Carlson Skunk Works

December 4th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust December 4, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

The past several weeks have been quite busy, but I have managed to achieve what I consider a major milestone. The first aileron has fabric on it!!!

Here is a picture of the aileron with its bottom fabric attached.


I am using the Stewart Systems EkoBond glue which is sort of like latex paint. There is no odor and things clean up pretty well with water. It dries fairly quickly and is quite easy to work with. I can do it, after all. There are a bunch of videos on YouTube showing how to use it.


I started by cleaning up the aileron using a fine rasp and then touching up the sealer where I thought I was getting close to the wood. Then I put anti-chafe tape on each of the ribs where I expect to tie down the fabric with a rib stitch. When that was done I “painted” the areas where the fabric needs to be secured with the EkoBond glue. The fabric is pressed into the tacky glue and sticks in place easily without any clamps. The fabric can be pulled off of the glue and repositioned until it is the way one wants it. THEN an iron set at about 250 degrees F is used to heat activate the glue and secure the fabric. When that step is done more glue is applied and worked through the fabric in the glued areas. Finally the fabric is shrunk to 250 degrees for the initial shrink.

The bottom fabric is now nice and tight and looks really good! Here is what it looks like from the top …


and from the bottom.


Notice that the hinges have been removed while I put on the bottom fabric. I reinstalled them before I started on the top fabric.


The top fabric is applied the same way as the bottom fabric was, but it is a little bit more difficult. This is because I needed to make a hole for the control horn to go through and because the front edge of the fabric needs to be secured around the inside of the leading edge plywood. I guess it wasn’t really any more difficult, but it was a bit more messy and took just a bit longer.


The finished product does look good, though.

Around the control horn I added a second layer of fabric. They guys on the Stewart Systems video do this on the wings where the strut brackets need to come through the fabric and I thought it would be a good idea to do the same thing here. I cut a circle of fabric using a quart yogurt container lid as a template. It is about 4″ in diameter. I folded it and marked where I wanted the control horn to come through and cut the opening for the control horn. Then I marked where it would lay on the top fabric and applied glue, positioned the fabric circle and worked more glue through it. I think it came out pretty nice.


Now I need to do the final shrinks on the fabric. The first pass will be to redo the 250 degree pass, then do a 300 degree pass and finish it up with a 350 degree pass. When that is done I will do some rib stitching, but that will be for the next post.

November 16th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust November 16, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

Another week and I am doing another blog post! Well, last week I ended needing to make some new brackets for the cabin end of the aileron control cables. The original brackets looked like this:


They were simply two inch wide pieces of two inch aluminum angle. The new brackets are made from 4130 steel. I marked out the locations of the required holes for mounting the brackets to the fuselage and for the control cables. Then I drilled the holes, cut the steel and bent it to shape. After welding the joint where the top of the bracket meets the side, I painted the brackets with self etching primer. The result looks like this:





When the bolts and cables were properly tightened and the stick was positioned in the neutral position, the ailerons were held in the proper neutral position.


The full deflection of the ailerons appears to be about equal up and down.



The only thing that I am questioning at this point is whether I should modify the brackets slightly so that instead of having holes for the aileron cables to go through, I should cut the area forward of those holes to make slots instead of holes. The advantage of doing this is that removing the wings would be slightly easier. However, I only expect to remove the wings once in the lifetime of the plane. Well, maybe twice if I live long enough to need to recover it.

The DAR that inspected Fred’s plane (Fred used these same type of cables) suggested securing them to the ribs so they do not flop around and cause damage in rough weather. I am planning to use zip ties to secure the cables to the compression ribs. Currently it is fairly easy to move the cables into and out of the wings from the inside of the cabin. Securing them to the compression ribs should eliminate that tendency.

Once the cables are secured I will remove the ailerons and cover them. Then it will be on to finishing the tail surfaces.

November 9th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust November 9, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

Well, it has been a very busy weekend. Actually the whole week was busy, but I did get a bit done on the plane. The quick overview is that I got the aileron control cables connected to the control torque tube. Things are mostly working, but the cable mounting brackets that I made will need to be replaced with new ones. So, on to the full description and pictures.


