LG Bulkhead Reinforcement Preparing Strut Attach Tab
Landing Gear Cover Axles, Brakes & Brake Lines Landing Brake
Based on all the discussion in the Cozy forum regarding the braking capacities, I decided to use the Matco brakes instead of the Cleveland brakes per plan. Matco's web site also has a section that helps you to determine braking power needed and recommends their brake model for your aircraft. It allows you to enter in the aircraft weights, landing speeds, etc. Then it cranks through their equations and provides you the results. I ran through that exercise and came up with the same model as most of the Cozy builders are using.
I ordered the Matco brake model W51LT( triple puck) from them directly. The brakes arrived within a week. I even got a call from their tech support, advising me that I had ordered a couple extra parts that are included in their kits already. Saved me some money... My experience with Matco was very good!
Axle Mounting Template |
Installation of the brakes and axles requires an precise positioning of the axles, the orientation of the calipers and trimming of the strut ends. Initially, I got a copy of the template (AutoCad format) from Jim Springer, who installed the Matco brakes and was gracious to share his template with anyone who needed it. I downloaded an AutoCad viewer and with some manipulation, was able to print it out to almost the exact size as my axle flange.
As shown, my template consists of the hole locations for the axle, the orientation of axle flange relative to the sides of the gear leg, relative position of the caliper and the cut line for the landing gear strut. I did follow the plan direction regarding the parallelism of the axle flange to the side of the gear leg. Once that's set, the orientation of the caliper is pretty much set as well. I also made a mirror image for the inside and outside of the strut.
This template is available to all Cozy builders. Just send me an e-mail and I'll send it to you. I think I can convert it to any graphical format (such as .jpg, bmp etc.). So, if you have any graphical viewing software, you should be able to modify, view and print as desired. |
Determining Axle Position |
The position of the axle was set as FS110.0 per plan. FS110.0 was easy to find, I just dropped a plumb line from the cross beam (picture below) and placed a vertical mark on the strut. However, I was a bit surprised that the vertical position of the axle was not obvious (other than .5" below the edge of the strut in Fig. 37). I eventually got my answer from Rick Maddy's search engine and found it at the back page of the plan. It is supposed to be at WL-19. The question is how do I know dropping the flange .5" from edge of the strut equates to WL-19? Especially since I am not using the Cleveland brakes and that the Matco brake flange has different dimensions.
Based on the measurement above, the center of my axles are 2" below the edge of my strut - making them around WL-19 to WL-19.125. |
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3 Layer BID |
Notice the markings on the strut are different - its because my axle position was off a bit when I re-confirmed its WL, therefore I re-drew the trim lines. Only the trim lines and axle flange orientation and position were included this time. |
Drilling the Axle Holes |
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One of the most difficult to achieve requirements (for this step) is setting the toe-in alignment - it must be set to 1/4 degree. Since I am installing the Matco (instead of Cleveland) brakes, the plan direction does not quite apply, though I followed the general concept and approach. First, I used a laser and projected a cross-hair on a white board 213.25" from FS110.0 - not the back of the fuselage. Then I transferred the distance between the center of the fuselage and the outside edge of the strut, onto the white board per plan. The next step is to calculate and mark the toe-in position on the same horizontal line.
I tried the 1/4" tube sighting method as suggested in the plan. I have to admit, I can't eye-ball a cross hair 20 feet away through a 3" tube with any precision or consistency! I gave up after several tries and decided to try a laser beam instead.
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Again, I followed the plans method to establish the outside edge of the strut from the center of the fuselage (d1), then I measured the distance between the outside edge of the strut to the center of the laser beam (d2). If the laser is targeting at a point (on the white board) that is (d1+d2) from the center of the fuselage, the beam should be parallel to the fuselage... right? Not quite, there is one more consideration...
Laser Beam Offset |
To determine the laser beam offset, I place my laser on a flat table, 213.25" inches from the wall (same distance between the axle and my alignment surface). I marked the cross hair position on the wall. Then I turn the laser body upside down and mark the laser cross hair position again. The horizontal distance between the two marks is 2x the laser beam offset. Therefore, take that distance, divide it by 2, then add or subtract (as appropriate) to the overall alignment measurement. |
Toe-In Calculation Summary |
- center of fuselage to outer edge of strut 33 15/16" - add laser position offset of 31/32" because it is further away from the center of fuselage - add laser beam offset 9/16" because my laser is exiting to the left of the housing - subtract toe-in calculation (based on my forward distance of 213.25") 15/16"
Therefore, my laser target position with 1/4" toe-in for the left wheel was calculated to be 34 17/32" left of the center of the fuselage. I did the same for the right strut, except I subtract the laser beam offset from the overall calculation. |
Trial Run |
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Preparing for Floxing |
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Floxing in the Axle and Back Plates |
After the flox was cured overnight, I removed the bolts & nuts and cleaned them off. The Turtle wax paid off (Thanks, Wayne). I also cleaned the wax out of the holes. The axle popped off cleanly, leaving a flat and smooth platform. I removed the packing tape and cleaned off the surfaces.
