Oz build SS7

[rosslr]

Another day on the wing and got the upper side false rib tapes and the leading and trailing edge tapes done. I have attached a photo of the topside - almost ready for spray coats of Polybrush.

I have also attached a pic of the other wing with the wrinkling. I think I need to release the glue attach points on the ribs. I am assuming that the fibreglass and the wing frame is moving with change in temps. I assume the f/g is fairly inert so guess the spars and perhaps the plywood ribs are moving with the temps. In any case, I think it is useful to think about how extensively the LLE is glued down, especially given the flex in the wings. Thoughts??

Ross
Mt Beauty, Vic
OZ

[alanr]

Hi Ross,
I am still following your every step with keen interest and learning a lot!..keep up the good work.

Just a thought re-LLE wrinkles....

As you say it possible that it is the rib structure that has changed with the temperature and not really the LLE itself so if released from the ribs all will be ok. Problem is though will it move again when the temperature warms up again and why hasn't the other one done it.
Thinking further ..Maybe the wing needs to be covered and therefore all tightened up as soon as the LLE is fitted to hold everything tight and in place. This would explain whay only one has done it.

Seems like a call to Kitfox to see if they have seen it before or possibly have any suggestions is the way to go.

Regards,

Alan

[rosslr]

G'day Alan,

hope you enjoyed seeing the rib stitching right fwd and drilling through the LLE.

I agree with your suggestion and think that is what is going on. Al the ply ribs have three coats of the epoxy varnish so they should not be absorbing too much moisture - I suspect the relative expansion/contraction of the aluminium. I plan to release the attach points of the LLe to the ribs ( thankfully I only spot tac'd them) - after that, if it is not rectified I will contact Kitfox for suggestions. But I think we need to keep in mind that the wings are flexible and make sure we dont restrict that movement. Only my present think ing and willing to change!

cheers to the old country
ross
Mt Beauty, Vic
OZ

[alanr]

Hi again Ross,
Think we cross posted as I was editing my post to add further thoughts on why only one had done it.

Alan

[rosslr]

Hi again Alan,

I will first release everything I can and see if it retains a fair shape.

Thanks for your thoughts. appreciated.

cheers
ross,
Mt Beauty, Vic
OZ

[HighWing]

I wrapped the bottom fabric up and around the front to the top trailing edge of the LLE. I bonded the fabric there and at the rib locations.

Do you plan on extending the top fabric to the leading edge and wrap a distance under the forward part of the wing? I think it is customary to have the fabric laid up so the airflow during flight won't have any possibility of catching an edge and possibly lifting it.

[HighWing]

I have also attached a pic of the other wing with the wrinkling. I think I need to release the glue attach points on the ribs. I am assuming that the fibreglass and the wing frame is moving with change in temps. I assume the f/g is fairly inert so guess the spars and perhaps the plywood ribs are moving with the temps. In any case, I think it is useful to think about how extensively the LLE is glued down, especially given the flex in the wings. Thoughts??

Lots of thoughts but all lead to more questions. Plastic tends to beat all metals in rate of expansion. You would think that the glass fibers would hold tension. Your experience is the exact thing I was worrying about when I put my aluminum leading edge on - the infamous oil canning. I am very interested in what you find out. Two questions come to mind, what were the relative temperatures at each of the leading edge installs - same, or significantly different? And were the wings suspended by a rotisserie? If so did the adhesive cure with the wing right side up or was it inverted during the cure?

[rosslr]

Today was 'finish off left wing day'. first I put on the inspection rings with Poly Tac and then used pre shrunk medium grade cloth to make the covers. Next were the drain holes that were made with an electric soldering iron. Finally, two good spray coats of Ply Brush and the underside is left to dry off overnight before doing the topside. It's nice to have a nice clean wing ready for painting!

I will do another post on the LLE issue shortly.

chers

Rossr
Mt Beauty, Vic
OZ

[rosslr]

So, the sage of the wrinkling LLE. In between spraying coats of Poly Brush, I decided to 'release' the LLE from where I had spot tacked onto the ribs - fortunately it came away by leveraging with a large, flat head screw driver. The result is it has all but resumed its proper shape.

In answer to your questions Highwing, I actually fitted the LLE while the wings were rigged on the plane. I did them both within a few days of each other and temp would have been mid to high 30's (c).

My thinking is that is is perhaps best to just tac the LLE along the leading edge and then just cover it - the fabric will hold it firmly in place and that way it would not interfere with the wing wanting to flex.

cheers

ross
Mt Beauty, Vic
OZ

[rosslr]

And a nice box of goodies arrived today from MGL too!

ross
Mt Beauty, Vic
OZ