The first thing to do was to get the proper access to the torque tube control horn and attach the cables. This was all done from inside the cabin. I used a Forstner bit to drill a 1″ hole at each end and then used my little pull saw to connect the new holes to the existing hole. I finished it off using my Dremel tool to smooth the edges.


Just having the ends of the cables attached did not result in the ailerons working correctly. What I needed to do was to make some mounting brackets to secure the outer sheaths of the cables. My first pass at this was to use a couple of pieces of 2″ aluminum angle with appropriate holes drilled in them. I mounted the brackets to the main cabin frame with two AN3 bolts. The hole for the cables is 5/8″.


The cables come from the wing roots behind the seat back and down to the torque tube. Now that the cables are in place, I guess I could have gotten by with cables that are 6″ shorter and saved a couple of dollars. However, what I have should work just fine.


The next step was to put the stick in neutral and see how things look.


The cables are about even and there is plenty of adjustment available.


However, there is a significant amount of “aileron droop” that will need to be eliminated. My understanding is that some aileron droop is a good thing, but I think this is a bit much. So I checked things out and found that the adjustment can be made by moving the mount point for the cables up by about 1/2″. However, what that means is that I will need to make new mounting brackets for the cable ends.

Well, back to the shop to cut, bend and weld some steel.

November 3rd, 2015

AMF 14H MARANDA SN:1026 Making Sawdust November 3, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

How about this? Two posts within a couple of weeks! However, that means that I must be making progress, right?

In my last post I made a comment about probably needing to notch the trailing edge of the wing to accommodate the aileron control horn when the aileron is pulled fully up. Randy emailed me suggesting that I rebuild the control horn to eliminate that requirement. I thought that was a good idea, so here is what I came up with:


As long as I was at it I decided to move the hole where the cable connects to the control horn about 1 1/4″ aft. That would allow me to eliminate the 1″ x 1″ square tube spacer between the rear spar and the cable mounting plate. So what I came up with are the pieces to the right of the two sets. The original control horns are the ones that lean to the right and the new ones sort of look like a hand with the index finger pointing up. I took the new control horns out to the plane and found out that they needed to be thinned a bit. The aft area needed to have a very shallow “V” removed to fit into the aileron.

Once the new control horns were fitted and the spacers were removed, things look pretty good.



Full down is about equal to the full up deflection.



Removing the spacers allows the cable mounting plate to fit flat to the front of the rear spar. I think this gives it a bit more stability than with the spacers. However, even with the spacers it was pretty solid. This should also save a few ounces.


The other thing that I forgot to get some pictures of earlier is the pitot static tube installation.


It is a bit difficult to see because the tubes sort of blend in with the ribs, but it shows where I have located the pitot static tubes. By positioning them between the wing and struts I am hoping to avoid walking into them at some point in the future.


I used plywood to build up a mounting area for the assembly. I drilled three 1/4″ holes and used three AN4 bolts to secure the assembly to the wing.


This is a little more clear, but the internal bracing strap blocks the view of the top mounting bolts.

So one of the issues I will be facing when I cover the wing is how to apply the fabric and allow for the pitot static tubes. But there is plenty of time to figure that out.

October 26th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust October 26, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

Little things are happening, but progress is being made. Having help is a good thing, too. Here is my crew helping with a couple of the little jobs.


Emmett was tasked with taking out four bolts so that I could remove the control torque tube. Uncle Jeremiah was tasked with helping him. They made a pretty good team.

I needed to have the torque tube removed so that I could take it home and make the aileron cable actuation plate. With the aileron cables close to being attached to the ailerons, I need to design and build something for the other end of the cable that will push and pull on the cables. The last post showed how the cables were threaded through the wing and met the aileron control horns. What I needed to do next was to make some mounting brackets that would allow the cables to be secured to the wing. Here is what I came up with.


The bracket is mounted to the front of the rear spar. I had to move it forward an inch to get the right length. I went to Menards and got a three foot length of square aluminum tubing. I cut the tubing to length and drilled the holes. The mounting plate was made from the same aluminum plate that was used for the aileron control horns. The cable required a 5/8 inch hole for the threaded mounting area of the cable to go through. Even that hole was a bit snug, but once it is in place it should never need to be moved again.




