Preping Right Wing Skins – 2 hrs

Thursday Feb 10, 2011

I’ve been struggling with a cold this week. That’s why my posts have been absent since Saturday. I got a couple of things done this week. For example, I riveted the right leading edge section to the main spar using the squeezer.

Leading edge spar rivets

I installed the right fuel tank using about half the bolts and some of the flat head screws.

Right Fuel Tank Installed

I removed the vinyl on the inside surfaces of the right wing top skins in preparation for priming these.

Devinyling wing skins

I made the scarf joint on the outboard top skin for the right wing. I still need to scarf the inboard skin.

Scarf joint

And I dimpled the skin holes in the ribs on the right wing using the squeezer.

Dimpling wing ribs

Finished Riveting Left Wing Top Skins – 5 hrs

Saturday Feb 5, 2011

Another business trip kept me away from the project for the better part of this week. So I hoped to get a lot done today and indeed I did with the help of my friend Scott. Before he arrived I did some solo work on the ailerons.

It was time to bend the trailing edge to the final angle but my bending brake from the empennage project had warped and was too short at 48 inches to do a good job on the 54 inch ailerons so I went to Home Depot and bought two more eight foot 2x8s and cut them down to 60 inches. Then I removed all the hinges from the old brake and installed them on the new 2x8s. These pieces of wood are nice and straight. Then I bent my first aileron skin. Here is the skin before bending (sitting on top of the brake).

Aileron skin before bending

And here it is after bending it to the final angle. The shape of the aft radius looks good.

Aileron skin after bending

After lunch Scott came over and we immediately started working on finishing the rivets on the left wing top skin. We made great progress on the rib rivets and along the main spar. Then Scott wanted to try the squeezer so after I tutored him a little he squeezed the remaining rivets along the aft spar. Here is Scott getting down low to get those rivets.

Go get 'em Scott

Left wing top skin rivets are all done and no more clecos! As we were putting in the last rivets Scott bumped the center support rod under the wing and it fell over. I almost panicked but then realized that with the skins riveted the load was all carried by the skeleton. I don’t need the support any more and that is why it fell over with virtually no weight on it.

No more clecos on this side!

Scott was still motivated to do more so he helped me rivet the right leading edge section to the main spar. This is probably the hardest part of building the wings so far because the inner rivets are really tough to reach and harder to see. Denise helped me rivet the left leading edge to the spar and I was not looking forward to doing it on the right wing. But it worked out fairly well. It is really a tough reach to those inner ribs and I drilled out a couple of rivets that leaned over but with persistence we finished it about 5:30 PM as it was getting dark. It really helped to have Scott assist me because this is an operation that you really can’t do solo. Thanks again Scott!

Right leading edge section ribs riveted to spar

Completed Riveting Aileron Stiffeners – 1.5 hrs

Monday Jan 31, 2011

Winter is flying by, no pun intended. I glad about that because I don’t really like working in a cold garage. But this is California so why am I complaining?

Tonight I finished back riveting all the stiffeners onto the aileron skins. These rivet look great. Nice and flush to the surface. That took about an hour to complete.

Aileron stiffeners finished

I also started riveting the leading edge section to the right wing. I was solo so I could only do the easy ones; the ones on the most outboard rib that I could get the squeezer on with a 3-inch yoke though the lightening hole.

Outboard rib rivets for the leading edge

Right Leading Edge, Skin Riveting, Started Ailerons – 5 hrs

Sunday Jan 23, 2010

Today I completed the last 42 rivets on the right leading edge section. These were difficult to reach solo so I got Denise’s help and we knocked them out in less than an hour.

Right Leading Edge completed!

Then we started working on riveting the top inboard skin on the left wing. The instructions recommend using a long double offset back rivet set and a large bucking bar to set these. So Denise held a 5 lb bucking bar on the top surface of the wing and I drove the back rivet tool from the inside of the skeleton. I was surprised that I had to turn up the pressure to get good shop heads. I usually drive 3/32 rivets at about 35 psi but I had to crank up the regulator to about 60 psi to get a well formed shop head in a reasonable number of strikes. I’m not sure why but I have read that other builders have also encountered this. The first three rivets were not great so I drilled them out and reshot them.

The instructions also say to start in the middle of the skin section and work outward to keep the skin tight. So we did the two middle vertical rows first. Denise needed to leave so we stopped there for today.

Started top skin riveting on left wing

Since I was solo again I started preparing the 32 stiffeners for the left and right ailerons. These are pretty much the same as the stiffeners used on the rudder and elevators so I knew the routine. Cut them out of stock along the pre-punched notches. Taper the web using snips, use the belt sander to achieve the final shape, and deburr edges with the scotch-brite wheel. Here are the 32 stiffeners cut to final size and shape.

Aileron stiffeners

Then I started match drilling the stiffeners to the aileron skins. I only had time to do one side of one skin (1/4th of the total) so I will pick up here next time unless I have help in which case I will work on the left wing skin riveting.

