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Archive for April, 2010

Rolling Left Elevator Leading Edge – 1.5 hrs

April 25, 2010 Leave a comment

Sunday April 25, 2010

Today I rolled the leading edge of the left elevator. It was a bit easier than the right elevator yesterday. What was the difference? I don’t know except the second time is usually easier than the first.

Here is a close up of part of the seam.

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Categories: Elevators

Rolled Right Elevator Leading Edge – 2.5 hrs

April 24, 2010 Leave a comment

My schedule was booked this morning with a flying lesson from 8 -11 AM so no work on the airplane until the afternoon. While I was in Corona I stopped and picked up some materials for the fiberglass work on the horizontal and vertical stabilizer tips which is coming up very soon. I chose the West Systems epoxy and ultralight filler. More to come on that story.

My task today was to roll the leading edges of the elevators. This is not really one of the “fun” parts of the building process. If you didn’t read my earlier post of the rolling of the rudder leading edge, the process is the same. You tape a cylindrical “rolling tool” to the skin and twist the wazoo out of it to form the general shape of the bend on each side, then rivet the edges together.

I started out using the broom handle I used on the rudder leading edge but after rolling the two smallest segments of the skin the hollow steel broom handle was getting squashed where I clamped it with the vice grips. So I took off to Home Depot and bought a 4 foot long 1/2 inch steel plumbing pipe. The middle sections of the leading edge are the hardest because they are the longest. After rolling each one once, I tried to rivet the edges together but they were not bent enough. So I rolled them again to get the edges closer. After that the fit was OK but there was some waviness to the seam when cleco’d together. So I removed the clecos and slightly bent the edge of the skin using the edge seamer. That helped but not enough. So I painstakingly shaped the edge by hand to minimize the waviness. After three tries I was satisfied with the fit. The seam is flush along the whole length except for a couple small areas where there is no more than 1/32 gap.

The inboard sections went better. I got them bent to final shape in two tries each and the seam looks very good. All in all the results are fine but I wish there was an easier way to do this.

After that I final drilled all the holes and put in the pop rivets. Then I installed and aligned the hinge bearings. I’ll leave these unstaked until I verify that they don’t need to be adjusted later when I fit this to the horizontal stabilizer. Here is a picture of the result with the West System epoxy materials in the background.

I’ll work on the other elevator leading edge tomorrow.

Categories: Elevators

Finishing the Trim Tab – 1 hr

April 19, 2010 Leave a comment

Monday April 19, 2010

The final step for the trim tab is to rivet it to the hinge and the elevator. I was able to squeeze all the rivets with the pneumatic squeezer. Here is the top surface of the elevator with the trim tab installed. You can get an idea of the range of down motion.

Here is the lower surface for reference.

Next step is rolling the leading edges. Oh boy (not)!

Categories: Elevators

Left Elevator Trim Tab – 11.5 hrs

April 18, 2010 Leave a comment

Friday April 16, 2010 – 1.5 hrs

After work tonight I started riveting the skin onto the left elevator. Since most of the rivets could be squeezed with the pneumatic squeezer it went together pretty fast. I had to switch to the 4 inch no-hole yoke to squeezer several near the trailing edge where it gets very narrow and I had to buck the last one on each side.

Saturday April 17, 2010 – 5 hrs

Up and at ’em early this morning. I was in the garage by 6:00 am. First thing was to install the pop rivets on the folded tabs at the trim tab cut-out of the elevator. The plans call for MSP-42 rivets here. I don’t know why they don’t use flush rivets but I followed the instructions as written. Here are the two rivets installed.

At this point the instructions shift to the trim tab itself so I made bending blocks for the outboard tabs first. Here is a photo of the blocks set up with the skin for bending.

I wasn’t as nervous about bending these as I was about the elevator tabs because I knew I could get a good bend if I set it up right and took my time. It turned out fine. Here is what it looked like after bending.

Then I made blocks for the inboard tabs which are longer than the outboard.

And here are the tabs after bending. I forgot to take the blue film off before bending but it didn’t really seem to make any difference.

Then I mounted the trim tab inboard and outboard horns to the skin and marked the edges that overhang for trimming. A few snips took off the majority of the material and then final trim to the line with the scotchbrite wheel.

Next I marked the aft side of the hinge with a line 1/4 inch from the edge per the drawing and clamped it to the trim tab. I spent some time studying the drawing on the lateral alignment and I reviewed the posts of other builders to see how others did it. In the end I lined it up almost exactly like it is shown on Vans drawing, perhaps shifted 1/16 inch laterally. Here it is after match drilling to the trim tab skin.

I had a flying lesson from 2-4 PM today. We practiced landings at Chino airport. I did seven landings in a Cessna 172 with just a little help from the instructor. I’m not there yet, but it’s getting easier.

Sunday April 18, 2010 – 5 hrs

Up early again this morning. The first step was to machine countersink the top flange of the E-607PP trim tab spar. I set up a piece of 2×3, drilled a #40 hole in it for the countersink centering bit and clamped it to the drill press table. Then after adjusting the depth of the countersink I could countersink a hole, slide it down, countersink the next, etc.

Then I deburred the parts and scrubbed the surfaces for priming. That was about it before church.

After church, I cleaned the parts for priming, dried them and put them into the sun for a while. I used the NAPA 7220 primer on the inside surfaces of the skin, Dupli-Color green self-etching primer on the spar, and white Eko-Prime on the trim tab horns and the hinge parts. Why? For consistency mainly. I’ve used 7220 inside skins from the beginning. I used green Dupli-Color on the exposed spars and ribs. But the trim tab horns will be painted later with the skins so white primer will be easier to paint over. It sort of makes sense.

After a 14 mile bike ride with my wife I started riveting the trim tab together. It starts with the bottom flange of the spar, the skin, and the trim tab horns. It was tricky getting some of these riveted because I could barely get the squeezer into position between the rather narrow space between skin surfaces. I ended up back riveting a couple that hold the horns on. Here is a photo of the horns after riveting. Notice that I added an extra rivet to hold the two horn pieces together. This should strengthen the assembly by making the two horns behave more like one part.

Then I clamped a piece of aluminum angle to the trailing edge of the elevator to serve as an alignment guide for the trim tab. That let me position the trim tab properly to align the forward side of the hinge to the elevator. This jig aligns the trailing edge and I used a 3/32 inch spacer between the trim tab and the elevator along the tab outboard edge to set the lateral alignment. Once in place, I marked the hinge at each hole in the elevator skin. Then I pulled the pin out of the hinge, clamped the forward piece of the hinge to the skin using the marks as reference and match drilled.

Then I removed the trim tab again and installed the pop rivets on each end. The plans called for CS4-4 flush rivets. I still wonder why it did not call for flush rivets on the elevator skin tabs. Anyway, I had to dimple the holes first and then install the rivets. This photo shows that the trim tab moves like a trim stab should move. The hinge motion is quite smooth with at least 30 degrees of motion in each direction. Oh yeah, I bent the lower skin edge per the drawing to keep the lower skin from bumping into the elevator spar over the range of down motion.

Categories: Elevators

Install Skin onto Left Elevator – 1.5 hrs

April 12, 2010 Leave a comment

Tonight I installed the skin onto the left elevator. The first step was to check the state of the folded tabs on the inboard edge of the trim tab cutout. I kinda felt like I should fold them a little tighter before installing the skin so I powered up the compressor and used the flush set in the rivet gun to tamp down the folds just a bit so they are dead perpendicular to the skin.

Feeling better about that I installed the E-713 counterweight skin onto the main skin with the two inboard rivets per side as directed. Then I put a “glob” of RTV at the root of each full-length stiffener pair. I remembered to do this but it really would be better if  Vans put a reminder in the step by step instructions. Here is one of the globs. I also remembered to take a picture this time.

Then I loosely placed the lead counterweight into position with the screws and slipped the skeleton into position in the skin. A bunch of clecos later I had everything aligned and secured in place ready to start riveting. Here it is.

Here are those trim tab cutout flaps that I bent one more time for good measure. I don’t think they could have turned out better.

Categories: Elevators

Left Elevator Work – 10 Hrs

April 11, 2010 Leave a comment

Wednesday April 7, 2010 – 1.5 Hrs

I had a little time this evening to work on the left elevator so I back riveted the stiffeners and the the E-616PP trim access reinforcement plate to the bottom surface of the skin.

Here is the outside surface of the skin around the reinforcement plate. Rivets are nice and flush. I like back riveting.

Thursday April 8, 2010 – 1.0 Hr

Tonight I finished riveting the stiffeners onto the left elevator skin – this time on the inside of the top surface. Then I removed the blue film on the inside surfaces.

