Posts Tagged wingtips
1.3 Hours -
Cooler temperatures, combined with getting a few home improvement projects out-of-the-way, allowed me to finally get back to airplane building tonight! There are a few final touches on the wings that I wanted to work on before riveting the last bottom skins on. Plus, I’ve got some extra motivation to finish the wings now that my fuselage kit will be arriving in just a couple of months.
The first thing I wanted to work on was to install the LED drivers/filters on the outboard wing ribs. Previously, I had made a drill template using Google Sketch-up, and transferred the paper template to a piece of aluminum sheet to provide some rigidity to the guide. After some indecision about where exactly to install the drivers, I settled on the bottom, aft area of the outboard leading edge ribs. With the drill guide in place, I started drilling the four holes that will be used to install the drivers with four #4 screws and lock washers. As it turns out, I can still easily access the driver screws even after the last bottom skin is riveted. I may go back and add some Loctite to these screws, but at least I know I can inspect the screws anytime the wingtips are off.
Next, I wanted to make a small adjustment to my pitot mast installation. When I originally installed the mast, it ended up just slightly askew. This was so slight, that it probably wouldn’t amount to much error, but I wasn’t happy about it. To fix this, I just realigned the bad side of the mast and enlarged some of the holes to #30 in order to account for the shift. During final installation, I can either use 4- rivets or NAS1097 “oops” rivets. Most likely, I’ll go with the 4- rivets since these will be on the bottom of the wing where no one will ever see the different head size.
Since I had to remove the right wingtip prior to installation of the LED driver, I decided this would be a good time to install the nav/strobe assembly and lens in the tip. This only involved 8 screws, so it didn’t take long, but it was nice to see the wingtip complete. My homemade nav/strobes may not have saved me much money over buying some pre-made ones, but I greatly prefer the look of mine!
0.5 Hours -
Due to the continued South Texas heat, I’ve been avoiding the garage like the plague. However, this morning, at 7:30, it was cool enough to do some non-noisy work where there was no risk of waking the neighbors.
Since I had tools scattered all over, my plan mainly involved garage clean-up. After getting everything put away, I decided to install the left nav/strobe assembly on the wingtip because I really wanted to see what the final product looked like. This should have only been a matter of installing 6 screws, but it’s never that easy. As soon as I fit the light assembly on the tip, I could tell that there was some interference with the cutouts in the tip. The main problem was with the heat sink, which wasn’t surprising since I had never done a final test fit after the heat sinks were installed. To get the assembly to fit, I just had to remove a bit more fiberglass in order to allow clearance of the sink. A file and my Dremel made quick work of this task, and I don’t think I made too much noise either.
Once the tip cutouts were adjusted, I slipped the light assembly into place and installed the six screws that attach the assembly to the tip. Once attached, everything looked good except for a slight bowing of the mirrored plexi on the strobe side of the assembly. The strobe and plexi are both attached to the aluminum plate with two screws, but there is nothing holding the corners firm. I prefer the look of fewer screws, so I’m going to live with it as is.
Happy with the fit, I removed the protective paper from the mirrored plexi and installed the wingtip lens. I purchased some #6 countersunk washers to use on the wingtip lens. They aren’t necessary, but I think they make the finish look much nicer. Needless to say, I’m pretty proud of my homemade nav/strobe lights!
1.8 Hours -
I wanted to finish up the right wingtip, so I hit the garage early. All that I had left to do was to rivet the W-412 rib, platenuts, and reinforcement strips to the wingtip. Once the riveting was finished, I deburred and dimpled the holes in the wing skin. Then, I was able to attach the right wingtip to the wing with screws, and the fit was great. Of course, everything couldn’t go smoothly. Before taking pictures, I started to clean up and managed to spilled a bin of AN426AD3-4 rivets on the floor…getting down on your hands and knees to search for and pick up rivets sure is fun!
3.5 Hours -
The picture says it all. It’s hot in the garage, and today is a little cooler than the last few days. So, you can probably understand why I haven’t been working on the plane as much lately. I must have a fan blowing directly on me if I want to spend any time in the garage, and, even then, I constantly have to wipe sweat off me and the parts. However, I did manage to spend over three hours working on the right wingtip today.
