Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: Wing Incidence

  1. #1

    Join Date
    Dec 2009
    Location
    Lawrenceville, GA
    Posts
    180

    Default Wing Incidence

    Question for the group:

    I'm working on a 2003 classic 4 fuselage and one thing that is notable is that the rear wing attachment is much lower than on my KF III. Looking over another builder's 1995 vintage KF 4 fuselage his rear wing attachment height looks the about same as the KF III.

    So when was the wing incidence angle increased and why? Can't make it go faster so is it to get off the ground quicker? This 2003 fuse has brackets for tricycle gear so is there a connection?

    Just curious,

    Mark Napier

  2. #2
    Senior Member SkyPirate's Avatar
    Join Date
    Apr 2009
    Location
    Edgar Springs MO
    Posts
    1,841

    Default Re: Wing Incidence

    not positive,..but a possibility,..is your kit a high lift wing kit?

    you can check the incidence or angle of attack,..by leveling the tail horizontal stab..then take a level and lay it accross the top of the wing mounts,.. if you've got as scientific calculator ..you can check the angle , once you have the dimensions ,..using sine cosine and tangent dimensions to get the angle or just get a protractor ,.

    most GA aircraft have a 6 degree incidence,..you'd have to ask John @ kitfox what the model 4 classic incidence is suppose to be and if there is a difference between the standard and high lift option.

    if a high lift wing option was available for that model


    Chase
    Last edited by SkyPirate; 02-10-2010 at 10:28 AM.

  3. #3
    Senior Member t j's Avatar
    Join Date
    Oct 2009
    Location
    Ellensburg, WA
    Posts
    861

    Default Re: Wing Incidence

    Mark, here's a measurement from a 1994 vintage Classic 4. I am curious to know if it is different than your 2003. From the top of the front spar attach lug to bottom center of the front float fitting and from the top of the rear spar lug to the wing strut attach fitting are both 39 inches.
    Tom Jones
    Classic 4 builder

  4. #4
    Senior Member SkyPirate's Avatar
    Join Date
    Apr 2009
    Location
    Edgar Springs MO
    Posts
    1,841

    Default Re: Wing Incidence

    good idea TJ ,..but now measure from top front to bottom rear ..and top rear to bottom front ..this will show if there is a difference,..it can still be the same measurement top to bottom on front and rear ..but diagonally will tell the angle..
    because the wing folds,..the pivot of the strut and the rear wing mount should be in line paralell to each other,..the difference from bottom rear, or pivot of the strut,.. to top front will give difference for the angle.

    unless the whole plane ,,,meaning pivot of the rear wing mount and strut mount is tilted ..then to get the righjt AOA ,..you need to go to first post and level tail horizontal stab ..then take a level and set it on top of the wing mounts ,,hold the level at level and measure the gap between rear wing mount and bottom of level ,..then do the cosine sine and tangent measurements to get angle of attack,..

    I'm guessing it is around 4.5 degree's

    didnt do the math ..just a guess

    Chase
    Last edited by SkyPirate; 02-10-2010 at 03:26 PM.

  5. #5

    Join Date
    Dec 2009
    Location
    Lawrenceville, GA
    Posts
    180

    Default Re: Wing Incidence

    Probably Saturday when I get back to the hanger but will write down some measurements then. I may already have those written down in my book.

    I do remember that it is hard to get a good number for the rear because the door frame is in the way.

    I'll try to get a couple of pictures too. The difference in the lengths of the tubes just above the side windows and the angle of the tube bracing just below the top rear carry through is very evident.

    Cheers,

    Mark

  6. #6
    Senior Member SkyPirate's Avatar
    Join Date
    Apr 2009
    Location
    Edgar Springs MO
    Posts
    1,841

    Default Re: Wing Incidence

    let me know the dimensions and I'll figure your AOA or incidence for you ..

    sounds like someone might have modified it or ..that model did offer the high lift wing set up.

    Chase
    Last edited by SkyPirate; 02-10-2010 at 04:14 PM.

  7. #7
    Senior Member t j's Avatar
    Join Date
    Oct 2009
    Location
    Ellensburg, WA
    Posts
    861

    Default Re: Wing Incidence

    Mark, the measurements I took are not to establish what the incidence is, just to verify if there was a change in the later classic 4. My plane is finished so on the rear measurement the tape measure was around the outside of the fuselage. the front float fitting is a few inches ahead of the front spar and was just an easy place to measure that you can duplicate.

    For what its worth. I can say from my experience rigging the wings and checking washout that there isn't hardly any and maybe no positive incidence on my Classic 4 anyhow.
    Last edited by t j; 02-10-2010 at 06:14 PM.
    Tom Jones
    Classic 4 builder

  8. #8
    Senior Member av8rps's Avatar
    Join Date
    Oct 2009
    Location
    Junction City, WI
    Posts
    680

    Default Re: Wing Incidence

    Mark,

    I'll take a stab at this one...

    Way back when in the model II and III Kitfox days they had changed the wing incidence in an effort to be able to see over the nose better in flight. In fact I have a magazine cover somewhere showing a Kitfox 2 or 3 flying alongside another airplane that looks almost funny because the tail is so high in the air. Now I'm not sure what the dimensions were for those with that incidence, or if it was all in the wing or in the tail, but it is one of the reasons I believe that some 2's and 3's have very low top speeds compared to the 4's (aside from the obvious wing design changes).

    Anyhow, it's free info, so take it for what it's worth. I'm sure someone may have some better, more exact specifications that may explain this better

    Paul S
    Wisconsin
    M4-1200 Amphib
    & M4-1050 soon to be a "Super Speedster"

    Quote Originally Posted by napierm View Post
    Question for the group:

    I'm working on a 2003 classic 4 fuselage and one thing that is notable is that the rear wing attachment is much lower than on my KF III. Looking over another builder's 1995 vintage KF 4 fuselage his rear wing attachment height looks the about same as the KF III.

    So when was the wing incidence angle increased and why? Can't make it go faster so is it to get off the ground quicker? This 2003 fuse has brackets for tricycle gear so is there a connection?

    Just curious,

    Mark Napier

  9. #9

    Join Date
    Dec 2009
    Location
    Lawrenceville, GA
    Posts
    180

    Default Re: Wing Incidence

    Hey Tom Jones,

    It was snowy in Georgia (big deal here) on Saturday but I did get those measurements. They are pretty close to what you mentioned.

    From the top of the front wing attach to the "flat" of the front float attach fitting is 39 1/16".

    From the top of the rear with attach to the "flat" of the strut attach fitting is 38 11/16".

    Mark

  10. #10
    Senior Member SkyPirate's Avatar
    Join Date
    Apr 2009
    Location
    Edgar Springs MO
    Posts
    1,841

    Default Re: Wing Incidence

    39.0625 minus 38.6875 equals .375 or 3/8" ..depending on the distance between the 2 points between the wing connection points,...let's say it's 27.5 inches center to center on the wing connect points,. that gives you a little over "2" degrees AOA if the pivot point's of the wing and the lower front measurement point is at 90 degree's to each other,and the horizontal stab is in the level position or perallel to the front and rear measurement points on the bottom ..

    due to the style of the wing on the kitox,..this is not an accurate way to measure the AOA of the wing ..just the connect points the wing connects to on the fuselage.

    Chase

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •