21-Strakes

 

Chapter 21 Strakes

(Double click images for larger size)

Strake pieces are marked on the foam. You cannot overdo the labeling. The yellow foam pieces at the far end of the table are top and bottom "rib support" pieces that are lined up parallel to R-57 and R-33. These rig supports run from TLE to DB.

This is the layup for cap strips for the top skin placement, I saved the extra to make the transition pieces for the gaps between the wings and strakes and with the landing light lens support.

I made a cardboard template and cut out this "wing guide". I floxed a cap strip onto this overlapping the wing.

I have the plans strakes up to within seven inches of the fuselage. The extensions go to within six inches of the IP, before they begin to taper.

At the transition point I placed a "D" shaped support. This support allows for the skins to be "ripped" on the inner side (like I did for the armrest in chapter 24) and allow the skin to be screwed down until the flox set and then the screws are removed. Later, I removed the cross piece on these supports and made the "D" into a "C" shape to allow for long objects like golf drivers to be stored there. I added a 205 inch wide support, flat, on the inner side of the lower skin from R-33 to the fuselage for support where TLE would have run. The second picture shows the full cutout and the fresh air duct and outlet. There will be pictures later showing the install of that.

This is before trimming. Later, I extended the BLE-TLE to the "strake cap" piece.

I added recessed doublers on R-57 and the end cap piece that allowed me to place the skins to the end. I did put the UND reinforcement on both the top and bottom skins. Put a little flox on the CS where the UND strip goes. Place the UND on the uderside of the top skin and leave the 3 inch piece dangling (you can place some short pieces of masking tape on the side of that to hold it). Press the UND strip onto the CS and lower the top skin onto the floxed doublers and weigh it down. This arrangement allowed for the install of the transition strips to cover the crack between the strake and wing and allowed me to uninstall the wing for the rest of the work.

Don't drill the three holes in the vent line.
The small tubing is the vent with the three holes added to the nose down parking position of the plane, or so I thought. I have read Wayne Hick's and John Slades' comments on this and the bottom line is don't drill the three holes. The other tubing is the return for the fuel injection (one on left and right). I added the reinforcement piece on top of the CS so that I could stop the tubing there and add fittings, I will complete the firewall and then extend the tubings.
It is late August of 2010. Since I delayed adding the top fairing, I cut into the top skin over the 1" X 1" square of 1/4' thick alum. and exposed it. I used a dremel disk to cut on the sides and then used a flat screwdriver and rotated the piece out. I used the vacuum and dremel sanding disk and opened the hole in the bottom skin and left a lip around the edges. Next I made a 1" X 2" rectangular piece of 1/4" alum. after I had tapped and threaded two holes. One for the Princeton probe and one for a 1/4" x 1/8' elbow with insert to attach a second vent line for the parked position. I extended the opening in the top skin for the insert. I extended the opening in the bottom skin and placed a small piece of floxed BID over the three holes. I let that cure and checked it. Then I floxed in the alum. insert, taped the holes and placed BID over the top. I trimed through the BID and ...You get the idea. All of this fits under the access door that is over this area and so I can do maintenance as needed. Pics to follow. 

The first pic shows that I have the firm idea where the vent and fuel return are located. I will cover the contructions of the aluminum piece and tapping and threading. I already covered the "fix" above. So, used a sharpie to give my outline on the 2024 1/4th inch thick aluminum. Within that outline, I did the following. Drill a 3/8th inch hole, and in this case I drilled two, but one inch apart. Then take the "Kobalt 1/8 NPT27" threader and using your socket wrench advance the threader and then reverse and test with the temporary plug (from ACE hardware). I reversed a 15/32 socket and used the 1/4 square side for the threader and the other side for the socket wrench. I'm sure that there is a special socket attachment for this, that you can buy. When the plug will screw to the opposite side of aluminum piece, THEN you are ready to cut out the piece. I did a test hole elsewhere on the block to get the skill. Keep the position of the squares marked as you go with glassing and the "micro big fill". Now, about the Princeton probes. You need to get the removable control line setup, so that you can drill a small hole in the turtleback in the fairing area and place the "box" on the forward side of the firewall. I cut off the probe to match my tank depth. You need to have the picture of the internal look of the tank when you place this to miss the screen and tubings. The Dynon folks don't support the Renesis engine with their monitor, so I used the Real World Solutions EM3 and ordered a dual tank Falcon gauge from AS to match these probes.

The black outline is where I will cut for access to place the landing light mounting.

This is the placement of the transition strips. Note: Go ahead and tape the leading edge of the wing and make a 3 ply BID strip for the LE of the strake cap section.

