Cozy

Chapter 9 - Landing gear & landing brake

Landing Gear reinforcements

The first two layups went well, but took much longer than expected. On the second layup I made a paper pattern, cut the BID, then found that the cloth was too small to lay down to the correct dimensions. Had to throw the cut cloth and recut 2 inches larger than the pattern, even though I made the pattern oversize. I left the fuse in the A frames for this, but tightened the pivot nuts to stop it rotating. Rest of the reinforcement layups were no problem.

Main Gear

Got my main gear from Featherlite. That is one strong piece of fiberglass. It's pressure molded S glass. I didnt have to do the first two steps in the plans because Featherlite had done them for me. There was no "flash" and no "bumps". Just sanded it down and did the leg trim - at 8 degrees, not 13 as the plans say in a couple of places. I went down to burger king, bought a coke and took a dozen straws. Got some strange looks, but what the hell. I dont think they'd have believed me if I said the straws were for my airplane! I used some long pieces of scrap foam to support the aluminium duct tape. Ended up with nice straight trailing edges. The brake pipe I got from Wicks (nyloflow 3/16) fits nicely. According to JD this stuff is too soft. He recommends 3/16 Nyloseal which has double the pressure rating. Costs about $10 to get the stronger stuff so I ordered it. At JD's [Infinity Aerospace] recommendation I also ordered some 3/16 5052 AL pipe for the brake pipes in the fuse. Cant see how it would hurt and its not expensive. Another recommended mod for the brakes is stainless steel braided pipe from the nylaseal in the legs to the caliper. Again, this makes sense so I'll be getting some of this once I find a source. The four UNI wrap layups were fairly easy. Glad I didnt pay $100 to have someone do these for me.

Making the box

This is where my troubles started. When I leant the strut against my bench and lined the legs up exactly 9.25 inches away I found that the strut didnt touch on one side. About 1/4 gap. Sent a maillist question and got back various good advice. Nat said not to worry, his was like this too. Just adjust later when fitting the wheels. Meanwhile I checked (a third time) all my angles and lines. Found that my line on the floor was 1/4 out. The strut was just fine. It was my brain and my "straight" edge that was out of alignment. Built the box, but I wasnt careful enough with the curvature. Ended up with some big gaps which I had to cover later to get a flat tab.

A stupid (and painful) human trick

Once I had the box and strut assembly upside down on my bench things really went wrong. Decided I needed to invert the strut. Put my hands in between the spacers and lifted. Once the legs were out of the verticle, physics took over. The moment of the legs is such that the strut wants to rotate. It did. Quickly. The legs went over my head and the box rotated until my fingures were going past 220 degrees. I dropped the strut and extracted my fingures before they broke completely off. Ended up with a very nasty sprain. Mentioned this to the group and got a message from Wayne that the same had happened to him, except that the strut had hit his jaw. Ouch.

Warning Lift your strut with care and, ideally, with two people. I'll be doing 8 figured layups for a while to prove it. [Later note. That "sprain" took about 2 years before I didn't notice it any more. I must have fractured the bones my fingers.]

Making the tabs.

It takes 45 plys (count 'em) to make each side of the tabs. 90 ply in all. Came together suprisingly easily and only took a couple of hours for each set of layups. Trimming the tabs cost me 6 sabre saw blades. The big problem for me here was the position of the attach holes. Followed plans to the letter, but went wrong somewhere. When I put my 12 inch drill bit through the holes for the first time I found that the gap to the chord was 1 inch on one side and .75 on the other. Plans say 0.7 to 0.75 max. Now I have to move the holes. I didnt do the candle wax thing on the second layup. Let the holes fill with epoxy. I dont care. It will be easier to drill new ones. I marked the outside tab to show where the holes needed to be. I'll move one side up 0.25 and the other up 0.5. Now I'll be out 0.2 at the legs which is within the 0.25 tolerance mentioned. I can take this out when adding the axles. The extra hole in my tab will be eaten away when I open up the holes later. Wow. I must be learning. I figured all this out without having to call Nat on the weekend!

Installing the gear.

I've been told that the plane now looks like a viking helmet or, worse still, a boat with hydroplanes. The strut was dead level, but I was about 1/2 inch out with my plumb line from the leading edge of the strut. I jiggled and elongated the holes a bit and got it down to .25 inch too far aft. I'm going to leave it that way and adjust when I install the axles. The 1/8 thick AL 4.5 * 4.5 for the MK2's is missing from the Wicks Chap 9 parts list, so I don't have it. I'll have to call them, order it and wait on this part of the job. Tempting to get it overnight, but not really justified. There's plent of other jobs to be done.