I used the Fein tool, palm sander and circular sanding stick to remove the strut cutout. Then I re-mounted the caliper and wheel (as shown). |
Initially, I got a set of Cheng Shin tires 11.00 x 4 x 5 tires to be used temporarily during the building process. The Cheng Shin tires were cheap (~$25 a set for tire & tube) and was recommended by someone in the Cozy Forum. It turned out that the valve stems were too short and the wheels were too narrow. After further investigation, I found the Cheng Shin tires were more for the Long Easy & not the Cozy Mk IV. I took them back and traded them for a set of Michelin Condor tires as recommended by Matco.
I went to an auto tire store and got a bit of slip-tac (fancy name for tire soap) and brush a bit along the contact surfaces between the tire and metal rim. Following the Matco instructions, I installed the tires and tubes without pinching the inner tubes. I also cleaned and packed (greased) the axle bearings as instructed. The wheel installation is now complete! |
There has been quite a bit of discussion on the Cozy Forum that the disc brakes generate lots of heat on the rotor which radiates onto the struts. Supposedly, someone's strut caught fire and the entire plane burned to the ground. Since then, many builders have made a set of heat shields and mounted them between the strut and the rotors. Most of the heat shields I have seen (from various Cozy sites) consist of a rectangular sheet metal with 4 holes (~1/16" thick) and are sandwiched between the axle flange and the strut. It's simple and supposedly, works fine.
Though not in the plans, I figured I better get it done while I am at it. However, I didn't like the way it was mounted because of the following reasons:
- Heat from the heat shield will conduct right down to the strut as it is in direct contact with the strut;
- The heat shield potentially messes up my 1/4 degree toe-in position;
- It adds thickness to the axle flange, which in turn, moves the wheels further out.
I made a template out of thick paper and trial fit it first before I made the actual part out of 1/16" aluminum sheet. Since there is an offset to accommodate the calipers, I have to make a left and a right shield. Its the same template, except its a mirror image. A friend of mine has a buffer and we decided to buff it up just for fun - see how nice and shiny they are! As always, the template (electronic format) is available for any builder per request. |
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How
well will this work? I dunno... I will find out when I do the taxi test light
years in the future! But for now, it looks pretty
[Hindsight]
There had been some discussion on the Cozy forum regarding the mounting location
of the heat shields. You should be able to find them in the archives. The key
concerns were 1) adequate clearance between the heat shield and the rotor and 2)
how does the heat (from the rotor) transferred to the landing gear. After
reading and weighing all the comments, I still prefer my design rationale.
First, the joggle provides clearance from the rotor and, second, the attachment
point - creates a heat gradient mid way between the gear leg and the heat source
- thus minimizes conductive heat from reaching the gear legs. But, bare in mind,
I am not flying yet, others are
[Hindsight]
During separate visits by a couple very well respected Cozy builders and fliers,
I have them take a close look at my heat shields and solicited their opinion on
the design and placement. I was pleased to receive their nod of approval... |
I have to turn the fuselage up-right to make the landing gear box. Since the next section (the landing brake) requires the fuselage up side down again, I decided to work on the landing brake first before I turn it over. Besides, I have to do the landing gear cover as well.
Landing brake completed and fuselage turned over...
I glassed both sides of the foam and then cut the circles out with a router and touch up sanding. I also BID taped all edges top and bottom. |
I decided not to install the brake lines until the structure at the front of the plane is in place. Then I know for sure where the brake paddles and reservoirs are. In addition, I still have to move the strut and brakes on and off, having the brake line in place now will be more of a hinder. Therefore, to be continued...
The plan suggests to wrap the strut and brake line opposite the disc with 1/8" fiberfrax and then aluminum foil tape. Since the strut is not painted at this point and the brakes lines are not in place, this task will just have to wait until then as well.
On to the landing brake...
LG Bulkhead Reinforcement Preparing Strut Attach Tab
Landing Gear Cover Axles, Brakes & Brake Lines Landing Brake