The left side was done before the top skin was finished. The doublers support the skin for placement.

This is the simpler way to do it.

You have noticed that I installed the aft part of the turtleback. I placed spacers and drilled alignment points and then cut the turtleback. This has worked out well. Placing the firewll reinforcements early on is good. You have better access for strake work on the baggage areas. As of 10-16-09 today, I have the fuselage turned over and I just completed the forward fresh air vents. Without the forward part of the canopy being there, I can glass the vent ducts in place with ease. The top becomes the bottom for glassing and you will always want to glass "down".

The wing is off now.

The cap strips on the aft side of the strakes are shown. This covers the gap between the strake and wing. I glassed over these strips when the exterior layups are done. What is that thing attached to the CS? That is a combination wing root transition piece and support for oil cooler and cooling coil (radiator). The holes allow for access for wing installation and for aileron control adjustments.

Parts for construction of the wing root "ribs".

Further along.

Top skin with layup.

Ready for bottom layup.

Note: I did the pressure test and I will refer you to Bernard Siu's website for a test setup that is better than what I did.
After the bottom layup, I placed a leading edge ridge of 1/4th inch thick by 1&7/8th inch hardwood. I cut triangle pieces and floxed them on, like the rear seat supports of chapter 24. I marked what I wanted to my dimensions of the fuel sump and then took blue tape to layout the shape of the fairing. Then is cut some blue foam pieces oversized.

Here is the blue foam after shaping. I did the left and right at the same time. The idea about the fuel sump is shown in the following pictures.

After using finishing nails to hold the pieces together I marked "tick" lines from the foam pieces to the sides of the fuselage and strake. I then cut out my sump foam core. The "tick" lines are needed all throughout the process.

I taped the strake and fuselage with masking tape and repositioned the foam and remarked the tick lines. I rounded the edges of the sump foam core and taped with masking tape and repositioned the foam on the fuselage and remarked that half of the tick lines and then glassed the sump.

Notice the tick lines. The glass picked up the lines off the masking tape. When I took off the tape from the strake and fuselage, these lined back up for the glassing of the sump to the fuselage/strake.

The sumps where trimmed and glassed on. Then I repositioned the other foam pieces and applied some micro in the strake/fuselage corner and let cure. Later, I stiffened the foam surface with a lightly applied coating of epoxy and let cure. That makes it easier to apply the micro and then the glass and work out the air.

I added drains on the sumps. I will add the pictures to the set above. I drilled some 1/8th inch holes on the sides of the inserts to have the flox hold the insert better. Of course, the drains are easier to do with the fuselage flipped and it's better to do this before the micro work has been done. I did a 4 ply BID layup for the "patch/insert" assembly with a 2 ply section placed on the backside to prevent displacement of the insert when the drain is used. I cut out the section on the sump, and almost missed the first one. I had added the fuselage and cowling lip and it made  the position fore/aft hard to figure. It worked out well, so this is only a good example of a retrofit of sumps drains.

I made templates and checked the airfoil shape and found that I had to add about 3/4 inch to the LE to get a good contour. I just floxed on some wood strips onto the LE. Some builders fill in the uneven spots at "the big fill" on top of the last glass layup. I have tried to even out under the last skin layup, as much as possible. You can use Featherlite foam cores for the LE. You need the BLE-TLE support. There will be over 200 pounds of fuel on each side and a hard landing will stress the LE of the strake. You can see that I have landing lights at the outboard LE of the strake (left and right). Landing lights are in the next section. I cut out blue foam and microed it to the wood LE support. I just placed the blue foam over the landing light area. I added the transition piece to blend to the wing, which will have to be changed after install of the wings for the LE there. In hindsight, I should have finished this part of the transition before I took the wing off. The 20/20 hindsight thing. Epoxy was gently painted on for stiffness. That works great. Less micro is needed and the shape is really smooth prior to glassing.

Here is the LE transition piece and the next picture shows where I trimmed the glass over the fuel drains and removed the portion of duct tape that was over the hole and took out the ortho wax. I tested the fit of the fuel drains and then covered the holes back over with just duct tape and marked the outline of the hole on the duct tape with a black sharpie. When you apply the "big fill" of micro for the final finish, you will want to taper down to the fuel drain point. The taper down is slight. Do not cover the sharpie marked area with micro.

Landing Lights

It may explain the excessive details, below, to say that I am a dentist. The lens production combines lab techniques for making dentures and soft night guards. Having said that, this is a no frills way to make great light covers that have the LE shape. The canard does come into play on the lights, but there are four of them and so two them are going to be angled down for use during taxi time and the other two will have some effect from the canard, but between the four lights, I can spread the pattern out to accomplish a lot of different angles and modify the settings as I get more experience with the Cozy.

