Carlson Skunk Works

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.

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.

How about this? Another post within a month! Yeah, I know. Just barely. BUT I did make it!

Yesterday was Thanksgiving. I have a huge amount to be grateful for and I praise God for all that He has provided for me, my family and friends. We enjoyed our Thanksgiving meal with three of our children, our grandson, and our friends Sandy and Una (pronounced EE-oo-na). Una and Sandy are single ladies that our family has adopted, especially for celebrations like yesterday.

Since we had two “adult” sons home with us, and they had arrived on Wednesday and spent the night, I had two “willing” helpers to provide some lifting assistance to mount the wings on the airplane. So Sawdust is now looking much more like it will eventually fly!

The temperature was in the high 20’s and low 30’s as we loaded the left wing into the back of the pickup and headed to the airport. We repositioned the fuselage and mounted the right wing first, then we moved the sawhorses, unloaded the left wing from the pickup and mounted it to the other side of the fuselage. Then I opened the hanger doors as wide as I could get them and found out that the east door has a problem and won’t open all the way. We ended up getting the plane out of the hanger by swinging the tail around and maneuvering the left wing outside first, then turning the fuselage around and backing it out to get the right wing out of the hanger. I am going to call the airport manager and let him know about the door problem. Right now it is not a big thing, but when the plane is ready to go in and out of the hanger more often it will become quite an issue.

OK. So, of course, you are wondering where the pictures are. We were so busy and excited to get the wings on, that we didn’t get any pictures until after the fact, but what I have follows:

Front view. You can see the full wingspan and the hoerner wing tips.

It is starting to look like an airplane! Here you can see the “gull wing” look that the tapered leading edge provides at the wing root. The horizontal stabilizer is finished, so I need to get it mounted to the fuselage on the next warm, sunny day.

Well, the fuel tank is currently where the seat will be. One of the next tasks will be to figure out how to mount the fuel tank. Also, the ailerons need to be built and mounted. Building the ailerons and doors will be the focus of this winter. Those can be built in the basement where it is warm. I already have most of my tools moved back down there, so they are ready to get going. The first item is to finish the elevator, then it will be on to the ailerons.

I followed the lead of Randy Holland and built up an area of a rib for the purpose of providing a mounting point for the pitot-static tubes. The area of the rib just behind the forward spar that has been built up is right in the middle of the picture. If you don’t know what you are looking for you will probably miss it.

The plane is back in the hanger and I am busy digesting turkey and pumpkin pie.

I had a really good weekend! The leading edge skins have been installed on the left wing, except for the small inboard section where the leading edge makes a break. The wing has sort of a gull wing look like some Stinsons that I have seen.

Friday afternoon I got the chance to work on the pitot-static tubes. Saturday morning I cleaned the carpet in the dining area. Once the carpet was done it was starting to get quite nice and my wife gave me the go ahead to spend the rest of the day working on the plane. I was careful to take a bunch of pictures, so here is what I got done.

Friday afternoon I gathered materials and tools to try to make the pitot-static tubes. I had done quite a bit of research about the cost of purchasing these and decided that trying to do it myself would probably cost about as much, but would deliver a great deal of satisfaction. So I bought a ten foot roll of 1/4″ copper tubing, some solder, a #60 drill, and two #10 x 1/2″ belt rivets. Tony Bingelis provided instructions and a basic design in one of his books and this information is also available in the homebuilder section of the EAA web site. I went to the EAA web site and grabbed the image of the drawing and printed it. I also have the book, but wanted a copy of Tony’s drawing that I could make some notes on.

I dug around in my plumbing box and found a tin of flux and my tubing cutter. I also had a propane torch from when we built the house in Minnesota and I plumbed in the hot water heating system. At this point I was ready to go.

My biggest concern was how to plug the end of the tubing for the static tube. The tubing cutter made it easy to cut the tube. Tony only said to seal the tube and suggested crimping it, putting a screw in the end of it, filling it with solder, etc. I wanted something that looks fairly nice, so I started hunting around and came across some belt rivets at my local Ace Hardware store. These were #10 x 1/2″ long and had a large, nearly flat head on them. I got two just in case and they were $0.32 each. These were copper, so they worked quite nicely.

I started by figuring the length of tubing that I would need for my tubes. I calculated that a two foot length would provide plenty of tubing, but would still be small enough to be relatively easy to work with.