Match drilling aileron stiffeners to skin

Riveting the Right Leading Edge – 3 hrs

Saturday Jan 22, 2010

Today I riveted most of the right leading edge structure together. Did not have a helper but I was able to buck all but three or four rivets along each rib solo. I’ll need a helper to shoot the rest.

Right Leading Edge Riveted (mostly)

I also reinstalled the fittings on the two small aileron pushrods. This was kind of a pain because the rivets are long a tricky to shoot. My squeezer won’t work on them because the rivets are so long. When I bucked them with the straight set the rivets want to bend over so you have to be really careful. I had to drill out one rivet and shoot it again. After successfully bucking these I cleaned the surface with a little MEK and brushed on a light coating of EkoPrime because there was some bare metal showing.

Reinstalled aileron fittings

I stopped by Aircraft Spruce today and picked up a few things; another quart of EkoPrime, some Aeroshell 7 grease for the aileron bellcranks, a tube of EZ Turn (aka fuel lube) for the fuel drain fittings, and some AN316-6 jam nuts because my kit was one short.

Redo on the Aileron Pushrods – 1 hr

Friday Jan 21, 2011

Well I’ve been out of town for a few days so there has been a short lull in the building progress. But I had some excitement while gone. I was at Vandenberg Air Force Base helping prepare the Glory satellite for launch on Feb 23 if all goes as planned. I had a role in building the aerosol polarimeter on the satellite and we are performing final inspections before launch. I happened to be there when a large rocket was launched on base and had a chance to see it lift off from about 5 miles away. Very cool!

While I was gone it occurred to me that there was something I forgot to do when assembling the small aileron pushrods. I forgot to prime the inside of the tubes. Dang! So I tonight I removed the two rivets on one end of each pushrod and coated the inside of the tube with primer. I thinned the Stewart Systems primer with distilled water to make it easier to get 100% coverage on the inside. I’ll reassembly the tubes later this weekend when the primer is good and dry.

Fitting removed to prime the interior of the tubes

I also had one rivet on the left leading edge that was bugging me. The rivet had leaned over a little and was probably OK but I decided to drill it out and replace it. I couldn’t live with it. Instead of bucking a new rivet I decided to use a LP4-3 pop rivet instead. Many builders use these for all the leading edge to spar rivets so the strength of the LP4-3 rivet is no issue. The rivet in question is the one on the far right in this picture. No new progress tonight but I feel better now.

Replaced a leaning rivet with a pop rivet

Primed Right Leading Edge Parts – 6 hrs

The forecast for the weather today was clear and warmer so I set out to prime a bunch of parts including the right leading edge parts and the aileron pushrods. While I was at it I decided to prime the aileron brackets as well. So I match drilled all the rivet holes first, then used a scotch-brite pad on my orbital sander to scuff up the surfaces of the parts. Here you can see the difference the scrubbing makes on the surface with a before and after comparison.

Before and after scotch-brite scrub

Then everything was washed with water and scrubbed with Simple Green. After a good rinsing the parts were laid out to dry. Then I loaded the spray gun with Stewart Systems primer and shot all the parts. Here is a shot in process.

Parts in the paint booth

After the parts had a chance to dry a while I brought them back into the garage. Here are just some of the pieces.

Leading edge skin, pushrods, and aileron bracket parts

After lunch I assembled the aileron brackets per the instructions. Gotta be careful here because there are several different rivet lengths and some must be countersunk on the correct side.

Aileron brackets assembled

I assembled the right leading edge with clecos to do a fit check on the spar with the right fuel tank. I wanted to see if a shim was going to be required under the splice plate. Sure enough, a shim on the lower surface is needed to reduce pillowing.

Leading edge fit check

So I made a shim out of 0.025 aluminum Alclad. In the next photo you can see the shim installed between the rib and the splice plate.

Homemade shim under splice plate

Here is the right leading edge ready to be riveted together.

Leading edge ready to rivet

Mounted Pitot Tube to Mast – 4 hrs

Sunday Jan 9, 2011

This morning I mounted the Dynon pitot tube to the SafeAir1 mast. I marked four points where I wanted to put the 6-32 screws and set the mast up on the drill press with the Pitot in place. Drilling with a #36 drill bit is very shallow to avoid drilling into the tubes. Then I tapped the holes in the pitot tube and opened the holes in the mast to #27. Using the countersink cage I machined countersinks into the mast for the screw heads.

Drilling pitot to mast

Here is how it looked when done. I may replace the Phillips head screws with socket flat heads at some point.

Pitot mounted to mast

Later in the day I dimpled all the ribs and skin for the right leading edge assembly. It was too cold and humid today to prime so that will have to wait.

Right leading edge parts dimpled

Then I deburred the four aileron brackets on the scotch-brite wheel.

Aileron bracket parts deburred

Finally, I mounted the left fuel tank and bolted it down with two screws per rib up through the main spar.

Left fuel tank mounted

Left Leading Edge Riveted to Spar – 6 hrs

Saturday Jan 8, 2011

First bit of good news today is the right fuel tank passed the 24 hr leak test! I set this up last night and pumped it up to pressure and left it alone. Tonight after more than 24 hours the balloon is still inflated as best as I can tell to the same size as last night. I still need to do a thorough soapy water bubble check but this is very encouraging.

