Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Results 1 to 13 of 13

  1. #1

    Join Date
    Nov 2005
    Location
    Bangkok, THAILAND
    Posts
    129
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    Airplanes yaws left uncontrollably when hovering

    Hi,

    I just bought a 3dhs extra 330sc and it's powered with a turnigy 5055 580kv motor, 80a esc, turnigy 3000mah 22.2v lipo, and a 14x7 prop. It flies well, very light and responsive, but I have a problem when hovering. The airplane yaws to the left and even full rudder is not enough to stop it from doing so. The rudder throw is maximum according to the recommended setup, but once the plane starts to yaw left, no amount of rudder will bring it back, even when I'm blipping the throttle. Is this a mechanical setup problem or is it something else? I have another sbach 342 57" that exhibits the same tendency...any suggestions would be greatly appreciated. My 3D skills are just at the beginner/intermediate stage.

  2. #2
    Zippi's Avatar
    Join Date
    Jun 2004
    Location
    Evansville, IN
    Posts
    4,858
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering


    ORIGINAL: cyborg1

    Hi,

    I just bought a 3dhs extra 330sc and it's powered with a turnigy 5055 580kv motor, 80a esc, turnigy 3000mah 22.2v lipo, and a 14x7 prop. It flies well, very light and responsive, but I have a problem when hovering. The airplane yaws to the left and even full rudder is not enough to stop it from doing so. The rudder throw is maximum according to the recommended setup, but once the plane starts to yaw left, no amount of rudder will bring it back, even when I'm blipping the throttle. Is this a mechanical setup problem or is it something else? I have another sbach 342 57'' that exhibits the same tendency...any suggestions would be greatly appreciated. My 3D skills are just at the beginner/intermediate stage.
    cyborg1,

    How much right thrust on the motor do you have?
    "It Ain't Lookin Good"
    http://www.evansvillercclub.net

  3. #3

    Join Date
    Nov 2005
    Location
    Bangkok, THAILAND
    Posts
    129
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    just what it had on the firewall, which is a small amount.

  4. #4
    KWJ48's Avatar
    Join Date
    Dec 2005
    Location
    Midlothian, VA
    Posts
    479
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    How does it fly inverted? I would set trims and CG to fly hands off for both upright and inverted flight. Then try from there.
    PRO BRO #2567

  5. #5

    Join Date
    Sep 2003
    Location
    St. Peters, MO,
    Posts
    724
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    are you hovering dead straight into the wind?

  6. #6

    Join Date
    Nov 2005
    Location
    Bangkok, THAILAND
    Posts
    129
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    yes, I've tried it both ways - into the wind and the other side as well. The same thing happens. It stays straight for a while, then it starts to lean to the left. Even with full rudder deflection, it just keeps going to the left.

  7. #7
    Jezmo's Avatar
    Join Date
    Jun 2006
    Location
    Spring, TX
    Posts
    2,132

    RE: Airplanes yaws left uncontrollably when hovering

    As asked in your other thread of the same name, how much total rudder throw do you have? You really need 45 degs or better. KWJ48's question is good, if you are too far forward on the CG it will behave this way. Do a vertical upline with the canopy facing you, wings perpendicular to your line of sight, and see if yaws to the left. If so you need some more right thrust as others have suggested. I have moved the thrust angle in my 50cc Extra and it makes a difference flying but not much when hovering. I've moved it between 0 and 4 degs and when hovering I won't say you can't feel it but it's not difficult to hold in a hover with it at zero or 4 degs. Certainly not enough change as to make it hard to hold. On the 50cc, CG affects it more in a hover than anything else but I do have 48 degs of rudder, 46 degs of elevator, and 39 degs of aileron travel so controlling the tail in a hover isn't an issue with that much throw. In the picture I've posted here the thrust angle is 0-0.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Da83282.jpg 
Views:	5 
Size:	129.3 KB 
ID:	1625908  
    Spektrum DX8i, DA DLE SuperTigre OS FOX Saito Enya Jett TT: John 3:16

  8. #8
    KWJ48's Avatar
    Join Date
    Dec 2005
    Location
    Midlothian, VA
    Posts
    479
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    Yep, it shouldn't be a thrust issue. Most of my profiles have 0 degrees of right thrust and hover just fine. Right thrust does help a little. The 3dhs plane should have plenty of r/t built in already, unless something really screwed up at the factory.
    PRO BRO #2567

  9. #9

    Join Date
    Dec 2008
    Location
    Tampa, FL
    Posts
    649
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    do you fly at a club ?

    I would let someone eles fly the plane who's decent at 3D


    I have the smaller SHP and it doesn't seem to have the same problem .. plus you said your Sbach does the same thing

    another club member would help narrow this down I dout it's right thrust 3DHS motor boxes have them built into it stock so maybe if you crashed the plane or really went wrong with the the standoffs it should be dead on

  10. #10

    Join Date
    Aug 2003
    Location
    hingham, MA
    Posts
    717
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    check overall thrust by measuring from the prop tips to a fixed point on the fin to check that the fuse doesn't give it a left thrust

  11. #11
    mdjohnson's Avatar
    Join Date
    Dec 2009
    Location
    Willow Point, BC, CANADA
    Posts
    121
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    Is the rudder servo the same torque as recommended? Also check the rudder linkage for bending/failure under load.
    Never left one up there yet.......

  12. #12

    Join Date
    Nov 2005
    Location
    Bangkok, THAILAND
    Posts
    129
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    Thanks for all the suggestions...to date, I have done several things. I've added 2mm shims to increase right thrust, balanced the plane until the CG is neutral which makes it fly straight and level right side up or inverted, and balanced the wings. I have also crossed the pull pull rudder slings as recommended in the manual (which I overlooked). Result? A better flying plane but still with tendencies to yaw left when hovering. Rudder input is better now, but it still doesn't respond as good as my Katana .46. Is there anything else that I'm missing out on?

  13. #13

    Join Date
    Jul 2003
    Location
    cleveland, UNITED KINGDOM
    Posts
    111
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Airplanes yaws left uncontrollably when hovering

    try a smaller prop, have you a video?????

    http://www.youtube.com/watch?v=GTtxStJJyFI


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -6. The time now is 08:47 AM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.