I had already drilled the right tip to the wing, but I wasn’t happy with the a small gap in the leading edge area. I tried to adjust the tip and re-drill, but no matter what I did, I couldn’t eliminate the gap. I’ll have to wait until the tip is installed with screws to decide if the gap is acceptable or if I’ll have to do some repairs. A little epoxy and flox should do the trick if needed.
Next, I cut the reinforcement strips and match drilled those to the tip. On the right tip, I decided to only make one strip per side and I’m not going to epoxy them into place. This is in contrast to the left tip where I cut several small strips for each side and epoxied them into place before drilling the tip. Once the strips were drilled to the tip, I clecoed on platenuts and drilled the platenut rivet holes through both the tip and the reinforcement strip.
Then, I reattached the tip to the wing and played with the fit once more. When I got it adjusted as best I could, I enlarged all the wing skin/tip holes to 5/32″ in order to accommodate the #6 screws that will attach the tip to the wing.
Finally, I removed the tip from the wing and countersunk all of the holes. As with the left tip, I found the best countersinking method to be the use of both a Dremel with a conical sanding stone and a deburr bit. I used this combo for both the screw holes and the rivet holes.
All that is left is to rivet the platenuts and the W-412 rib to the tip. This should take me only another hour or so tomorrow.
3.4 Hours -
I started working on the plane in the morning with the intent of finishing the left wingtip before it got too hot.
The first thing I did was to rivet the W-412 rib to the wingtip with some CS4-4 blind rivets. With the rib webbing flush with the inboard edge of the wingtip, I think the finish looks nice. The edges of the fiberglass still look a bit rough, but I’m OK with them the way they are. If I get very bored, I may try to fill the area between the rib and the edge of the fiberglass to create a nice, smooth finish, but I’m going to have to get be really bored before I do any extra fiberglass work.
Next, I installed all of the wingtip platenuts. Since these can all be reached with a squeezer, installation was simple.
With the platenuts and rib installed, all that was left was to dimple the holes in the wing skin for #6 screws and test fit the wingtip. As I started to install the screws, I began to worry because the wingtip just wasn’t fitting the same as it did when I originally fit and match drilled it. As I worked my way toward the leading edge with screws, eventually, I couldn’t even get them started. After looking over the tip for a bit, I finally realized that I didn’t have the leading edge of the rib seated correctly in the skin. I removed all the screws I had installed, repositioned the tip, and, with great relief, I could instantly tell that the tip still fit OK.
Once all the screws were installed and tightened (barely), I checked the fit of the tip, paying close attention to aileron clearance. When swinging the aileron, the top outboard corner of the aileron was rubbing against the wingtip when the aileron was moved into the up position. To fix this, I had to remove the wingtip and trim off some of the area near the aileron. For now, I just removed a small area. I don’t want to keep installing/ removing the wingtip and risk stripping screws or platenuts, so I’ll leave it like this for now and adjust it again, if needed, once the wings are attached to the fuselage.
My plan was to quit here for the day, but I returned to the garage later in the afternoon to start working on the right wingtip. I was able to get quite a bit done, but it was really hot in the garage!
I’ll complete the right wingtip in, more or less, the same fashion as the left. However, on the right side, I decided that I’m going to try to install the reinforcement strips without epoxy. The reason for this is that about half of the strips didn’t stay glued on throughout working on the left tip. I figure that I should be able to match drill the tip to the wing and then just use clamps and clecoes to hold the strips in place until they are riveted on permanently. This should work since it is what I ended up doing on at least half the strips on the left.
So, I started on the right tip by trimming about 1/16″ off the edge all the way around and a bit more in the aileron area. Then, I test fit the tip and trimmed as needed to barely allow aileron clearance. Once the fit was satisfactory, I positioned the tip and clamped it to the aileron (the aileron was locked in neutral with the bellcrank jig). After one more inspection, I used my EAA membership card to create a small gap between the wing skin and the wingtip joggle, and I started to drill. As with the left wingtip, I’m only drilling to #40 now. I won’t drill to final size until all the holes for the platenuts are drilled.