First, I made the holes for the landing lights in the TLE. The landing lights are 55 watt fog lights from Autozone and are "Navigator Driving Lights" number NV-5508. They are 1&7/7ths inches tall and 2&1/2 inches wide. I used a dremel disk and cut off the glass fog lens and then cut off ine "arm" of the mounting bracket to make the light fully removable from the front with the angled install position. The remaining arm with adjustment bolt does fine by itself. The second picture shows the support that is floxed to the OD support. I used cardboard to get this shape established and then transferred to this scrap piece of 3/8 piece of glassed foam. You have to cut out an access door on the strake endcap piece. The third picture shows my OD support without a cutout. The next two pictures have to do with lining up the angle of the bracket. I used a large sheetrock square with a straight board to shoot a line off the FW and extend the 90 degree forward over the bottom of the strake to the landing light area for the light alignment (parallel to the centerline of the fuselage).

You can see the lines marked. Because OD is not parallel to the TLE, the bracket will look askew. The next picture shows the lights installed. There are left and right sets. The outer light will be for landing and the inner will be seperately switched for taxi illumination. After the LE layup was done, I taped over the area where the landing light lens cover was needed. I glassed with one ply BID and two plys UND(orientation fore-apt).

Double click the first picture for the to see the details. A lot is shown there. On the far right of that picture is the 3 ply template that was made. On the far left is the same template for the other strake with the tape on it for the first plaster pour. That first pour "cast" is shown on the second from the left with masking tape on it. I filled the glass template half full of plaster of paris and pushed the taped "cast" into that "yogart consisteny" plaster of Paris and then let it set, to get a reverse cast to fit over the first one. The center of the picture shows the regular cast covered over by the reverse cast. I added some stone (or plaster of Paris) on the outer side of that to make it stronger and keep it from rocking(when on the grill). The acrylic sheets are .08 Acrylic sheets (6X12 inch size). I got a 24X24 inch sheet and had the Lowe's guy cut it to make 8 pieces.

The next picture shows the cast being preheated to 350 degrees F. Between that picture and the next there was some work. I put on some oven mits and held a sheet of acrylic over the grill and rotated and flipped it while it warmed up. I did not set it on the grill. When the acrylic gets flexible, but not drooping, then I placed it on the top of the reverse cast and placed the cast down onto it. Notice that the cast are labeled for inboard with tick lines. I placed the weight and closed the grill top for thirty seconds. I took off the brick and flipped the cast over and smoothed down the drooping edges of the acrylic and took it out of the grill and placed on a safe surface to cool. When I could barely touch the excess acrylic with a bare hand, then I used my oven mits and took the cast apart. I took the not too hot acrylic lens and taped it onto the LE of the strake (keeping up with which end is outboard) and let it cool and conform. Mark the inboard side on the lens cover and left or right. Expect to go through 2 to 4 acrylic sheets to get the knack of it. I made spares for the lens covers and stored them away and I stored the cast away also. Years from now, I can still come back and remake lens as needed.

Several things happened between the last two pictures of this set. I cut out the light opening through the glass on the LE at the premarked area. Before, I had glassed the LE, I marked the start and stop points of the inboard limit of the opening. These were sharpie lines further aft on the strake top and bottom. Before you cut, make sure that your uncut lens extends past this border. After I cut this shape out with a dremel disk, I took out the blue foam to expose the lights. I smoothed up the edges and at this point I took out the lights to be sure that the cutout was shaped for that also, and then took the 3 ply template and laid it over this opening and traced the shape onto the template. I cut the template out and then trimmed it until it fit into the opening. I took that cut template and laid it over the outside of the shaped lens cover and traced the outline onto it. I used my dremel disk and cut out the lens. The last picture shows the lens cover in place before the lip support is placed.

In the first picture, you see the green piece of scrap cap strip from the strake work. I taped the lens. I put some micro on the green strip and used masking tape to hold it in place inside the enclosures, and then placed the lens in place flush to the strake. I used masking tape over the outside of the lens onto the strake to keep it from "falling in".

Next, I glassed the interior with some BID strips overlapping the inner side of the "retention lips".

The next picture shows the lens taped back on. I put some ficro on the "green lip" on one side and placed the taped lens back in place and let cure. I took off the lens, trimmed the excess and then repeated for the opposite side. If you do both at one time, then you might get the lens stuck with an overlap situation. This is a necessary step to close any gaps between the "lips" and the lens cover. If you have a gap and you screw down the lens, then it will flex and crack! No, I did not do that (yet).

