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Thread: PA-18A Flap Settings

  1. #1
    Cubonaut875 SchulerJL's Avatar
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    PA-18A Flap Settings

    Does anybody know the flap setting in degrees for the 3 notch PA-18A flap ratchet? I searched the site, I know I saw it before but I can't find it.

  2. #2
    Steve Pierce's Avatar
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    This is all I have ever seen from the TCDS.
    Flap 0° Up 50° ± 2° Down
    Steve Pierce

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    Likes mike mcs repair liked this post

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    BC12D-4-85's Avatar
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    My 18A had ~12, 25, 50*. The 12* was great for slow cruise and didn't buffet. It's easily cut into a regular ratchet. Pull 12 or so, mark the ratchet where the flap handle tab sits, then cut the notch to match the others. So I've heard at closing time.

    Gary

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    phdigger123's Avatar
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    My 18A had a notch at about 10*.

  5. #5
    Cubonaut875 SchulerJL's Avatar
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    I was comparing the ratchet to the standard and it looks like the first notch is probably about 12, but the second notch looks greater that the first notch on a standard ratchet like the 25 and the third notch definitly looks less than the standard ratchet like about 45 degrees. Why would a PA18A have less flap than a PA18? hmmmmmmm - inquiring minds want to know.

    Quote Originally Posted by BC12D-4-85 View Post
    My 18A had ~12, 25, 50*. The 12* was great for slow cruise and didn't buffet. It's easily cut into a regular ratchet. Pull 12 or so, mark the ratchet where the flap handle tab sits, then cut the notch to match the others. So I've heard at closing time.

    Gary

  6. #6
    BC12D-4-85's Avatar
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    My measurements were from a new 18A rachet in 1977 that I put on a straight 18. Used a bubble level but now we have digital ones. The original two-position ratchet would sometimes "slip out of gear" as they wear from use. Later I owned a 18A and checked it and they were close to the new specs. But they do wear, as does the flap tab or pin that extends from the handle, so over time the flap deflection may decrease some. Loose flap cables can do that too.

    Gary

  7. #7
    BC12D-4-85's Avatar
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    www.SkupTech.com mike mcs repair's Avatar
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    all you can "set" is MAX deflection... then just depends where you grind the notches.... and some Univair ones were made wrong overall length.....(too short the one I ran into)

  9. #9
    S2D's Avatar
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    According to AR7 and 1A2, all flap equipped 18s should have 50 deg. deflection. So if you can actually measure 50 deg on your 18 or 18A , should be easy to measure what the other settings are. (probably what Gary said) .
    I'll see if mine has 50 deg. from full up to full down and measure the other settings.

    I'm sure somebody way smarter than me could just measure the ratchet with a compass and figure it out.
    Last edited by S2D; 03-11-2018 at 09:21 PM.
    I may be wrong but that probably won't stop me from arguing about it.

  10. #10
    BC12D-4-85's Avatar
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    That older SC.org link in #7 has some pics of the ratchet and use of flaps. Lots of good comments and suggestions. First notch is a working-spraying option I assume for additional lift and visibility over the nose with a load at application speed (?). I like them having that option just like I used 10* in Cessna's for the same reason. I wore out a set of flap tracks (roller grooves too deep) and various parts at the 20* setting so decided to use 10 for loitering when possible.

    Gary

  11. #11
    cubpilot2's Avatar
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    I’ve heard that this can be a function of the cable routing design between the two airframes. ( sort of a geometry thing) I have not tested it but was told that an original 18A ratchet installed in a standard cub will give less deflection whereas in the A it is proper.
    We used to just modify the standard cub ratchet when converting them to sprayers be adding a ten deg or so setting.

    I find the first 10 deg notch in use much of the time. Especially in any slow speed mode or in any sort of tight turn where it helps in bringing it around. As sprayers you always saw the first notch being pulled going into a turn.
    Ed

  12. #12
    Cubonaut875 SchulerJL's Avatar
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    That makes sense. I bought a new standard ratchet and a PA18 A ratchet from Univair and I traced the two out. As some of you may have read in previous posts, I just had Performance STOL flaps installed and I am learning how to use them effectively. I tried the A ratchet and it does allow full retraction, and it gives me that what looks like 10 degree setting with about a 25 degree setting and just short of full 50 degrees - it was that last couple of degrees that was very difficult to pull with the shortened handle. I'll measure the angles and report back. Hopefully I can fly it this week - ya hoooo time change.

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    Quote Originally Posted by cubpilot2 View Post
    I’ve heard that this can be a function of the cable routing design between the two airframes. ( sort of a geometry thing) I have not tested it but was told that an original 18A ratchet installed in a standard cub will give less deflection whereas in the A it is proper.
    We used to just modify the standard cub ratchet when converting them to sprayers be adding a ten deg or so setting.

    I find the first 10 deg notch in use much of the time. Especially in any slow speed mode or in any sort of tight turn where it helps in bringing it around. As sprayers you always saw the first notch being pulled going into a turn.
    Last edited by SchulerJL; 03-12-2018 at 05:02 AM.

  13. #13
    Gordon Misch's Avatar
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    I’ve heard that this can be a function of the cable routing design between the two airframes.
    Yes. The location of the first pulley (closest to the flap handle) in relation to the clocking of the flap handle bellcrank can make a lot of difference.

    I played around with that a lot in my -12 rebuild, in order to get 52 deg at full deflection (on the ground, no aerodynamic loading).
    Gordon

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