Once the right wingtip was match-drilled to the wing, I marked where to cut for the aileron gap and returned the wingtip to the bench. After trimming the aileron gap, I returned the wingtip to the wing, removed the bellcrank jig so that I could swing the aileron out of the way, slid the W-412 tip rib into place, and marked the wingtip at the trailing edge of the rib. Removing the wingtip once again, I drew out the rivet lines for the tip rib, positioned the rib, and match drilled the rivet holes for the rib/tip. Once the W-412 rivet holes were drilled to #40, I decided that I had enough fun in the heat of the garage and called it a day.
1.5 Hours -
I was able to get a lot done on the left wingtip today, but I still have another day of work to go on it. For today, I finished prepping the W-412 rib (deburred and primed), enlarged the skin to wingtip holes to 5/32″, and I completed all the deburring and countersinking tasks on the wingtip. Since the countersinking had to be done on fiberglass, I used a combination of my Dremel with a conical grinding stone and a deburring tool. I’m trying to avoid using my countersink cutters on fiberglass parts since the fiberglass will quickly dull them and deburring bits are cheaper than countersink cutters. All I have remaining on the left wingtip is to install the platenuts and dimple the wing skin. Maybe I’ll be able to get to it tomorrow.
2.6 Hours -
Back to the left wingtip for another day of work.
With the wingtip ready for match-drilling to the wing, I needed a good way to hold the tip in position. While a third hand would have been the best solution, I decided to make a small clamp by bending a small square of aluminum to match the trialing edge of the aileron and wingtip. Using this piece of aluminum and a “C” clamp, I could line up the wingtip’s trailing edge with the trailing edge of the neutralized rudder and then lock it in place.
Once the trailing edges were aligned, I played with the wingtip until I had it properly aligned throughout its length. I then used a credit card (in this case, my EAA membership card) to ensure proper spacing between the edge of the wing skin and the joggle in the wingtip. I’m told a small gap here will make it look better after paint.
Next, I started drilling. To make sure the space was consistent, I held my EAA card in place while drilling each hole. I started by drilling the aft-most hole on the bottom, then the aft-most hole on the top, then the next on the bottom, the next on the top, and so on until all the holes were drilled. For now, I just drilled everything to #40.
With the wingtip drilled and clecoed in place, I used a sharpie to mark the areas of the wingtip near the aileron that needed to be trimmed in order to provide aileron clearance. I trimmed the wingtip so that there would be a 1/4″ gap between the aileron and the tip. This gap is the same size as the gap between the flap and the aileron, making the appearance consistent across the wing.
While trimming the wingtip, I caught a glimpse of some movement out of the corner of my eye. I turned to see a small dog standing at the corner of my garage watching me work. He was cute, so I took a couple of pictures of him. He had a collar, but no tags. However, when I set my camera back down, he had disappeared by the time I turned back around. At least he asked fewer questions than many others that stop to watch what I’m doing!
Now that the wingtip is trimmed to its final size, I went ahead and drilled all the platenut attach holes. Its easier to do now, while the holes are still #40, because a silver cleco will hold a #6 platenut perfectly centered if the hole in the surface is #40. If I enlarged the holes to 5/32″ now, the size of a #6 screw, I would have to use sacrificial screws to keep the platenuts centered…a serious pain in the ass with this many platenuts!
After all the platenut rivet holes were drilled, I reattached the wingtip to the wing so that I could fit the W-412 tip rib. For now, all I could do was figure out how far aft the rib would be placed. Van’s doesn’t give you much instruction here, only that the rib should fit snugly in the wingtip without distorting the shape of the wingtip. Once I found this position, I marked the wingtip where the aft end of the rib was positioned. Then, the wingtip had to come off the wing again.
Back off the wing, I had to mark out the rivet line for the rib on the wingtip. The instructions here just call for the rivet line to be 5/16″ from the edge of the wingtip with the rivets spaced 1.5″ apart. For me, this ended up being nine rivets per side. I also decided to stray from the plans a bit and install the tip ribs with the rib webbing facing inboard. While I’ll have to use pop-rivets instead of solid rivets to install the rib, I think the flush surface next to the aileron will look better.
