My CX4 Airplane Build Blog

Forward skins and cockpit work.

2011-12-21T08:24:00.000-08:00

I have have been making progress on the forward fuselage in recent weeks. I installed the floor ribs and then the floor skin was cut, bent, shaped and rivet holes drilled in preparation for its installation. In the 3rd photo below you can also see that I created the center control cover which is held in place by screws instead of rivets so it can be removed.

Click on images to enlarge

Next came prepping the side skins for installation. (These side skins were cut and sized last winter when the fuselage was still on the table.) This is a tedious process as you have to fit, remove, mark the hole locations, then drill holes in one piece, then debur them all. Then repeat the process with the adjoining piece until you have what you are looking for. I countersunk the lower longeron near the spar and dimpled the skin for flush rivet installation where the leading edge rib will be mounted later. I also creased any overlapping skin edges in hopes for a smooth, gapless edge once the rivets are installed.

I have yet to drill the rivet holes near the firewall or along the upper longeron as I still have work to do in these areas.

I then removed these skins so I could work on creating the interior side panels that go between F3 & F5 bulkheads. These panels will be made so I can remove them to have access to the landing gear bolts and rudder pedal cables.

In the series of photos below, you can see that I created a tab at the top of these panels that will sandwich the F5 bulkhead flange near the top. On my bulkheads, I found that the F5 flange becomes too narrow for me to install screws. This tab will make the panel fit snugly with the flange at the top.

In the photo below, you can see that I also created an angle from some .032 aluminum stock to hold the bottom edge of the panels in place. I slid these angles between the floor skin and the outer floor ribs so they can share the same rivets.

I still have some work on all of the above and should have pictures of the final product in the near future.

I have a new set of wheels!

2011-11-15T19:09:00.000-08:00

Click on image to enlarge

It's a big moment when you get to sit in your creation and and make engine noises! But let's back up and see how I got here.

Once the gear was in place, it was time to assemble the wheels, axles, brakes and wheel pant bracket. I bought everything shown in the pictures below from Great Plains Aircraft Supply. I had drilled the 4 mounting holes months ago. The caliper housing comes to you fresh from the casting mold and needs to be "machined" to allow the calipers to fit inside snugly, but able to slide side to side nicely with out binding. You just use a combination of files and sanding tubes to slowly remove just the right amount of material to get the fit you want.

My axles had a "knob" on the back side of the mounting plate the same diameter as the axle. This is used in other installations, but not on the CX4. You have to grind this "knob" off to make the back side of the axle mounting plate completely flush. I didn't take a photo of this, but you'll figure it out if your axles come with the "knob".

There is a lot of assembly and dis-assembly in this process. You have to create a spacer to keep the wheel the correct distance away from the mounting bolts so as not to rub them on the brake disk. I used a piece of PVC tubing to cut a sample spacer until I found the distance I liked. My spacers were 1.75" long and I made them from .759" ID 4130 steel tubing. I would say this gave me a clearance of approximately 1/8".

Once you have everything the way you want them, you disassemble everything so you can pack the wheel bearings with grease. When you are done with that, you reassemble everything and mark a dot on the axle threads where you want to drill a cotter pin hole to hold the castle nut in place. I was told to only hand tighten the castle nut. Over tightening doesn't allow the wheel to rotate freely.

Also in the photos you can see the piece of aluminum where the wheel pants will be attached later. I used the pattern from the plans and found I had to modify them slightly to fit around my brake assembly. No big deal though.

Next I finished installing the tail wheel. When you tighten the forward bolt it will dent the bottom fuselage skin slightly. This is normal according to Dave Thatcher. I spent an afternoon trying to figure a way to avoid the dent, but the solution eluded me. Mine will have the dent like Dave's does. It is so minor that when you turn it over you don't know it's there.

