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Thread: Slat applied to the airfoil USA35B (PA-18)

  1. #1

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    Slat applied to the airfoil USA35B (PA-18)

    hello to all colleagues,
    I'm Salvo from Italy and i'm an amatorial homebuilder of light aircraft.
    Now in my Garage I'm building a Corby Starlet (construction is at 65%).

    I joined this forum mainly to search for information about the aerodynamic wing of the legendary Piper PA18.


    I would like to know the exact dimension of the slat applied to the airfoil USA35B of the PA-18.

    thanks to all.

    Salvo from Italy

  2. #2

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    Are you wanting dimensions for slats (which vary), or for flaps?

  3. #3

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    I suspect he'd like a dimensioned section drawing.

  4. #4

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    Of a slat?
    Or of a flap?

  5. #5

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    Quote Originally Posted by stewartb View Post
    I suspect he'd like a dimensioned section drawing.

    hello to all my friends!

    forgive me for the quality of my English...

    says the colleague who I quoted i need a dimensioned section drawing of the SLAT in relation at the airfoil.

    Is there someone who can help me?

    thanks to all
    Salvo from Italy

  6. #6

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    There are a number of different slat designs (though none for stock Cubs). Which one do you want?
    Need more information.

  7. #7

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    thanks for the reply.

    I'd be the size of the slat that have proven most effective in the field to provide STOL performance.

    My idea would be to copy the entire wing section without changing the chord of the airfoil and use the same size of the slats and then design an ultralight plane STOL around.

  8. #8
    Southern Aero's Avatar
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    Quote Originally Posted by kickboxing View Post
    thanks for the reply.

    I'd be the size of the slat that have proven most effective in the field to provide STOL performance.

    My idea would be to copy the entire wing section without changing the chord of the airfoil and use the same size of the slats and then design an ultralight plane STOL around.
    Kick

    If you are wanting to use a "slotted" type USA35B section as Piper used on the L14, Dakota Cub has these readily available in the 63" sized for the Pipers with 31" spar centers................. If you need a different chord and/or size you can use the section as a pattern for your needs. The old L14 prints are available but can be difficult to read, they are from the 1940's. But if you only need the profile they should work fine. .............. Or do you mean you want to add a "slat" to existing section as in the Turbine Cub type of slat? or Helio style?
    ......... It doesn't cost any more to go first class! You just can't stay as long.

  9. #9

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    USA35B section in the 63" sized is perfect but i need it with the slat profile....

    I did a quick drawing of what I would need in the attachment

    very important is the relationship between airfoil and slat in X;Y .... raise, lower or farther away and closer the slat respect the airfoil sezion changes all the wing behavior worse.

    I hope I explained myself... sorry for my bad English

    Salvo
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	example section airfoil + slat.jpeg 
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Size:	86.8 KB 
ID:	28293  

  10. #10
    Southern Aero's Avatar
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    Quote Originally Posted by kickboxing View Post
    USA35B section in the 63" sized is perfect but i need it with the slat profile....

    I did a quick drawing of what I would need in the attachment

    very important is the relationship between airfoil and slat in X;Y .... raise, lower or farther away and closer the slat respect the airfoil sezion changes all the wing behavior worse.

    I hope I explained myself... sorry for my bad English

    Salvo
    I believe this is what you are looking for........... I dont have actual dimensions but this is the profile.

    Click image for larger version. 

Name:	Turbine Slat2.jpg 
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Size:	967.3 KB 
ID:	28294

    This is the Mackey/Turbine Cubs style slat add on. Google them for more info. It changes the section from a USA35B to an "unknown" section with pivoting slat/slot but works quite well. I work more with tracked slats such as in the Helio
    ......... It doesn't cost any more to go first class! You just can't stay as long.
    Likes AK_Logan liked this post

  11. #11

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    if I have understood well, this information is too generic and inaccurate to calculate exactly a wing and consequently an airplane

    impossible to calculate on an unknown profile

  12. #12

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    hello to all!

    No one who can give me a scale profile?

    Salvo from Italy

  13. #13
    fobjob's Avatar
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    Is everyone aware that the cub airfoil is "modified", it's upper ordinates are increased by 4%, I believe....
    Likes pzinck liked this post

  14. #14

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    This begs the question: Who has spent money in a wind tunnel to optimize the position of their slats? Now that Zenair owners are leaving theirs off and not missing them, does anyone have proof that amateur efforts are effective? It seems some let them float because they really don't know. The trailing edge of a sailboat jib doesn't float.
    Not talking about Helio style, they pop out to a fixed position.
    What's a go-around?

  15. #15
    skywagon8a's Avatar
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    Quote Originally Posted by Skywalker View Post
    Not talking about Helio style, they pop out to a fixed position.
    And they are controlled aerodynamically. And, were designed by an MIT aerodynamics professor, Otto Koppen.
    N1PA

  16. #16
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    Quote Originally Posted by skywagon8a View Post
    And they are controlled aerodynamically. And, were designed by an MIT aerodynamics professor, Otto Koppen.
    Like the A-4. Q controlled slats.