With the rivet lines marked, I re-clecoed the tip to the wing and slid the W-412 rib into position. Once I was satisfied with the position, I started drilling near the trailing edge on both sides and worked forward. After a few holes were drilling in both sides, I removed the tip from the wing and sat it back on my workbench to finish drilling the rib. With the tip on the bench, it was easy to maintain proper positioning of the rib.
One of the aluminum reinforcement strips was interfering slightly with the tip rib, so I marked the area of the strip that was causing problems and carefully removed that section with my Dremel. With the aluminum removed, I re-clecoed the rib in place and double-checked the fit. Happy with the fit, I final drilled all the holes to 1/8″ to accommodate the CS4-4 pop-rivets that I’ll be using to attach the W-412 rib to the tip.
At this point, I decided to call it a day. All that is left to be done on the left tip is to prime the W-412 rib, final drill the skin/tip to 5/32″ for the #6 screws, install all the platenuts, and pop-rivet the W-412 rib into position…EASY!
2.9 Hours -
I’m starting to run out of things to do on the wings. Basically, I’m down to riveting the last bottom skins on, installing the wingtips, and installing the leading edge landing/taxi lights. Riveting the remaining bottom skins is going to be so much fun that I’m saving it for last (sarcasm!), so I decided to start installing the wingtips.
There are many options for installing the wingtips. The plans simply have you use pop-rivets, others have used hinges, but the majority uses platenuts and screws. I’ve opted for the platenut and screw method using #6 countersunk screws. It’s definitely more work than the pop-rivet method, but I like the idea of being able to easily remove the wingtips if needed. Since I’ll have lights, and possibly other electronics (AHRS) in the tips or on the outboard wing rib, easy wingtip removal may come in handy at some point.
The first step in fitting the wingtips is to make a temporary rib out of Styrofoam or some other rigid material. The fiberglass tip collapses slightly under its own weight, so the temporary rib is needed to expand the tip to the full size of the outboard end of the wing. To make the rib, I pressed a 4′ x 1′ sheet of Styrofoam against the outboard end of the wing so that the outline of the wing’s shape was left on the foam sheet. I then cut the shape out using my band saw. Once the rib was cut, I could simply press it into the wingtip where it is held in place by friction only.
Next, I measured the distance from the outboard rib to the edge of the wing skin. I then measured the same distance from the joggle on the wingtip to the edge. Anything past my mark on the wingtip had to be cut off. However, this only amounted to about 1/16th of an inch.
I then test fit the wingtip on the wing and marked where more material needed to be removed to allow space for the aileron hinge and aileron. For now, I’m removing just enough material to get the tip to fit. Once the tip is drilled and clecoed to the wing, I’ll clean up the aileron area.
Once I had the wingtip trimmed sufficiently for it to seat properly in the wing, I used a sharpie to mark the wingtip with the location of all the holes in the wing skin. These marks will be used as reference for making aluminum reinforcement strips. The reinforcement strips will help give the platenut rivets a little more bite, and they are simple to make…Van’s even includes some 1/2″ wide strips of aluminum for this purpose. I opted to make several strips for each side of the wingtip rather than using one long strip since it seemed like it would be easier to glue several small strips to the wingtip.
After the strips were cut to length, I glued them in place with some 5 minute epoxy. With these strips in place, I’m now ready to match drill the wingtip to the left wing.
1.5 Hours -
Tonight, I decided to do a little test fit of the wingtips to wings. Based on what I’ve seen on other builder’s sites, it looks like a significant amount of the fiberglass flange has to be removed from the wingtips in order to get them to fit properly. I measured the distance from the outboard wing rib to the edge of the wing skin, and then compared this measurement to the fiberglass flange. They were almost the same…meaning, I won’t have to remove much fiberglass. If I remove any, I’ll probably just need to use a sanding block. The tricky part will be trimming the wingtip to fit around the aileron hinge and clear the aileron. There’s no marking on the tips for where to cut in this area, so I’ll have to proceed cautiously. However, I’m going to hold off on that for another day since I need to get a large sheet of Styrofoam to make a temporary rib to fit inside the wingtips. Without this temporary rib, the wingtip doesn’t hold its shape well enough for continuing the fitting process and drilling it to the wing. Looks like another trip to the Lowe’s aviation aisle is in my future.
