RELATED PROJECTS / DESIGN IDEAS
Up until now, I have had little exposure to tools, less to fiberglass work, and no exposure whatsoever to aircraft building,
except radio controlled models. With regard to engines, I used to change oil, filter and spark plugs to my first few cars while
in college. In addition, I do not like researching on the internet what others have done. I tried it at the beginning and I believe
it is much faster and easier to discuss issues directly with the kit’s manufacturer or with some of my close builder friends.
This proves that you do not have to be experienced in any of the above to build the airplane’s fiberglass structure.
With respect to the electrical and engine installation, I will give you my impressions when I get there.
I am sure that others have come up with similar, or even the same methods and ideas listed below. I apologize if I do not know
and give them proper credit. I list below what I have come up with for my own records and for the benefit of others that, unlike me,
seem to like internet research or do not have the blessing of available experienced builders. I give proper source credit in the text
below whenever I am given and use, what I believe to be, ingenious and uncommon ideas from others.
LINKS TO PHOTOS AND EXPLANATIONS BELOW:
Instead of building a wooden box, I decided to buy an unassembled plastic cabinet and adapt it to keep the epoxy hot during the winter season. I had scrap wood around that I could have used but I did not want to spend the time building and I wanted the box to be light so I could move it easily between the garage and the laundry room (heated area) while not in use. Although I was limited to the sizes available, I found one that gave me plenty of space to place the epoxy pump; a Black and Decker Space Right Wall Cabinet (Lowe’s). I installed a slide switch dimmer in a plastic box on the top left back corner, making a hole to access the dimmer switch. I found a large plastic cap to use as a base for a ceramic socket and installed it on the left side of the cabinet. I made the proper connections between the dimmer and the bulb socket and finished them with the use of a recycled appliance cord. I insulated the inside of the cabinet with garage door insulation and double-sided tape. A 75w incandescent light bulb took care of the heating. I placed a $7.00 digital thermometer on top of the cabinet with the outside sensor inside the box. As much as possible, I sealed any joints through which heat could escape with clear and /or electrical tape. I placed the sensor away from the bulb and moved it around until I was satisfied with the average inside temperature reading.
I never thought that this piece built with wood recycled from the kit’s crate would turn out so useful. By lifting the outboard end of the wings for access, I easily match-sanded and installed the ailerons and rudders from a standing position, without ever removing the wings from it. Almost all work on the canard ends and tips was done with the canard on the rack. In addition, I move the whole assembly around in my garage without help, and very little effort, once the casters align with the direction I am pushing. When put away, the fuselage fits between the winglets and the work benches. The wings and the fuselage (without strakes) would occupy less than one car space in my garage allowing me to fit the kit and my two cars in the garage when not working. This lasted only until I started building the strakes, of course.
Same as above, these dollies allow me to move the fuselage around without effort. Although it has become heavier as building advances, I still can take the gear legs off the dollies by myself, when necessary. I used 2x4s and 3 inch caster wheels.
I glued or taped some foam pieces to the wing and canard incidence gauges supplied with the kit to make them stable while in use during construction.
I bent a clothes hanger wire and placed it on my adjustable speed drill to help mix the epoxy or Jeffco. I formed the base as wide as the bottom of the mixing cup to avoid unmixed epoxy components at the bottom corners. It helps mix any epoxy resin fast, thoroughly and effortlessly and works perfectly when mixing in cabosil, flox, milled fiber or microballoons. It turned out to be a very effective mixing tool.
Open holes at the bottom of 9oz plastic mixing cups and secure them to the top of the cans with strips of duct tape. Let the setup sit for a while after pouring and the resin or paint will return from the cups to the can.
I noticed the left bottom strake leading edge ended up about 1/8” aft of its position so I devised a set up with some sprinkler PVC pipe to correct it. I applied pressure and heat to bring the leading edge forward and minimize filling and sanding later.