Now it was time to turn it over! My son was the first to sit in it and he liked it. Then it was my turn. Here is where I get to caution the rest of you. It is best not to put too much weight on the seat area until you have attached the side panels. Why you ask? Because when I stepped on to the spar with one foot I heard a loud bang! I took my foot off and looked around and everything seemed to be in place. So I tried again. This time when I place my second foot on the spar I heard another loud bang! I step off and looked around. I still didn't see anything wrong. So I tried again to get in and this time there were no annoying sounds, but when I sat down and look forward, I could see that the single rivet at the top of each F5 bulkhead had popped free from the top longeron. I decided I needed to go on a diet.

I got out and found my two long wood clamps and pulled the lower and upper longerons together and drilled out and replaced the two rivets. I used longer rivets as well. I'll have to wait until the side skins have been installed to make engine noises again.

I have started installing the forward floor ribs so that will be my next update.

Attached forward bottom skin.

2011-10-31T10:02:00.000-07:00

I finished shaping and attaching the forward bottom skin. I dimpled and installed flush rivets along the forward edge so that the cowling will lay across it smoothly. The sides are attached in this manner as well because the side skins overlap in this area. The only difference is that I dimpled the bottom skin and countersunk the longeron underneath.

Click on image to enlarge

I'll begin to install the wheels and brakes so I can then turn the fuselage over.

Began landing gear installation.

2011-10-10T05:53:00.000-07:00

I began installing the landing gear. I use a laser I bought at Harbor Freight as my main alignment tool. It has magnets on it, so I attach it to a long handled clamp and clamp the clamp to a small work table and place it in front of my project. I use it to align all the center lines from front to rear. I also used a tape measure to check all distances to the tail wheel bolt in the rear. Once I had everything where I thought it should be, I clamped the landing gear to the lower stingers with 4 clamps.

I should mention that I did this twice. The first time was see where the hole locations should be. I then removed the landing gear and drilled 1/8" pilot holes in it with my drill press. Then I re-aligned the gear and drilled those pilot holes through the stringers in the fuselage. Even though I used 4 clamps to hold the gear in place, I also used 1/8" bits, AN3 & AN4 bolts to place in the holes while I enlarged the holes to their final size to accept an AN5 bolt. The idea here is to make sure the holes stay aligned while you are enlarging the other holes. Here are a couple of photos.

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I had seen in other builder photos indicating one needs to be aware of possible interference of the side bolts that hold the side angle support in place between F3 & F5 bulkheads. I happened to be using pan head screws instead of countersunk screws at these locations, so I will be able to remove these screws temporarily to install the gear bolt nuts. Here are a couple of photos showing this situation.

I just noticed that I have mislabled the locations of these bolts. They are the right side, but I have the forward/rear locations reversed from what they should be.

Installing forward bottom skin.

2011-10-06T11:31:00.000-07:00

The last two weekends I have continued working on the forward bottom skins. Everything is going fine, but there is a lot of trial fitting and trimming that has to take place before actually pulling rivets. I have also been preparing to install the landing gear by drilling pilot holes in the gear in preperation to locate it on the fuselage and transfer the hole locations to the lower longerons.

Here are a few photos. As always, look in my photo album for additional photos.

Misc. work effort

2011-09-06T08:00:00.000-07:00

click on image to enlarge

I did work over the weekend, but didn't really accomplish a whole lot. I worked on shaping and attaching the the channel at F3 and began to install the tail wheel.

Look Ma, no work table!

2011-08-29T06:26:00.000-07:00

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This was a big weekend as I was able to remove my fuselage from my work table. I flipped it upside down so that I could finish installing rivets on the underside of the belly skin. These are the rivets that you are not able to get at because of the jigging.

Before I flipped over my project, I cut the exit slots for the rudder cables where they come out of the fuselage in the rear.

Above I am attaching the belly skin to the center section.

Now I'll work on installing the forward bottom skins and install the tail wheel before I flip it over.

Pulled rivets on fuselage side skins.

2011-08-21T20:06:00.000-07:00

click on image to enlarge

Feels good to make progress that you can see. After taking the skins on and off umpteen times to shape, file, debur holes, install cables etc., I was able to pull some rivets on both forward side fuselage skins today. I'm happy with the results.

