-0235212939-RELEASE-x649_28_202112_43_11PM.png BeamNGdrive-0235212939-RELEASE-x649_28_202112_41_31PM.png
    Notice the "Engine Info" UI app
     
  4. Agent_Y

    Agent_Y
    Expand Collapse

    Joined:
    Jul 10, 2020
    Messages:
    4,560
    Still cool that the powertrain is made the proper realistic way with many diffs rather than the lazy way with multishafts like most people would probably do. So these issues are probably realistic. The friction could be lowered though, it's possible to change static and dynamic one of each diff in 0.23
     
  5. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    How is that realistic when you put it in D and it begins to creep backward 1km/h?
     
  6. Agent_Y

    Agent_Y
    Expand Collapse

    Joined:
    Jul 10, 2020
    Messages:
    4,560
    Idk I have never driven a vehicle like this so idk if it's realistic or not, I just guessed
     
  7. TrackpadUser

    TrackpadUser
    Expand Collapse
    Documentation support
    BeamNG Team

    Joined:
    Aug 24, 2019
    Messages:
    336
    It is possible that there is too much friction in the drivetrain, however the number of diffs itself isn't really the issue, since I could lower their friction to 0 if I wanted.

    Torque spikes are probably a mix of all wheels (and rotator inertia) on one side fighting each other slightly. combined with the slight flexibility that locked diffs have for stability reasons. However since nothing is exploding I think it's probably fine.

    The backward creeping issues are weird though :confused: It's not something I've seen myself, so I'm wondering if it might also be caused by ghost force issues in some specific conditions due to the pressure group required for flotation.

    Keep in mind at the end of the day that it was a mod thrown together fairly quickly just to try making something weird and different, so there might be some weird issues here and there.

    I wouldn't necessarily say it's more realistic, as those things use chains between each wheels, however it works and I preferred to avoid using multishafts mostly because they're technically deprecated.
     
    • Like Like x 1
  8. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    After digging into the vehicle, I found something
    1. The engine inertia may be a bit high
    2. There's a centrifugal clutch instead of a torque converter between the engine and the CVT (I can help implementing it by editing this mod)
    3. The CVT is controlled by a speed governor, the gear ratio is solely controlled by RPM, throttle is not taken into consideration
    4. The differential is not exactly an open differential (I didn't quite understand it, any help?)
    Source: How Does My Argo’s Transmission Work? and 8x8 Frontier EFI Parts Manual
     
    • Like Like x 2
  9. TrackpadUser

    TrackpadUser
    Expand Collapse
    Documentation support
    BeamNG Team

    Joined:
    Aug 24, 2019
    Messages:
    336
    Yeah, total engine inertia might be a bit on the high side. I think it might still be the pigeon's diesel engine inertia (which was fairly high IIRC?) combined with the torque converter that I think is unmodified from the Sunburst. Using the lockup clutch to "cheese" a centrifugal clutch seems like a decent idea TBH, and the next best thing to a custom powertrain element.

    For the diff I don't really understand. Even from the schematic it looks like there's only a single planetary open diff? Unless I missed something.

    If you want to play with the drivetrain and see if you can fix it up, have fun. I'd be super happy to add your work to it. :)
     
    • Like Like x 1
  10. Agent_Y

    Agent_Y
    Expand Collapse

    Joined:
    Jul 10, 2020
    Messages:
    4,560
    The Pigeon has always had unrealistically high inertia and still kinda has. As far as I know in cars like this (low power and light engine) most of the inertia should come from the flywheel rather than the engine. (Shouldn't be too big of a difference though.) Because the flywheel has way smoother rotation due to its regular shape, it makes no sense to keep engine inertia high if it has low weight because that can cause the whole car to shake. I don't think this is simulated in BeamNG though. So I wouldn't treat the Pigeon as a good reference.
     
    • Agree Agree x 1
  11. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    THIS, very this. I was tuning the torque converter lockup clutch to behave like centrifugal, and "empty" the torque converter (making the converterDiameter to 0), then the engine RPM went all over the place since the torque converter lockup clutch acts like a TORSION BAR SPRING
    --- Post updated ---
    Use Viscous Clutch between the engine and the CVT seems to work
     
  12. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    OK so here's the solution

    Engine inertia:
    Tuned out the inertia is caused by the torque converter, not the engine itself. Removing the TC solve the problem.

    CVT:
    The original Sunburst CVT when put in the Beaver, tend to maintain 3500 RPM, this is when you hit it from a standstill, it will accelerate very slowly until the engine reaches 3500 RPM, then the gear ratio suddenly changes, making the Beaver accelerate very quickly from 6km/h to 35km/h.
    The CVT in the attachment removed the throttle logic and the closed-loop feed back logic. As the simple CVT used in mopeds and ATVs are not computer-controlled, the gear ratio is solely depends on RPM(centrifugal force), not the throttle. This type of transmission doesn't care about fuel efficiency and (realistically)not be able to maintain constant max power RPM.

    Centrifugal Clutch:
    The deprecated viscous clutch is still usable and can be tuned to behave like a centrifugal clutch.
    When the engine RPM is below the "cutInAV" the clutch is fully disengaged, this is likely to prevent stalling the engine, when the engine is at "stallAV" above "cutInAV", the clutch is fully active, at above this RPM the clutch behaves the same like viscous differential, the higher the RPM difference between input and output, the higher the torque, the sensitivity is determined by "viscousCoef". There's also a "viscousTorque" to cap the max torque transferred for stability reason.
    To make it feels like centrifugal clutch, the "cutInAV" is set to slightly above idle RPM, and the "stallAV" is set to make "cutInAV" + "stallAV" near the engine max torque RPM. Set the "viscousCoef" to 15000 to make the fully engaged clutch rigid, just like the left/right "welded differentials" used to represent chains
    , and set the "viscousTorque" to the centrifugal clutch's rated torque(slightly higher than engine torque).

    The file structure in the attachment zip is arranged, to implement, simply copy all the files(2 files in total) to the mod zip "folder" and replace when asked.
     

    Attached Files:

    • Like Like x 2
  13. TrackpadUser

    TrackpadUser
    Expand Collapse
    Documentation support
    BeamNG Team

    Joined:
    Aug 24, 2019
    Messages:
    336
    Thanks :)

    I'll take a look at it.
     
    • Like Like x 1
  14. default0.0player

    default0.0player
    Expand Collapse

    Joined:
    Nov 30, 2018
    Messages:
    1,124
    The oil starvation still exists, strangely, climbing 45 degrees cause oil starvation, while reversing at the same slope does not starve, use nodegrabber to tile the vehicle sideways 90 degrees does not cause oil starvation.
     
    • Agree Agree x 2
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice