[NSRCA-discussion] Rudder

Thu Oct 11 09:41:55 AKDT 2007

I'm with ya, Ken !   Even on the ground, things are contingent on whether the engine is running or not and at what RPM.
G.

  ----- Original Message ----- 
  From: Ken Thompson 
  To: NSRCA Mailing List 
  Sent: Wednesday, October 10, 2007 7:26 PM
  Subject: Re: [NSRCA-discussion] Rudder

  Nope, only until the side area towards the wind, aft of the CG, is lessened enough to not be affected by said wind, due to the rotation of the fuse on the CG.  In theory, the fuse would "yaw" to a point where the area in front and behind the CG becomes equal.  In forward flight the pressure on the vertical fin counteracts some of that rotation.  When the bird is stationary on the ground, no forward motion, the fuse will rotate until the nose is directly into the wind, unless friction from landing gear prevents that rotation.

  my .02

  Ken
    ----- Original Message ----- 
    From: Dave Lockhart 
    To: 'NSRCA Mailing List' 
    Sent: Wednesday, October 10, 2007 6:15 PM
    Subject: Re: [NSRCA-discussion] Rudder

    So if I follow that theory to its conclusion, the airplane would rotate in yaw until it was pointed directly into the wind?  This of course assumes the moment of side area is greater aft of the CG (which it is for pattern planes, otherwise we'd find ourselves regularly using "bottom" rudder as with many a 3D foamy).

    Just a question.  I'm not pledging support to either side of the discussion <G>.

    Dave

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    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Stuart Chale
    Sent: Wednesday, October 10, 2007 6:11 PM
    To: 'NSRCA Mailing List'
    Subject: Re: [NSRCA-discussion] Rudder

    It does.  That is what causes the plane to weather-vane, weather-cock or whatever you want to name it into the wind.  The nose does turn into the wind (again from my experience).  The faster you are flying the less this occurs due to the aerodynamics of the vertical fin etc coming into play..  

    Theory on my part

    There is a point on the plane close to the CG where the plane will yaw around when a force is applied be it with rudder or wind blowing from the side.  If the forces were equal in front and behind this point the plane will just blow with the wind.  If the force is greater behind this point (think of the vertical fin and rudder on a long moment arm, the fuse) then the plane should turn into the wind.  The wind blowing on the rear of the plane will produce a greater force than the wind blowing on the plane in front of this point. I do not think it matters if the plane is on the ground or flying.  It will still turn the same way, obviously much greater with the plane on the ground and a friction point available.

    Stuart

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    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jerry Voth
    Sent: Wednesday, October 10, 2007 4:34 PM
    To: NSRCA Mailing List
    Subject: Re: [NSRCA-discussion] Rudder

    I've been folloing this thread and there is one thing that puzzles me. The vertical fin and rudder are (and I'm guessing) about 20% of the total side area of a pattern plane. If it were weathervaning,why wouldn't the nose be more prone to blow in the direction of the wind?

      ----- Original Message ----- 

      From: Del K. Rykert 

      To: NSRCA Mailing List 

      Sent: Wednesday, October 10, 2007 2:23 PM

      Subject: Re: [NSRCA-discussion] Rudder

      Thank goodness judges don't have a T & B ball in a panel in front of them to watch how many are skidding through the air.. grins..  I have always felt if all things are pure the pattern airplane in true corrected crab maintains it same speed when pulling to vertical and the crosswind component stays constant then no further input is needed till your speed starts to decay when pulling vertical.  What many are doing is flying one wing low when in level fight then when they pull vertical have to sneak in some extra correction for pulling a highly visible vertical to the judges. 

          Del 

        ----- Original Message ----- 

        From: Woodward, Jim 

        To: NSRCA Mailing List 

        Sent: Wednesday, October 10, 2007 1:31 PM

        Subject: Re: [NSRCA-discussion] Rudder

        Bob - the correct answer on using aileron during a radius, for the purpose of wind correction, is that if you are NOT using it is a downgrade(able).   It's impossible in every way to use only rudder through a radius actually keep the "wings-level" to the intended flight path.

        Maneuvers are to be wind-corrected and flown in a single vertical plane - anything less is uncivilized J 

        The wings should be "level" at every part of the curve/radius, and the only way to do that is by rolling the plane, slightly.

        Thanks,

        Jim W.

        From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Bob Richards
        Sent: Wednesday, October 10, 2007 1:19 PM
        To: NSRCA Mailing List
        Subject: Re: [NSRCA-discussion] Rudder

        That is the best description I have read so far. Agree 100%.

        Not long ago, I was talking with someone about wind correction and mentioned that a very small amount of aileron should be used when pulling a radius to a vertical line. He said if he ever saw me do it while he was judging, he would downgrade. I told him if I do it right, he will never see it. :-)

        Bob R.

        J N Hiller <jnhiller at earthlink.net> wrote:

          This has been an interesting discussion. The airplane dose not establish a crab angle on it's own when in the air. The airplane has a crab angle in horizontal flight and when it is pulled vertical the wings will not be perpendicular to the flight path without a roll correction. The need for the correction will be apparent and automatically applied prior to finishing the radius. When a roll input is applied with elevator it changes the heading in the direction of roll, (think barrel roll) in this case into the wind as it finishes the radius. Most of the time it will be excessive requiring a little opposite (down wind) rudder correction unless the upwind wing was high entering the pull-up. Once the airplane is leaning to one side in a vertical the lean will increase and is especially noticeable as it slows. Some increase is needed to maintain wind correction and the need for opposite rudder to maintain a vertical track depends on how rapidly the airplane is decelerated. Most of the time I will try to apply some down wind rudder with the roll correction at about 45 degrees, before the need becomes visible as it is nearly always required. In short just point the airplane in the direction you want it to go and stir the sticks as necessary.

          Jim Hiller

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