Got my aluminum and made the MK1s and MK2's. Wrote the orientation in felt tip pen, then rubbed this off one of the plates while getting the bondo off. Now I have to try all the possible permutations to get the holes lined up. Next time I'll scratch the info on the plate. Got my bushings from Brock. In reasonable time and they look good. Maybe all the bad things I've heard about Brock are untrue, or have been fixed. Time to drill the 5/8 holes in the bulkhead and strut. I got the "spot facing tool" in my initial supplies kit. I think it cost around $35. I'm thinking "I've got the right tool. This should be easy". Not easy. First the 1/4 steel rod did NOT want to come out. I was not impressed with the fancy expensive spot facer. By the time it's gone through 3/4 of AL and 1/2 of glass on one side its worn out, and so am I from pushing the drill. Finally got through both sides and was about to start on the tabs when I realised that I have to use the 3/4 spot facer here. Widening a 5/8 hole to a 3/4 would not have been easy. Good thing I need the other tool, cause the first one is practically useless after doing the bulkhead holes. Cut the holes in the tabs per plans and it was time to install the gear and "slip" the steel rods through the holes.

I've come to expect trouble whenever the plans use a word like "slip", "slide" or "pop". Must be an inside joke or something. This was no slip. More of a hammer. I got about 1/2 inch passed the first tab, then the rod would not move further without "massive persuasion". Hmmm. Can't get it in. Can't get it out. Took me an hour with some sawn off bolts pushed down the tube, and a hammer from the rear. Not a lot of room to swing a hammer between aft gear bulkhead and firewall. When I got it out I found that the first 1/2 inch was quite scored. Removed the gear (again) and tried the rod in the tube. I've heard of an "engineers fit" but this was more likely to cause one than be one. The fit in the bulkhead bushings was perfect. No play, but easy to push through. The fit in the bushings in the tube must have been 1/32 out. Such precision! I'd read the archives about bad fitting parts from Brock. Now I can add to the complaints. Whenever I have a choice in future (rudder pedals, front wheel parts etc.) I will NOT buy from them. I used a 1/2 drill to ream out two of the bushings and continued. Things still didn't line up right. I jiggled and joggled and persuaded a bit, and finally got the rods all the way through. I checked all the measurements again and was delighted to find that I was 1/8 inch low on one leg and dead on the FS. At least something went right during this job.

Once the gear was in place I contoured the landing gear cover and the fuse side for about 1/4 gap around the strut. I didnt see anything in the plans about finishing the edges after contouring, but I glassed it with 2 ply bid and made a flox edge anyway. I'm quite pleased with the way everything fits with a nice even gap. I plan to put fairings on eventually, but this will definately do for now.

Wheels

I'd held off on ordering the main wheels. Partly because of the expense and partly because I was wondering whether to put 6 inch wheels on. I'd like to know I can get down in a rough field if I have to, and the stopping distance is supposed to be much better. But, then again maybe I'll just stick to what's recommended.

I decided to read the archives in depth on this wheel / brake issue. I went off the end of a runway once, and its no fun. But that's another story. Suffice it to say I'm a little particular about being able to stop when I want to. Reading the archives turned into a real pain. I printed the Chap 9 archives for '95 - '99. Almost 200 pages. Decided I need a way to search the data, downloaded it all, wrote a quick & dirty program to generate an index and process the text into HTML. I uploaded the converted text and index and wrote a perl script to do the search. Bingo. In 2 hours I had a way to find everything anyone ever said about wheels & brakes. Based on this input, the fact that Marc Zeitlin went this way (and I can use his pictures to help me with the installation), and a conversation with JD Newman, I decided to go with the triple puck 5 inch Matco wheels & brakes from Infinity Aerospace. These have about 338,000 ft lb braking capability each compared with 192,000 ft lb for the Cleavlands. They weigh about the same and are a little narrower in profile (= less drag). I ordered the "full monty" (includes parking brake and 6 ply Michlin tires) and they're on the way. Now. What do I do about the axles, spacers and nuts I got from Wicks? Called them. They said to ship them back with a copy of the invoice and a note as to whats wrong. They'll credit my account. Excellent service from Wicks once again.
I expanded my archive search program a little and made it available to other Cozy builders. Later, Rick Maddy wrote a MUCH better search engine so I removed my quick and dirty out of date one.