    Too bad they're a heavy and complicated design, it gets rid of a lot of the drag compromises an "add-on" slat has.

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    The problem is just that, I would like to have the measures of something already experienced and tested!

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    Quote Originally Posted by kickboxing View Post
    The problem is just that, I would like to have the measures of something already experienced and tested!
    I have a good feeling that Wayne Mackey has a pretty good idea of what works on an experimental Cub....seems like he's been getting some awesome performance figures...and as a bonus has increased the safety margin tremendously in the biggest flight hazard in a Cub IMHO...the stall-spin at low altitude.

  19. #19
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Randy View Post
    ...has increased the safety margin tremendously in the biggest flight hazard in a Cub IMHO...the stall-spin at low altitude.
    ??????????

  20. #20
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    No stall-no spin

  21. #21
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Randy View Post
    ..has increased the safety margin tremendously in the biggest flight hazard in a Cub IMHO...the stall-spin at low altitude.
    No stall-no spin
    moved it.... to a lower, smaller range?

  22. #22
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    Not exactly what you mean about "lower, smaller range"....I'm talking about lethality....I spose if you are talking absolutes..yeah..somebody will find a way to stall one...maybe a few less "moose stalls" happening.

  23. #23
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Randy View Post
    Not exactly what you mean about "lower, smaller range"....I'm talking about lethality....I spose if you are talking absolutes..yeah..somebody will find a way to stall one...maybe a few less "moose stalls" happening.
    lower start MPH... smaller gray area...

    been proven a few weeks ago in Valdez and Talkeetna...

  24. #24
    Randy's Avatar
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    I saw that video, I don't think that is the typical scenario that leads to the statistics we don't like to see.
    Like I wrote...no absolute method to stop low altitude crashes...I'd say that incident would have been an outlier.

  25. #25
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    Leading edge flaps(slats) increase the angle to which you can rotate the wing , hence higher lift coefficient....trailing edge flaps increase the lift coefficient at any given angle, BUT what is going to keep you alive, is to make SURE that the inboard wing stalls well before the outboard section in front of the ailerons. Full span slats (and VGs) make me nervous....
    Last edited by fobjob; 07-18-2017 at 11:30 PM.

  26. #26
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    I feel sorry for this guy. I knew what he was asking for from his first post and it has gone to 25 answers now with no information for the poor guy. If I had it I would give it to him. Does no one have a PDF, IGES, DXF, DWG file that provides the profile for the slat and brackets that is used by almost all the cubs out there. This is what he is asking for.

    Never mind I see this is an old thread that was never helpful for the poor guy!

  27. #27
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    Since I'm bored today, it's a good time to enlarge some of these thoughts....even the classic book on theory of wing sections (link below) won't give you exact layouts on leading edge devices. However, they aren't real critical..what is critical, is the interaction of the whole wing with these devices. You don't want to run one contiguous slat per wing, due to torsional rigidity (flutter) considerations and the fact that if the wing is twisted("twist-out"), the outboard section wants to "deploy" at a different point than the inboard section, but this can work backwards, and you really don't want that. (you want the outboard section to deploy first)(this is going to depend on the amount of twist-out and you may have to use a return spring on the inboard slat) Ideally, the stall on a wing should start on the inboard trailing edge and migrate outboard until the entire wing is involved. However, the cub wing does not do that, exactly. It starts at the leading edge of the inboard end of the aileron due to the excessively wide gap between the wing and the aileron. (Jerry Burr determined this during his tuft testing) The 2 1/2 degree twist in the wing delays it's progression, but at the cost of a large amount of profile drag. So, if I was building an experimental cub, (and didn't change the airfoil itself), I would put slats on, but leave the inboard 4 feet or so of wing unslatted... different ailerons (PA-12, maybe) with a pointy-er leading edge, to improve adverse yaw problems and close the gap... a stall initiation strip on the inboard leading edge of the wing....and a fence on the top of the wing between the flap and aileron, and another short fence on the bottom of the outboard end of the flap to reduce spillage from a deployed flap onto the aileron. I would want the stall to be delayed, but very obvious with pitch axis turbulence right up to the point that it did a full stall with NO drop in either wing, but DID NOT stall the horizontal stab at forward CG conditions. (resulting in a severe nose-down divergence) (probably use a strake at the tail like one of the VG stc's....) I would then adjust twist-out to the minimum necessary. Just my opinion...
    https://www.amazon.com/Theory-Wing-S...+wing+sections
    Last edited by fobjob; 07-19-2017 at 11:04 AM.

  28. #28

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    Quote Originally Posted by Mauleguy View Post
    I feel sorry for this guy. I knew what he was asking for from his first post and it has gone to 25 answers now with no information for the poor guy. If I had it I would give it to him. Does no one have a PDF, IGES, DXF, DWG file that provides the profile for the slat and brackets that is used by almost all the cubs out there. This is what he is asking for.

    Never mind I see this is an old thread that was never helpful for the poor guy!

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