Re: Rudder size effect on control

From: Sandy Schaefer <SandySchaefer708_at_msn.com>
Date: Fri, 21 Sep 2007 23:06:28 -0400

Pete Wrote:

"I've seen a stable flying model under power suddenly start to rock
and not turn so well in the tail end of the cruise phase and wondered
if it needed a larger rudder."

 Could be to small a rudder area if the air is turbulent enough or draft. Normally, if everything else is sound (No warps, good straight built etc.) that rocking late in the flight is caused by to much stab tilt being used for turn. To sharp of rudder angle will cause this also. I'm speaking of Wright Stuff planes by the way have little idea on many other indoor classes where physics varies.

 If stab is to small sliding to outside of circle could occur (some people consider that good if circle gets bigger slowly on way down). The angle of rudder and flight speed comes into play also regardless of size Many people add left thrust into prop bearing, tilt the stab or another of ways to make a model turn to excess creating to one degree or another a bind that results in added drag. Any single turning point if excessive will start showing later in the flight by some type of rocking or un level model. It's best to make all points assist in the turn in a moderate way. That can be a hard thing to determine only by watching the flights with final result being stop watch.

 Added weight is always a concern when another part of plane could have been built stronger. Frontal drag when taller rudders are used. I've always been surprised how small rudders are on many of best models. They tend to use all points of turning to achieve the circling.

MS

  ----- Original Message -----
  From: and4metoo<mailto:stankos_at_att.net>
  To: Indoor_Construction_at_yahoogroups.com<mailto:Indoor_Construction_at_yahoogroups.com>
  Sent: Friday, September 21, 2007 8:58 PM
  Subject: [Indoor_Construction] Rudder size effect on control


  When deciding how big or small (surface area) a rudder should be,
  what behavior would you see if the rudder is too small? I guess there
  would be a point that big enough is enough and then you just gain
  weight if you continue.
  I've seen a stable flying model under power suddenly start to rock
  and not turn so well in the tail end of the cruise phase and wondered
  if it needed a larger rudder. Not more angle (drag), just more area.
  Any thoughts? thanks
  Pete..



   

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Received on Fri Sep 21 2007 - 20:14:55 CEST