Got my wheels from Infinity Aerospace. Marc says he "figured it out" so I disassembled the parts and did the same. In a couple of hours I had my tires inflated and axles ready to install. No big deal. I assembled the wheels, tubes & tires and inflated the tires. Then JD mentioned that the red dot on the tire goes next to the valve for balancing. Maybe I should have known that. Dissassembled everything and did it again the right way.

Installing Wheels & Brakes

I didn't like the look of Marc Zeitlins installation, so I followed Brain DeFord's Chaper 9 description, printed out his pictures and figured out how to carve the struts and mount the axles without gouging big notches out of the strut. Ray Cronise (Cozy #770) was due in for a weekend visit, so I wanted the plane on its wheels just to make him jealous. I aligned the axles per plans without problems and managed to get the wheels sitting on the axles before he arrived. Next day I carved the struts, installed the calipers & disks and we flipped the plane onto its wheels. I sat in the pilot's seat for the first time, but still couldn't bring myself to go vroom vroom. Must be the British in me. We celebrated with bloody mary's and a dozen Maryland crabs each. Later I fitted the brake lines. I got Nyloseal (not Nylaflow) for the lines up the legs. Was going to order Statoflex stainless braided for the bit by the wheels till I saw the $40 price. Instead I ordered some firesleeve and clamps for $10. I also ordered two 0.063 AL sheets 8 * 12 inches to make heat shields. Was also going to get AL tube for the fuse section, but then decided to use the Nylaflow I have in stock. Jeff Russel uses this for all the lines and is quite happy with it. If I decide the brakes are too spongy I'll change the lines later. [Later note: I'm doing taxi tests and they're not at all spongy.] Inserting the 2030 brass inserts (in either nylaflow or nylaseal) to "ensure a tight fit" was interesting. It took a LOT of persuasion to get the inserts in place. I'll hold off installing the master cylinders and parking brake until I get the rudder pedals from AeroCad. I found that the brass connectors for the brake lines fitted just nicely in the holes I made in the bulkhead. I pushed half the connector in from one side, and half in from the other. This way the lines can't move or rub against the edge of the hole. [Important note: See footnote on the brakes for information about why the drawing in newsletter 64 is wrong, and the how laydown master cylinders should be installed

Landing Gear Cover

I read Marc's method and decided to go with the 3/8 foam per plans. Joined strips of foam with micro and shaped after cure. Now for the layup of the outside. Made a 3 ply layup on wax paper and cut to exact width. Got it layed down on the cover with some effort. Stood back to admire the result, then thought - wait a minute... I went to a lot of trouble to get a 90 degree corner along the rest of the NACA scoop. Apparantly this is important for good efficiency. Now I have a radiused outside corner (the LG cover). Apart from being inefficient it's going to look bad with sharp corners front and back, and the radiused corner on the cover. I look carefully at the outside corner and notice the glass isnt laying down very well. I lift the layup off the sides and scissor trim for verticle at the scoop. When it cures I'll do the flox thing and glass the sides like I did for the scoop. Now - what about the two nice wax paper 3 bid 45 degree layups for the sides? Pity to waste them, but I can't use them till the inside cures. Hmmm. Heat makes the stuff cure. Maybe if I put them in the freezer...
This is the experimental catagory, right? I put the layups in the freezer and waited for the first layup to cure. Three hours later I trimmed, floxed, then got the layups from the freezer. They were stiff as a board . Ok - that didn't work - but then they began to flex as I carried them. The heat from my hand was "melting" them. They were stiff from being frozen. I warmed them with my hands and, in a couple of minutes they were as soft and "fresh" as they had been three hours previously. I stripped the wax paper, painted the cured micro with epoxy and layed them down. No problem. Stippled in a little new epoxy, though they didn't seem to need it, then squeeged as normal. After cure I tried to pull the layups off, bend them and delaminate them without success. I wouldn't try this on a wing, but I may have discovered a way to save a wax paper layup till needed. If anyone reading this knows something that I should know - please tell me! Its only a landing gear cover, but I dont want it in my prop at 100 feet on takeoff!
After cure I popped the cover off the plane. It wasnt so much of a "pop" as a groan, lever, crack, groan, thump - but it came off finally. Now for the underside. radiused, tapered and microed the foam. Now - two plys BID on the ledges. Hmmm. 3/4 wide strips. OK. Wax paper layups. My ledges were a bit uneven in width so the strips hung off the sides here and there. Layed the overall one ply, then lifted it at the edges to remove the wax paper I'd inadvertantly left on the edge strips. Box taped the ledges on the plane and put the cover back. Looks good and fits fine. Weight (and wait) for cure. Later I fitted the cover with the strut in place. Had to remove quite a lot of glass & foam, but better oversize than too small. After carving the cover I was left with a foam edge where the cover meets the strut curvature. The plans don't say anything about this, but I figured you dont want bare foam, even on the inside of the cover, so I had to floxed and glassed a corner. I got a drill & tapping set for $12.95 from AC Spruce. Had no trouble drilling and tapping the screws except for one hole which missed the slug entirely. It's tough to tap a thread into foam. I drilled another hole and will have to fill in the other one. The cover now fits well and can be screwed on tight.