The plans call for you to put on the left side skin and then pull the fuselage off your jig and table to install the controls before the other side is attached. I had heard that some who had followed these steps found that the fuselage would twist because only one side skin was being install at a time. They would have to remember this and somehow take the twist out before riveting the second side skin in place which usually solved the problem. I decided to install the controls and then rivet both forward side skins on at the same time to avoid the twisting issue. I pulled a few rivets on one side and then went and pulled some on the other until I was done. I left off both the rear skins so I can finish installing the controls. I have some minor things to clean up, but I should be able to pull my fuselage from the table and jig next session.

Control cables & fuselage skin.

2011-08-14T18:30:00.000-07:00

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I strung the control cables and started to install the right side skin. I still need to bring the rudder cables out the lower rear skin, but I'll do that before I start pulling rivets.

Working on controls.

2011-07-15T08:49:00.000-07:00

Yes, it has been a while since I posted. What have I been doing? Mostly coaching my son's Little League baseball team.

Click on image to enlarge.

Also, if you have been keeping up with the news, the Missouri River basin is being flooded due to excessive snow melt and spring rain fall (so "they" say). The water at Gavins Point dam is being let out at a rate of 160,000 cubic feet per second. My hangar is at Eppley Airfield here in Omaha and is about 400 yards from the levy that holds the water back. They have been successful in keeping the water on the correct side of the levy so far, but I took precautions anyhow. This photo shows me tending to my CX4 wings which I am now storing 7 feet above my hangar floor in the loft of my work bench.

I was able to work on my project recently and I am now working on my control linkage. I installed the elevator push rod and the rudder cables. I am using the hanging rudder pedals and I purchased them from Dave Thatcher and found that I had to raise the hole location where my cable is to go through the F5 bulk head, as my attach points on my rudder pedals were 1.75" higher up on my pedals than what is shown on the plans. The cable was binding at the plans location. After speaking with Dave, it was determined that the higher attach point was done to take out some sensitivity in the rudder. I moved the F5 hole location up just enough to remove the binding in the cable, but kept it at a location that was still under the arm rest. Most builders these days are building the floor mounted pedals, but of course Dave is there to support my efforts. Here are a few photos of my efforts.

I have more photos in my album.

I will have one more weekend to work on my project before heading north to AirVenture. See you there!

Preparing to install left side fuselage skin.

2011-04-04T06:54:00.000-07:00

click on image to enlarge

I made fun progress yesterday. For weeks you work on prepping and making parts and visably you don't see any progress. Once you begin to install these parts, you really feel like you have made progress. Yesterday was one of those days. I pulled some rivets to replace the clecos holding the bottom skin in place and the cross bars I installed to keep the sides of the bottom skin from flexing outward. Then I drilled and cleco'd the forward side skin into place. It's starting to look like something!

Filing! And I don't mean my taxes!

2011-03-26T11:08:00.000-07:00

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When you build a fiberglass airplane you do a lot of sanding, with metal airplanes, you file! I used the paper patterns to cut my side panels out. Now I'm just filing them down to final size.

Now making side skin patterns.

2011-03-01T14:49:00.000-08:00

Click on image to enlarge

I started making patterns for my side skins by using construction paper. This should allow me to get the bottom to line up properly. The panel between bulkhead F10 & F12 is per plans. The panels between the F6 seat back and F10 can be done as one, two or three pieces. I will be doing mine using 2 pieces of skin.

Bottom skin attachment continues

2011-02-15T19:02:00.000-08:00

I have been working on my project, but it is slow going. Here are a couple of photos which shows my progress.

I had a gap at the bottom of bulkhead F9 & F10 that I didn't think I could "squeeze out" with rivets, so I created spacers to fill those gaps. Here are some photos of the spacers. Notice that I am holding them in place with hot glue until I can turn the fuselage over and install rivets in F9 and the tail spring bolt in F10.