Of course I didn’t have the required bolts on hand, so a quick Aircraft Spruce order was required.

Once the brackets were in place and the cables were properly secured I pulled and pushed on the other end of the cable to verify that aileron movement was about equal up and down.



I thought I might be able to get by without making a notch in the upper trailing edge of the aileron opening, but it looks like the notch will be needed. That is a minor issue.



The aileron ends of the cables are now secured, so the focus of my effort will now return to the control stick end of things. Here are the pieces that will now be installed.


On the left is the plate that I made to attach the input end of the cables to. The torque tube has been built according to the plans with a plate where the aileron cables are intended to be attached. However, using the push pull cables requires these cable connection points be moved out horizontally. Therefore the new plate bolts to the torque tube using the cable attach holes. I should be able to provide more pictures and detail in my next post.

All of the steel parts are being painted as I go. Once each part is finished I am using a self etching primer to paint them before I install them for the final time. At least I am hoping that this will be the final time.

October 9th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust October 9, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

Progress has been made! More parts are in place and things are looking good.

The tail is coming together and we should be ready to run control cables before long. The tail needs to be in place before the trim control cable can be run and the trim mechanism tested. The only concern that I have with this is figuring out how to run the Bowden cable through the horizontal stabilizer and elevator, and still be able to remove the stabilizer and elevator and put them back on again. I guess I need to study the plans again.

I decided to use the same approach as Randy Holland for stabilizing the tail surfaces. I am installing jury strut material instead of the cables called for in the plans. This is actually less expensive than using cables. The shackles for connecting the cables to the tail pieces are extremely expensive! Each one is $10.85, so the cost for the 16 that would be needed for the tail comes to $173.60! All the jury strut material for the whole plane came to less than that. Using the jury strut material looks nicer, too.


The connection points on the fin were changed so that I now have separate connectors for the front and rear jury struts. This was not nearly as difficult as I had envisioned, but I ended up doing it a bit different than the change bulletin that Chris sent out. I made some fir mounting blocks that sit on top of the upper fin rib and cut a couple of pieces of aluminum to go through the fin for the jury struts to fasten to. Then I drilled a hole in the middle of each block and aluminum strip and bolted it all together. I stopped in to see Gary Forbess at Marlatt Machine Shop to see if he had some aluminum that I could use for the jury strut connection points on the bottom of the fuselage. Gary has been a great resource for metals for my project and he is our EAA Chapter Secretary.



I managed to finish the plates that clamp the internal bracing straps where they cross and they are positioned in the wings. So far I have been able to get two sets of them fully secured in place. It is a bit tricky getting the screws and nuts to tighten fully. It would be a lot easier to use AN3 bolts, but I am not going back to order them at this point.

The aileron cables were ordered and have arrived. These are custom made industrial cables that I got from Baum Hydraulics in Omaha. The cables are 132 inches long and have bulkhead mounts on each end. They come with 1/4 x 28 threaded ends, so I ordered AN665 threaded clevis ends from Aircraft Spruce to go on them.


The cables go through 5/8″ holes and have a threaded area with two nuts and two 1 1/4″ washers to tighten on each side of the hole that the cable goes through. This mounting area just happens to end up above the front edge of the rear spar. Therefore mounting an aluminum plate on the rear spar is the ideal way to mount these cables.





Things are moving again!

August 24th, 2015

AMF 14H MARANDA SN:1026 Making Sawdust August 24, 2015

Posted by Roger in AMF 14H Maranda SN1026, news

Has it really been more than a year since I last posted??? Wow! Time does fly!

Things have been busy and life has sort of derailed many attempts at actually doing things to/for Sawdust. Now I think I am back on track and am once again beginning to make some progress. Much thinking and planning have been done and I have a spreadsheet of tasks that need to be done to move construction toward completion. A rough list of items that need to be purchased has been assembled and it should only take me another $10,000 to be flying.

The past weekend was very productive. I started building the trim control. I like the trim wheel type of control and have been puzzling over how to actually build one. Last year at AirVenture I purchased a sheet of plastic that was about a foot long, five and a half inches wide and half an inch thick. I was planning on using it as part of my comm radio antenna. However, there was more than enough material for that purpose, so I used one end of it to make my trim wheel.

