Ch 20 Winglets/Rudders

One of the CP’s has a reminder to put a vent in between the two wing bolt cavities. This is to allow drainage so that the bolt and fittings don’t become corroded. Seems a good idea. I found some longlife milk in the kitchen, as I don’t drink the stuff myself, that had nice little straws attached. So now you know that when you visit my build I will have some milk for the excellent coffee I serve …although its better without. Bring your own straws.

So I drilled a little hole in each bolt access recess with the idea that I’d easily connect through the foam and micro in a straw. Over two hours later I had the straws through the holes. You’d think it would be easy. Wrong. I microed them in as you see in pic 2 and I’ll carefully trim tomorrow.

The lower winglets got a little drainage hole too per plans. I can see if that section stayed filled with water the rudder bellhorn and cable might start to corrode. I put the hole at the back for the least disruption to the airflow.

Vent as suggested in a CP

Wing bolt vent

Rudder drain

Over a couple of days I’ve sorted out a few small rudder details.

I’m going to use AN111C-3 cable fittings (Pic1) instead of the AN100C-3 eyelets. I like the round ones as they stay in position better than the others and don’t tend to jam slightly when between the bell horn ‘plates’. They also have a smaller footprint in the wing so that the rudder now gets more than the full travel I need with no catching anywhere. I did have to file the bellhorn plates slightly to ensure there was no possibility of the cable wearing on the edges. A lick of black paint and we were good.

Pic 2 shows the rudder which now is a better fit and with good clearance. I noticed it was just scraping on the outside at 3/4 deflection on the left rudder… so I have sanded that away and then added yet another lot of flox to the lower winglet and trimmed to size. I had cables in position with fittings and tested both rudders now and I’m happy with the movement, range and clearances. Pic 2 also shows I’ve made two return springs which I tested. They can catch slightly at full deflection on the edge of the 1″ spring tube. I’ll wait till final fitting and might grind one side down a bit. It may not be necessary so I’ll leave it for now.

Pic 3 shows the wooden rudder return stops. I’ve floxed in 4 pieces of firewall plywood as these stops and they will get a final adjustment after flying.

Rudders and lower winglets are all done for now. Time to move on to the ailerons.

Cable check

Rudder lower refit

Wooden rudder stops

Yesterday I added the lower glass to the fairing and after cure, trimmed to size today. I used 3 plies of BID on the bottom and full width as you can see in the first pic. Foil technique as usual.

My thinking for so may plies is not only so the area is not damaged during ground handling but also to give a lot of extra strength to the lower winglet in the event of the plane tipping backwards one day. This is now a very strong area.

It is possible that this fairing is wider than it has to be and after I am flying I may do some oil flow tests and if indicated cut the area back a little. This is much easier than adding!

For now it looks nice, addresses an area of flow separation and is a bit of individuality. Of course it also adds at least 10 knots extra speed due to drag reduction. hahaha

Foil application

Fairing completed

Lower fairing intersection

This fairing is my design. Oil flow photos on my flying plane suggest this wing/winglet intersection is good but at the trailing edge the high pressure air from under the wing separates the flow on the rudder up about a foot. So I’m just putting in a simple fence to prevent this separation.

I’d previously made some 3 ply BID for this fairing and cut it slightly oversized but to shape. Using the hot glue and some sticks I secured the fairing in place from the bottom as you see in pic two. I have set it in line with the airflow and about 0.3″ below the rudder cutout so I can get a nice transition.

I lined the join with flox and laid up 1.5″ wide tapes with the foil method on the top side. These will add a little extra strength to the fairing which I am mindful of needing some thickness in that position for ground handling and when cleaning the winglet. I’ve peel plied the joins and will do the underside after cure…and a bit of a clean up.

Cardboard test shapes

Hot glue positioning

Upper tapes in place

These are the rudder return hooks that go in… the rudders. I bent more 3/32″ wire into a shape that covers a bit of area. I made a hole in the rudders a bit smaller than the bent wire diameter and cleaned out a little foam beyond the hole edge too.

My idea here is that with the hooks potted there will be flox pushing against the glass edges making it very hard for them to pull out as a unit.

After mixing the flox and potting the hooks I added one ply of BID over the top as well to seal off the hole and give a bit more strength. You can see this in Pic 3 with some peel ply on top. I dulled the glass first, wiped with acetone and coated with pure epoxy just like the big jobs of course.

3/32″ wire bent

Trial fit

Floxed and glassed

These hooks are made of 3/32 piano wire and it was something different to bend them into a hook. Next I cut some leftover firewall ply for the plugs. I got a little creative and very carefully ground a lip so the 1″ spring tube would be a tight interference fit even before it was glued. You can see that in pic 2.

I also bent the hook wire into a curve so it would sit into the outside of the plug. I put another piece of piano wire through that loop on the outside to spread the load. I got even more creative and potted the hooks in flox in two cured session on both sides to ensure they were centered. I also checked that I could get a spring on the hooks when they were in the tubes.

Having gotten this far I glued the plugs to the tubes which I had previously alodined. Once that was all done I sharpened another piece of 1″ OD tubing and used that to cut a hole in both winglets. Finally the tube assembly was microed in place.