The plans call for eight holes and show them as being positioned in two radial groups of four holes about 1/2″ apart. I measured where I wanted the holes to be and chucked the #60 drill into my drill press. Then I used my tubing jig for positioning the tubing in the drill press. I position the bottom of the V so that the drill hits the bottom of the V and clamp the jig in place, then I position the tubing and drill the holes. It is not fancy, but it works pretty well. The hard part with soft copper tubing is that it is pretty difficult to get the tubing to be perfectly straight. I decided to drill these holes before I put the plug in the end of the tube just in case things got messed up. That way I could be sure that these holes were done correctly before I committed one of my plugs.

The next thing was to cut some small pieces of solder. The order of assembly is to use a pop-cycle stick to stuff some flux into the end of the tube, push the rivet into the end of the tube, then drop the pieces of solder into the tube from the open end and have them end up at the rivet end. Once all the parts are in their assigned locations I just needed to heat the end of the tube by the rivet and let the solder pieces melt. Unfortunately, the matches that I had in the garage had gotten soggy, so I had to go find some other matches before I could heat things up.

I don’t know if the tubing had some protective coating, or if my torch wasn’t burning cleanly, but the tube seemed to get pretty sooty. I was careful to hold the rivet end down while I heated the tube so that the solder would melt. The flux bubbled up nicely and some bubbled out of the holes that I had drilled in the tube. At least I was sure that I had heated things enough to be sure that the parts were soldered together. Next I needed to grind the rivet down to the same size as the copper tubing. I tried using a hand file and that worked reasonably well, but I found that my bench sander worked really well.

I found some paper towels and a Scotch Bright pad and got the static tube cleaned up pretty well. Then I took it back to the drill press and made sure that the holes were open. I am able to blow through the tube without difficulty, so I think I am ok. The rivet shaft is 1/2″ long, so I should be able to safely file the end to a nice rounded shape without compromising the finished product. However, I don’t think that is really needed, so I am leaving it as is for now.

The next thing to so was bend the tube. I happened to have a set of tube benders that I had bought for a plumbing job. These are basically coils of wire that the tubing fits inside of. With the tubing in the bender one gently bends the tube while making sure that the bender continues to slip along its length. Of course, I needed both a static tube and a pitot tube, so I needed to cut another two foot piece of tubing and bend it appropriately. The pitot tube is a lot easier to make because it is just a tube. I didn’t need to plug the end or drill holes crosswise through it. Just cut it to length and bend the end. Then I soldered the two tube together so that they became a single unit.

The final task will be to make a mounting bracket for the unit. Once again my local Ace came to the rescue with a piece of copper sheet. This is fairly thin, but yet thick enough to make a durable mount. I still need to complete this, but the intent is to make a U channel just wide enough for the two tube to lay in. Then I will solder the tubes to the bracket and bend the copper plate to make mounting ears. The plate is about four inches wide and a foot long, so it gives me enough material to make a couple of mistakes if I need to.

I took Randy’s lead and made a mounting place for these tubes on a rib just behind the front spar. The rib I chose is between the strut mount and the jury strut mount and is about 66 inches from the root end of the wing. This will be mounted on my left wing, so that the length of tubing to the instruments is as short as possible. Having the pitot tube located in the triangle formed by the strut, jury strut and wing should help to protect it from people accidentally running into it.

Saturday afternoon was very nice and provided a good time to finish applying sealer to the areas of the wing that would be covered by the leading edge skins. Then I needed to scarf and bend the skins. Once again I used the heat gun to apply heat to the plywood in the areas where I wanted to bend it. This works really well! Heat the side of the plywood that will be on the inside of the bend. Gently bend the plywood as it heats, but be sure to spread the heat over the entire length of the bend. When the plywood is bent about right I grabbed some of my clamps and held the bend in place while the plywood cooled. Using this method allows me to bend a sheet of 1.5mm plywood to a 1″ to 1 1/2″ diameter without any problems.

The next thing was to seal the inside of the nose skins. I held the plywood in place and marked where the ribs would go, then taped the areas where I would apply glue when it was time to attach the skins. I put on a good solid coat of sealer, reapplied the clamps to retain the curve and called it a day.

Sunday was colder, so I moved my wife’s car out of the garage, positioned the wing where I could work on it and closed the garage door. I removed the tape from the areas where I now needed to apply glue and went over the surfaces to be sure that everything looked right. I mixed up a batch of T-88 and started smearing it over the inside areas of the skins that did not have sealer on them (where the masking tape was). Then I held the skins in place (one at a time) and stapled them in place.

