2.5.0  Winglet to Wing Attachment

There is a large layup schedule that needs to be followed for attaching the winglets to the wing. The winglet needs to be braced in place and temporarily bonded before the figerglass layups begin. Since some of those layups are internal to the wing and winglet, a small amount of foam needs to be removed (and saved for later replacement). Here I am removing some of the foam on the winglet.

Cleaning Out Winglet Foam (1)

Here I am cleaning out some foam in preparation for fiberglassing the winglets to the wings.

You can tell how much fun I’m having doing this! Thank goodness for my Dremel Multi-Max tool. It’s one of the most versatile and handiest tools I’ve ever purchased!

Dig! Dig! Dig! (1)

Sure do love the MultiMax tool for digging this stuff out!

To begin the process, the wing itself has to be perfectly leveled on the table. The manual does a good job of explaining that process. Once the wing is level, the winglet needs to be temporarily held in place with some sort of homemade contraption. You can’t see it all in this photo, but the i-beams are clamped to one of my saw horses and held somewhat vertically in place. I then use bungie cords to hold the winglet to the i-beams. In addition, I’ve clamped some wood blocks to the i-beams to temporarily set the angle of the winglet.

Winglet Alignment (1)

If there's one pain in the butt I've run into is getting the winglet trimmed properly and then aligned properly with the wing. The backside of the winglet needs to be at 90 degrees to the wing and the leading edge needs to be at 60 degrees. It's a real 3D puzzle!

The backside of the winglet needs to be set perfectly vertical. I can set that angle with the i-beams. That’s one part of the 3D puzzle I mention above. The other part is setting the leading edge of the winglet at 60 degrees. The factory permits a bit of wiggle room here but wants no less than 60 and no more than 62 degrees incidence. Both winglets need to match so when I attach the left winglet to its wing I’ll need to match this setting as closely as possible.

Measuring Winglet Leading Edge Angle (1)

The factory has a spec of 60 degrees incidence for the leading edge of the winglet. Max is 62. 60.5 degrees is pretty darn close!

Once all of the angles are set properly, the winglet needs to be temporarily supported and bonded to the wing because we need to flip the entire assembly upside down for doing the internal attachment layups. In this photo I’ve attached the first angle bracket. I will also apply some Bondo along the edge of the joint for added stability.

Locking in Winglet Alignment (1)

The first of a few braces to lock in the winglet alignment in preparation for turning the whole assembly upside down!

And now for the big flip! In order for the winglet to clear the floor I placed saw horses on top of my construction table. It took four of us to flip that sucker over and raise it up! Before flipping it though, I added two more support brackets which you can see in the next two photos.

Upside Down Right Wing Assembly (1)

It took four of us to flip the whole thing upside down and on top of the sawhorses on top of my table.

Winglet Support Brackets (1)

These additional support brackets were added before flipping the wing upside down to provide more stability.

Here’s a view of the inside joint before the first layup is finished. You can see the areas of foam that I dug out in order to make room for this layup. The brown cable is the coax feed from the communications antenna in the winglet. The colored wires will be used for the navigation lights that eventually get attached to the bottom section of the winglet.

Inside Joint - Wing to Winglet (1)

Here's the before-fiberglassing photo. The next step is to glass all of this to strengthen the joint.

Inside Joint - Wing to Winglet 2 (1)

Here's another view of the joint. The brown coax is for the communications antenna embedded in the winglet and the colored wires will be used for the navigation lights.

Inside Joint - Wing to Winglet 3 (1)

And yet one more view of the inside joint pre-fiberglass.

There are a total of four layups that are used to attach the winglet to the wing. Once these layups are done, the winglet is very firmly attached!

This is the first layup done in order to attach the winglet to the wing.  This is called "Layup A" in the manual.

Once the internal layup is finished, I need to reinstall the pieces of foam that I removed from both the wing and the winglet. They are glued back into place and once the epoxy dries, the foam pieces are sanded to create a nice, smooth surface for Layup B.

Right Wing - Layup 'B' (1)

And this is the second layup, called "Layup B", used to attach the winglet to the wing. Once the epoxy is dry the scrap is removed. See the next photo.

Layup 'B' After Trimming (1)

And here's what the layup looks like after the scrap is trimmed.

Layups ‘A’ and ‘B’ both use a total of eight pieces of BID fiberglass. This creates an extremely strong joint. But even with these two layups we aren’t finished yet. Layup ‘C’ comes next but before I do that layup I need to create an angled piece of foam to fit into the gap between the wing and the winglet.

Right Wing - Layup 'C' (1)

A completed Layup 'C' - before doing this layup a wedge of foam needs to be formed and placed in the gap.

So here we have another seven layers of BID and UNI wrapped around that piece of foam that I installed and onto the bottom side of the wing and back side of the winglet. After all of this is trimmed, the wing gets flipped back right-side up for the final layup. Before that though, here’s a photo of the wing looking at it from the inside.

The first three layups need to be completed with the wing upside down. You can see some of the temporary bracing used to hold the winglet in place.

You’ll notice that Layup ‘C’ actually wraps around the leading edge of the winglet and slightly around the leading edge of the wing. Finally, we (and it takes a couple of guys) flip the wing right side up again.  Here I am doing some preliminary sanding on Layup ‘D’, which is the final layup.  ‘D’ also uses two layers of BID and seven layers of UNI.  This layup also partially wraps around the leading edges of both the wing and the winglet.

Sanding Is My Life (1)

You can never do too much sanding on a project like this! And wait until I start finishing the wings!

Once both wings are completed, the next step is filling and sanding the wings using Velocipoxy and Micro-balloons.  That job is really messy, as you’ll see when this continues here in the next section.


© John Trautschold 2016