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June

 

Once the tranverse bulkheads were in and the layups were complete, it was time to permanently install the main gear bushings. The main landing gear is located between the firewall (at the very rear of the fuselage) and the main gear bulkhead. There is a hold drilled in the main gear leg where a steel sleeve is installed. A bolt goes through the two bulkheads and through the landing gear leg. The gear then pivots on this bolt which allows it to be raised to the retracted position. Where the bolt goes through the two bulkheads, an aluminum bushing is installed as a bearing point. Up until now, all these components were present, but not permanently installed.

 

Left main gear leg viewed from the inside. This is before the transverse bulkhead was installed. But you can see the gear leg, pivot bolt and forward bushing.

 

View from the inside showing the bolt and aluminum bushing temporarily installed.

 

My first order of business is to get the bushings in place. I removed the bolts, pulled the bushings, and coated the contact surfaces with structural adhesive. Then put everything back together and lightly tighten down the nuts. The manual says to also glue the sleeves in the gear leg at this time, but I was nervous that I wouldn't get everything in position before things started setting up.

 

Once the bushing were in place, I pulled everything apart and used structural adhesive on the steel sleeves in the gear legs and put everything back together again. That's when I discovered... a glitch.

 

Turns out when I tightened everything down in the previous step while the bushing were setting up, I didn't get the nut very tight. Since the bolt head is on the outside and the nut is on the inside, I couldn't hold a wrench on both. The result was that the nut wasn't tightened enough. This resulted in an excessive space between the two bushings which allowed the gear leg to move front to rear. Since the sleeves had adhesive on them, I decided to position the gear leg as best I could and figure out what to do next.

 

I checked with the factory and they said I could either stuff some washers in or I could remove the bushings and put them back in. This was a bit of a surprise since I thought the adhesive was "permanent". Turns out that if the adhesive is heated to the right temperature, it's possible to remove the bushings. I removed the left gear again, put a soldering iron in the bushings for about 15 - 20 minutes and using a home-made press they popped right out. Then I cleaned up the openings. I hoped that I would be able to glue the bushings back in and be finished. But the steel sleeve wasn't where I wanted it. In hindsight, I should have pulled the gear leg when I discovered the gap, removed the sleeve from the gear leg and cleaned off the uncured adhesive. 

 

So now I had to remove the sleeve. Which means sticking a soldering iron in the sleeve, waiting 20 - 30 minutes and with Steve's help, we got the sleeve out.

 

Then I covered the bushings with adhesive and bolted everything back together. Once that cured, I removed the gear leg, put adhesive on the sleeve and put everything back together.

 

Once that one done, I had to put a two layer triax layup on the back of the firewall over the bushings and over the front of the main gear bulkhead over the bushings.

 

All this took about a week. It should have a taken a couple hours. Pretty steep learning curve.

 

Next was reinforcing the doghouse and doghouse opening. The "doghouse", by the way, was my first clue that things were not going to be easy. If you look at "Task 2" on the task list, you'll notice it says "Cut out Doghouse". In the actual task list, it also says that task is in "Chapter 6". But it doesn't say WHERE in Chapter 6. There are 31 8 1/2 x 14 pages in chapter 6 with about 41 separate tasks. Some of these tasks do not apply since they were already done during the pre-build done at the factory (these steps are not identified in the manual so you have to read through another list to find out that it doesn't apply to you). So the only way to find the steps involved with this task is to read through the entire chapter.

 

I eventually found the section on page 35. Which means the very fist step in building the airplane was in Chapter 6 on Page 35.

 

Go figure.

 

Anyway, I cut the doghouse out back in January. The reinforcing is supposed to be accomplished by first digging out some of the foam between the inner and outer skin and filling it with a mixture of epoxy and cab-o-sil. Cab-o-sil (called "cabo") is an additive that is mixed with epoxy to make it thick.

 

Here's the front of the doghouse opening after I removed some of the foam between the inner and outer skins.

 

Here's where I made another "engineering change". Malcolm at Hangar 18 doesn't fill the groove with just epoxy and cabo. He lays in a bundle of glass fibers the entire length on the groove. This creates an extremely strong arch. The only problem is that the fiberglass strands that he uses come in very large quantities that I would only need a fraction of. So I took some unidirectional fiberglass cloth (in unidirectional cloth, the fiber run in one direction only and are held in place with some small cross fibers) and stripped out the fibers by hand until I had enough to do both sides of the opening and both sides of the doghouse.