Since I still had some time that I could spend in the garage, I returned to the wingtip lenses. The lenses still needed to be drilled to the wingtips, and I needed to install corresponding platenuts in the wingtips. To make sure the lenses fit how I wanted them to, I taped them to the wingtips with some blue painters tape. Once taped, I drilled two #40 holes in each lens/wingtip…one hole on the top corner and one hole on the bottom corner of the lens.
With the lens clecoed in place, I removed the tape and looked at the fit once again. I decided to remove a bit more material from the lenses in a few places. This was quickly completed with my belt sander, which was followed up with some sandpaper of various grits to smooth the edges.
Once I was happy with the fit, I enlarged the holes in the lenses to 5/32″ and countersunk them for the #6 screws that will hold them in place. I used a deburr tool to countersink the lenses, and I wasn’t very happy with my first attempt. It will do, but I may get some countersunk washers to cover-up the countersink in the plastic and also disperse the clamping force of the screws over a little bit more area.
After the lenses were drilled, I finished drilling the wingtips for the platenuts that will hold the screws. Fortunately, my squeezer could reach all the platenut rivets since I’m a little afraid to go near fiberglass with a rivet gun and bucking bar.
My only other problem with the lenses is that I managed to put a few scratches/scuffs in them. I think most of these happened earlier in the build, before I realized how easily the plastic scuffed. I can admit that I wasn’t as careful as I should have been with how the lenses were stored in the parts bin. However, for now they are good enough, and I can easily replace them with new lenses at some point in the future if the scratches/scuffs start to bother me. A new lens blank costs $52 (one blank is used to make both a left and right lens), so another option may be to try a plastic restoration kit such as Micromesh.
2.1 Hours -
The first thing I did on the plane today was to install six platenuts in the right wingtip cutout. These will hold the screws that will attach the wingtip light assembly to the wingtip. I had already attached the platenuts on the left side, but I left the right with only the screw holes drilled. Drilling the rivet holes for the six platenuts and installing them only took about a half hour.
There are a few parts of the airplane build that I worry about being able to do correctly. Then, when I actually do them, I realize that, while the process may be something new to me, it’s just like any other part of the plane and I can learn to do it correctly. If I do some research ahead of time, then take my time completing the task, things usually turn out OK. The wingtip lenses were one of these cases.
There’s really nothing complicated about the lenses. They come from the factory as a single piece of thin plastic (acrylic ?) shaped like a dome. The dome is separated into two halves, and then each half is fitted to a wingtip. The problem is that you hear so many horror stories about cutting and drilling plastic parts. Since I had recently worked with mirrored plexi for the wingtip lights, I wasn’t as worried as I might have been otherwise, but the mirrored plexi is much thicker and more rigid than the lens plastic. After a little research, I determined that most builders use a combination of a band saw, Dremel, and sanding blocks/paper to cut and shape the lens…time to cut.
I cut the lens in half using a Dremel. It worked OK, but the Dremel would either spin to slow and bind, or too fast and melt more plastic than it cut. No problem since this is just the first rough cut, but I decided to put the Dremel away after the lenses were separated!
Once cut in half, the lenses are still way over-sized for the wingtip cutout. About two inches of material still needed to be removed from all sides. To figure out where to make the next cuts, I placed a lens on the wingtip and then used a Sharpie to mark the shape of the cutout on the lens.
With the shape traced on the lens, I used my band saw to cut right up to the outside edge of my Sharpie line. The band saw did a better job cutting the plastic compared to the Dremel. The cut edge was smooth with very little melting. Once this cut was finished, I put the lens back on the wingtip and checked the fit. Then, I slowly worked the edges down using a combination of a belt sander, sand paper and sanding blocks until the lens fit the wingtip cutout perfectly.
With the first lens finished, I moved on to the second and it went much more quickly. Once both lenses were fit to the wingtips, I used a plastic edge scraper and some fine grit sand paper to smooth out the edges. All that is left is to drill the holes for the two screws that will attach each lens to the wingtip. Simple!