Flaperon Rigging Question (Mk2)

[waterboy]

Can anyone tell me what the angle of incidence of the flaperons on a Mk2 should be in their neutral position, with flaps NOT extended?

Also, what are the reference point(s) on the flaperons and the aircraft against which this angle should be measured?

I am trying to re-rig a 1991 aircraft and the builder's manual I have, which is in loose leaf format, is missing this information.

Thanks in advance.

[GDN]

Same KF2 same question and same documentation...

[waterboy]

Sorry, but can you be more specific? Do you mean that this question has already been answered in another thread, and if so then could you point me in the right direction, please?

I have searched the forum but not found what I'm looking for.

Thanks.

[GDN]

No as i have to push the stick right to fly with no roll i tried to find a method to check the correct setting of my flaperons.

So no answer and so same interrogation like you.:(

[waterboy]

GDN,

Replying to my own question, I've now found the answer, and it was in my builder's manual all the time, though I couldn't see for looking.

It's in section CF (Covering and Finishing) page CF18, diagram CF12.

If you don't have that page, let me know and I will email you a scan/photo, but in words the neutral position with the flap lever fully forward and the control stick centred is as follows:

The datum on the flaperons is the flat bottom surface of the flaperon. Extend that flat line forwards (using a suitable straight edge) and measure the distance to the underside of the forward wing spar (leading edge of wing). The gap between the forward spar and the straight edge should be 1 inch.

HTH

[GDN]

Will see my documentation.
Thanks.

If the 2 flaperons are not symetrical on wich part do you correct the setting ?

[waterboy]

I forgot to mention yesterday that the flaperon/wing spar measurement should be made immediately outboard of the wing struts.

In your documentation, do you have the section F (Fuselage), and specifically page F8 which shows the complete control system as an exploded drawing? The following paragraphs make reference to part numbers in that drawing:

Level the FBK-7 Mixer Bellcrank and clamp to keep it level.

Adjust the length of the aileron control tube FCT-21 by extending/reducing its associated rod ends in order to centre the control sticks.

IMPORTANT: If you are extending any rod ends, ensure that at least 1+1/4 times the thread diameter is located within the rod, in order to ensure adequate purchase. Some female rod end bearings have a "witness hole" drilled through the shank - if you can pass a length of siezing wire through that hole then there is insufficient thread within it.

If there is insufficient thread in the rod ends of FCT-21 to centre the sticks (bearing in mind the proviso above) then look to see whether you can safely adjust the male/female rod end bearing combination (FRE-48 & FRE-49) which leads from the bellcrank FBK-6 to the part No. FCT-20 (the tube connecting the two control sticks together).

Once the sticks have been centred and while the mixer bellcrank is still level, adjust the flaperon neutral position by first ensuring that the flap lever is fully forward. If your Mk2 is complying with the AD that mandates the flaps be permanently wired up then it should already be so.

Measure the flaperon/wingspar distance (1inch) as previously discussed and adjust this setting by adjusting the threaded rod(s) FRU-47. Remember the warning about rod ends above.

If you find that there is insufficient adjustment possible in the threaded rods to set the flaperons properly to neutral, it may be that when the AD regarding the flaps-wired-up mandate was complied with, a clamping plate was added to the frame which affected the positioning of the flap controls (this is what I have found in my aircraft). As a result, a longer U Joint FU-58 at the lower end of push-pull rod FCT-25 was substituted (by a previous owner) on each side to compensate, but unfortunately they seem to have made the replacements too long (1+7/8 inches) and my aircraft has been flying around since then with a small amount of flaps applied. I have now fabricated a complete new set of U Joints FU-58 with two being the original length (1+1/8in) and two slightly shorter than the too-long ones I removed (1+5/8in). I haven't rigged that setup yet - I will let you know how I get on.

Hope that helps. If you need a copy of the exploded diagram please let me know.

[GDN]

Thanks a lot that's clear i'll see on monday my documentation at work ;-)

[akflyer]

I am guessing that the flaps wired up AD is just for you folks on the "other side of the pond". I have several hundred hours in mod I and II and use the flaperons every take off and landing. Too bad there is an AD over there for that as it really makes a difference getting in and out short!

[GDN]

Level the FBK-7 Mixer Bellcrank and clamp to keep it level.

