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Thread: yet another bouncer

  1. #1

    yet another bouncer

    I guess I'am not living right because I have more problems with planes that bounce on takeoff.
    I just downloaded the BF 109B/D from Flightsim by AF Scrub and of course on the takeoff roll it acts like I'am applying the brakes and reapplying them. It bounces like crazy ,you can even hear the brake squeal and see the dust fly.
    I assume it's a contact point issue ,so anyone have a quick fix?

  2. #2
    Some people seem to have this problem with my models, but I of course do not!!! Although I must admit that if someone reports a problem & I install it on my laptop, I can replicate it! Why? Dunno!
    It does seem to affect some installations - try pressing 'y' (transition) & see if the model moves at all, if it does then try adjusting one of the vertical height values in the contact points part of the aircraft.cfg file. Sometimes though it can be the damping or the compression ratio - you will just have to experiment, but keep a copy of your original before modyfying anything!
    HTH
    Keith

  3. #3
    To the best of my knowledge the overall problem is caused by some modification to FS itself, I heard AFCAD, runway material modification etc. Not necessarily at the airport you are flying. Once the bug is in FS it is dang near impossible to get rid of. From then on if the aircraft is close to being bouncy on everyone else's systems it will bounce on the modified one.
    We ran into that issue with the Connies that worked beautifully for all but one of our Team members...where she turned into a bronco.

    Generally if the airplane sits still on the ramp and doesn't bounce there I start by modifying the damper rates or the overall suspension travel to soften the ride a little.
    If you are not sure what column of numbers means what open the cfg file for one of the default Cessna aircraft. You will find the notes there, which is which.

    Cheers
    Stefan

  4. #4

    Thanks for the reply

    Since I haven't a clue as to what numbers to change ,I'll leave well enough alone and live with the shimmy.The plane does sit still on the runway ,but I really don't feel like experimenting with numbers that I don't know about where to start.Thanks anyway.

  5. #5
    The numbers I was talking about are these (pulled right out of the 109BD zip: I would start by making the green numbers slightly bigger. Say 0.64000 and see if things get better.

    [contact_points]
    point.0=1.000000,-9.166667,0.000000,-3.133333,2165.354400,0.000000,0.563861,36.600000,0.536530,2.500000,0.341479,5.000000,5.000000,0.000000,0.000000,0.000000
    point.1=1.000000,7.250000,-5.416667,-7.153333,2165.354400,1.000000,0.563861,0.000000,0.542039,2.500000,0.867589,3.500000,3.500000,2.000000,0.000000,0.000000
    point.2=1.000000,7.250000,5.416667,-7.153333,2165.354400,2.000000,0.563861,0.000000,0.542039,2.500000,0.867589,5.000000,5.000000,3.000000,0.000000,0.000000
    point.3=2.000000,0.000000,-18.500000,0.000000,1181.102400,0.000000,0.000000,0 .000000,0.000000,0.000000,0.000000,0.000000,0.0000 00,5.000000,0.000000,0.000000
    point.4=2.000000,0.000000,18.500000,0.000000,1181. 102400,0.000000,0.000000,0.000000,0.000000,0.00000 0,0.000000,0.000000,0.000000,6.000000,0.000000,0.0 00000
    point.5=2.000000,-14.166667,0.000000,-0.500000,1181.102400,0.000000,0.000000,0.000000,0. 000000,0.000000,0.000000,0.000000,0.000000,9.00000 0,0.000000,0.000000
    point.6=2.000000,9.250000,0.000000,-1.916667,1181.102400,0.000000,0.000000,0.000000,0. 000000,0.000000,0.000000,0.000000,0.000000,4.00000 0,0.000000,0.000000
    point.7 = 5,7.14,0,-0.5,1600,0,0,10,0.4,2.5,1,0.2,0.2,4

    And the explanation is here:

    //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 (0=Undamped, 1=Critically Damped)
    //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)

    Since you likely just downloaded the AC from Flightsim.com or AVSIM the cfg file is probably still virgin stock so worst case scenario you simply have to pull that one back out of the original zip.
    Careful experimentation is part of the fun of FS :ernae:

    Stefan

  6. #6
    A quick look at it in ACM shows the contact points to be ....... well, way out of whack; makes Itosan's look like models of perfection.