Landing Brake

I cut through the skin with a hacksaw blade held almost flat up against a T square to keep it straight. Eventually the brake came free with a little persuasion. Made the plywood pieces, alum slugs and all. Stuck the slugs on the L23, 5 min expoxied it to the prepared it to L16. Then read the FAQ which say to make L16 1/2 wider each side if you're going to fit the Lanza actuator. Scrapped my L16 and made another. Noticed that the slugs were on the wrong side of the hinge. I'd expected the 45 degree angle on L23 to butt against the glass of the floor, but no. It's at the other end. "Popped" the slugs loose and stuck them on the other side. I used 3 layers of duct tape to simulate the AL shims called for, as per the FAQ and installed the brake in the fuse. I widened the tab by 1/2 inch on each side per FAQ's. I got an actuator from AeroCad. Jeff knew someone who had a couple spare. The actuator itself only cost $89 plus tax. It came without a bracket, so I had to make one out of aluminum. The actuator has the following markings:
Warner Electric, 1300 N. State St., Marengo, IL 60152 815-568-8001
Electrak 1, Linear actuator S12-17A8-04, 12VDC
75lb load rating 9307-448-002
602 2684

Once I'd figured out how big and where the hole needed to be I cut through the floor. It's a much smaller hole than plans. Doesn't need the long thin area. Had a bit of trouble getting the glass to lay down in the hole. I ended up glassing this seperately after making a flox corner at the top. The glassing and attachment of the landing brake went well, except that I had to wait up till 2am to knife trim and place the brake in place. I'd already drilled and tapped the screws, so I floxed the hinge surfaces, tightened the screws, put some shrink wrap film under (above) the brake and weighted everything down. Next morning all looks well. The brake needs a little fine trimming / sanding around the edges and its done. Now all I have to do is get all the bondo off my brake. Later I devised a way to use the existing hard point installed in Chap 7 for the plans landing brake. I made a new hard point about 5 inches higher and a bit further aft, then linked the two hard points with alum brackets on both sides of the central seat support. The problem with my installation is that it is not adjustable, so I had to get the distances exactly right to make the brake fully close just as the actuator stops. My first attempt was about 1/4 out so I remade the angle brackets on the brake with new holes 1/4 higher. I wired the actuator through the heat duct and set the switch on top of the instrument panel. With a battery charger providing the power I proudly demonstrate my first automated part to anyone who will watch.

Don Bowen sent some pictures of his landing brake installation. His bracket is different to mine and I notice that the angle of the actuator is more acute.

Bulkhead cover

I glassed the cover over the bulkheads. Plans show a couple of large holes, but no dimensions. I presume these are inspection holes. I'll cut them out later when I know what size they need to be. [Later note. When it came to doing the fuel system, I decided to go with a fuel sump over this area to accomodate the fuel injection system. This cover had to be cut out and replaced a little lower to make more room for the sump] [Much later note - I dumped the sum and went with a solenoid valve to flip the return. See Chapter 21.

A note on supplies

Either I'm being inefficient, the calculation is wrong, or I got shorted because I'm out of BID again. I have the materials through Chap 12 and I'm supposed to have 5 yds BID for the Canard, but its all gone somewhere. Gotta get some more. My original epoxy order of 5 gals for chaps 4-7 is still going strong. I have about 1/2 gal left. I'll need more for Chap 10. My 5 minute epoxy would have been fine, but one of the nice Denny's syrup jars I got leaked so I have plenty of A, but no B. The leak went into my box of tongue depressors, so I have to get more of those. I need to get some wide peel ply, but this time I plan to get 10 yards of the 60 inch roll. Also, based on current progress, I think its time to order Chap 13 parts. I ordered more 5 min from Wicks. They have a new kind that comes in a bottle with a small nozzel. Works much better.

