Chapter 20 Winglets

Sunday July 20, 2014

The winglets are the vertical stabilizers at the wing tips and also contain the rudders. These should be pretty simple to make the difficulty comes in making the hinged rudders similar to the ailerons on the wings. I'll also be doing the hidden bellhorn modification which adds some complexity.


 

Here is the result of our hot wiring, pretty straight forward except that the airfoil template at the tip is much smaller than the template at the base which means the person at the tip is moving the hotwire very slowly while the person at the base is going as fast as possible. It gets tricky for the person moving slowly not to burn the foam. I set the voltage lower so the wire wouldn't be so hot. We got a little bit of burning but not bad, easy to fill with some micro.


 

Here the foam cores are ready for the layup. The hotwired foam beds are bonded to the table with some micro/flox and then the foam cores are nailed to the foam bed to keep them straight. The second picture shows the foam cores mircroed.


 

Here is the completed layup consisting of two plies of UNI angled corner to corner and a smaller ply of BID at the base.


 

June 28 & 29 Columbia Canard Fly-In Photos.

Lynn and I went to the Columbia Canard flyin to get some inspiration.


 

Marc Zeitlin and his plane always answering questions.


 


 

David Orr "Beagle" in his beautiful Berkut.


 

The Cozy Jet! - "Kerosene Dreams"


 


 

Lynn and I really like this Cozy MKIV.


 


 

There was a good turn out of airplanes, probably 20+.


 

Winglets & Rudders

Saturday December 30, 2023

So I've decide it's time to glass the winglets to the wings and cutout the rudders and make them functional. I'll be doing the hidden bellhorns so that will add a little complication but will look much sleeker without the external bellhorn. There's a lot to do and it's a bit intimidating.

 

This is what the plans for the hidden bellhorns look like and are available on Marc Zeitlins website.

 

So you need to trim the bottom of the winglet to match the contour of the top of the wing and Drawing M-20 provides a template. Took some digging to find that, so I lined up the template with the hot wire level line and the base of the winglet as best as possible, didn't really match up very well and drew a line. The plans have you cut the piece out with a coping saw while keeping the blade vertical. I've never had good results with a coping saw. I decided I would cut through the winglet fiberglass skin with the Fein sander and then cut through the foam with a Japanese pull saw or sand to keep the cut vertical and then cut through the other side of the winglet skin with the Fein sander again. This worked perfectly. It was a bit touchy cutting near the coax cable for the COM antenna.

 

So now I needed to trim the end of the wing to match the winglet. I bondo'd a nail at the front inboard aileron cutout as a measuring reference point per the plans. The measurements for positioning the winglet on the wing need to be within 0.05" except the top of the winglet can be +/- 1.0" which is how much the winglet is canted inboard. The plans have you use filament tape to make that measurement so you can tape the top of the winglet at the correct angle. I used filament tape for all the measurements because I could just run it through the bondo'd nail and make an accurate measure several times since the filament tape doesn't stretch. I had to notch the fiberglass at the wing leading edge to provide relief for the antenna coax cable so the winglet could sit flat.

 


 

Once the three measurements (winglet leading edge, trailing edge and tip) were confirmed Lynn helped to hold it in place while I drew a line along the inboard edge of the winglet onto the wing for cutout. I cut the piece out just like I did for the bottom of the winglet by using the Fein sander to cut through the fiberglass and the flush cut saw to cut through the foam. Also used a Dremel to smooth out the spar cap & web.

 


 

I bondo'd the winglet in place on the wing supporting it with foam blocks and strips of wood. A 3 foot piece of would is also bondo'd as a brace.

 

I doubled checked all the measurements before the bondo took a set.

 

Bondo blobs.

 


 

I let the bondo harden overnight. The next day Lynn and I carefully flipped the wing over without breaking the bondo blobs and brace. Had some old wood to elevate the wing high enough for the winglet to clear the ground. Now I can do the internal layups which is nothing like anything I've done before. It looks simple when looking at the plans figures but in reality the layup is curved, so the wedges and foam block need to be curved and the antenna coax cable and rudder cable conduit get in the way.

 

Hogging out the foam for the internal layups and getting an idea how the internal bellhorn will fit with my cardboard mockup. I've ordered the internal bellhorns from the Cozy Girls but they're backed up with orders so I may have to try and make them myself.

  Monday March 4, 2024

I made the internal bellhorns per the Internal Bellhorn Plans. I was hoping to buy them from the Cozy Girls but they didn't have the lazer cut parts to make them. It would have been less expensive to get the bellhorns from them and excellant quality. But I think I did pretty good.

 

I am following Joe Polenek's Perpendicular Internal Bellhorn Installation here is the plastic dam and bellhorn cavity cover made from report cover plastic. I made the foam wedges and numbered them so they'd be easy to put in place. The winglet and wing inner skins have been sanded and ready for glassing.

 

I've got the 9 plies of BID in place. That was a bit of a challenge but with a popscicle stick I was able to get it all flat and oriented correctly, this is layup #1. In the second picture you can see all the foam wedges floxed in place which keep the 9 plies of BID firmly pressed against the internal skins of the winglet and wing.

 

After letting Layup #1 setup for about an hour layup #2, another 9 plies of BID was done. This also included floxing the corners.

 

Next was shaping a urethane foam block to fit in the cove. I made a cardboard template to get the curve at the top of the wing and then hand sanded to get a close fit.

 

Troweled in plenty of micro to ensure there were no air pockets when pressing in the foam block.

 

Shaped the foam block per the plans except for the aft section which is kept level with the height of the bellhorn cavity per Joe Polenek's plans.

 

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