Cozy

Chapter 16 - Control System

Visit from the Competition

Wayne Hicks & I have been running neck & neck, at least until I caught up and then past him. We have chatted back and forth almost daily about various details of Cozy building, amongst other things, for almost a year. We've become good freinds via email and it was a pleasure to finally meet him at Sun & Fun. After the show, George Shell and Wayne came in for a "flying visit" in George's gorgeous LongEZ. They gave my bird the most complete inspection it's ever had. The only problems identified were a few flat spots on the wings and canard and the fact that the nose is a touch too low to blend nicely into the canard cover.

Sticks

In between big jobs I carved my control sticks from two lumps of walnut. By the time I was ready to do the rest of the control linkages, I had two nice custom made wood sticks. At Sun & Fun 2000 I bought two "top hat" trim switches and two tiny push to talk switches from Menzimer Aircraft Inc. Next day I drilled my sticks, carved out sockets for the PTT switches and fiddled until I had both switches fitted. Later I'll put a gloss epoxy on the sticks and embed the switches permanently.

Aileron Linkage

Cutting the torque tubes and connecting everything was no big deal once I figured out that the bushings in the firewall are angled slightly and I have to twist the control arm so its parallel with the firewall after installing the tubes. I'd received four FMN-10 teflon swivel bushings with my order from Wicks. I can't find these on the parts list anywhere, but they seem to do a good job of replacing the phenolic bearings, so I fitted them. I had to sand my brass bushings lightly to get the 5/8 steel tubes to fit. My only real problem was that I'd elected to leave drilling the holes in the bulkheads during Chapter 4. Now I had to drill a straight line through the firewall, both landing gear bulkheads and the seatback. This was not as easy as it sounds. I went to home depot and got a 12 inch drill extension and proceeded to bore the holes. Plans say to dress the holes to get everything lined up. For me it was more like undressing. My seatback holes ended up much too big (and had to be fixed later) and modifying the hole in the rear landing gear bulkhead wasn't at all simple.

The bondoed wood blocks didn't work for me at the front. Somehow I had trouble getting them in the right place. Instead I used blue foam blocks with the sticks stuck into them. Positioning was much easier. Plans say to use 5 min epoxy and flox, and two people to align everything. I did both sides at once on my own and with straight flox. Once everything was buttered up and held in place, I went around (twice) remeasuring everything. When this cured I layed-up 2 ply of BID over the plywood bearing blocks and onto the fuselage sides.

CS121 (the rearmost 5/8 AL tube) is supposed to be 37 inches (but plans say to cut long and trim to fit). There's supposed to be a one inch overlap with the 3/8 steel tube which goes through the rear bulkheads. I had a 5 inch overlap so my CS121 ended up at 32 inches. Seemed strange to have to trim so much. Could my fuselage be 5 inches too short. Nah! Everything works and turns smoothly, so its on to the aileron and elevator linkages.

Ailerons

I spend an evening and most of the next day fitting and refitting one aileron. I've must have had the sucker on and off about 12 times getting the linkage, clearances and travel just right. A little sanding here, a little adjustment there. I only drilled the linkage the wrong way once! I had to remake one small torque tube and had to dremel the ends off a couple of bolts to get full travel on the aileron. I'd planned to get the special bearings to replace the plans phenolic bushings in the wing root. However, I'd double ordered on the FMN-10 teflon swivel bushings and they work fine in the fuselage, so I made a birch backing plate and installed one of these in each wing root with 1 BID. (I've noticed a tiny amount of play on these bushings, so I'll probably invest in the expensive wing root bearings and retrofit them later. This is a reminder for me. - Done)

When it came to fitting the CS127 brackets I realized that this wasn't going to be possible with the wings on. The bolts come in from between the wing and the spar and there's no room to get them in. I loosened all the wing attach bolts and, by moving the wing a little, managed to get the four AN3-7A bolts in place. This would have been much easier to do while the wing was on the bench. At the end of a long Sunday (April 16th. '00) I got the left stick working the left aileron. Cool - but the linkage is a little stiff and there's a bit of play in both the stick bushing assembly and the wing root bearing. I may have to replace the torque tube that the stick attaches to, and I definately need those wing root bearings. As for the stiffness - I think this is the aileron hinges which have absorbed a bit of flox and primer. Not perfect (yet), but still - its nice to wiggle the stick and have something happen.