I found trying to get the bottom skin to stay in place at the flange was a challenge. I could not install a cleco or a rivet near the flange because I want to place the side skin on top of the bottom skin and attach the rivet through both pieces. The natural "memory" of the aluminum would flex the skin outward. You can not hold it in place with straps when you have to attach the side skins. I finally decided to attach an aluminum angle to the flange that spans the width of the fuselage at each bulkhead in addition to the angle in between the bulkheads (as called out in the manual) to keep it in place until I can attach the side skins. These angles will remain and don't add very much weight.

I will be cutting and trimming the sides skins in the near future. Progress is being made even if at a slow pace.

Work continues on skinning the fuselage belly.

2010-12-18T13:38:00.000-08:00

I haven't posted in a while, but I'm still working on skinning the belly of my CX4. I had to remake the middle skin that goes between F8 and F9 for the same reason I had to remake the forward bottom skin. It was too short when you rolled it up the sides of the F9 bulkhead. The scrapped piece of forward bottom skin was large enough to re-cut the middle piece, so I didn't have to order more material (yet). It appears the rear piece of bottom skin will be long enough that I won't have to remake it. No photos this time. Work is going slow, but sure.

Sealing My Fuel Tank - Part 2

2010-11-15T18:04:00.000-08:00

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Finally finished sealing up my fuel tank by gluing on the top. I did this with out the help of a friend. I had no problems or issues with this. I am quite pleased with the outcome. Before putting on the top I plugged the drains and filled it with water and observed no leaks!

Since the tank was basically finished, I did work on attaching the bottom skin of the fuselage on Sunday. I'm making progress but it is slow going for me.

Sealing My Fuel Tank - Part 1

2010-10-21T19:07:00.000-07:00

Yes Paul, I have been working on my project...

My friend Larry Geiger came over yesterday to help me seal my tank with ProSeal. Larry had completed an RV12 not too long ago and he had some experience with ProSeal on his RV12 fuel tank. Over the last several weeks I worked on preparing the tank for sealing. I cut both holes for the filler cap and the fuel sender. Attached the corresponding nut plates and prepared the fuel sender for final installation.

I made a few changes to how the top attaches also. While using the EAA chapter metal break to bend the end flanges on my tank top, I decided it might be easier to mount 1/16"x3/4" aluminum angles to the inside side walls at the top and use them as a mounting surface for the tank top. I think it turned out well. Bending the flanges to the sides of the top would have been possible (just like I did for the bottom), but not nearly as easy to construct.

I purchased solid pull rivets from Hanson Rivet & Supply Co. (800-777-4838). I needed 3 different grip sizes to complete the project. These rivets are on the pricey side, so be warned. You don't have to use this style of rivets, but they don't have to have their centers sealed like regular rivets do.

Here are several photos of the tank after part one of the sealing. I don't think I'll have to add sealant to anything I have done, but I will do a leak test with water before I put on the tank top (Part 2).

I found that working with ProSeal wasn't tough, but I was glad to have some experienced hands around to help. Larry applied ProSeal to the stem of each rivet before placing it in its' hole. I placed a bead of sealant on each surface and then flattened it out with a popsicle stick. Towards the end of the project, the ProSeal was not as pliable as it was when we first mixed the batch, but it was still manageable. I used acetone as a solvent and was able to clean up spots yet a day later with no problem. Just make sure the room is ventilated when using this stuff. After the ProSeal is squeezed out of the seems, just use a popsicle stick(s) to smooth out and scrape off the excess sealant.

I have added many photos to my project album, so don't forget to take a look at it if you want to see more than what I posted here. Just click on the slide show in the right hand column of this page to be linked to the album.

Continued to construct fuel tank

2010-09-07T12:15:00.000-07:00

The last couple of weekends has been spent on constructing my fuel tank.

Click on image to enlarge

I spent some time locating where I wanted my fittings and what size I wanted. I am putting in an extra fitting in the top rear so I can plum in a auxilary fuel tank later. I figured now was the time to do this regardless if I ever do it. In the photo above, I found a way to center the hole in the tank side with the weld puck so I could drill the rivet holes.

I am going with a 3/8" fuel line because it will be plenty big enough and requires fewer fittings. I bought this shut off valve from Great Plains A/C Supply. It fits into the finger strainer which fits into the weld puck.