I did not like the method recommended by the manual and used this one to cut the strakes’ baffles and bulkheads. After installing the bottom shell permanently and fitting the top shell, I drew the exact position of all bulkheads and baffles on both inside surfaces of the shells (1). Using the same method of transferring the contour of the fuselage to the strake shells, I transferred the contour of each shell to an oversized piece of thick cardboard for each baffle/bulkhead. I trimmed/fitted the cardboard pieces to the inner surface of the shells. This was easy to do since the inside of both shells could be easily accessed and all shaping and fitting was done comfortably. Note that each cardboard piece was about 3/4 the total height of the part, allowing the cardboard pieces to overlap (2). I hot-glued pieces of tongue depressors as a base to the bottom templates and taped them to the bottom shell to keep them in place (3). I cut a hole on both matching pieces to use for internal clamping in place. Initially, I estimated the height of each part based on factory paper templates (4). I temporarily fixed the top shell with clecos. By looking at the setup from the inside, I was able to determine the necessary adjustments for correct shape of each part. Actually, placing the top shell on top of a slightly high set would normally push the top portion to the right height. In any case, by loosening the clamps I could easily move the top of each template (up or down) to touch and exactly match the height and contour of the top shell (5). I then fixed the templates with some wood screws. These now became my definitive templates. I transferred them “very” carefully to the sheet of glassed foam, to minimize sanding. I cut them about 1/8 oversize with the air saw and used a 36 grit sanding disc on the air grinder to get to the cut line and finished with some rough sanding. Most sanding adjustments were done to fit the part to the bottom shell. I hot-glued the trimmed parts to the bottom shell (6) for final shaping with the top shell on and I had to hardly sand anywhere. I worked my way inboard to not block vision to any of the parts. Once you trim the bottom, the top matches rather accurately the first time. The absence of tongue depressors on the definitive part lowers the bulkhead/baffles a bit and adds to the small gap that you will need on top for the strake top (7).
I went longer than the actual cardboard templates to allow adjustment due to the thickness of the glassed foam (thicker than the cardboard) and for the necessary sanding to match the angles between the parts; especially the acute angle of the parts that meet the strakes’ leading edges. Pay close attention to the leading edge contour area where the foam starts. It is kind of tricky because it has the same acute angle, as the leading edge, across the part. It takes some time to make the templates accurate but you work comfortably (much better than in and out the fuselage). Support the inboard of the top shell. Its own weight will lower it and this will give you an incorrect and changing reference. I hot-glued small pieces of 2”x2” to the fuselage for the top not to move (8). The parts came out really clean (9 and 10) using this method. I expect to use the same templates for the other side, significantly decreasing building time on the second strake by not having to make a second set of templates.
I placed small beads of modeling clay on top of the cap strips and leading edge and fixed the top with clecos. This gave me a rough idea of the gap and the amount of Jeffco needed to install it. I know that the modeling clay is harder than the Jeffco mix and that the actual gap should be narrower than shown. However, it gives you a good idea of how the top sits. I removed all clay residue, cleaned thoroughly with denatured alcohol, sanded the areas and cleaned thoroughly again with alcohol to remove all clay residue.
I used circular saws to open the wing bolt access holes on the bottom strakes and found them hard to control for fine accuracy. Unlike wood, the foam density is not enough to grip and guide the drill bit, yet the fiberglass skins grab onto the saw and make it vibrate and move around. Maybe others have used them successfully but I will never use them again on fiberglassed foam. Now I use the following method to open all holes bigger than a ½” drill bits accurately. I draw the exact circle with a fine point marker on a compass. I use a grinding bit on a Dremel to remove the inside material and change it to a sanding drum to get closer to the edge. I then finish the edge by hand with rounded files, sanding discs and sanding paper as needed. I found this method to be simple, fast and very accurate. I follow the same method when I want to cut rounded parts. The picture of the gas cap (link above) is an example of a hole I made with this method.
The manual instructs to close the strake, complete the main spar-top strake reinforcements from the sides and install the rear bulkheads as a final step. During construction of my first strake, although I knew that neither approach would be easy, I thought that it should be less difficult to install the bulkheads before closing the strake and reinforce the main spar-top strake from the sides later, with the fuselage inverted. However, ideally, one should be able to close the strake without having to work further behind the fuel tanks. So, for my second strake, I started thinking about ways to accomplish this and came up with the following process, which I ran by S. Swing at the factory. 1) I installed the rear bulkheads with their corresponding top flanges as I did with the other bulkheads; 2) I formed a couple of foam pieces that adapted to the inside top of the main spar, as much as possible, and two other to fit between the rear bulkheads and fuselage, at the same level of the corresponding flanges, placed some ½ inch upholstery foam on top and covered them with duct tape; 3) I applied a mix of EZ-Poxy and cabosil to the inside of the spar to even out its surface for better surface contact of the layups; 4) I pre-soaked two-ply BID on plastic and lay it on top of both foam pieces; 5) I positioned the assembly in place with one half of the layup pushed against the inside of the main spar and the other sitting on top of the foam piece between the bulkheads; 6) I removed the excess cabosil mix and finally placed peel ply over the assembly; 7) I used clecos to keep the duct-taped top strake in place for curing. This method produced flanges that were filled with microglass and structural epoxy, as needed, during final installation, allowing installation of the top strake in one step. Picture 6 above shows an upside down view of the flanges, from the outboard access hole, after final installation. Unfortunately, I did not take the time to think about this process before closing the first strake. I know reinforcing the outboard portion of the closed strake should not be a big problem but working from the cabin on the inboard section will not be as fun.
