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View Poll Results: Was this weather related, or a mechanical issue?

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  • Weather/Thermals/Wind

    12 48.00%
  • Mechanical

    13 52.00%
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Thread: My wings began flapping - scary - what was it?

  1. #41
    Senior Member
    Join Date
    Dec 2008
    Location
    Garland, Texas
    Posts
    1,476

    Default Re: My wings began flapping - scary - what was it?

    Pete, I am glad you made it back to Leander! I missed you at Oshkosh. I walked and walked and walked, by Thursday this Old Man had had enough!
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  2. #42
    Senior Member Peteohms's Avatar
    Join Date
    Sep 2008
    Location
    Leander, TX Hangared @ KGTU
    Posts
    272

    Default Re: My wings began flapping - scary - what was it?

    Paul, I stopped by, but you were out. I loved your plane. I want one when I grow up.
    Attached Images Attached Images
    Pete
    Leander, TX
    Model III SN 1000
    912
    Grove

  3. #43

    Join Date
    Jun 2010
    Location
    Mahanayim Israel
    Posts
    41

    Default Re: My wings began flapping - scary - what was it?

    If you think the vibrations come at certain RPM, check you engine mount.
    Sometimes it is hard to find the source of vibrations.

  4. #44
    Senior Member
    Join Date
    Dec 2008
    Location
    Garland, Texas
    Posts
    1,476

    Default Re: My wings began flapping - scary - what was it?

    I walked by your plane. Sorry I missed you. I will probably be flying to San Antonio to see my sister soon, maybe we can get together on my trip down to Dirty SA.
    Quote Originally Posted by Peteohms View Post
    Paul, I stopped by, but you were out. I loved your plane. I want one when I grow up.
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  5. #45

    Join Date
    Apr 2013
    Location
    Hillsboro, NH
    Posts
    95

    Default Re: My wings began flapping - scary - what was it?

    I will try the half flap trick. After some thought, I'm going to also try running the engine at various RPMs on the ground and see if I can find a range that excites some movement. With the damping from sitting on the gear it shouldn't shake as much but I think I'd observe something. If there is a consistent RPM range, I'll put a yellow arc on the tach.

  6. #46

    Join Date
    Apr 2013
    Location
    Hillsboro, NH
    Posts
    95

    Default Re: My wings began flapping - scary - what was it?

    And I will check the motor mount, fasteners etc again. Maybe the rubber bushings have gone soft. Thanks for all the advice, folks.

  7. #47

    Join Date
    Apr 2013
    Location
    Hillsboro, NH
    Posts
    95

    Default Re: My wings began flapping - scary - what was it?

    Haven't found any problems w engine mount, etc, fixed all looseness in the control system - but I think I have a harmonic with the engine/prop at about 3600 - 3800 RPM. Ground runs in that range cause some wing tip movement. The wiggle looks a lot less severe at 0 feet than 3000! I'm sure that's all perception on my part. My changing RPM and airspeed stopping it makes sense, low airspeed occurrence is when the RPM would be that low, and all I really needed to do was move the throttle. Looks like I need a yellow line on the tach. I'm running an HKS with the lower reduction ratio (2.47:1, I think) and an IVO 2 blade. I don't think that's a common combo, so that's probably why others haven't seen it..

    Cheers,

    Larry

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