The elevator trim tab is actuated via a Bowden cable. This cable will run from the elevator, through the fuselage to the trim control mechanism which will be under the seat. I will be using a bench seat arrangement, so the trim wheel will be mounted inside the seat support and will come through a slot at the front. Therefore, accessing the trim wheel will be similar to the way it is done in a Cessna 150. The other thing that I had to figure out was how to move the center wire of the Bowden cable in and out when the wheel turns. What I decided to do was to bend the Bowden cable 90 degrees under the seat so that it ends up running parallel to the wings in that area. Then I purchased a 3/4 inch diameter threaded rod at Menards and a square nut with the same threads as the rod. The rod and nut use coarse #10 threads.

I started by laying out the wheel on a sheet of paper. First, I drew a five inch diameter circle. Next, I divided the circle into twenty degree segments. Where each segment radial crossed the circumference I made a half inch circle. The paper layout was taped to the plastic and I drilled a small hole at the center, then drilled half inch diameter holes at each of the half inch circle locations around the circumference. It ended up looking like this:

Notice that the nut is sitting there as well. I drilled a hole at the center of the wheel that was the same diameter as the nut was wide. Then I used a Dremel tool cutting bit in my drill press to remove the plastic for the corners of the nut. I was careful to ensure that the nut fit quite snugly into the finished hole. Like this:

I drilled two holes through the threaded rod to facilitate a couple of AN3 bolts. These bolts will keep the rod from turning so that turning the trim wheel will move the rod right or left. The bolts will also be used to mount a plate with a clamp for the center wire in the Bowden cable.

In order to hold the threaded rod I cut a couple of mounting blocks from some left over delrin. This is the material that was used for making the elevator and rudder hinges. These blocks have a 3/4 inch hole centered in the block and located 1/2 inch from the front edge. Then two holes are drilled in each of them to allow them to be mounted to the front of the seat base with AN3 bolts.


So, at this time the assembly looks like this:



April 11th, 2014

AMF 14H MARANDA SN:1026 Making Sawdust April 11, 2014

Posted by Roger in AMF 14H Maranda SN1026, news

Well, it is spring and, even though I did install the engine on the fuselage a couple of weeks ago, you are probably wondering what I have been doing all winter. I have been working on the ailerons and elevator. All of them are nearly done, but the ailerons are the farthest along. That is probably because I had some help with them.

A group of young men from church spent a couple of Sunday evenings working on the spars for the ailerons and on the skins for the elevator. Then my son, Nathan, came from California for my birthday and we installed the aileron ribs. The rest of the process I did by myself. Oh, and I did take some pictures.

This shows the aileron spars with the ribs sort of attached. The locations for the nose ribs are being marked.

The trailing edge of the ailerons is being made the same way that I made the trailing edge of the wings and elevator, rather than the way the plans call for. The plans call for the trailing edge to be cut at the appropriate angle with a notch cut lengthwise to accept the gussets. What I have done is to cut a piece of 2mm plywood to run the full length of the aileron, then I marked the desired location of the aileron ribs and glued them in place. Once that much was assembled I cut fir strips to be glued on each side of the plywood. Later I shape the trailing edge with a planer and sander.

All of the aileron nose ribs are identical. I rough cut the ribs, then stacked them together and sanded them to make them identical. I used my little pull saw to cut the notch for the leading edge stringer.

The locations of the nose ribs were marked. These are not all placed directly on the other side of the spar from the rear ribs.

To make gluing the nose ribs into place a bit easier, I clamped a couple of boards across my bench to allow me to hang the ailerons with the front of the spars up. I could mix up some T88 and glue the nose ribs pretty easily. Of course, I stapled the nose ribs as I glued them and pulled the staples once the glue had cured.

Before I glued the trailing edge strips I marked where I wanted to cut out the plywood. This results in some weight savings and makes everything look like the plans. However, I think it makes things a bit more durable and secure.

After the first trailing edge strip is glued to one side of the plywood, I used my pull saw to cut out the area ahead of the trailing edge strip. The areas of the plywood that I left correspond to the gussets that the plans call for. I cut the angles to 45 degrees because it was easier to mark that angle with my combination square, than to mark the 30 degree angle called for in the plans.