 

Here are the four bundles of glass fibers. Two short ones for the front and two longer ones for the rear.

 

Then it was time to saturate the glass with epoxy and embed it in the groove.

 

One of the bundles being saturated in epoxy.

 

Close up of the end.

 

Rear opening with epoxy/cabo mix ready for the "horsey tail".

 

Once the fiberglass strands were in place I covered them with a layer of BID. After it cured, I needed to get the space between the canard and fuselage consistent. So I covered the doghouse side with a layer of duct tape and mushed in an epoxy/cabo mix in between. Afterwards, I pulled the tape off and I had a perfectly even gap between the doghouse and the fuselage.

 

Finished edge.

 

Next it was time to finish the sump tank. Previously, I had chopped off the bottom corners and put on some flat pieces on fiberglass to allow for the engine mounting bolts. Then I learned that the fuel fittings that connect the main tanks to the sump will interfere with the landing gear. The fix is to move them to the side of the tank. This required installing   additional hardpoints for the relocated fuel fittings.

 

Once that was done I was able to proceed with sealing the inside of the tank. This step is not required by the manual. Current aviation fuel will not breakdown the epoxy. However, it's possible that future aviation fuels may not be... compatible with the epoxy. The reason behind not requiring the sump tank to be sealed is you could always build a new sump tank should aviation fuels change. I'd rather not build another sump tank so I decided to seal this one. I also wanted some practice with the sealing epoxy. It's called Jeffco and it's extremely touchy. It has a rather short pot life and can get really hot if you mix too much at once.

 

First I cut the back of the sump tank to the correct shape and size. Then I sanded both the tank and back.

 

Sump tank ready for Jeffco.

 

Back of sump tank ready for Jeffco.

 

I wasn't sure how much to mix so I guessed. I guessed wrong. With Jeffco, when starts to kick, it gets hot. the hotter it gets, the faster it kicks. The faster it kicks, the hotter it gets. The more you've got...

 

Melted the cup!

 

I did get the first coat on before it started to melt the cup.

 

Then once it got tacky, I mixed up a much smaller batch and put on the second coat.

 

Back cover of sealed sump tank.

 

Inside of sealed sump tank.

 

After the Jeffco cured, I mixed up another batch and mixed in some cabo to make a think cake frosting like consistency. I put this mixture in a ziplock bag and clipped the corner off. Then I squeezed it out on the perimeter on the back. Then the sump tank goes on until it cures.

 

Once it cures, I covered the seam with two layers of bid. Then I made the mounting tabs. At this point, the sump tank is done. I still need to test it plugging the openings and submerge it in water to make sure there are no leaks.

 

Finished sump tank!

 

Next are the elevators. Okay, so there's a small wing on the front. This is the canard. On the trailing edge of the canard is a moveable surface. This is called the elevator. By changing the position of the elevator, the amount of lift that the canard creates can be changed.

 

Here's a picture of the canard and elevator from January when I was installing the hinges. In this picture, the elevator is upside down. So this is looking at the bottom. On the right is the canard. On the left you can see the two elevators (left one on the bottom of the picture, right one on the top). The two elevators will move as one. They are connected with the white tubing in between (called the elevator torque tube). At the time this picture was taken, the torque tube is not attached to the elevator. That's what I need to do next.

 

Now the position of the torque tube is rather precise. If it's not in the exact correct position, instead of rotating it could bind and not move freely. So to locate the correct position, I decided to use my handy laser again. The problem is that the "tab" on the end is not perfectly aligned with the tube so I can't just align everything to the center of the tab. I need it aligned to the center of the torque tube. So here's what I did: I made a jig to allow me to rotate the torque tube so I could mark the exact center of the tube on the tab.

 

Here's the torque tube end with the marks identifying the center. The jig wouldn't let me make a complete circle, but I was able to adequately mark the center

 

Then I mounted the elevators and torque tubes on the canard. I left the three inboard hinge screws out. I put the laser so that it would shine through the holes on the three hinges without screws.

 

My setup with the laser.

 

Here's the laser shooting through the first hinge.

 

A little more to the right will have it dead-solid-perfect.

 

Once it's in position, I drilled through the elevator and torque tube. Then put in the screw and nut.

 

 

Hours (this month/total):  20/193