    Having, unfortunately, some time on my hands I'll give this a proper look over tomorrow to see if I can get any better numbers (although I do have a website to finish for a certain Greek chappie first)
    Andy

  7. #7
    Since I have a head cold and not feeling well enough to model, I thought I too would look at this.

    Andy was right on with his assessment as the FM is really off.

    The reason for the bounce is because the contact points were about 6' forward of the visual model, and the CoG was generally well placed.
    This caused about 50% of the weight of the aircraft to be on the tail wheel... not good. Should be about 20% on the tail wheel.

    Anyhow, corrected the contact points, moved the mains toward center (they were about 3 feet too wide (but left them about 12" wider than the visual model)), decreased the suspension movement abit to stiffen them up (since there is no suspension animation), moved the CoG back to 25% MAC, moved the fuel tanks back inside the wings, changed the flaps-caused lift and pitch, the stall angle, corrected engine parameters so that the prop would turn faster than 1450RPMs (now 2150), added some Turbo boost, corrected prop min beta, corrected approach angle so you do not run out of trim, decreased rudder authority a bit, added a flight tuning section in case you want to tweak it, etc.

    Anyhow, she is improved although still a bit rough.

    Try it, and if anyone wants to take this mod further you are welcome to. It needs more than I have desire to fix. :-)
    Trim is too course but useable, pitch moments are okay but you can feel that there is too much damping, she is stiff, not fluid.

    Still a large improvement and very flyable. It's really a nice low-poly model and would make a good AI model.

    Andy (or anyone), feel free to tweak it further or go your own way.
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  8. #8

    ok

    Well after much experimenting I finally got this beast to fly with out bounceing on takeoff. First I tried to change the numbers in the config file which didn't look like the config file in Sunny's post. But I found the numbers that you said I change and went clear up to 70000 with no change.My numbers were off by one, for instance 0.536530 was 0.536531.
    Anyway that didn't make any difference.
    So I had a brainstorm and decided to try flying from some strips in Germany,both paved and unpaved,and darned if it didn't takeoff without bounceing(unless I got off the runway which happens a lot with my CH pedals which are too sensitive)
    So then I went back to Seattle and it took off without any bouncing or shaking.
    So it must have to do with the scenery that I take off from,and once I take off from a strip that doesn't cause the shaking it doesn't shake from a strip it formally shoke and bounced from.
    Go figure

  9. #9
    You need to scrap that FM and try what I posted above. The issue is not scenery although some areas may be more sensitive to this aircraft's issues than others.
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  10. #10

    Thankyou Milton

    I swapped out the old config and air files and the plane now flys great. Takeoffs are bounce free. I thought I was on to something with switching airfields but your work on the new config and airfiles is so much better.
    I don't know how you did it with a cold ,I know that must have been miserable.
    The only thing and this seems to be the case with all your wonderful planes that have guns is i can never get the gun sound to work. They have the effects with flash and spent cartridges but no sound.

  11. #11

    Thank you Milton
    Indeed first flight I believed that the fat Hermann was in the luggage bin .. and that the engine was sabotaged by some forced workers ....
    I was in half way to solve some of those problems (already had put a few "Popeye spinach" in the engine) .. when I read your post Just tested your tweak .. and seem's that fat Hermann and other are out of way

  12. #12
    Thanks guys; I am happy that it works better for you.

    I don't claim any accuracy with that work; I simply corrected glaring errors.

    If anyone wants to use that as a basis for further improvements, they are welcome to.

    Have fun
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  13. #13

    just wondering

    I can never or rarely get the sound of the guns to work on Miltons planes that are armed. Tried putting the wav file in the main sound folder and tried the aircraft folder but no luck. Any thoughts? I get the effects but no sound.

  14. #14
    Quote Originally Posted by hurricane3 View Post
    I can never or rarely get the sound of the guns to work on Miltons planes that are armed. Tried putting the wav file in the main sound folder and tried the aircraft folder but no luck. Any thoughts? I get the effects but no sound.