This time I used 3/4″ wide scarf joints and took a bit more time in applying the skins and the joints where the skins met turned out much nicer than on the right wing.

Today and tomorrow are supposed to be a bit cool, but after that things are supposed to be in the mid to upper 50s. I am very hopeful that I will be able to finish this wing before the winter weather sets in.

Wow! Another month has gone by since the last post. Well, I am still making progress, but have not taken many pictures of the steps that have occurred in the past few weeks. What I do have is project pictures and a report about the EAA Sportair Workshop that I attended in Dallas, TX on October 19 & 20. The experience was fun and I learned a great deal!

The EAA Sportair Workshops are presented at multiple locations around the country. This was my first workshop, but I am already considering attending another one as Sawdust progresses. I went to the Electrical Systems & Avionics course, but there were other courses being held at the same site at the same time.

I chose to go to the workshop in Dallas because I can get free lodging while I am there and can see my son and grandson at the same time. So I took some vacation and did the ten hour drive on Thursday afternoon so I could be with on a school outing on Friday with my grandson. I left Kearney just at noon and arrived at my son’s apartment at 10:30pm even with a supper stop at Braum’s on the north side of Oklahoma City. I can make pretty good time if I am by myself.

This is what I came home with from the workshop. The manual has lots of good information, includes a copy of every slide that the instructor talked to and notes about what he said. There is enough room around the edge of the slides to include quite a few notes. The hands on portion of the workshop provided instruction and practice of soldering and crimping and the theory portion helped me to understand why things need to be done in a particular way. The projects that I completed were mine to keep and take home with me. I should be able to reuse some of the parts.

The manual is really well done and has lots of additional material that will be useful for reference.

The first project was learning to use crimpers to connect wires together and to attach terminal ends. What I found really interesting was that using crimped connections is the preferred technique for aircraft wiring. My electronics background had me prejudiced toward soldering, but in our airplanes there is a lot of vibration and soldering the multi-strand wires that we use turns them into a solid wire which becomes quite susceptible to work hardening and breaking where there is vibration. Anyplace where the wires are soldered we need to add strain relief such as shrink tubing collars.

The second project was to wire up an intercom harness. We only wired it for one headset, but it gave us experience with crimping and soldering and applying shrink tubing and planning ahead. Be sure to put the shrink tube on the wire before you solder it to the connector, or you will have to unsolder it and put the shrink tubing on and re-solder it. This also provided experience working with shielded cables.

Sunday morning’s project was to install a BNC connector on a coax cable. This was a bit more involved and required some careful measuring, cutting, trimming and crimping. Not hard, just detailed.

The final project was to wire up a circuit by following a wiring schematic. This circuit simulated something that most people will end up doing in their planes. There is a switch that will turn on the navigation lights and the cockpit lights. If you need the cockpit lights it is probably dark enough that you will need the navigation lights, so one switch controls both. The cockpit lights may need to be dimmed, so there is a rheostat for dimming them. Each circuit needs to have a protective fuse so that a short in that circuit will not remove power from other, possibly more important, circuits. Therefore, there is a fuse in the circuit. Then there needs to be a power distribution bus and a power supply. Our power supplies were a AA battery that is in a holder on the underside of the chassis.

When the switch is turned on the lights come on.

Adjusting the rheostat dims the cabin light, but leaves the navigation lights on full.

I really enjoyed the class! They also had coffee and cookies available at the start of each day.

Where did September go? I didn’t even get a chance to post last month. Oh, well. I guess I was too busy working on Sawdust and stuff to take time to post.

The right wing and fuselage are in the hanger and the left wing is nearing completion in the garage. Plus I have signed up for an EAA Webinar that is taking place tomorrow night and I am registered for an EAA SportAir Workshop in Dallas on the 19th and 20th.

The most visible project of the past month is my Arduino based electronic altimeter. A couple months ago we took a drive to see our son and grandson in Dallas and while I was there I picked up an Arduino starter kit. For those who don’t know what an Arduino is, it is a very small computer. The Arduino has lots of connections that can be used to connect various parts and it has a program that runs on your computer that you can use to program it. Lots of people are using Arduinos to build controllers for their sprinkler systems, blinking lights with lots of lights, robots and UAVs or drones. There is even a special version of the Arduino called the Ardupilot that is designed as an autopilot for model airplanes.