Adjust the length of the aileron control tube FCT-21 by extending/reducing its associated rod ends in order to centre the control sticks.
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...
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Hope that helps. If you need a copy of the exploded diagram please let me know.


How can you level the FBK-7 ?
Horizontal with a spirit level ?
If think it is important that the airplane is really horizontal before checking the fbk-7 ? And how do you fix the FBK-7 when leveled to check if the stick is vertical ?

2 persons for that no ?

Thanks a lot with your method i know now how to check...now how to control...

see you

[dholly]

This info might be of interest to you guys.

From Dec 1988 Kitfox Owner Newsletter, pg 2.


Some of our builders with the Model 2 have had problems with the FBK-5 aft aileron bell crank. The bushing was not properly located on some of them delivered over the last 4 months. If yours will not fit and pivot freely, send it back and we will send you another. If you have access to TIG or oxyacetylene welding equipment, you can grind away the excess material at the corner of the FBK-5 and re-weld it.From Jan 1990 Kitfox Owner Newsletter, pg 3.


RIGGING DETAIL: on page CF-18 of your builders manual, step 69, it tells you to have the tops of the FBK-9 Individual Flaperon Bellcranks approximately parallel to the Mixer Bellcrank. Actually, on the Model 2 the inward ends of the FBK-9's when properly rigged will point down, possibly 15* degrees or more, with the flaperons leveled according to instructions.

MIXED UP BELLCRANK: About 25 FBK-7 Mixer Bellcranks were inadvertently built incorrectly, as a mirror image. Most of these incorrect bellcranks were shipped in November 1989. Please check to see if your Mixer Bellcrank looks like the one in diagram F-5 page F-6 of the builders manual. lf your bellcrank is not correct, please let us know and
return it for the correct bellcrank.

[Marshawk]

Thanks for the Post Dholly ,we were wondering why the rigging instructions wouldn't make sense. Our KF2 was manufactured in 1989 so I'm pretty sure we got the wrong bell crank.Does anyone know if the proper bellcrank is still available some were. If not has one made the incorrect one work

[Peteohms]

No as i have to push the stick right to fly with no roll i tried to find a method to check the correct setting of my flaperons.

So no answer and so same interrogation like you.:(

GDN,

I believe you have to adjust the struts to remove the roll. I used a digital level to adjust mine.

Pete

[akflyer]

Im with /\ . A rolling tendency will not be fixed by re-rigging the flaperons. The only thik that will accomplish is perhaps centering the stick if it is off to one side or the other in level flight. To fix the rolling issue, you must adjust the struts.

[GDN]

sure but i have to apply a strong force on stick to keep it centered in flight like when you have hard crosswind.

[akflyer]

sure but i have to apply a strong force on stick to keep it centered in flight like when you have hard crosswind.

The flaperons are going to seek level in the wind. The rolling issue is because the warp on the wings are not the same. One rod end should be adjustable on your lift strut. If you have to hold in Right stick (just like I had to) then shorten up the left rear heim joint on the lift strut. That is why they have the adjustable end on it. When I turned mine in 2 turns it took away the roll, and as an added bonus, I am now able to run my elevator trim in the neutral position and not at full up. I also gained a little in climb and a few MPH in cruise because the plane was not fighting itself to fly straight and level now. It is the first time in 2 yrs that I have been able to fly hands off without rolling to the left and diving.

One good test is to fold the wings. Are the flaperons and trailing edge lined up with each other? My left flaperon and trailing edge was about 3/4" higher than the right wing. By turning the heim joint in and mathcing up the trailing edges, it made a HUGE difference.

[Geowitz]

One good test is to fold the wings. Are the flaperons and trailing edge lined up with each other? My left flaperon and trailing edge was about 3/4" higher than the right wing. By turning the heim joint in and mathcing up the trailing edges, it made a HUGE difference.

Idealistically, yes, but this is not always true. Especially with older kitfoxes. When I rigged my wings I had them perfectly aligned in flying mode, but when folded they we 6 inches off :eek:. This was because of a warp in the fuse due to welding processes at the factory. The geometry of the wing and spar connection points was a bit off and as the wings folded the dihedral would change on each wing. I had to rack the fuse using several large binder straps to bring it back closer to square. It's still not perfect, but the tips are now within 1/2 inch or so when folded. They are perfectly aligned in flying mode.

