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  1. #1
    Don Szczur's Avatar
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    Control throw philosophy- pattern

    Why use more control throw than you need? Someone recently asked for my control throw setup on the FOCUS II pattern airplane. The discussion triggered thought on some experience I found that may be helpful to you. I utilize low rate for normal flying and high rates for stall turns, spins, and snap. This is a setup that is just a personal preference. It was once suggested to me that a single rate is preferable- providing control at all times without the worry of dual rates. I tried this and found that there was just too much contol around neutral, and when a significant amount of expo was put in, roll rate and radius segments became inconsistent. The "happy medium" was a single dual rate switch (activating the ailerons, elevator and rudder dual rates simultaniously, through the COMB function on the 10X). The additional expo on the high rate provided nearly the same feel around neutral for either high or low rate. This means that if a little elevator was being held, for example on the way up for an avalanche, that there would be no movement or change in radius of the loop segment if the dual rate switch was activated just prior to snap roll. Any case, here are the settings for the Focus. The expo for low and high rates provide nearly the same feel out to about quarter stick.


    Ailerons low rate 9 degrees up and down. Expo 19 percent. High rate ailerons 11 degrees up and down, expo 26 percent

    Elevator low rate 8 degrees up and down, expo 25 percent. Elevator high rate 14 up and 13 down, expo 50 percent.

    Rudder low rate 1 inch (measured from the top of the rudder) with 44 percent expo. Rudder high rate 1 3/8 inch, 70 percent expo.

    Normal flight is low rate, stall turns, snaps and spins on high rate.

  2. #2

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    RE: Control throw philosophy- pattern

    I do believe I'll give that a try.

    Thanks much.

  3. #3
    Don Szczur's Avatar
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    RE: Control throw philosophy- pattern

    Two more thoughts on this. Control responsiveness is quite a bit to do with airplane design. For example, I'm able to snap, spin and one-roll loop on low rates with the Brio. This is very interesting- would not be able to do that on the Focus.

    Another thought- I was thinking about servo speed, control responsiveness and servo setups.

    The mainstream line of thought is that one wants to move the control horn away from the surface as much as possible, and only put in enough throw (mechanically) so when you fly on low rate you are maxed out on the stick deflection, with 100 percent throw rate. Anything above 100% ATV or dual rate and its going to lose resolution on the PCM.

    What about effective servo speed? To get a nice clean snap, one wants crisp responsiveness on the controls. Here is a thought. If you move the control horn in closer to the surface rather than far away, and then use dual rates, so high rate is for snaps, basically you've sped up the (effective) servo speed. You move the Tx stick and the control surface moves faster because its got a lot of throw (but not all of it is utilized). I'm going to give this some more thought.

    If I could draw my own expo curve, I'd want it to be insensitive around neutral yet not as steep of a curve (elbow) on the mid-stick. See, too much expo results in inconsistent roll rates and a "pitchy" elevator. If you are flying and having a hard time maintaining consistent heading or roll exits (hunting) you may have too much expo. By moving the control arm in, and then taking back the dual rate, it flattens out the expo, and quickens up the servo response. The trade off is loss in servo resolution, but what loss is that (at least on a windy day as most seem to be these days).

    Random thoughts on control throw philosphy.

    Don

  4. #4

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    RE: Control throw philosophy- pattern

    Don....Thanks for posting the Focus control setup. I put about 12 flights this weekend on my just completed Focus II. Followed your setup. I have never had a first flights go so well!


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