Once I'd done one side, the other side was easy. I had to "modify" the torque tube holes in the instrument panel to get full travel on the ailerons. I fixed the play in the sticks by adding a washer. Plans don't show one, so I hadn't put one in. With the washer in place the nuts hold the stick more firmly and the play is gone. I tried to get two wing root bearings from JD at Infinity Aerospace, but couldn't get hold of him in time. I ordered two stainless bearings part # W-MBFS-10 from www.smallparts.com ($11.47 ea) to replace the teflon bushings. I'd ordered the bearings on the web without even checking where the company was based. Incredibly they arrived via UPS ground from Miami the very next day. The bearings were a REAL tight fit on the 5/8 tubes, so my buddy, Bill, "adjusted" the 5/8 tubes a little. I dug out the teflon bushings, fitted nutplates on the backplates of the new bearings and glassed the backplates in place. The bearing itself fits between two plates and can swivel to line up with the torque tube. Once the glass was cured I put the ailerons back (again!) fitted the bearing, tightened the set screws and screwed the front plates in place. Perfect! No slop at all and VERY smooth movement. Now I'm glad I didn't spend $100 for bearings from Infinity Aerospace. Sorry JD!

Rudders

Connecting the internal bellhorns looked like it was going to be a bear, but I decided to cut a small 1 * 1.5 inch access door under the wing, just where the conduit enters the wingtip. The door extends about 1/2 into the winglet. When attaching the winglets I'd deliberately made sure that the reinforcement layups didn't go over this area. With the door removed the connection was trivial. Rather than reglass this area I plan to leave the door attached with silicone to simplify inspection of the rudder cable attachment.

Warning: Do not do this!

Carl Denk pointed out later that this hole is in a structural area. He also correctly pointed out that you can inspect the cable attachment by removing the rudder. There is no need for these holes. They helped during construction, but cutting holes in structural areas is never a good idea. I repaired the holes per plans structural repair. Thanks, Carl.

Next thing was to install the rudder springs. Plans say RTS springs. Hmmm. I looked through my miscellaneous parts box. The only springs I could find were about 2 feet long. What could they possibly be for??? After studying the plans for Chap 17 & 20 and the respective parts lists, it finally dawned on me. You're supposed to cut a length of spring, just as you do for the pipe. Geeezz! I know it's plans built, but I kinda expected the right length springs to come precut.

I made the electrical conduits using a piece of wood for a plug, then floxed the top edge only. Plans say to flox them in completely, but I figure that leaving the bottom unconnected for now will help me run the wires later. I cut the rudder conduit, then the door bell rang. Ed the UPS guy had brought my rudder pedals from Dennis Oelmann. What a beautiful piece of work! I was expecting welded steel, or maybe powder coated. What I got was white enamel with all the rods and sliders needed. My compliments to Dennis. I just hope the outside of the plane looks as good when it's painted.

I learned a new verb today. "to swage". Apparently it means to correctly squish or crimp those little metal ends (nicopress sleeves) on control cables so they don't come off and spoil you're underwear. The nicopress sleeves called out in the plans are 18-1-C copper, but Wicks shipped 28-1-C Zinc which, I discovered, are the correct sleeves to use with a stainless cable. I ordered the (relatively) cheap HST-2 Nicopress Tool on Nat's recommendation. While waiting for the tool I made the 4 inch al tubes for the springs, cut the birch plugs, bent the piano into hooks and floxed them in. I was wondering what that short length of thick wire was for. When eveything was assembled I found that the spring on one (Char's) side wasn't under tension until the rudder moved 1/2 inch or so. I cut the spring back a bit and tried again. If I'd spotted this when burying the 4 inch al tubes I could have drilled them a 1/4 deeper, but I didn't realize it until after they were microed in place. Later I glassed over the ends of the 4 inch al tubes and recut the hole. The micro would probably hold fine, but I wanted to trap the edge of the tube with glass, just to be sure.

Using my recently aquired swaging skills, I fitted the 1/16 steel cable to the end of the hidden bellhorns. When the rudders were screwed tight I found that, on my side for a change, the bellhorn was hitting the winglet skin and forcing the rudder into a slight (1/16 inch) outboard position. This will need a minor adjustment next time I take the rudder off. Also, the other rudder has a little less tension in the spring, so the force needed to move it is less. Finally I was able to stand between the wing roots, pull the cables and make my rudders wiggle. All the control surfaces are now wiggle appropriately, and its on to chapter 13 to fit the rudder pedals.

Later I needed the special springs that go just before the pedal per the hidden bellhorn plans, but couldnt find my plans. I asked on the CA list if anyone knew the part number. An hour later, Phil Collins replied that he could do better than give me the part number - he could send me the parts because he had extra. Wow. Manna from canard heaven! Later that day I found out that they come from Century Springs Corp. part # 1887. They used to have a minimum order of $25 so you may have to order several of them. When the springs arrived from Phil I went to put them in my parts box and what'dyaknow - there was an identical set already there. I mentioned that I now had a spare set on the Canard Community Forum and Nick Ugolini was first to the plate. I shipped them out to Nick on the basis that what goes around comes around. The next week, when I came to install the springs, I could only find one. Aghhhh! Finally I came across the missing one in my electrical parts box. The cats must have moved it. This last task was the one thing I'd been keeping the wings on for. I used the dremel to cut off the swages at the rudder pedals. Amazing how much effort this took. Those little swages hang on for grim death and I used a couple of cutting blades removing them. I got three feet of the 0.050 music wire from Wicks and set about making the links that put the springs in compression. I ran out after making three (you need four) and also discovered that I'd made the links too short and the spring catch on the edge of the rudder pedal. Damn. I ordered another 6 feet of wire, remade the links and assembled everything. I found the easiest way to cut the rudder cable wire is the dremel. With the cables pulled tight I swaged the loops back on and - bingo. I got rudders. I'll have to wait till I fill the brake system with fluid to test the travel, but everything looks good.

