CHAPTER 9 – MAIN LANDING GEAR AND LANDING BRAKE
Wheels in place
Step 1: Landing Gear Bulkhead Reinforcements
Step 2: Preparing the strut for installation
Step 3: Attach Tabs & Installation
Step 5: Installing Axles, Brakes and Brakelines
Step 6: Constructing the Landing Brake
STEP 1: LANDING GEAR BULKHEAD REINFORCEMENTS
The Landing gear bulkhead reinforcements were done prior to me buying the project. I will add photo’s detailing the bulkhead reinforcements later.
STEP 2: PREPARING THE STRUT FOR INSTALLATION
I bought the MLG strut from Featherlite and received the delivery after approx 2 months. The MLG was 94 inches on the inside measurement, so no need to cut it down.
I sanded the MLG strut down. It took me a good few hours to sand it dull.
I made some jigs out of plywood, cut off at an 8 degree angle (per the plans) to guide the hacksaw. The S-Glass is VERY strong. It took me a LONG time to cut the ends of the MLG off.
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I cannot figure out how to get 13 strips of UND, cut at 30 degrees to cover 8 strips of the MLG . Here is a picture of me trying it out with white material.
Bernie Siu sent me the JPG below as a guide to cut the UNI. I just need to gather enough cores of paper towels to roll the strips on to. I also need to find space to cut these strips.
Since I put the UNI strips on rolls, the first 4 layups went on like a dream. No problem whatsoever. . After the layups were done, I peel-plied everything and allowed to cure. Some folks reported taking 6 to 8 hours to get the first 4 layers laid up. I took 2.5 hours from start to finish. I used small batches of epoxy, due to the heat (in the high 90’s)
It is strange how the shortest instructions in the plans sometimes take the most time to complete. I am currently sanding the trailing edge flush with the strut, in preparation for the next layup. I have already spent 3 hours, and probably have 3 more to go.
STEP 3: ATTACH TABS & INSTALLATION
This step seems to be going on forever, and is broken up into several smaller activities:
a) Creating the “tab box” upon which the attach tabs are going to be built.
b) Doing the layups over the “tab box”.
d) Cleaning up the attach tabs
f) Installing the MLG in place to check fit
g) Performing the layups on the “inside” and cleaning it up.
h) Opening up the tabs and bulkheads for the bolts, MKMG’s and MKMGA’s
There is a LOT of measuring that goes into creating the tab box. Everything has to be absolutely square before starting this step. The floor has to be measured, the table, etc.
I used an old dresser as the “recipient” of the presswood upon which the tab box is built.
b) Doing the layups over the tab box
There is WAY more BID, UND and epoxy that goes into this step than what I would ever have imagined. I must have mixed 600g of epoxy. Also, since everything is cut at a bias, it takes A LOT of cloth to make the simplest layups.
I taped two strips of wax paper together and drew the 15inch x 3.8inch strips on it with a Sharpie felt tip pen. Great idea. More about that later.
It gets really slippery with all the layers on. I peel plied it and then used some clamps that I had to pull the pieces of wood together.
The next morning, I checked the cured tabs and were a little taken aback by the fact that there were some air bubbles.
The attach holes are drilled with a jig. The plans call for a piece of 2x4 with a ¼ inch hole drilled in it. The theory is that the 12 inch drill bit would follow the pilot hole (no pun intended) and stay 100% level. BEWARE. If you clamp the one side of tab tighter than the other, then the whole thing will be off a little. Clamping in the middle is best, but I did not have a clamp that would work for that.
After I drilled the ¼ inch holes, I saw a strange phenomenon. There were white cloudy circles around the holes that I drilled. I picked at it and the white cloudy circles became larger. I felt a headache come on QUICKLY. I lifted it from the side and found, to my dismay, that I have left some of the wax paper on the upper few layers. I will have to sand the wax off and redo the BID layups. Great!
Look, it comes in a stereo option. Oh well, I have to check both sides VERY well before proceeding, but this is the beauty of this construction method. Mistakes can be fixed.
A little bit of time went by, but I finally laid up the additional layers and cured it under a heat tent that I built.
I cut the attach tabs off with my Fein tool. Removing the Bondo took a VERY long time. I was very careful though, because I have heard that there has been a number of delaminations in this area.
I had placed the screws on the tab box in areas that would be easily accessible for disassembly. It was a simple case of using the electric screw driver to remove the screws and then pulling the box apart.
f) Installing the MLG in place to check fit
I followed the instructions in the plans to determine the different stations at which the MLG should be. I used a plumb bob, several levels and several shims to get it into position. This took several hours. Once in place, I put a 12 inch x ¼ inch drill on each side and tried to line it up. It was a little off-center. I just drilled the holes bigger and installed them. It looks good.
g) Performing the layups on the “inside” and cleaning it up
I first created the flox corner on the inside of the MLG ears. Then I added the layups on the inside (per plans).
Once the layups cured, I rough-trimmed it with a hacksaw. I will do the final trimming once the attach holes are drilled.
i) Opening up the tabs and bulkheads for the bolts, MKMG’s and MKMGA’s
I printed out the templates (as received from Jim Springer) for the MG-1’s and MG-2’s and pasted them on the aluminium sheets as required (1/8 in and 1/4 in). I drilled the holes per the templates and installed them in place by the center hole. Finding the holes in the bulkheads was quite difficult.
