Relative position of flaperons to wing

[EDMO 1078]

Re the flaperons:   The 1,2,3, are the same - so is wing.  The KF4 used the Riblett designed rib and symmetrical flaperons which attached differently.

     Later, Kitfox (Skystar) advertised, "a new and better, flat-bottomed flaperon" to replace the better symmetrical ones - They must have had some leftover KF3 flaperons - Kitfox owners were not fooled, and were about ready to lynch the Skystar bunch for that boondoggle!

     I wouldn't even dream "nightmares" of changing any wing fittings or dihedral to fix flaperon problems.

     Good to hear that your turtledeck and nylon bearings are not finished -

     IMO, It wont cost you anything but a little time to try putting the flaperon hangers one bolt-hole forward and put temporary clamps to hold them while you try the controls.  You may have to adjust the controls a little?

EdMO

Edited 4 Aug 2015 by Ed In Missouri

[LSaupe 123]

Hi Jim:

 

The original holes are predrilled.  I did have some recently purchased/new HF3 ribs and they are in the same location.

 

Gonna try the re-rig again when I get it out next week to see if I missed anything and will increase my gap to 1+3/4 vice 1" for the neutral setting and see what happens.

 

If no joy will set the flaperons forward one hole and see how it affects slot distance and other things.  Hopefully something will turn up.  If they do go one hole forward I would need then to trim off the tails of the ribs as they would prevent folding the flaps vertical (rib contact on top of the flap).

 

Or... I could live (maybe) without being able to use flaps or fold the wings.  Worst case scenario I guess.

[EDMO 1078]

If you need to cut rib tails, use a grinder with a thin cutoff wheel - Jig or saber saws shake it too much.

I cut mine that way and finished rounding it with a sanding disk.

Keep us posted.

EdMO

Edited 5 Aug 2015 by Ed In Missouri

[dholly 718]

Personally, I would NOT change the position of the flaperons relative to the wing. If the factory location dimples in the rib tails were used and you've confirmed the wing and flaperon build and install measures are correct, that is not your issue and it will be impossible to reverse. Also, changing the boundary layers and pressure drag of the airfoils WILL change the flight characteristics and, in this case, I suspect not for the better either. There are many reasons a specific distance from the wing was chosen for the flaperon position and you might unwittedly open up a can of unintended consequences. Or, worse yet, a can of whoop-ass.

 

Better to continue checking the control systems and rigging. If all that checks out (though I don't know how it could, clearly SOMETHING is wrong), the suggestion by Jim Chuk might prove helpful if you are willing to give up the fold option. Although, I think I might try lengthening the flaperon control rod mounting ears on the outside FBK-9 mixer arms before cutting and welding on the rods themselves. A little extra length there might give you the clearance you need without unbalancing the system. At worst, you might effect the amount of roll input required by a tiny measure, to the less effort side right? Just fab up some temp extensions out of scrap to test without making any permanent changes. I also think this would be preferable to cutting down one swivel block up near the flaperon horn as was shown over at TKF. Having uneven flaperon control rods like that doesn't seem very appropriate to me.

[1avidflyer 1983]

Hi Doug,  not arguing with your comment about loosing the ability to fold the wing if one follows my suggestion, but why would that happen.  I should look closer at  my plane before I comment, but just sitting here and looking at the pictures, how would turning the top of the control rod 90 degrees effect the wing folding? Jim Chuk

[EDMO 1078]

     IMO, 3/4" forward on the flaperon hangers is not going to change the flying characteristics of this plane.  The flaperons are in the free-air slipstream, separate from the wing, unlike some other designs.

     Certainly not like the one fast plastic bird, that changing the paint stripe on the fuselage was detrimental to the way it flew. 

     After all, these planes are "Experimental" - They are not like the ridged Spam Can FAA rules that say you can't put a Matco tailwheel on a Piper Cub without an STC, and none exists.  

     I respect the designing of Dean Wilson, but probably 90% of the small details were built on the TLAR principle, and look at all the changes that have been made, especially the longer/wider fuselage, controls, landing gears, engines, tailfeathers, struts, wing ribs, and longer wings - and they all fly just fine!

     The ability to change or adapt or adjust is the greatest benefit of the Experimental category.

EDMO

Edited 5 Aug 2015 by Ed In Missouri

[dholly 718]

Hi Doug,  not arguing with your comment about loosing the ability to fold the wing if one follows my suggestion, but why would that happen.  I should look closer at  my plane before I comment, but just sitting here and looking at the pictures, how would turning the top of the control rod 90 degrees effect the wing folding? Jim Chuk

 

@ Jim - Sorry, poor use of words on my part. I did not mean your suggestion to modify the vertical flaperon control rods (and/or my suggestion to modify the mixer arm ears) to address interference between the rod ends and fuselage at the flaperon horn, would have any impact on wing foldability (or not). As it is, I believe Larry simply considers it 'unfoldable' due to the current interference between the top fuselage cross tube and rotated flaperons when placing in the folded position. Our suggestions simply attempt to address the flaperon control rod and fuse interference but would have no impact on the foldability issue.

 

@ Ed - Making changes is the 'Experimental' way, you'll get no argument from me (remember the flack I took in my 'Mix 'n Match Ribs' thread?). Never the less, again, before I personally did something so drastic (read: permanent) as repositioning flaperons forward and cutting off the rib tails, I would need to first find out why, without a shadow of a doubt, I was experiencing the issues Larry has. I, personally, would need to know that it was the only option and definitively solved BOTH problems. Which I personally do not believe you have done. Who the hell wants to do something like that only to find out it didn't solve their problems, or even exacerbated them?

 

@ Larry - I've avoided bringing attention to the big elephant in the room... but did you not mount the wings and flaperons, install, rig and test the wing fold function and controls before covering? I'm curious if something that worked before has somehow gone bad?