The center rib for each aileron was built just a bit differently than the plans as well. The plans call for two ribs to be positioned in the center. These ribs needed to have a gap between them for the aileron horn. Since I plan to use push-pull cable to activate the ailerons, the aileron horns will only protrude above the ailerons. Therefore, the horns can be inserted from one side. Therefore, I used 3/4″ fir in place of the two ribs. Then I cut a notch in the rib to accept the horn.

Partial plywood skins are glued on the top and bottom of the ailerons. Holes needed to be made in the skins to allow the horns to be inserted and bolted into place.

The bottom skin is flat, but the top skin is curved. There is a solid fir strip on the leading edge to hold the top skin while the rest of it is bent to the contour of the aileron top surface.

The way that I did this was to glue the fir strip to the plywood first, then I smeared glue on the top of the ribs and spar. As I positioned the skin assembly in place I glued and stapled the gussets in place to hold things securely. Once all the gussets were in place I could staple the skin to the nose ribs, spar and aileron ribs. I had to carefully work things to fit the required curve. I used enough staples to hold things securely.

When the glue cures things should look nice. Then the trailing edge strips were planed and sanded to the proper shape.

The next step will be to cut the piano hinge to make the hinges for the ailerons.

March 31st, 2014

AMF 14H MARANDA SN:1026 Making Sawdust March 31, 2014

Posted by Roger in AMF 14H Maranda SN1026, news

It has been a while since my last post. I have been holding off until I have some progress to report. I wanted to report that the ailerons were done and on the plane, but that is not quite true, yet. They are close, but the weather has been too cold to work at the hanger until very recently and there are a few details to finish up on the ailerons before they can be mounted.

However, Saturday was very nice, so I went ahead and mounted the engine on the plane in my spare moments.

I ordered the mounting hardware from Aircraft Spruce and found that the bolts that I ordered were about half an inch too long. So I put in another order. The bolts that were too long for mounting the engine turned out to be the right length to attach the engine mount to the fuselage. The new bolts arrived on Friday, so Saturday was a good candidate day for mounting the engine. The original bolts that I ordered were AN6-45 and the replacement bolts were AN6-41. After mounting the engine this time I find that the final mounting bolts may need to be AN6-40. Fortunately, when I made the second order I ordered both the AN6-41 and AN6-40.

Fred had built an engine hoist to mount the engine in his airplane and Cal had just gotten done using it to remount his engine. I drove down to Cal’s hanger over lunch on Thursday and picked up the hoist and took it to my hanger. The hoist had to be disassembled for transport, but it is not very difficult to tear down and put back together. So Saturday morning I went to the hanger and assembled the hoist and hooked it to the engine.

The engine was on a stand. The engine was pointing down with the crankshaft fastened into a hub which was bolted to the stand. I had to lift the engine and stand, then remove the bolts and remove the stand. With the stand removed the engine sat pretty level. Then I pumped up the hoist to be sure that it would lift the engine high enough and it did. However, when I tried to insert the bolts, the holes were just a bit too tight. I let the engine down so it was just off the floor and headed home to get the drill and do a few other things.

Later Saturday afternoon I had a bit more free time, so I went back to the hanger. First I drilled out the tubes on the engine mount. The problem was that there was some build up where I welded the large washers to the tubes and I needed to just open up that area. It only took a couple of minutes to run the drill through those holes and the bolts slid through just fine. I put the bolts in place, added another washer, then an engine mount bushing. This held things in place while I hoisted the engine into place. Then it was just to wiggle and jiggle things until I could add the other bushing, washer and then the nut. The lower mounts went together first and the engine had to be tipped back to get the upper mounts to fit correctly. The whole process of mounting the engine by myself took about an hour.

With the engine in place, I disconnected the hoist and moved things out of the way, then pushed Sawdust out of the hanger into the light and took some pictures.

With the engine mounted and without the tail feathers I can grab the end of the crankshaft and easily lift the tail. I don’t think that I will work on the cowling until I have the tail pieces in place. But then that is about the next thing to do anyway.