I used a 5/8 in hole saw to open up the ¼ in hole in the MG-1 / MG-2 across the bulkheads. This did not work very well. There was A LOT of slop and I had to remake them. Fortunately I decided to not install the MG-1’s and MG-2’s per the plans instructions, so it was not too big a pain.
I made some wooden clamps to drill straight lines through the MLG ears. I then followed it with a 3/4 in hole saw, switching from one side to another and clearing the glass that built up inside the hole saw as I went along. It worked really well. Since the MLG sits at an angle, it was deeper on the one side than the other. This lead to a little scouring on the inside layups. The MKMGA’s slipped through very nicely and fit like a glove.
Installing the gear took several iterations. I would install the gear, remove it, shave a little off the MLG ears and redo it. After a little while, everything fell in place and the MLG bolts went through.
Only after everything fitted in place, did I flox everything together. A word to the wise, make sure that you wax your MLG bolts before exposing them to the floxed MG-1’s and MG-2’s. Ask me how I know. I got to manufacture a rough bolt-puller.
STEP 4: LANDING GEAR COVER
Not started yet. I am considering downdraft cooling and that will impact what type of NACA scoop, if any, I will have.
STEP 5: INSTALLING AXLES, BRAKES AND BRAKELINES
I sold the Cleveland brakes that came with the project and ordered a set of MATCO brakes from Infinity Aerospace.
The set of Matco brakes arrived on Oct 18, 2007. The quality is excellent. I have to find the instructions though.
a) Square the tub and measure FS positions
b) Mark the cut-out positions on the MLG legs
c) Set toe-in
d) Add reinforcement layups to the MLG legs
e) Install back-up plates and axles
h) Close in the landing gear box
a) Square the tub and measure FS positions
I spent a lot of time ensuring that the tub is level in both directions and that all the stations mentioned in the plans are in the correct positions and square to the garage front wall, so that my measurements will be correct. I used a digital level, shimmed with tongue depressors and kept measuring, measuring, measuring. Time spent here, will be rewarded later.
I also used a laser level, which I mounted on a photography tripod, to make sure everything was square and level. I later used the laser level for toe-in setting also.
b) Mark the cut-out positions on the MLG legs
I used the templates that I received from Jim Springer to create jigs for mounting the axles and brakes. I used spray-glue to paste the templates on some scrap chip-board and cut it out with my table-saw. Remember to measure the water-level of the centerpoint of the template to make sure that it is in the correct position. Mine was at WL19 (per the 3rd Generation plans). I later drilled a midpoint between the four mounting holes to make sure that I keep the WL19 point centered.
I drew the cut-out outlines on the strut with a Sharpie and marked the axle positions so that I can find them again later.
This was one of the steps that I dreaded. I wanted to make sure that I set the toe-in properly, but the plans method just seemed VERY confusing to me. This is not a criticism of the plans. I just didn’t get it. Plus, it didn’t seem very accurate to me. Spotting a dot on a wall 15 foot away through a metal tube, just didn’t seem that it would give an accurate ¼ degree measure.
I dropped plumb-lines, per the plans and then sighted the midpoint with a laser level against the garage wall. I then measured half the distance between the gear legs off on both sides of the midpoint and had something to aim at with the laser level. This was zero degrees toe-in.
Since the axle midpoint (at WL19) was 200 inches from the far wall a toe-in distance of d = 200 tan ( ¼ ) = 0.87 inches was required. I marked this point and then sanded a flat spot on the strut, on both ends until the laser level hit the toe-in point.
d) Add reinforcement layups to the MLG legs
I laid up the 3 layers of BID and then clamped it with some scrap flooring that I had. I used cable-ties through each end to slowly pull and tug the ends until I could hit the ¼ degree toe-in points on the far wall. I decided to not mount the axles at this point yet. Naturally, I had peel-ply under the flooring.
e) Install back-up plates and axles
I installed the back-up plates and axles with copious amounts of flox. I clamped it in place (it now had a nice flat spot to flox onto) and measured the toe-in position again with the laser level. Worked like a charm.
This was one of those very daunting steps. After spending a small fortune on the strut and MONTHS on the tortional layups and attach tabs, I now get to hack into it with a hacksaw and drill holes into it. I did not like the idea of having to scrap it and start over again.
However, all the measuring that I did earlier, I was confident that I had it right. While the axles were still clamped on, I used a 12 inch long ¼ in drill bit to drill out the holes for the axle bolts.
I used a hacksaw for the rough-cuts (per the lines drawn from the templates) and then used burr on a angle-grinder to smooth the lines out.
Mounting the axles, brake assemblies and wheels were easy once I figured it out.
Not started yet.
h) Close in the landing gear box
Not started yet.
STEP 6: CONSTRUCTING THE LANDING BRAKE (actually done first)
The landing brake was done when I bought the project. However, the hinge was floxed closed and the landing brake was busted in a few places. I decided to make a new landing brake. At the same time, I decided to put a full-length hinge on it for sturdiness.
This was the first real lay-up that I did. Kent helped me with the first layup.
Here are a few pics of the landing brake. I will use an electric actuator to deploy and retract it.