To get the lens attached to the lips, I first marked three spots on the upper lip and three spots on the lower lip. I laid the lens edge on the shop bench edge and drilled holes for 8-32 screws and used a dremel metal crosscut bur to bevel the holes. I placed the lens back on and slowly drilled through these holes to make the same size hole through the "lips". In this picture you see 8-32 Tee nuts with the prongs going towards the lip. I did the other side reversed and they were more low profile. In the picture, you see that the screws are holding the Tee nuts in place. I placed some ortho wax on the open end of the Tee nut and placed a small amount of ficro around it to bond it to the surrounding glass. The last picture shows the final product. I spray painted the interior with some silver metallic for light reflection.
I drilled two holes through the centerspar where OD joins to it and ran pull strings for the wiring section. These holes are made through the access door where the light support was placed through.

Fresh Air Scoops


Here are three reasons to make your own scoops. The strength of the strake is not effected. due to the 100% glass to glass makeup. There is very little cost. Last of all , they look nice on the plane. You really need to plan to do this when the fuselage is flipped over and before the final micro surface finishing (a.ka. "big fill").

I did the extensions to carry golf clubs, but it turned out great for the pilot and copilot fresh air intake points and into the cabin exit points. See later pics. As for the first picture, you need to cut this hole offset towards the fuselage like this. There will still be room outboard of the ducting for the end of the golf driver.

I made a plastic template that was a rounded triangle shape of seven inches by 3.5 inches. I used this template for the fore and aft and left and right (flipped).

I used the dremel disk again to cut through the skin and carefully peeled off the glass. If you don't gouge the blue foam, then you have the "roof" of the scoop ready to form and shape in the blue foam. I used one wide piece of stiff yellow foam to contour the duct through the blue foam to the previously cut hole in the strake extension support.

The aft fresh air scoop area does not have any foam "below" (floor of baggage compartment), so I drilled the three corners and inserted three finishing nails. I put some micro on the blue foam piece and went inside the upside down fuselage and blocked it up into place. You can position the aft end of the foam to be one inch forward of the beginning of the rear baggage access, so that the outlet will not get in the way for access to that space. I brushed on some epoxy to the blue foam to stiffen it prior to glassing and that worked well.

I used masking tape strips to extend the duct sides where necessary and did the following.

I wet out some BID on plastic and cut two inch strips. With the plastic backing in place, I curved the strip of BID and slid the piece down the duct, touched it to the micro and then carefully peeled off the plastic. Do the "lower" side of the duct, wedge in a foam scrap and cure, and then do the "top" side and place a foam scrap to hold it up in place. Next, I taped over the aft scoop opening and placed a 4 ply BID layup. The rear fresh air scoop will be covered, when there are no rear passengers and/or winter flights. The cover is shown next with the three circles, being the future places for the screws that will run down to the flushed out Tee nuts on the scoop "roof". I stored away this cover and taped the scoop over with duct tape (1/4th inch overlap) for the micro fill of the bottom of the strake.

The first pic shows the expansion of the forward access opening. The fuselage is still upside down and blocked up. I sat a a short step stool and easily did this work. As always "glass down".
Here are the two foam pieces for the duct with a couple of finishing nails to hold together. Where the duct ends, is where the "Whisper flow" vent is going to be installed. I took the foam out between the two glassed surfaces at the "top" middle area of the border of the opening and set the lip of the vent into that space. The next pic shows the ducting foam ready for glassing.
I trimmed off two of the corners on the vent and carved out a depression in some blue foam and then started carving the outside down to this shape. There is a gap between the shape of the duct and this shape that I bridged with a little masking tape for the glass over. I glassed the duct and the vent piece and sanded off the excess blue foam. I trial fitted it all first and then glassed in this order. I glassed the "roof" of the extension first, and the "C" shaped support and the TLE interior angles. Then glassed in the ducting with BID strips. Cure. Then I added the vent ( masking tape over the rotating ball part!) and vent enclosure in place and tacked it down with a little micro and let cure. Then I glassed the vent enclosure to the ducting. Later, I added a little micro around the gap of the enclosure to the vent, being careful not to overlap the taped part. The end product gives a large adjustable flow of air directed at your chest and not your hand.
Last of all I glassed the rim of the access on the "top" and sides. I will do the other side, after I flip the fuselage over and before I add the forward section of the canopy. Note: tape the canopy hinges over. I almost got some epoxy on the hinges, before I did that.