I was a bit concerned as to how the plane would look with the engine mounted. I was afraid that it would look like the nose was sticking out way too far, but I don’t think that is the case at all.

I really wanted the tail to be light enough that it would lift things off the ground early in the takeoff run and I think this will be the case.

The engine mount was built according to the specifications provided by Tony Bingelis in one of his books. The engine is a Continental C85-12. The starter and generator clear the firewall by about three inches.

The starter has the old “pull starter” arrangement. This uses a cable to pull on the lever which pushes the starter gear into place on the starter ring on the engine, then a bit more pull depresses the starter button to supply power to the starter motor. I think that the pull cable will need to be run over the top of the gas tank. I may use a solid rod instead of a cable, but haven’t decided yet. I will talk to Jerry about that since he has used this type of engine in his planes for years.

It has been a while since I welded up the engine mount and I guess I should have painted it right away. However, this is a temporary mounting of the engine to get the controls and instruments fitted. Then everything will need to be taken apart to apply the fabric and paint. The ropes are to hold the gas tank in place temporarily while I figure out how to build the permanent mount for it.

The hub that held the engine to the stand is still on the engine. I am not sure exactly how to remove it, yet. There is probably a very simple solution to this, but I will need to do a bit of research to find out the secrets. In the mean time the two bolts that held the hub to the stand are stuck in the hub and there is not enough clearance to remove them.

I wonder if those holes in the hub are the secret to getting it off.

The front view is pretty impressive. Well, at least to me. The red tag says that I need to add lock washers to the screws holding the heat muffs onto the exhaust tubes.

I was a bit concerned about the way that the wheels were sitting, but adding the weight of the engine helped things considerably. I didn’t get a good picture of their current positions, but there will be more weight added which will continue to make changes to their attitude. Fred and Cal recommended not making any corrections to the landing gear until I get everything else done. They think that the additional weight of the covering, windshield, gas tank, instruments, seats, etc. will make a big difference.

A look at things from the back. I am very pleased with things as they are at this point and am looking forward to a busy summer at the hanger.

January 7th, 2014

AMF 14H MARANDA SN:1026 Making Sawdust January 7, 2014

Posted by Roger in AMF 14H Maranda SN1026, news

Happy New Year!

I was wondering what to do for the first post of the new year. Then one of the guys on the Maranda Yahoo group asked for some details about the process that I used to prepare and attach the leading edge skins to the wings. After putting together my explanation I thought it might be useful to have it in my building blog just in case anyone happened to read it and it would be a way to sort of archive this in case I ever needed to remember how I did it. Therefore, what follows is the overly long explanation of the process that I used:

What I did was scarf the plywood before I bent it. However, I did not glue the scarf joints together until I fastened the plywood to the wing. So the overall process went something like this:

1. Cut the plywood to 2′ x 4′ pieces.

2. Mark the plywood pieces so that you know what order they will be in when secured to the wing. This is also important when scarfing.

3. Scarf the plywood. I applied the plywood from the root to the tip. The first sheet of plywood used the first full sized rib (the 14-H has sort of a gull wing and the root rib is smaller) as the starting point. The root end of the first sheet should not be scarfed. The tip end of each sheet should be scarfed so that the scarfed area is outside of the wing. This makes it easier to mate the next sheet to this one.

4. Mark the location where the nose strip should meet the plywood. I used a sewing tape measure determine the distance from the lower back edge of the spar to the center of the nose strip. I marked that distance on each sheet of plywood. That was where I heated the plywood and is the center of the bend. The result is that the portion of the plywood that covers the underside of the leading edge is about two inches longer than the portion that covers the top of the leading edge.

5. Mark the location of the ribs on the plywood as well as the location of the top and bottom of the front spar. I clamped the plywood to the bottom edge of the spar and marked the ribs on the inside of the plywood from the spar to the nose strip, then I marked the rib locations on the top edge of the plywood on the outside, but close to the edge of the plywood. This allowed me to finish marking the inside of the plywood after it was removed from the wing and the outside rib location marks helped with keeping things aligned during the gluing process. While you are at it mark where the plywood should end on the top of each rib and where each sheet of plywood will end on the spar. Be sure to allow for the scarf joints.