[EDMO 1078]

Doug,

     I agree with what you said.

     However, temporarily moving the hangers forward to see if controls would work would be a non-change.

Jim Chuk said his hangers were 5/8" closer to trailing edge than these - and his plane flies just fine - one hole forward on these would be about the same distance.  Moving forward could also raise them a little - maybe enough to clear fuselage?

     If it works, drilling a new hole and making the bird flyable would be a change that could be changed back.  Looks like he has the reinforcements on the tips.

     Cutting the rib tips would be a permanent change if he has to do that to fold wings.

If something was built wrong, then he has to find a way to make it work now.

     I can see another permanent change like changing the fuselage tubes, but wont even go there....

If he disconnects the rods to fold wings, then does he need that swivel thingy on the ends of the rods

     I am just guessing at options in case his control rods turn out to be correct, since the wings are set.

EDMO

Edited 7 Aug 2015 by Ed In Missouri

[LSaupe 123]

Hi Doug and Ed:

 

Yep, the wings were not mounted and folded prior to covering and painting the fuselage.  Actually, it wasnt even a consideration (didnt realize it was a concern).  Just assumed things would go together well (which they had up to this point).  This is my first rodeo so to speak, so much to learn in that department.  I did work with several local builders on this project, however, (none of them with Kitfox/Avid experience) and the topic never came up.

 

I do appreciate the concerns over any mods, and believe me, I am very cognizant of those concerns as well and what performance effects might be out there as a result.   Any changes would be very measured and as minimal in nature as possible.  Hopefully I can rig my way out.

 

I have seen a few instances on a Google search where others have had the same binding problems with attempts to use flaps on the earlier Kitfox's.  Maybe a case of tolerances stacking up?  Who knows.  Will get a chance to play again next weekend and sharpen the pencil a bit.

 

Larry

[LSaupe 123]

Larry,

    I see now that the elbow is inside of the turtledeck, as it should be.

Just a real wild idea - I know the book says it should go as you have it - BUT, what if you could turn the control rod upside-down, so the small end would be sticking up? - Crazy ideas sometimes work! 

    I think the max degrees for the flaperons has been posted before - some say you can get reversal of controls beyond a certain degrees - others have exceded that and did not have the problem.

    I would bet that Doug has the numbers, and Suberavid has exceded them!

EdMO

    I cut 2.5 inches off of my rib tails, but mine is not regular Kitfox....

Ed might be on to something here.  I turned the gray control rod upside down (the bulky weldment is now down near the mixer).  This helps a great deal.  Any reason why not to run it this way?  Seems like a simple way to go on the surface.

[TJay 1041]

Boy I have looked at yours alot and compared it to mine. everything is identical other than mine has about 3/4 inch clearance. I dont think you did anything wrong I think the green tube may be welded in the wrong spot or something take a picture of the all the tubing inside the turtle deck sometime. I would like to see if it all looks right.

[EDMO 1078]

Larry,

     If you try the control movements and they work (maybe with a helper putting a little pressure on the flaperons) you should be OK, but you will probably have to disconnect rod to fold wings.

I would have tried moving the hangers one hole forward on one wing, to match Jim Chuk's measurements, and putting clamps in place of the forward bolt, and trying both the rod clearance and the folding - that seemed like another simple fix to me.

EdMo

Edited 15 Aug 2015 by Ed In Missouri

[LSaupe 123]

Quick update.  Ended up going with the upside down rods and those would just touch at full deflection.  Added a bit of curvature to the rod (each side) and the world is a happy place.  Will forgo the folding problem for now.

 

Thanks to everyone for providing feedback on this problem.  Thanks to Tim T for making the trip up today to help in the final resolution and rigging!

 

Larry

 

Edited 16 Aug 2015 by LSaupe

[1avidflyer 1983]

Great if it works with no problems down the line. Would be curious to know why this problem cropped up in the first place. Jim Chuk

[EDMO 1078]

Larry,

      Thanks for the posts and good photos - Keep them coming - They may help someone else.

I'm with Jim Chuk - Wondering why you had a problem to begin with, and interested in any more problems.

EdMO

Edited 15 Aug 2015 by Ed In Missouri

[TJay 1041]

It sure is looking like a nice bird so far

[KFfan 151]

That much curvature makes me immediately think rod too long??? or something out of place.

[TJay 1041]

So what would happen if he was to take a tin snips and cut off 12 inches of the inboard flaperon? Then he could fold the wings.

[EDMO 1078]

TJay,

      It would be somewhere between having full flaperons, and the Avid guys who extended the wings and used the shorter flaperons, or with an extension on the control end - it still works...maybe not quite as well...

      There is at least one on here that extended his short wings.

EdMo

       Larry should be able to fold his wings by unhooking the control rods.

Edited 18 Aug 2015 by Ed In Missouri

[KFfan 151]

On my kf2, when folding the wings I have to hold the wing with one hand while I use the other hand to maneuver the flapperons to clear the fasteners for the turtledeck. Disconnecting the rods is probably a better idea.

Lou

[LSaupe 123]

TJay,

      It would be somewhere between having full flaperons, and the Avid guys who extended the wings and used the shorter flaperons, or with an extension on the control end - it still works...maybe not quite as well...

      There is at least one on here that extended his short wings.

EdMo

       Larry should be able to fold his wings by unhooking the control rods.

Interesting thought.  I disconnect the control rods regardless.  Doesnt help with the folding issue. I also remove my aft flaperon hing bolts and rotate the hinge updward which then gives clearance to fold.  Kind of a pain in the shorts and time consuming, but does work (kinda).

[EDMO 1078]

LarryS,

      I still think moving the hanger one hole forward would have solved both of your clearance problems - maybe still have to disconnect to fold?

EdMO