    I have no clue, never tried to get an FS9 gun to work. All show, no go in FS9. :-)
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  15. #15
    semi retired Mudmover Cees Donker's Avatar
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    That's a far better fm! Thanks Milton! I goofed around with the panel cfg and adjusted the texture of the panel in the VC.

    Cees
    Rolling, turning, diving, going in again. Iron Maiden 'Aces High'

    : My personal site:
    http://home.planet.nl/~donke069/

    : My Outhouse stuff:
    http://www.sim-outhouse.com/index.ph...=Cees%20Donker

    : My space:
    http://www.myspace.com/cees_donker



  16. #16
    Thanks Cees. Oh, I din't look at the VC; did not know there was an issue there. LOL Head colds!
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  17. #17
    Thank you for the updated FDE Milton. It is much improved if maybe a little too powerful now for the early 109. But that is easily tweak able. I was playing around with the AC a bit yesterday after I got home and noticed that the flap animation is not visible from the VC. Almost managed to crash the bugger while troubleshooting the flap deployment....which was happening but not visually confirmed
    I think the late version E model from the same author had the same issue.

    Of course that can't be fixed after the fact by anyone but the author....just wanted to warn fellow pilots of that issue. The VC and gauges do need a little work IMHO to make it fully functional such as installing a VSI.

    Cheers
    Stefan

  18. #18
    semi retired Mudmover Cees Donker's Avatar
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    Here's what I came up with so far.... Back up the originals!

    Cees
    Rolling, turning, diving, going in again. Iron Maiden 'Aces High'

    : My personal site:
    http://home.planet.nl/~donke069/

    : My Outhouse stuff:
    http://www.sim-outhouse.com/index.ph...=Cees%20Donker

    : My space:
    http://www.myspace.com/cees_donker



  19. #19
    Quote Originally Posted by Sunny9850 View Post
    Thank you for the updated FDE Milton. It is much improved if maybe a little too powerful now for the early 109. But that is easily tweak able. I was playing around with the AC a bit yesterday after I got home and noticed that the flap animation is not visible from the VC. Almost managed to crash the bugger while troubleshooting the flap deployment....which was happening but not visually confirmed
    I think the late version E model from the same author had the same issue.

    Of course that can't be fixed after the fact by anyone but the author....just wanted to warn fellow pilots of that issue. The VC and gauges do need a little work IMHO to make it fully functional such as installing a VSI.

    Cheers
    Stefan
    As I said, I only fixed some obvious things to get her flying ... gave her some boost too that you can drop. The main issues were beta min at 25 and prop rpms limited to 1500 by the prop ratio, so I changed those to 15 and 2150 respectively just to get some speed out of her. She showed a supercharger or turbocharger with no boost and no representative MAP so I added some to pick up the takeoff roll and cruise speeds. Please change as you wish
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  20. #20
    I did not mean this as negative or criticism. Simply an observation relative to the documentation I have found on the Bf-109 series.

    Stefan

  21. #21
    I did not take it as such; just wanted to clarify that my role was to get her going, did not have the data or time to focus on an accurate flight model (as I mentioned in an earlier post).
    Milton Shupe
    FS9 Modeler Hack

    New Website Location: http://www.gjsmith.net/Milton_Shupe/

  22. #22
    OK...just wanted to clarify as well. Far be it from me to want to step on your shoes after all the great gifts you continue to give to the community.

    :ernae:
    Stefan

  23. #23
    semi retired Mudmover Cees Donker's Avatar
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    Here's a two bladed prop!

    Cees
    Rolling, turning, diving, going in again. Iron Maiden 'Aces High'

    : My personal site:
    http://home.planet.nl/~donke069/

    : My Outhouse stuff:
    http://www.sim-outhouse.com/index.ph...=Cees%20Donker

    : My space:
    http://www.myspace.com/cees_donker



  24. #24

    runway showing through

    I noticed after applying the fixes by Milton ,on the takeoff roll you can see two slices of runway showing through the cockpit on the takeoff roll ,they go away after liftoff. Not a big deal ,but what causes this?

  25. #25

    forgot

    I forgot to say this happens in the VC mode

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