My approach may be somewhat unorthodox but it has proven to be fast, simple and secure every time. When I want to remove a rivet, I use a drill bit of the same rivet size in a slow drill and very carefully drill the rivet head until it separates from the body. The hole in the rivet head acts as a guide for the drill bit. Sometimes I just stop slightly short of separating the head and just brake it off with a slight pull. If done slowly and carefully, it allows easy removal of the rivet parts leaving the hole intact for the new rivet.
UPDATE: I just saw this method explained in a new building video at the EAA website.
Instead of a 12v battery, I use a 12v AC adaptor with alligator clips to activate both the elevator trim and speed brake actuators during construction.
I noticed that the screws holding the aileron bearings in place would not sit flat against the flange. This actually deformed the ball bearing case when tightened in place in the rear aileron bracket, causing an abnormal friction when rotating the bearing and giving the impression that it was damaged. By removing the bearing, the deformity was eliminated and the bearing was back to proper functioning. To resolve the problem, I Dremel-grinded AN960-416 washers to fit in place and level the screw heads against the bearing flanges. Make sure the washer allows proper tightening of the flange against the bracket so the bearing does not become lose. I did not have to, but you may have to slightly sand a face of the washer for this. I used the same setup with the bearings of the aileron torque tubes and all rotate smoothly now.
This is a known way of doing this. However, I felt like documenting as it took a lot of planning and preparation to do it in such a steep driveway. Having to bring several of my friends and relatives to help, I wanted it to be a quick and effective process. I used the semicircles that John and Craig had passed on to me. I bolted them to the main spar with only one bolt to allow rotation for clearance through the garage door height. With the help of my brothers Ed and Javier, and fellow builders Russ, John, Craig and his brother in law Mick, we rolled the fuselage down the driveway mounted on my fuselage dollies. We removed the dollies, straightened the semicircles and inserted the second bolt. Some of us lifted the nose up toward the driveway and others received it on the opposite side as Craig was slowing down the drop from the street with a rope tied up to the gear and looped around the bumper of his car. Once upside down, I supported the canard bulkhead on a rolling table, bolted the fuselage dollies to the semicircles and rolled it up the driveway back to the garage. I removed the fuselage dollies and left the fuselage supported by the semicircles and a sawhorse under the canard bulkhead. Finally, my brother Javier announced the arrival of the snacks to those involved, brought by my then relaxed wife Ygebor.
Several months later, once done with all the building steps I could think of that would be better done while the fuselage was upside down, we reversed the process to roll it over back on its gear. Friends John Schoorl, Craig Woolston, Juan Carrillo and Glen Kadohr came to help me with the task. We attached the dollies to the semicircles; lowered the nose slightly to clear the garage’s doorframe and started rolling it down the driveway. We rotated the nose 180° and took it all the way to the street. We removed the dollies and started rolling it over supported by the semicircles. Once over the top, we all started moving to the receiving side while Craig continued to control the rotation with ropes tied to the nose gear strut. We placed a dolly under each gear and then pushed it up the driveway. This time the fuselage cleared the garage doorframe without a problem. It only took us about 20 minutes to do it this time.
Although he does not appear in the pictures, my 9-year old son Alan helped too. As usual, I designated him as official photographer for the events due to the quality of his pictures.
Cutting - I use a Sharpie marker to draw the shape of the part, which is easily removed with denatured alcohol. I score the sheet with a utility knife and a ruler and then bend it against an edge as if it were glass to roughly cut the piece oversize. I then use a 36 sanding disc on the 90° grinder for fine shaping. Applying the disc slowly against the edge of the part melts the plastic. Although it normally remains attached, it brakes of cleanly and easily by hand or by sanding it off from the other side. I finish the edges with fine sandpaper (180 - 320 grit).
I use a method initially recommended
to me by
Drilling - I do not find it necessary to use special drills for acrylic; at least not for the thickness of the parts that we normally use (3/32” to 1/8”). The key is not to rush the drilling by applying pressure, as you would normally do in a wood or metal part; and to use increasingly bigger bits to get to the necessary size hole. I usually mark the drill guide point by rotating an X-acto knife, or some other sharp pointed tool, where I want to drill the hole. I then drill a guide hole with a small bit, applying very slight pressure and letting the heat that builds up on the point do the drilling. I use increasingly bigger bits finishing with the correct size.
Countersinking Acrylic – I decided to try this and it has worked beautifully for me. I use a countersink bit in a “dog-leg” deburrer. I go slowly and visually check the progress frequently for centering, as well as for depth, with the screw or washer to be used. It is a slow but safe and effective method, allowing you total control. I also slightly debur the opposite side of the countersink hole. I believe there is less tendency for it to crack this way.