[akflyer]

Idealistically, yes, but this is not always true. Especially with older kitfoxes. When I rigged my wings I had them perfectly aligned in flying mode, but when folded they we 6 inches off :eek:. This was because of a warp in the fuse due to welding processes at the factory. The geometry of the wing and spar connection points was a bit off and as the wings folded the dihedral would change on each wing. I had to rack the fuse using several large binder straps to bring it back closer to square. It's still not perfect, but the tips are now within 1/2 inch or so when folded. They are perfectly aligned in flying mode.

Look at it this way. If you have a left rolling tendency, and you fold the wings and the left trailing edge is higher than the right, then guess what.. Of course each plane may be different but you have to have a starting point. Without a starting point, why even bother rigging them to begin with, just bolt everything together and hope for the best on the first flight. :D

[Geowitz]

Sorry, didn't mean to come off as correcting you, but I have a lot of experience with the process and the geometry involved. Really, the correct starting point is to level the plane with the wings in flying position and measure the dihedral, sweep, and washout. Who said anything about not rigging them and hoping for the best? He needs to check it the right way. The height of the trailing edge when the wings are folded can be misleading for the reason I stated before as the difference in height doesn't necessarily mean one wing has more washout than the other, thus causing the roll. None of the rigging measurements has anything to do with how they look as they are folded. Idealistically, yes, it would correlate, but the best starting point again for this guy is to rig and measure it in flying mode.

[Jfquebec]

You are right Geowitz,that the best way to fly straight..that's what i do to,,
It have no logic to set dihedral ,sweep and washout and after folding the wing and remove all your measurement for a good look when it's fold.:confused:

Jf

[bbryan]

OK, I know this subject has been tossed around, I'm trying to rig my MK-3, and things are not going to plan. Did all the leveling, have a digital gauge, have set the flaperons with the 1" at the leading spar, but when I try to have any flap more than netural position the vertical push/pull tubes FCT-26 that move the flaperons hit the fuselage when trying to move the flaps down limiting control. Sounds confusing, but with flaps, even 15 degrees from netural, the only thing i can do is fly level, no banking allowed because the flaps cant defelect anymore. also cant fold the wings with flaps set at netural position. I have to go to spolier range to get the wings to fold without hiting. Right now I have about 5 degrees down torward the center on the FBK-9 in relation to the mixer belcrank. Also does the model 3 suppose to have any spoiler range on the flap handle or is it all netural to full flaps. I KNOW , LOTS OF QUESTIONS... Thanks for any input.

[Av8r_Sed]

You wouldn't really fly with a control issue, right? I'm sure you're talking figuratively.

I don't have any interference between the flaperon controls and the fuselage on my Model III. Could you take a picture with the turtledeck off to show the flaperon connection interference?

[bbryan]

Not flying with bum controls, just trying to explain the anomaly. The first pic is with neutral flaps the second is with about 15 degree flaps. Notice in the center of the photos where the ailerons pushrods hit the frame limiting travel.

[Av8r_Sed]

I'll try to take matching pictures of my setup tomorrow for comparison.

[GT280flyer]

Only my two cents, is the angle between the flapperon horn and the flapperon riveted correctly? In the pics it looks like a very steep angle.

[bbryan]

I'm thinking you are right about the angle of the flaperon horn. i followed the book which states 1 11/16 to the center hole.looks like it should be 1 inch.. not sure how I'm going to fix this issue yet, its pretty permanent.

[Av8r_Sed]

Here are the pics from my model III: Flaps Neutral, Flaps fully deployed, side view to show the orientation of the horn to the flaperon.

[Av8r_Sed]

If it turns out that the control horns are oriented incorrectly I think I would cut them outboard of the flaperon bearing area and have them re-welded in the proper orientation.

[bbryan]

I"m beginning to wonder if I'm using the wrong reference for the flaperons. Just from the pics the angle of the flaperons in relation to the horn look very similar between yours and mine. With full flaps my flap angle looks greater. I'm still confused.

[Av8r_Sed]

Can you move down the chain and post a picture or two of the mixer & FBK-9 bellcranks?