Trimming Help

[Keith Black]

Been there done that scratching the head wondering if it's me, the wind, or the plane thing! :-)  

With all the variables it's really hard to tell, especially when you consider that the wind at altitude often isn't the same as the wind on the ground. In addition to the unintentional mixing of controls there's also the incredibly critical, and deceptive, wings level issue. If you're wings aren't level on your pulls it will make the plane look like it's veering off to one side when it's really going straight (from it's vantage point). To the unseasoned eye it's very easy to *think* the wings are level when they're not, especially on downlines at the end of the box.

Last year I wasn't sure if my plane was unreasonably pulling to one side on uplines until I finally had Art Wagner fly it. He flew it through the F05 sequence and was favorably impressed. He said he thought it flew nice and straight, so I stopped worrying about the plane and started focusing on my flying.

Keith
  ----- Original Message ----- 
  From: Larry N Lisa 
  To: discussion at nsrca.org 
  Sent: Wednesday, April 07, 2004 2:18 PM
  Subject: Re: Trimming Help


  I'm a newbie also and won't advise on what to do about trimming for this problem. But my experience with trimming issues was fairly humbling.

  After struggling for many weeks with suggestions about trimming on my plane, I did finally go to a contest and asked a seasoned pilot to check it out. After putting it through a few masters maneuvers that looked impressive to me, he landed and said it just needed a couple of clicks on the aileron.

  After a full season in Sportsman, I look back and reflected that most of the problems were not trimming of the plane. I was coupling control inputs every-time I moved a stick. Looked like I was having trimming problems, and it was repeatable. I could actually screw it up the same way every time.

  I focused on stick movement at every contest and replaced the factory springs with some stiffer springs from one of the Chicago folks, Bobby Satalino. Jim Hubbard did the surgery replacing the springs after the contest and I have been flying much better since.

  Every contest I went to had great folks very willing to help out. Allot of advise on flying maneuvers that allowed me to see improvements at each contest I entered.

  My only recommendation is to follow the advise of others in this thread and get a seasoned pilot to help out.

  Good Luck...

  Larry Diamond
  NSRCA 3083
  AMA 5024


    ----- Original Message ----- 
    From: Bob Pastorello 
    To: discussion at nsrca.org 
    Sent: Tuesday, March 30, 2004 7:57 PM
    Subject: Re: Trimming Help


    Courtesy of Buddy, I've placed (with his permission) his summary of the "trimming" issues.  Probably many of you share my view that his summary was one of the most on-target, concise statements I've read about trimming in a VERY long time, if ever!!!  Posted here for your reference:
    http://www.rcaerobats.net/trim_chart.htm

    Thanks, Buddy!

    Bob Pastorello, Oklahoma
    NSRCA 199, AMA 46373
    rcaerobob at cox.net
    www.rcaerobats.net


      ----- Original Message ----- 
      From: BUDDYonRC at aol.com 
      To: discussion at nsrca.org 
      Sent: Tuesday, March 30, 2004 1:08 PM
      Subject: Re: Trimming Help


      Paul
      I am no aerodynamics expert, but I have learned some basic's over the years that work for me.
      1. The wing must have a positive angle of attack to create lift.
      2. the stabilizer and elevators steer the pitch attitude of the airplane resulting in more or less lift.
      3. Balance can change the angle of attack which will change the pitch attitude.
      4. Aileron's up or down will change the pitch attitude .
      5. Up or down thrust will change the pitch attitude.
      Therefore:
      A. Increasing the positive wing incidence will cause the airplane to climb, which will require down trim to achieve level flight.
      B. Likewise adding tail weight will cause the airplane to climb and require down trim to achieve level flight.
      C. Added weight does not alter the vertical down line BUT elevator trim added to maintain level flight because of the added weight will effect the down line. Tail weight will require down trim which will steer the airplane more to the belly in a down line, and added nose weight will require up trim which will steer the airplane to the canopy.
      D. In the vertical up line elevator trim and the engine thrust line will effect the vertical and/or yaw direction   
      All of the above will effect the knife edge flight of the model.
      Combinations of adjustments to any or all of the above trim items done at the same time will leave you confused and frustrated.
      Most models will require some mixing to achieve near perfect lines in all flight attitudes in order to minimize / eliminate control inputs by the pilot to maintain a perfect course.
      I have yet to see the perfect airplane should such an animal exist, but I keep looking and building since I truly believe that nothing is impossible.
      When trimming an airplane make a written log of every change no matter how small so you don't have to start over when changes are not correct.
      Buddy 
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