Cleaning - I have used Goo Gone for cleaning acrylic windows and covers with great success. It removes Sharpie reference lines, as well as masking and duct tape adhesive. With masking and duct tape residue, especially if it is large, I apply it generously over the area with my fingertip, and as much as necessary, and let it soak. I then rub gently with the fingertips until it dissolves, to avoid scratching the surface. I then clean with soapy water, rinse with water and dry it with a soft cotton (T-shirt) cloth. Do not let the Goo Gone- adhesive mix start to dry out or the adhesive will tend to stick to the surface again. If it dries out, apply more Goo Gone and repeat the above process to dissolve it. Also, you may have to repeat the process, depending on the amount of adhesive.
I did not want to attach the wings to the fuselage
while the airplane was inverted. So, I
transferred the contour of the wing to an acrylic poster face and made a very
slightly oversize template that I taped to the outboard end of the strake (1). I then filled the leading edge of the strake
to the contour of the template and let cure before sanding (2). I did the underside while the airplane was
inverted. I believe that after several
coats of primer buildup, I’ll get it to easily match the wing contour without
much sanding. This is a modified version
While still building, I was told by
To me, this kept the rubber
of the shock compressed and did not
bring back its load absorption capacity.
Consequently, this would not make the nose gear drop or taxiing any
smoother either. In my opinion, even if
the metal plate would not bend, the shock absorption capacity of the original
part was minimal due to the load being spread over such a wide area.
I ran the part specifications and set up by Daniel and he believed it to be appropriate, with an estimated safety factor of at least 2.5 to 3 on a very rough landing. He also confirmed that it should work better if installed vertically. Kevin was waiting for Daniel’s opinion, as he was doing his annual and wanted to try an alternative to installing another original part. He would be the first one to test the modification. By the time we ordered the parts, a couple of other builder-owners believed in the set up and had joined. Kevin made a seat for it against the canard bulkhead with microglass and installed it under compression as planned. His comments follow.
“The airplane feels perfect taxiing and landing. The rubber shock shows no signs of deformity after several landings. It is still tight against the captivator.”
“Two landings this weekend - both in x-wind conditions - no shimmy, no adverse issues.”
“I did taxi with the thicker spacer and the shock mount performed flawlessly. The real test will be how if feels during touchdown/landing.”
“I finally flew today with the new shock mount. The shock mount worked perfectly. All crosswind landings and touching down with a slight crab on one of the landings. It’s great to know that if you don’t make a perfect landing, you won’t bend a part on the airplane. For my installation, the 5/16” spacer seems to be correct. This provided the shock mount to be installed with good compression. Nothing more to report because everything worked great..”
Picture (4) above shows my final installation. The detailed description and pictures of my installation process can be accessed on #2 of the Nose Gear section of the LANDING GEAR/ WHEELS/ AXLES page.
I made a support system to apply primer to the elevators. I screwed a couple of angles to my wing rack, with a separation ½ inch wider than the length of the elevators. I then used a couple of screws and castle nuts that I tighten by hand. It allows me to apply primer to both sides, by flipping it up or down.
I used PolyFiber UV Smooth Primer which requires mixing every cup of primer with 4 mL of crosslinker. For easy measuring and mixing of the primer, I marked one and two cup levels on a capped container with a permanent marker. After measuring the desired amount with the help of the markings on the container, I add the crosslinker with a small industrial syringe that is provided, cap the container, and use it as a mixer. This has proven to be a fast method to measure, mix and pour. I clean the container with water soon after every use to avoid the build up in the container or the threads.
The factory includes fixed aluminum tie-downs for bolting to the spar. I opted to design retractable tie-downs for myself. I have applied for a patent on the design and will no longer show them in this site. I will look into manufacturing and selling them in the future. You can contact me via email (WEBMASTER) for additional information.
My fuel servo intake is 3.875 inches in diameter, as opposed to the more common three inches. Therefore, I had to make a four-inch round fiberglass cylinder to use as the base for the flanges to attach the 4-inch SCAT hose. I could not find an exact diameter container around the house to make it, so I decided to make one slightly larger and then adjust it to the right size. I used a 4-inch cylindrical plastic container, covered it with duct tape, a thin film of petroleum jelly and laid three layers of BID with peel–ply over it to make a tube about 5.5 inches long. Once cured, I cut the cylinder lengthwise, inserted it on the hose and made a mark where the ends overlapped. The overlap was about 3/8 inch. I removed the excess material with a sanding disc on the air grinder so that both edges would align with each other and the part would fit inside the hose. I immobilized the joint with hot glue points on the outside and laid a 2-BID strip with peel-ply on the inside of the cylinder for a perfect fit inside the SCAT hose. Once cured, I finished with one BID on the outside. II cut the cylinder in sections, as needed, to fabricate the actual flanges for the runner and the air filter box.
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© Jorge A. Bujanda / 2004-2011