Clean up

Later, after completing the firewall, I was ready to reattach all the linkages. The Florida humidity had done a number on all the steel parts, including the root bearings, so I removed them, cleaned them up with 220 grit and spray painted them all with white appliance epoxy. Next day, everything looked great except that I couldn't get the oil impregnated bushings onto the steel aileron bellhorn rods because of the paint. I sanded the paint off again, adjusted the ID of the bushings a little with 220 grit and slid the bushings into place. I added a little grease at the end where the bearing goes, then repainted the steel rods. Yes - I know this means I won't be able to get the rods back out easily after I flox the bushings in place. I'm hoping I won't have to, and I've seen what a few months of humidity can do to unprotected steel.

Once the new bushings were floxed back in place, I reassembled the aileron linkages and bolted the rudder pulleys in place. Threading and swaging the rudder cables was fun, but I was a bit concerned about travel. The rudder pedals only move 1 1/4 inches before they start to engage the brake cylinders. I may have to do some adjustments after I've put the fluid in and bled the brakes. Still, it was kinda neat to sit in the plane, press the rudder pedals and watch the rudders move. Seems obvious, but its nice to do nonetheless. I pressed the rudders alternately, then both both at once, then one at a time, fast then slow, for a full 10 minutes before getting bored. It must be the vroom vroom syndrome most builders get in chapter 8 when they first get to sit in the fuselage.

Upgrading the Aileron push rods

Long after I built my controls using the plans MM3 rod-ends, someone somewhere bent an MM3 rod-end on a Long-Ez, so Burt mandated an upgrade of all the rod-end's behind the firewall to MM4. Nat Puffer followed suite, so I ordered 10 MM4's and set to work upgrading my controls. Brian DeFord's note in the Cozy Archives about this job is very accurate. It's not a trivial task.

After discovering the thread I needed was 1/4 28 I bought a tap and drilled out the first hole with #3. Either my hand tapping skills are weak, or my tap was no good, but the result was a poor thread with the first 1/8 inch missing. The fit was a bit loose. I decided that these were parts I didnt want to screw up. Given that my life is going to depend on every one of these fittings, I called Jack Wilhemson Who made my steel inserts. Jack offered to retap the inserts (and replace the one I'd screwed up) if I would mail the rods to him. I figured that an hour of Jacks professional labor is well worth the many hours of doubt I would have suffered instead. I mailed them off and got on with something else. While I was waiting I ordered stop nuts for the rod-ends and AN4 bolts, nuts and washers for all the connections.

The rods came back a week later and I set about putting my controls together in 'flight ready' status. I reassembled everything and found that the MM4s need to be cut back about 3/16 to get a good fit. As the parts went together I added locktight to all the threads and grease to all the bearings. The ailerons seem a little stiff, but it's hard to tell with the roll trim springs pulling at it. I got Char to wiggle each aileron ever so slightly. I could feel it on the stick. next I jiggled the stick and yes, every tiny movement was transmitted to the ailerons. There doesnt seem to be any slop in the controls at all.

A note for others who follow. Jack Wilhelmson had suggested that I eliminate the "quick disconnect" fittings in the aileron torque tubes, but I insisted on them. He was right. Once the aileron controls were finished, and I needed to remove for the FINAL time, I found that the quick disconnects were unnecessary, perhaps even a liability. Why? Well, when you remove the bolt for disconnect, there isnt enough travel on the ailerons to remove the tube - so you just slide the wing off right? I may be paranoid, but it seems to me that moving the wing, and backing it off the bolts with that tube still connected might well lead you to move the torque tube rearwards and bend the aileron rod end. Anyway, it didnt look good to me, so I decided to remove the rod end at the bell crank. The other potential problem is introduction of slop at the quick disconnect fitting. My recommendation to new builders is skip the quick disconnect and make the torque tube all one piece.

Moving the rudder conduit

This note may save you some time and cramped leg muscles. When it came time to do my wiring I followed 'Lectric Bob's creed and got fuse-blocks. It turns out that the rudder cable conduit on the starboard side goes right through the ideal spot to put the main and essential bus fues blocks. See Chapter 22 for more details. Suffice to say that I had to cut away the flox supports and raise the conduit so that it runs directly against the bottom of the passenger map pocket rather than parallel with the electric conduit as I had it earlier.

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