20-Winglets

 

Chapter 20 Winglets and Rudders
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These winglets have the plans layups and I only extended the "footprint" of the layups in the TE outboard wing area.


20-1
The pictures show the use of the Featherlite forms. They are so easy to work with. I used the last of my ghosts peel ply here. It was great stuff.


20-2

I did my last solder work for the com antennae and figured that this work might look better than the canard pictures. The practice work is shown to the side. It had been a year since I soldered last. I marked the rudder future cutout lines before the glassing was done.

Hidden Belhorns

There are lots of pictures of the belhorns. I made the rudders larger and with a deflection of 37 degrees. The increase of the deflection allows me to use clickbonds and get access to put on the nuts (tight space, but simple). The increase size and longer moment of rotation allows for better braking more air braking on landing and a simplier brake cylinder activation. (That's wordy, but how else could I say that?) I see on some sites about springs on rudder cables and sliding tubes on the brake cylinders, so there are lots of solutions. You will see the addition of a small pulley to guide the rudder cable just inboard of the belhorns. That was necessary because of the greater arc for the belhorn.
On final appoach, if I'm too fast, then I can use a forward slip at the beginning of the final and then level wings and apply both rudders just before touch down. At that point, the rudder pressure is released and returned after touch down of the mains. I have no experience with the belly air brake, but it will be used along the final, after landing is assured.  I have read the e-mails for and against the use of the rudders for braking, and this is my two cents worth. I will update this after some landings. I will have 8400 feet of runway to work with and so there is some margin for error.

Hinges are important. I used six inch length for all three and the -06 size. One more thing, is the temporary external install of the hinges (see below).


20-3

The first picture is of the left wing after using the water level. I did both wings at the same time and both winglets at the same time. The supports are made to have the fiberglass piece bonded to the winglet by 5 min epoxy, but held to the board by the screws. When I took this off, the removal of the bonded epoxy was very easy and I did not disturb the glassed surface of the winglet. I went ahead and glassed the inner corner of the wing to winglet with a 2 ply BID layup to give stability for the trial fitting work that was to come. In the third picture, that layup was very helpful as I flipped the wing over to trial fit the lower winglet. The fourth pic is of the tick marks across the cut lines and across the upper to lower winglet junction. In the last picture, the lower winglet is trial fitted. The rudder is four inches taller and one half inch wider on the inner surface, but the outer surface is 3/4th inches wider. so the two forward points (plans call the inside one "A") are "angled". There is no decrease in the control surface, but it gives more room to place the nuts on the clickbonds, due to the better angle to get to the clickbonds. The square with the tongue blade taped to it, shows the plane of rotation of the belhorn.


20-4

I used a sharpie and marked this rotation plane on the exterior. In the second picture, there is a red line. I cutout the bottom part of the rudder, but I extended the cut line along the dotted red line.  In the third picture, I took out some foam and trimmed off some of the conduit to make room for the small pulley, and I glued the conduit down, and later I surrounded it with some micro for stability. The hole is in the temporary layup area and it will be glassed back over. After I add the small extension to the aft of the wing, then there is some more room for inboard travel of the belhorn. The next to the last picture is of the prep work for the Layup #1. The last picture shows the foam in place over Layup #1. It is hidden. Also in the last picture see that layup #1 extends to the LE to resist torquing action. I used flox to bond Layup #1 to the outer skin. In January of 2010, there were postings on a winglet failure at this point and micro was used instead of flox.


20-5

The first picture shows layup #2. I made sure that there was some flox (the flox has a white color due to the addition of a small amount of micro to add some firmness) touching the outside corner of layup #1 to #2 (inside corner).  MICRO IS LIKE PEANUT BRITTLE when it comes to torquing forces, so what you see in the pictures is 95% flox. The important thing is to do the layups on plastic for good orientation and make sure that the outer skins and these internal layups are "connected" with flox between.  After the install of the belhorn, I was able to extend layup #1 and #2 further aft (see pics). The green pieces are some 3/4 inch wide pieces of bulkhead hardpoint scraps. The junction of the small lower piece of the rudder to the top piece is a weak spot, if you don't add reinforcement. The second picture shows the lower part of the rudder (and the wedge shaped around the belhorn area). The third picture shows the footprint of where the belhorn will be.