Right fuel tank passes the leak test

This morning I set out to finish riveting the left leading edge to the spar. This is the challenging part. The rivets I shot the other day were the easy ones.

Before starting with the actual riveting I spent a couple of hours designing and making a couple of tools to help hold the bucking bar. Since many of the rivets are difficult to reach or must be bucked blind I had an image in my head of a block that would hold the tungsten bucking bar in a slot to position it and keep it flush to the rivet shank. Here is a picture of what I came up with. I made two blocks out of a piece of 2×4. One has three slots on one edge to buck the center and end rivets on each flange, and the other block has two slots to buck the other two rivets. I might have been able to combine them into one but I was afraid the wood would crack if the slots were too close together. Ignore the single slot on the far side of the block on the right because that was cut too wide for the bucking bar so I just flipped it over and used the other side.

Leading edge riveting aids

The other side of the blocks had grooves cut along the rivet lines to clear the rivets already set in the spar. I also sanded down a groove that runs lengthwise along the edge and about 0.7 inches wide to clear the rib flange and allow the block to sit flat on the spar. This things aren’t pretty but they did the job.

Other side of blocks

Here is how it was set up inside the leading edge with the bucking bar in the center slot. The bead around the rib lightening hole causes the bar to be offset about 1/8 inch from the web but the bar still sits on the rivet adequately. With this setup all you have to do is hold the bucking bar with one hand and apply light pressure while someone else drives the rivet from below the spar. It won’t walk off or tip at an angle. It worked quite well even when set up on the third rib in from the end which is quite a reach. I can’t imagine bucking these blind with no jig to help although I know many people have done that.

Bucking bar in the center slot

Here it is with the bucking bar moved to the right slot. Because the rivet shop head is not visible and you can’t see how much it has set while you are driving it, you have to guess at how long to drive it then pull the block out to check it. We ended up shooting all three rivets with this setup, then pulled the block out and checked the quality of the shop head. Then put the block back and shoot some more if necessary. When all three were well set, we switched to the other block and shot the other two rivets on that rib. Then we moved to the next rib and repeated. I am sure the results are far better than if we had tried this unaided. We will definitely use this technique on the right leading edge as well.

Bucking bar in the right slot

Some people use pop rivets instead of going to all this trouble. I considered that but the rivets are so close to the rib web that I was concerned about damaging the ribs if I installed them from the bottom. Some people install pop rivets from inside the leading edge. While that is apparently possible, some that have done it cautioned others that it is no easy task.

After the ribs were riveted to the spar I squeezed the row of rivets along the spar on each side. That was simple by comparison. So here is the completed leading edge with all rivets driven.

Left leading edge riveted to the spar

Some new stuff arrived this week by mail. The Dynon heated pitot tube with AOA was drop shipped from Dynon even though I ordered it from Stein Air.

Pitot tube arrives!

I received a Parker Rolo-Flair tool and tube cutter that I ordered from Aircraft Tool Supply. A great deal on the Rolo-Flair at $80.

Parker Rolo-Flair and tube cutter

This 5 lb bucking bar will be used to back rivet the top wing skins to the skeleton.

New 5lb bucking bar from The Yard

Here are some additional supplies I ordered from Stein Air for wiring the heated pitot tube.

Wiring stuff from Stein Air

Last but now least I received two replacement brass bushings for the aileron bellcranks from Vans. The ones in the kit, shown on the right in this picture were too short. You can clearly see the difference. Vans usually gets it right, but somebody cut these too short.

Replacement brass bushings from Vans

Started Riveting Leading Edge to Spar – 4 hrs

Monday Jan 3, 2011

I worked on a couple of different tasks today, the most significant is starting to rivet the left leading edge to the front spar. I was able to squeeze the rivets on the most outboard rib and I bucked one rivet in the next rib inboard but decided to call it quits there until I could get some help. This is really a two-person job and it looks like it is going to be a real challenge.

Yesterday I said I would try to get a picture of the left leading edge to tank seam. The weather was overcast today so there wasn’t a lot of light so here is the best I could do. Pretty good seam, but not perfect.

Left leading edge to tank seam

Second task was to make a custom bracket on which to mount the pitot lines and connector(s). Since the pitot tube is one bay outboard from the inspection hole, I am planning to route the pitot connections directly to this bracket and tie them down with Adel clamps. Then they will be easily accessible for inspection. I will drill for nut plates after the pitot tube I ordered from Stein Air arrives and I can firm up the routing.

Aux bracket for pitot tube lines and heater connector

I made another custom bracket to mount to the bell crank hangers through which the pitot static and AOA tubes will route. This bracket will ensure that the lines pass safely under the bell crank but cannot touch it. I will drill two holes in the vertical flange for snap bushings when I finalize the routing of the pitot lines.

Another aux pitot tube bracket

Just to mix things up a bit I started identifying all the parts for the aileron brackets. These are just cleco’d together for now.

Aileron brackets

And I started the final prep of the right leading edge ribs for priming and final assembly.

Preping leading edge parts for priming