pls. comment: strange wrinkles

[motortommy]

Hi all,
I`m dreaming of a Mod. IV. Soaking up each and every topic of this board for years, now I have the chance to jump in the KF world. You should know that offers in Germany are very rare! So I shortly inspected a IV-1200, (serial #1860), first flown `95. I´m looking for a project to rebuild, adding some upgrades like Grove gear, 912 swap, etc. So time is not an issue. More important is that finally I own my personal perfect plane. In 2010 the nicely recovered (Ceconite 102, stamped) plane unfortunately was painted with car system (I guess). Paint is very thick, high gloss, but brittle. There are several fissures with non-elastic, bulged borders. Underneath clean white fabric shows off. Seems like the whole job has to be done again…As loosing some weight is a target anyway, I plan to do covering an paintwork from scratch.

Question: trailing edge of both wings (rightside much more) show heavy wrinkles, feeling like a sheet of plastic. Any thoughts how this happened? I could not find any damage or bending of the structure…

Thanks,
Marc

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[Dave S]

Marc,

Congrats on getting your Kitfox and saving it for a new life of flying.

Can't say that I have ever seen wrinkles like that; and, speculating how it got that way is anybody's guess. If it is not due to physical damage, maybe incorrectly installed fabric or something that developed with an incompatible paint/solvent system - who knows.

When you strip the fabric you will be able to determine if the structure is ok - if so, as it seems to be from your examination, the cause of the wrinkles may just have to go as one of the unsolved mysteries of all time.

Having the time to refurbish and install new fabric and paint is certainly the way to go.

Sincerely,

[David47]

I'm definitely with Brian and Steve on this. Unless you determine what caused those fabric wrinkles, I wouldn't be flying anywhere. Severe wrinkling like this is an indicator that something's moved in that structure, and a ground loop is a potential candidate. Stripping the fabric to do a visual inspection and dimensional check makes a lot of sense, and will give you peace of mind.

[motortommy]

...meanwhile I bought the plane.
HERE the journey starts...

[Esser]

Congrats. The fun begins! Your goal is very obtainable

[sturdee]

Hi,
well done on getting a kitfox. Personally I would remove the fabric on the wings, the paint certainty isn’t poly tone, it has ring worm damage due too to heavy a coat and obviously not flexible.
The wrinkles on the trailing edge are possibly caused by the way the trailing edge has been installed,
it comes in sections and should be riveted and scotch welded to the feathered ends of the ribs, obviously back strips so that the rivets don’t pull through the thin wood cap strip. If not installed correctly the fabric will pull them in whilst tensioning with the calibrated iron, and looks a mess.
Later models re-in force the trailing edge with round tube scotch welded into trailing edge before fitting to wing.
Do-not remove the leading edge extrusion when removing the fabric also give the wing tanks a good check as earlier tanks are not ethanol proof and have been sloshed with kreem, if this has deteriorated it would be a very good time to change the tanks or try to fix.
covering the wing is straight forward , check all ribs and false ribs for damage, and if not installed bottom false ribs make a huge difference to the wing profile, add three to the bottom of the tank also,
check the scotch weld on the ribs with the wing folded out in the flying position try twisting from the tip any flexing suggests the rib glue has gone , now you have a bigger job than recovering,
if you have have the build Manuel great the section on covering is daunting but read it twice, and get mr stitts manual,
once you have covered the wings and all tapes, i would rib stitch the ribs, it says in the manual its optional and ok my machine isn’t, however if i was doing it again I’d rib stitch.
rgds mike. G-FOXF

[Esser]

Try and heat it up to 250F and then 350F with an iron. I don’t know what’s causing it but you might be able to get of them

[Slyfox]

don't use an iron. go to an rc store and buy the heat gun(used to install monokot) and try that. I have a spot that's not as bad but will show it's ugly head in the winter. I take the heat gun and run it over the area and wallah it's gone. safe and doesn't hurt the paint.

[rv9ralph]

Do not use a heat gun. You cannot adequately control the temperature with the gun. If the fabric is over heated it will relax and cannot be tightened again.

ralph

[jabkwab]

Use an iron, don't apply much pressure and use a piece of baking paper (is that what you guys call it?) or wax paper in between.
Don't move the paper until the fabric has cooled down again. This helps keeping the paint intact.