Those Bleedin Brakes

Many years later, in Sept '02, my Cozy got it's first fluid. Appropriately it was the blood red mil spec brake fluid. I've read the discussions about using the DOT 5 silicone based fluid used by Harley Davidson, but decided on the plans stuff for a few reasons.
1. I'd ordered it a while back and had it on the shelf
2. Its more available at airports
3. It doesnt screw up the paintwork, or the ability of the paint to stick
4. Its per plans
5. I dont expect my triple puck Matcos to get very hot
6. I like the color
I found an old metal oil can with a pump handle, cleaned it out and filled it with fluid. A six inch length of 1/4 nylaflow fitted tighly over the nipples on the oil can and the brake cylinder. I unscrewed the nipple and started pumping. After a while I could see the red fluid progressing along the pipe in the gear well. It took about a third of my quart bottle to get fluid all the way to the reservoir on one side. As the fluid progressed up the fuselage I had a bet going... I wasnt sure which pipe was connected to which wheel because they disappeared behind the electrical conduit and the seatback. When I connected the parking brake I'd just guessed. Yes. I have a Matco parking brake unit mounted on the left forward side of the panel. Why do I have a parking brake? Here are The top ten reasons for having a parking brake in a Cozy. Anyway, I'd pump a few squirts, close the bleed nipple, then climb out from under the plane and look at the pipe to see how far the red stuff had come. As it came into the nose I noted which pedal it was going to and yes, it was going to the correct one. My 50/50 gamble paid off (for once). Once the reservoir was full I tightened up the bleed nipple and went over to the other side. On the first side I'd seen the calipers close as the fluid filled them. This didnt happen on the right (Char's) side. Once both reservoirs were full I called Char out to see the first fluid. While I had her attention I lifted one strake (by bending down under it and standing up lifting it with my back - very easy with no engine), and stuck some foam on top of a saw horse to support the spar and lift the wheel off the ground. I asked Char to push the rudder pedal while I turned the wheel and, sure enough, the calipers locked the wheel. Great. We have brakes! The same procedure on the other side produced the same results, except that Char said she had to push much harder to lock the wheel. Something aint right with that caliper. A little later I heard the caliper "pop" into place and then it moved normally. The other issue was that Char noticed a one inch long air bubble in each of the pipes just where they start downwards to the master cylinder. It was interesting to note how the bubbles moved downstream, shortened and almost disappeared as she pressed the pedal.

I'd considered installing aluminum brake lines, but kind of defaulted to what's specified in the plans because it came with my Wicks order for the chapter. There's lots of discussion in the archives about this, and the consensus seems to be that you get a more positive feel on the brakes. Also there are stories of the nylaflow getting brittle. Unfortunately, you have to install nylaflow down the gear leg where it bends anyway. I studied the catalogs, but never did figure out what fittings I'd need to connect the various parts, so the nylaflow stayed. I fitted some braided steel pipe over the nylaflow where it came out of the strut so it'll never see sunshine. Hopefully my Matco triple puck brakes will have enough bite that I wont find the expansion of the pipe to be a problem. If I have a problem with it maybe I'll swap it out later. Right now I'm really glad I have Nylaflow because I can see those damn bubbles. With aluminum lines I'd be guessing. In fact I wouldnt even know I had bubbles.

I tried pumping more fluid to get rid of the bubbles, but all I managed to do was push them into the master cylinders. Pushing the pedal sent them back along the pipe. I tried removing the bolts for the master cylinders so I could lift them up and encourage the bubble to travel along the pipe. Nothing would get the bubbles past the master cylinder. The solution was very simple once I found it. I loosened the pipe where it enters the master cylinder, then Char held the pipe up while I pumped more fluid in from the wheel. Provided that the pedal stays still, there's no tendancy for air to enter the master cylinder. Once the air was forced out of the pipe, char reconnected it while I maintaned a positive pressure by pumping very slowly from the wheel. This worked first time on both sides. There were a couple of small bubbles in the reservoirs also. I got these by removing the reservoirs and holding them at an angle so the bubble could make it's way upward.

The whole bleeding procedure took a couple of hours. Now my Cozy has brakes. I can set the parking brake and the plane doesnt move around when I push it. One interesting point is that the pedal movement required to engage the brakes is only about 1/4 inch. I like that. This will match the other control movements.

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