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 8 of 8

Thread: servo placment


  1. #1

    Join Date
    Mar 2006
    Location
    mt shasta, CA
    Posts
    408

    servo placment

    When building a wing is there a formula to where the servo goes. Like one third of aileron or just as close to wing root as possible. Thanks Steve

  2. #2

    Join Date
    Nov 2003
    Location
    MT SHASTA, CA
    Posts
    368
    Bump,
    Anybody? I too would like to know !!!


    Mike

  3. #3
    sensei's Avatar
    Join Date
    Jul 2002
    Location
    SAN ANTONIO, TX
    Posts
    2,490
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback
    As a rule I place mine 25 to 30% outboard of the aileron root in a single servo scenario.

    Bob
    Fly It Like You Stole It!!!

  4. #4

    Join Date
    Nov 2003
    Location
    MT SHASTA, CA
    Posts
    368
    Thanks Bob!
    I have followed several of your threads over the years, Mostly at the other forum sites, LOL. Your willingness to help others and this hobby is greatly appreciated and I know my building skills have improved as a direct result of your work.

    Mike

  5. #5
    Moderator BMatthews's Avatar
    Join Date
    Oct 2002
    Location
    Chilliwack, BC, CANADA
    Posts
    12,050
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback
    I've seen references to the idea that you don't want to put the control horn where the inboard and outboard portions are evenly divisible. So don't put the control horn at the 50% point or the 1/3 point. Instead make it an oddball number like 45% or 28%.

    The theory being that exactly even or related divisions can promote flutter. Sort of like the old Tacoma suspension bridge. By putting the control horn at some oddball location along the span length you break that possibility.

    And of course at that point you put the servo just ahead of the horn if using outboard servos with one on each surface.

    To avoid high mass moments in the wing I like to put the servo as inboard as possible within reason. So I look to put the horn at around 27 to 30% out from the inboard end of the surface. That puts the servo out far enough that I don't need to worry as much about flex and I avoid the 4:1 ratio of putting the horn at 25%. But the outboard mounted servo is not so far out that it builds on making the tips heavier too badly.
    Witty saying to be plagarized shortly.....

  6. #6

    Join Date
    Dec 2001
    Location
    FL
    Posts
    7,409
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback
    A good rule of thumb is to place it at an odd multiple of the span; i.e. 1/3, 1/5, 2/5 2/3 etc. This minimizes the chance of flutter as it tends to cancel out some of the possible flutter frequencies. For best use of the forces required of the servo, the farther out on the wing the better.

  7. #7
    speedracerntrixie's Avatar
    Join Date
    Jun 2010
    Location
    San Jose, CA
    Posts
    4,765
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback
    Put the servo wherever it's convenient and keep the linkage tight. Most issues are caused by poor linkage choices or poor mechanical set up.

  8. #8
    Moderator BMatthews's Avatar
    Join Date
    Oct 2002
    Location
    Chilliwack, BC, CANADA
    Posts
    12,050
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback
    Quote Originally Posted by Rodney View Post
    A good rule of thumb is to place it at an odd multiple of the span; i.e. 1/3, 1/5, 2/5 2/3 etc. This minimizes the chance of flutter as it tends to cancel out some of the possible flutter frequencies. For best use of the forces required of the servo, the farther out on the wing the better.
    1:3 can still set up a strong resonance. 1:4 is better but still possible. 1:5 is better again but still possible. The problem is that you're still using evenly divisible ratios. The higher the ratio the less strong any resonance will be but it can still achieve a size based resonance.

    What's needed is a real oddball like 1:3.2. The surface may still flutter but with a non integer based ratio such as this it'll be due to other factors than resonance due to the horn location.
    Witty saying to be plagarized shortly.....


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 10:22 AM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.