I started checking around the web to see if anyone had used an Arduino as the base for instrumentation for real airplanes, like homebuilts. Sure enough! There were a couple of sites that came up with altimeters and airspeed indicators. The catch is that these sites have been done mostly by non-fliers. Therefore they have big disclaimers about how the projects presented are not for use in real airplanes. However, homebuilt airplanes can use homebuilt instruments and avionics. With that in mind, I want to make my own disclaimer with regard to my current airplane project. Because this is my first homebuilt airplane and I want to be very careful with it, I am going to install regular, old fashioned, steam gages for the primary gages. My experimental gages will be installed on the right side of the panel until I am comfortable with their accuracy and reliability. Since this is a homebuilt aircraft, I can redo the panel later on and install my experimental instruments later.

The altimeter consists of a barometric pressure and temperature sensor, two two digit seven segment displays, four shift registers, three push button switches and an Arduino Uno R3. There are also a bunch of resistors and some wire. The parts are soldered to a perf-board that I got at Radio Shack.

I started by assembling the display and writing a program to count up from 1 to 9999, then start over. There is a decimal point LED on each display and the right most decimal point is lit at the start of the program. As the counter goes past 9999 and starts back at 1 again the next decimal point is lit and the others are turned off.

Next I put together the sensor and switches on a project board and modified the program to show the altitude, temperature, barometric pressure and rate of climb, well sort of.

So, I took the display, the Arduino, my battery pack and a project board with the pressure sensor on it and mounted it in my “test panel” in my pickup and drove around and watched the numbers change. Here is how it looked:

Here is a closer look at the pressure sensor:

This shows the altitude. Notice that the right most decimal point is lighted.

This is the temperature in degrees Fahrenheit. Notice that this is to the tenth of a degree and the appropriate decimal point is lighted.

The barometric pressure is next. Well, not really. This is the equivalent of the Kohlsman window on a regular altimeter. In this mode I can adjust the reference pressure to pressure at the airport. The program sets a default pressure of 29.72. There is a button to increase the value displayed by .01 and another button that will decrease the value by .01.

The fourth mode is to display the rate of climb. I will need to do a bit more work on this since it is currently setup to sample the altitude once per second. The altitude is saved for that second and is subtracted from the next altitude. This gives the change in altitude per second, but we want the change per minute, so I multiply this value by 60. That gives me the rate of climb in multiples of 60. I need to figure out some way of getting a more granular value here.

Of course, just sitting in the truck doesn’t really have a rate of climb, so it is showing “000” FPM.

Next I wanted to move everything to the display board. So now I have it all together and could theoretically complete a package to house the unit.

Here is a closer look at the display board, so you can see the sensor and the switches. There are three push button switches which are used to set the display mode (top switch), increase the pressure setting (middle switch) and decrease the pressure setting (the bottom switch). In my haste I forgot to add the wires that go from the switches to the Arduino, but I will fix that pretty quickly.

The left wing is coming along nicely. I need to pull some staples and sand the filler blocks between the ribs on the bottom of the wing. Then I can start applying sealer and install bolts and brackets and tighten the internal bracing. I need to order a few more sheets of plywood and more T88, but I want to get all the bolts in to be sure that I order everything that I need to complete the wing in one order. If the weather holds I think I will make my goal of completing the wings before winter.

This is the second post this month, so I must be making progress!

At this point the right wing is “mostly” done and has been moved to the hanger. The “mostly” means that I still have a few staples to pull, some sanding to do, and some sealer to apply. All of this can be easily done at the hanger where I can go on Saturday and Sunday afternoons and “forget” what time it is.

This summer has been hot and working on the wing in the afternoons and evenings has been quite uncomfortable. I have done a bit during my lunch time, but was limited by wearing my better clothes and needing to get back to work. I thought I was about done at one point, so I decided to double check the plans and saw that I still needed to add a couple of gussets at the inboard end of the aileron opening. I added those and things are looking pretty good.

Last Saturday afternoon I applied sealer to the top side of the wing. Getting into all the little spaces between gussets on the ribs was a chore, but I think I got the vast majority of them. When I flip the wing over and apply sealer to the bottom side I can go back over all of the ribs and apply more sealer wherever it is needed. The sealer manufacturer recommends at least two coats of sealer, so I will probably be applying sealer until the snow flies.

