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Thread: Series 7 flying question.

  1. #11
    Senior Member jrevens's Avatar
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    Default Re: Series 7 flying question.

    I think John McBean gave an excellent description of how they adjust for a "heavy wing" at the factory (I believe it's posted somewhere on this forum), and that's how I attacked my slightly heavy left wing...

    First check that you don't have a yaw issue that's causing the turn.

    For a left turning tendency - adjust the right wing rear lift strut rod end out 1 turn (decrease the wash-out). Pre-flight and test fly after each adjustment.

    If not enough, adjust the left wing rear lift strut rod end in 1 turn.

    If still not enough you can start adjusting the front lift strut rod ends ... right one in first, and lastly left one out.

    John wrote that you might only need 1/2 turn, or maybe as much as 1 1/2 turn... it depends on the severity of the roll rate.

    It seems to me that doing the adjustments in this order should result in the least amount of necessary twisting of the structure on any one wing to get the desired result.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  2. #12
    Senior Member jiott's Avatar
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    Default Re: Series 7 flying question.

    Good post John, however we need to clarify some nomenclature. If you adjust the rear rod end OUT, that Increases the washout because it is reducing AOA. Unless I am mistaken, washout is defined as the wingtip having LESS AOA than the root of the wing so it will stall later than the root. If I am wrong about this please advise.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #13
    Senior Member jrevens's Avatar
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    Default Re: Series 7 flying question.

    Thanks, Jim. Yes, I think you're right. I mostly copied that statement from John's post, but what he had actually written was "decreased twist (wash-out)"- sorry I don't know where it is in the archives of this forum, but I had copied and printed it a long time ago for reference. I interpreted his statement as saying that decreased twist was the same as decreased washout, which it isn't in this instance of course. The twist is actually increased by extending the rear strut rod end further out. I guess it would have been more correct to say "decrease the angle of attack of the tip", rather than "decrease the wash-out". Is that confusing enough for everyone?
    Last edited by jrevens; 06-13-2019 at 10:14 PM.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  4. #14

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    Default Re: Series 7 flying question.

    Thanks for the clarification on how to adjust the struts, saved me a lot of time searching for the info. I’ll check the measurements and adjust it this weekend. Thanks for the help.
    Les
    Model 7 SS flying
    160hp 0-320 lycoming

  5. #15
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    Default Re: Series 7 flying question.

    Does anyone do stall tests after these adjustments are made ?. Just interested to know how much/if they make much of a difference to handling ...
    David
    SS7 Builder

  6. #16
    Senior Member Dave S's Avatar
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    Default Re: Series 7 flying question.

    David,

    On first flight, noticed a slight wing heavy but entirely controllable - did one power off stall at significant altitude over the 'port in order to accurately determine what approach IAS to use for the first landing. That stall was the typical Kitfox gentle power off stall everyone indicates. Refrained from any more stall testing until the wing heavy issue was perfectly resolved so all stall series done in phase I, except for the initial one on first flight, was done after resolution of the wing heavy deal.

    My thinking was to get the wing rigging right before continuing testing. The theory I was working off is get any observed anomaly corrected before continuing.

    Now, had the wing heavy observation been extreme, I probably would have avoided doing a single stall test on the first flight.

    As to your question - I am not sure that it is possible to compare one power off stall before getting the wing adjusted with the entire stall series after adjustment other than to say that all power off stalls with the kitfox have been gentle. Cannot address power on stalls since I had no intention of doing a power on stall on the first flight in any case.

    Hope that helps some.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  7. #17
    Senior Member jiott's Avatar
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    Default Re: Series 7 flying question.

    I did some stall tests after adjusting the heavy wing and could not tell any measurable difference, which was what I wanted to know. Unless you build a crooked airplane that takes a lot of heavy wing adjustment, I don't think the stall characteristics are affected to any noticeable degree. However, I like your thinking about fixing all flying anomalies before continuing the final Phase I testing.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  8. #18
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    Default Re: Series 7 flying question.

    Thanks DaveS and Jim. Yes, my question probably relates more to the situation where larger adjustments were necessary, but I think you're right ... wing rigging or build symmetry would have to be way off for any noticeable stall behaviour changes.
    David
    SS7 Builder

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