 

20-6

All of the clickbonds are spaced the same for all hinges left and right, by using this tongue blade template which is marked up and down. All of the hinges are labeled for individual placement. When you take out the hinge pins to safety them, you will want the extra labeling. This will minimize problems of fit and alignment.  The "C" channel will make for a straight lining up of the three hinges. I used the "tongue blade template" and drilled holes through the C channel and bolted the hinges on with some flathead bolts (slightly smaller diameter than the clickbonds). This lined up the hinges, and then I used self taping screws (vinyl fence screws, smaller in diameter than clickbonds) to drill the forward side of the hinges onto the exterior of the winglet. These holes are the future holes for the clickbonds to go through, and with the hinges install inside. After I screwed down the forward side of the three hinges, then I took off the C channel and screwed down the aft side of the hinges, also on the exterior. After the hinges are all in place, I got out my dremel disk and cut out the rudders. I took off one of the three hinges at a time to cut the outboard side where the hinges covered the cut line. You get great alignment with ease and the ability to trial test the movement of the belhorn before and after it is installed and before it is covered up. I added the other pics on the external to internal hinge install, because I refer to this section for the "hybrid FHC" use of piano hinges for the small TB section.

I used the "plane of rotation" line on the outside of the rudder to guide me in the foam removal and then placed the belhorn down in this  recess. In the last picture the small blue arrow shows the pull direction of the end of the rudder conduit. There is a big swing in direction during the travel of the belhorn and so I added the small pulley. I drilled a clickbond size hole in the top of the wing and used the clickbond to rotate about. The end of the clickbond almost touched the bottom glassed skin. The last picture shows the pulley in trial action. Also, in that picture you can see the extension for the aft of the wing. I made a cardboard template for the extension and marked a left and right on some plastic and did a layup of 4 ply BID and cut it out and used 5 min epoxy to tack it to the TE of the wing. This extension does not attach to the winglet, but does touch the rudder inner surface side. Last of all, you can see the gap that I will have to attach the nuts to the clickbonds.


20-7
Hidden belhorns
Before the belhorn was installed, I extended Layup #2 under the bellhorn.

Here is the big moment, the layups around the belhorn. In the first picture, I wedged the rudder open with a piece of foam and supported the cable end of the belhorn with some cardboard so that it did not "drag' on the surface. After a partial cure, I took out the wedge and closed the rudder to make sure that the cable end of the belhorn would not hit the outside winglet skin before the rudder retracted all the way. I had a little premature contact on one. I used a hair dryer a little bit and moved the tip of the belhorn over and all was well. I retested the open position again. You can see the TE extension of the wing in the first picture, but you need to see later pictures to see how that extension helps. The hinges are still mounted on the outside at this point.


20-8

The first picture shows the foam placed for Layup #3. It will be over the belhorn area also. The second picture is a before the foam picture to remind about taping the cable, but a better idea is a simple pull string on the end of the cable. The cable slid back on me and I had to fish it back out of the pulley area.  The last two pictures shows Layup #3 going past the TE of the wing and onto part of the "sharks tooth" wing extension.


20-9

The duct tape is on the outside to prevent the micro from pressing through the holes. I place a saran wrapped board, like for the aileron, on the inner surface where the hinges were to be placed. It is very important have enough recess to allow the board to go down as far as the hinges. Lower winglets also go this layup on a recess. Next, I moved the hinges from external to internal and trimmed for the hinge rotation point. The clickbonds were placed and I trial fitted and then bolted them down with some oversize nuts as spacers, and added the one ply BID strips over the clickbonds.


20-10

The first two pictures are still in the "rough". There are pics in chapter 25 with the finish look. The hybrid wingslets shown do not modify the lift factors of the wings, but give a means to make stronger hidden belhorn installations. I say that because none of the plans layups were cut to do the hidden belhorn install and the plans layups extend further aft in the winglet to wing junction.