The sealer that I am using is water based, urethane, outdoor spar varnish that I got at Menards. The brand is Varathane and according to what I found when I Googled them it should be available at Home Depot as well, but I couldn’t find it at the Grand Island store. Since this is water based there is no odor and cleanup just takes warm water. I really like that and the cost was about $50 per gallon. I spent less than $60 for a gallon of sealer and three pretty good brushes. This appears to be quite similar to the sealer that Stewart Systems offers, but at about 1/4 the cost.

So my wife has decided that she is going to have a garage sale next weekend and the garage needs to be cleaned up and cleared out well before then! That means that I need to move the wing out of the way and vacuum up all my sawdust. Then I need to hang tarps around the perimeter of the garage to hide all of my tools, so they won’t get sold accidentally. Saturday afternoon I rolled the wing out onto the driveway while we cleaned and did the initial preparation of the garage. Then I applied the sealer while the wing was outside. After the garage was prepped I rolled the wing back into the garage for safe keeping until I could move it to the hanger.

Move the wing to the hanger? I have a 16 foot long wing and a short bed, club cab pickup. How am I going to get that thing moved? Let me show you my approach.

I had gotten a “bed extender” some time back with the intention of using it to get the canoe to the lake to do some fishing. That has not happened yet, but the intention is still there. The wing is about the same length and a bit lighter than the canoe, so I thought I would try it. It worked! My only problem was that I didn’t have a red flag to attach to the end of the wing. That is something that I will need to get before the second wing is ready to move. The crosspiece of the bed extender has a metal loop to connect a strap or rope to. I didn’t want that to mess up the leading edge plywood of the wing, so I wrapped some carpeting around the crosspiece which raised the wing up just enough to avoid it.

The bed of the truck was just wide enough to allow the wing to ride flat. This was a good thing since I have the bed cover. I couldn’t have had the wing ride upright at all.

My wife and our son’s dog accompanied me on the trip to the airport and my wife helped to unload the wing and put it on some saw horses that I had at the hanger.

So now I need some time to do some sanding and sealing and the first wing will be ready to mount onto the fuselage.

Here is a closer look at the bed extender and how I covered the metal with carpet scraps.

Now Sawdust has its fuselage and a wing reasonably close together.

When the garage sale is over I am taking the other wing down from the garage ceiling and starting work on getting it finished. I may just make my goal of having the wings done by the end of summer.

OK. The whole month of July has come and gone since my last post. AirVenture is over with for this year and I did not attend it, but I watched it on the webcams. The yard seems to need mowing continuously and the garden needs regular attention. Then there are issues with parents, kids, my wife and a potential dog. All this does not even take into account needing to go to work on a reasonably regular basis and doing my part at church. HOWEVER, progress has been made!

The leading edge skin has been applied to the right wing! Well, most of it. The last section of this is the root end of the wing where the leading edge angles down and back. However, I don’t see that this will be a big problem.

Yes, I took pictures of the finished product and I think it turned out pretty nicely. I did not take pictures of the steps that got things this far. Maybe I will take a few pictures of the process when I do the other wing, so that I have it all documented. There are a few details to work out, but I am not going to peal back what I have applied just to make it look perfect. I am going to have the chapter TA come over and give a formal opinion before I haul the wing to the hanger.

Over the past few weeks I have been working on all of the hardware that needs to be installed on the wings. These are things like the brackets for attaching the struts, jury struts, the spar mounting plates and the control cable mounting brackets. As I installed each of these and the bolts that hold them in place, I applied wood sealer in quite liberal amounts. I wanted to be sure that the wood was fully sealed in all the areas that would be inaccessible once the leading edge skins were in place. I also wanted to be sure that the insides of the holes where the bolts went through the spars were fully sealed as well. This resulted in some excess sealer covering the bolt threads, so the nuts are “sealed” to the bolt as well as being the standard AN365 elastic stop nuts. I think they should stay on quite well.

The internal drag bracing needed to have its final adjustment as well. The Maranda uses plastic strapping material for the internal drag bracing. This is the type of strapping that is used to secure large boxes and to strap down equipment to pallets for shipping. There are brackets on each end to secure the straps to the wing spars. The wings have four sets of bracing each.

The front spar needed to have filler blocks attached between the ribs so that the leading edge skin will have something to be glued to. These had to be fitted to both the top and bottom of the spar. When the glue had dried they needed to be sanded down to make a nice surface for the skin to attach to.