Why so much trouble on these? A friend of mine flew a Long-EZ from England and this hook failed and needed to be repaired on a day of thunderstorms and rain at my home field here in Melbourne. The rest of the plane made it here with no problems!

Hooks with plug lip

Hooks in the tubes

Tube microed into the winglet

After nearly two weeks I seem to have the tiny rudder gaps sorted out. I made fences in tongue depressors lined with tape and built areas of flox that were then sanded down to 1mm or less as you can see in the previous entry. Both rudders were fitted and removed dozens of times… too many to think about. I had to go slowly, one area I redid due to excess enthusiasm with a sanding block

Once the long gaps were sorted out I had the bottoms to fill. First up was as you see in pic one. Just some flox to later sand down to a good fit. Pics 2 and 3 show the second fill area which was just the slight curve on the inside. As you can see it worked out. This offset hinge line was a typical minor mod that takes a huge amount of time.

I suspect I’ll have to remove a bit more material to allow for paint. That’s something to look forward to.

I still have the cables to recheck using AN111-3 instead of AN100-3 …expect some pictures later. I will have to shave a fraction off the bellhorns and repaint. There is also the return spring I’ve been working on. Getting there!

Buildup

Inside curves

Inside curves open

As you see in pics 1 and 2, I have gaps to fix now. Pic 2 shows on the inside of the rudder where I had to allow for the non parallel line with the hinge. I will have to slightly round the inboard edge of the rudder too. This is a relatively easy thing to sort out compared to some jobs.

First up I’m building a line of flox on the winglet side as you see in pic 3. It will only be an addition of about .1″ or even .05″ at most and tapering. I will try to get nice lines here. I’ve used aluminium straight edges and other things to try for a st right line with the edges and then just some fitting with the rudders. We’ll see how it works out.

Once thats sorted I’ll do a glass fill for the larger bottom inside gaps. This will mean getting the wings flat on the floor again and thats a lot of fun to try and walk around!

Minor gap

Offset to correct

Flox gap filling

The next couple of days was fitting the rudders with cables to see if I had full range. I just fed them in from the inboard end, pulled the cable out, added the eyelet, popped it on the bellhorn and then back in place for testing. I just cut the ends off to use on the other wing with the same procedure. Easy.

The plans allow 4″min to 4.5″ for maximum travel and this is taken from the Cozy numbers which measure from the extended rudder. The important numbers are 22 degrees minimum and 26 degrees maximum deflections so the gap is less important if this is correct as it doesn’t matter as much about the measurement. The Long-EZ plans say 5″ to 5.5″ which works out if you do the kink measurements at the bottom. Of course I don’t have that kink 😉 In other words I’m getting the deflection I need. There is a slight catching of the swage tips at full deflection but I’m certain I don’t want or need all that I have so its going to work out.

I spent many hours installing and removing the rudders and tweaking the hollow where the movement takes place. I also bent the bellhorns very slightly as others have done to get the required clearances. I think it could have lined up a fraction better at the bellhorn and probably the only way to do that would be to do a temporary fitting, cut out the rudder and then set it up. In some ways a retrofit might be easier. Maybe. I will have correctly working rudders so I’m good to move on.

Cable in place for checking

Proof of range

A working rudder

This step took nearly a week. I drilled 4 holes in each click bond so when floxed in they will grab well although my testing showed no tendency for them to turn when torqued up. I’ve also inlayed them slightly so the bottoms are flush as you see in pic 1. I used pure epoxy and flox for the bond with a light ply of fibreglass on the outside which is also peel plied. Pic 2 shows a set in place.

I did one hinge on each side at a time, let it cure and then another one in an attempt to maintain the rudder position. Especially after I spent a lot of time masking an epoxy bed for each hinge. Despite all this they are a fraction out gap wise although seem to be pretty much inline which was important. I am fixing this at the moment.

Pulling the rudders off and on for fitting is very, very time consuming with the clickbonds rather than bolts and I have skills with little sticks and probes to get nuts on the threads. I’ll use lock nuts later.
I probably spent 20 or 30 hours fiddling with all this. 10 hours is enough in this log, I really don’t want to know.

Slight inlay

Click bonds in place

Aligned

I’ve been working on this simple step the last three days. The left rudder fits but it wasn’t perfect with the hinges in place. I’ve made a flox ramp with some release tape on the hinge and setting it in place. We are probably talking 0.05″ or so that needed a little support to let the hinge sit as it should.

Its been a real fiddle to get things just right and quite a lot of thinking, trial fits and patience. Although its hard to see, Pic1 shows a thin bed of flox that fits the hinge perfectly. I did the bottom one and then the top in separate cure cycles. The middle hinge seemed to sit happily so I let it win the discussion.

I also had more work to do to ensure the bellhorn swings freely and without any chance of binding. I still have the fasteners to fit, but for now its on to the right winglet rudder and I’ve just done a little bit of flox for the lower hinge. More tomorrow.

Hinge fitting ramp

All lined up

Lined up and swinging