Saturday April 10, 2010 – 5.0 hrs

This morning I pulled out my homemade bending brake and bent the trailing edge of the left elevator skin to the final angle. Interestingly, the 2×8 pieces had warped a bit since I made the brake a couple of weeks ago. It still worked OK and in just a few minutes the skin was bent to shape. Here is a shot of the trailing edge with the skeleton cleco’d in.

Then I installed the skin onto the skeleton and final drilled all the holes. Then I disassembled the elevator and started deburring, dimpling, buffing, and cleaning for priming. Here are the parts laid out on the work bench at the start. No, I didn’t prime the elevator trim tab hinge on the table.

I didn’t take pictures of the priming steps. It looked basically the same as the right elevator priming.

Later in the afternoon I started assembling a few of the skeleton parts. I followed the advice of several other builders here by riveting the E-704 rib to the E-702 spar before riveting the E-705 to the E-704. This was a little awkward but definitely worked out better than the “normal” method because I could get the pneumatic squeezer onto the rivets that hold the E-704 to the spar shown here.

Alas, you may notice that I forgot to dimple the holes in the E-704 rib before priming. Not to worry, the squeezer took care of that without a problem. In the next photo the E-610PP and E-611PP spar reinforcement plates are riveted on with the nut plates.

Sunday April 11, 2010 – 2.5 hrs

Today is a big day because the next dreaded step was upon me – the bending of the elevator skin tabs that close out adjacent to the trim tab. This step has caused more than one builder to have to do a do-over on the left elevator. A lot is written on the web about this step. Some have vented at Vans for not supplying a rib for this close-out rather than bending the tabs. Some have made their own rib and cut the tabs off. I even made a paper template for a rib in case this step went south.

So with some anxiety I began to set up for the bending. I decided to give it a try and hope that I could fall back to the homemade rib if necessary. I took my time and marked the position of the trim tab so I could check the gap. I measured everything and marked where I thought the bends should be. Then I made wood block wedges for clamping the pieces and as a form for the bends.

Here are my blocks and the marked skin.

Here the parts are clamped to the blocks with double back tape between them. The tape definitely helps prevent slipping.

Then I used a wood block and a rubber mallet to tap the lower tab down (the skin is inverted) along the edge of the block (which I rounded slightly to provide a small bend radius). Here is the result of the first tab bending.

Looks OK so far but what you can’t tell is I had to stop half way through and snip a little material off the edge of the tab and file it out smooth because the tab was on a trajectory to hit the opposite tab. Either the tab is too long or I should have moved the bend line out a little further. I’ll find out later on that one. Anyway, after getting the edge trimmed by a 1/16th or so, I finished folding the tab down to where you see it. By the way, the wedges kept creeping on me and I had to reset them several times in the process. I used the flush set of the rivet gun to do a final shaping of the tab with the pressure at about 15 psi.

Then I started folding the other tab up over the first tab. It was looking a little shaky about half way through because the outer tab was not looking flat or smooth. However once I got it down against the other tab it seemed to get better. Here is the result.

I am more than happy with this result. I have to thank all those who documented their trials and lessons with this process on the web because I definitely helped me succeed here. Here it is looking along the edge of the bend from the top surface.

Everything is not perfect however. I have one of those smile marks on the bottom surface of the skin new the trim access cover shown here. I’m sure you can tell which one.

This happened when I was dimpling the skin. The yoke of the squeezer caught the edge of the reinforcement plate on the inside as it came down. Drat! It was looking so nice. At least it is on the bottom surface of the elevator and after it is painted it will be hard to find, and it won’t affect structural integrity or aerodynamics, but there is the principle. Oh well – build on!

Categories: Elevators

Priming Left Elevator Skin and Stiffeners – 1.5 hrs

April 5, 2010 Leave a comment

This post is for Sunday April 4th, 2010

Not a lot of time today on the Project since it’s Easter. But I did apply primer to the inside surfaces of the left elevator skin and the stiffeners. Of course that means dimpling, buffing, cleaning, and drying first. Here is the skin after the primer dried. That blue film will come off after I back rivet the stiffeners on.

Here are the bottom stiffeners primed and laid in their respective places. By the way the 7.2 Mexicali earthquake hit right as I was setting up the paint gun to apply primer. That’s about 150 miles away as the crow flies and the ground here was moving quite a bit.

Categories: Elevators