6. Heat and bend the plywood pieces. I clamped them at the nose to help maintain the bend while they cooled.

7. Put masking tape over the inside areas of the plywood where the ribs, spar and nose strip will contact the plywood. I used 3/4″ frog tape which worked really well. I wanted to be sure to keep the sealer from preventing the glue to make good contact. I also put tape over the scarfed area. I also masked the areas of the ribs where the plywood needed to be glued and the top and bottom edges of the spar. While I was at it I masked the top and bottom edges of any ribs where plywood would be attached later. In my case this was the root two ribs and the tip two ribs.

8. Apply sealer or spar varnish to the inside of the plywood and to the areas of the wing that will be inside the area covered by the leading edge skins. I only sealed the areas that would be on the inside. I did not seal the portion of the plywood sheets that would be behind the front spar. If you want to and if you have everything masked that needs to avoid being sealed, you can go ahead and seal the whole wing. I only did the first coat of sealer on the whole wing at this time.

9. Remove the tape once the sealer has completely dried.

10. Apply glue to the areas of the inside of the plywood where the tape was removed. The glue not only secures the plywood to the wing leading edge, it also is the sealer for the areas where the tape kept the sealer from covering, so be sure to cover the entire area where the tape was.

11. Secure the glued up plywood to the wing leading edge. I used LOTS of 1/4″ staples for this. I began with the wing tip end and stapled the plywood to the underside of the leading spar so that the plywood used the spar as sort of a straight edge to guide it. Then I stapled the plywood to the underside of the ribs and continued around the leading edge until everything was secured. Work from side to side to keep things even and straight. Watch the markings that you made earlier to be sure that the glue lines are actually mating with the ribs in the correct places. As stated above, I started with the plywood sheet at the wing root end and worked my way to the wing tip. I was sure to apply plenty of glue to the scarf joint, but didn’t staple the scarf joints themselves. If you were careful with the marking and scarfing, the scarf joints should pretty much take care of themselves. Imperfections can be touched up later.

12. After the glue has cured completely, remove the staples and inspect the joints.

13. The plywood for the wing root area between the root rib and the next one where I started gluing now needs to be marked, bent sealed, etc. The first sheet of plywood will now need to have its inboard edge sanded to match the angle that this new piece of plywood will meet it. This sanding was only done on the top of the wing and around the nose to the place where the angle is such that the new plywood should be sanded on the inside. I think you will see what I mean when you get that far.

14. If there are any gaps in the scarf joints mix some sawdust (or sanding dust) with some glue and work it into the gap. On my first wing I had to do this a couple of times to close one gap. Once the glue is cured it can be sanded smooth. When the wing is covered, you will be the only one to know where the imperfection is. I used a palm sander to go over the whole wing leading edge before I applied sealer to the whole wing. I paid special attention to the scarf joints, but found that they were not a problem at all. There will be a bit of a ridge of glue at these joints that can be easily sanded down to make a nice surface for your wing.

An extra pair of hands (or maybe more) can be a lot of help for holding and handing you things. I was able to do my wings mostly by myself, but having another set of hands to hold the plywood in place while I put the first staples in would have helped a lot. I had several occasions where I found that I had to pull a skin off and reposition it. Having more hands to hold the skins in place while they are being stapled will help the scarf joints to come out much better as well. Extra eyes can be a big help as well. You could have someone watch the alignment of each piece as you apply staples.

Speaking of having an extra pair of hands …

For the next two Sunday evenings the youth from our church are going to come over and “help” me work on the plane. This winter I am wanting to finish the elevator and build the ailerons and doors. These are fairly simple tasks and the kids from church should be able to help with quite a few of the tasks involved.

I have been told to expect about eight teenagers, so I need to have tasks for them. Therefore, I don’t want to have too much done ahead of time.

There are several things that will need to be glued, so they will learn how to mix T88 and use the staple gun.

I am going to have a team work on laying out the aileron spars and another team work on laying out the aileron ribs.

Some of the others can be cutting out parts, including wood pieces for the ailerons and elevator, and metal parts like the aileron control horns.

I hope to get some pictures of the activity for the next post.

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