Once all the hardware was in place and the wing was fully sanded, I needed to seal the front side of the front spar and the parts of the nose ribs that will end up inside the leading edge skins. The sealing process starts by applying masking tape to the areas where sealer is not wanted. My wife had some standard tan masking tape, but I went to Menards and got some green painters tape to use for this instead. My reasoning was that the tan tape might blend with the wood and it would be easy to miss removing some of the tape when I was doing the glueing. The green tape stands out nicely and I don’t think that I missed taking any of it off at the appropriate time.

The next thing was to prepare the plywood for the leading edge skins. This is the thing that I have been dreading since I first purchased the plans about seven years ago. The skins are made from 1.5mm birch plywood which is reasonably flexible, but not to the point that it will readily wrap around the radius of the front of the ribs. I researched lots of ways to bend wood, but found very little information regarding how to bend plywood. Many people use steam to bend wood and my research indicated that the steam is primarily a means of conducting heat to the wood. I had purchased a heat gun for the purpose of bending the plexiglass that I will be making the windshield from, but since I already had that and since my research indicated that the bending of wood relied on heat, I put two and tow together and came up with the idea of heating the plywood in the area where I wanted to bend it. This worked great!

I marked the plywood where I wanted it to bend around the nose of the ribs. Then I used my belt sander to scarf the ends where the plywood sheets would meet. Then I clamped one side of the sheet to a piece of 1/2″ plywood (for stability) and turned on the heat gun. I pulled the other side of the plywood toward me and heated the area along the line that I had drawn and before long I was able to bend the plywood back. This allowed me to achieve a bend diameter of 1 1/2″ to 2″. When things started to get close on the back side I switch the heat to the outside of the bend for finishing. Then I clamped each sheet to ensure that it retained its position while it cooled.

I used 2′ x 4′ sheets of plywood. The leading edge of the wing has a reinforcement piece of wood that runs the full length of the wing and connects all of the ribs. This piece was at 10 3/4″ from the back side of the bottom of the front spar. That is where I wanted the bend to be centered. Therefore that edge of the plywood ended about 2″ from the other side once the sheet was bent. I clamped the plywood so the one side was 2″ from the other side.

When the skins were cool I marked where the ribs would be and where the spars would meet them. Then I applied masking tape to these areas and applied sealer to the rest of the inside of these skins. I let everything dry and cool overnight.

Now that everything was ready it was time to apply the skins!

The tape was removed, glue was mixed and applied, the skin was held in place and staples were driven home! I used plenty of staples to ensure that the skins would stay in place and not pop out.

Here is what things look like from the front. I have a couple of small gaps where the skins meet. I scarfed the plywood on the ends that would come together and put plenty of glue on them, but glue doesn’t pull things together by itself.

From the back you can see (or imagine that you can see) how the skin fits to the spar.

The root end of the wing still needs to have a skin fitted and attached. This will require that I sand the area where the current skin is attached to the rib so that I develop some area on the rib that will provide area for the new skin to be glued to the rib. The area between the two ribs at the root end of the wing will have plywood skins both top and bottom. The wing tip area will have similar skins applied. However, the root end has some interesting angles that will need to be dealt with. But that is later.

Well, today Sawdust moved to her new home. The trailer was JUST wide enough as long as I tied the wheels in place securely.

Gary loaned me his trailer this morning so I could move Sawdust. Thanks, Gary!

I guess it is just a quick post today.

Well, it has been a couple of weeks so I thought I would show a little bit of progress.

The big news is that a hanger has opened up out at the local airport, so Sawdust will be moving to a new home about the first of June. It would be really nice to get a bunch of the little things finished up before the move. To that end the elevator and horizontal stabilizer have been connected via the hinges and things lined up very nicely.

I wanted to be sure that everything will clear properly, so I took the stabilizer/elevator assembly out to the garage and set it on the fuselage. Then I put the vertical fin in place to see how it looks.

Not too bad! However, I will need to do some work to provide a secure mounting both front and back. I need to move the horizontal assembly just a bit farther forward than what I had expected. This will require a bit of engineering. I think I will follow the idea of what Randy has done with his stabilizer mount shown on his web page: http://www.mywoodenairplane.com/Fuselage/20110424.aspx

Everything fit other than the final mounting points and it looks like the clearances are good, too.

Marsha came out to the garage to let me know that supper was ready and was reasonably impressed with things and insisted that I take a few more pictures of how it all looks. So, here are a few additional pictures.

As you can see things are getting pretty tight in the garage and I can’t leave anything assembled overnight. After each work session I have to take everything apart again so the car can come back inside. I am REALLY looking forward to moving things to the airport!