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Thread: Elevator Trim Assist

  1. #1

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    Default Elevator Trim Assist

    I have installed the trim assist kit. It is still necessary to hold the nose up with the stick to achieve the final approach airspeed. I would really like to be able to trim out all forces to on final. Any suggestions?

    Tom Livermore
    S7 Supersport

  2. #2
    Senior Member Dorsal's Avatar
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    Default Re: Elevator Trim Assist

    Mine will fly final hands off (not that I would recommend that ), settles in around 60 mph @ idle, full up trim, 1/2 flaps.
    Dorsal ~~^~~
    Series 7 - Tri-Gear
    912 ULS Warp Drive

  3. #3
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    Default Re: Elevator Trim Assist

    Any back pressure at final approach speed was unacceptable to me when I started test flying my Series 5 many years ago. With 1/2 flap and a over the fence speed of 55 MPH (solo) back pressure was required, which I decided I would have to fix. Mind you I have the Continental IO-240 up front which is a 250 lb engine so this was part of the problem, always bumping up to the forward CG limit in solo conditions. Adding a tool kit to the aft baggage compartment helped and with the addition of the trim assist kit when it came out solved the problem. Now I can do hands off like Dorsal says at my final app. speed. So I would suggest rechecking your Wt & bal. and try some different weights in the aft part of the baggage compartment to see if it helps your problem. If it does, then maybe consider moving some required equipment elsewhere aft to aid the problem. As an example with the IO-240 the battery must be in the empennage and has to be a heavy one not one of the new lightweight units, my holley fuel pump is behind the header, heavy 3 leaf tail spring in other words anything I could put aft I did. good luck Bruce N199CL

  4. #4
    Senior Member jiott's Avatar
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    Default Re: Elevator Trim Assist

    Also make sure you are getting maximum nose-up trim by adjusting the rod end on the top of your trim ballscrew so that when you command max nose-up, the horizontal stab leading edge tube is just a whisker from touching the bottom of the slots in your tail access covers. This is different from what the manual tells you, but it helps a lot and you will still have plenty of nose-down range. You will never be able to get hands-off trim for 60 mph with full flaps, but with 1/2 flaps you should have some trim to spare.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  5. #5
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    Default Re: Elevator Trim Assist

    Related question to trim .... I recall someone saying that kit aircraft have slightly different flap settings than factory built. Is that correct or have I smoked something I shouldn’t have ... ?
    David
    SS7 Builder

  6. #6
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    Default Re: Elevator Trim Assist

    David , My Series 5 flap settings are 11 deg, for first notch and 22 deg for full flaps. Full flaps is very rarely used by me as the aileron/rudder control harmony goes out the window. For true soft field takeoffs out of snow or muck I will start my takeoff run with 11 deg and at around 35 MPH pull full flaps and she is instantly airborne, then I retract back to 11 deg after speed picks up in ground effect and climb to 400 AGL with 11 deg . then clean up from there. Bruce N199CL

  7. #7
    Senior Member jiott's Avatar
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    Default Re: Elevator Trim Assist

    Yes David, the SS7 kits have more aggressive flap settings than the SLSA. That's why many of us have been recommending adding another flap notch between 1/2 and Full on the kits.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  8. #8
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    Default Re: Elevator Trim Assist

    Thanks Jim, I had an idea it was you who posted something along those lines before. Think I'll incorporate a flap setting midway as you suggest.

    And Bruce, I like that takeoff method. Must be a hoot to watch from the sidelines, something akin to instant levitation !. I'm gonna try that when I get mine airborne in couple/three months. And an interesting comment about aileron/rudder effects past full flap. Han't heard that before. Thanks.
    David
    SS7 Builder

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