I carefully bent one flange at a time and then test fit before bending the next flange. I could only use my 18" mental brake on the 1st end flange. From that point on I had to clamp the piece to my work bench using a 2x4 cut to size and hammer the peice to form the flange .

Here is where I'm at today. There are some gaps, but experienced builders tell me that the Pro-Seal will fix all this. I'll let you know...

I will begin to form the lid this coming weekend.

Finally back to work - Fixing mistakes on my belly skin.

2010-08-22T11:21:00.000-07:00

I am finally back to having time to work on my project! Please take notes from this entry so you do not make the mistakes I made on my belly skin installation!

My 1st mistake was not cutting my belly skin with the extension at the forward edge that overlaps onto the bottom of the center section. I simply forgot to review the plans carefully and when I laid out my bottom skin, I just forgot to include it. The plan was to put a splice that would overlap both the center section and the belly skin and rivet it into place. But then came my 2nd mistake which has caused me to re cut the forward section, so now I have included this extension.

So I cut my belly skin out in one long piece as shown on the cookie cutter sheet (sheet #7) in the plans. Reading the posts on the Yahoo Groups email list about how best to install the belly skin, most people agree that it is too difficult to install a single piece of skin. Most builders agree that 3 pieces is the way to go. I chose to cut my skin into lengths that would span between F6 and F8, F8 to F9 and then F9 to F12. But wait a minute!!! It's not that simple.

I measured the distance at the center line from the bottom of F8 to the bottom of F9 and cut my forward skin piece using this measurement. This was my mistake. This piece needs to be about 1.5" longer than this measurement because of the geometry involved at the F9 bulkhead. As you can see in the photo below, my 1st attempt was not long enough so that when I rolled the skin around the bottom of F9, my bottom skin edge did not mate up with the F9 bulkhead flange.

Click on image to enlarge

After a conversation with Dave Thatcher and a trial fit of the other two pieces, I came to the conclusion that I just needed to re cut the forward section bottom skin.

One other thing that I would like to mention is that the forward edge of this forward section of the bottom skin will need some trimming to fit around the F6 bulkhead as well. I can't find where the Instruction Manual or the plans tell you this. Again this is because of the geometry of the F6 bulkhead which leans rearward at the top. You must trim the outer forward edge so as to fit nicely around the flange of the F6 bulkhead. This trimming also eliminates any interferance from the rear spar of the center section gives you when you try to roll the skin up around the F6 bulkhead flange. I found that the trimming starts where the F6 bulkhead flange begins to curve upward. Take your time trimming, so as not to remove too much material. I used some poster paper to get to shape and transferred this shape to the metal before I began cutting. Below is a photo of both the before and after forward skin pieces.

The re cut piece is on the right and is 2" longer, has the forward overlap extension and does not yet have the side flanges bent. I'll get the flanges bent this week and attempt to install the bottom skins again next weekend.

Bending up the fuel tank "box"

2010-06-06T13:36:00.000-07:00

Click on image to enlarge

I haven't done much lately but I did bend up my fuel tank "box" today. I used an 18" table top metal break that I bought at Harbor Freight a while back. This took ten minutes to complete. I bent the 1st two sides and then turned the piece around. I then bent the "joint" flange and then the final side. Again, I do not have any flanges for the top and bottom attach points because I decided to put them on the top and bottom pieces themselves.

Fuel Tank Construction Begins

2010-05-17T07:21:00.000-07:00

I haven't worked a lot on my project lately as I have been managing my son's Little League baseball team, but I found some time this past weekend to start on the fuel tank. Actually, I have been in the planning stages for a while now. In one of my conversations with Dave Thatcher about how to proceed with the fuel tank construction, he mentioned that he had drawn up a new design for the tank which eliminates the mounting angles that are attached directly to the tank and instead incorporates straps from which the tank hangs from. This sounded good to me, so I had Dave send me the yet to be published drawings. In these drawings was a new 10.5 gallon tank design which works well with the floor mounted rudder pedals, but not the hanging pedals. So, I'm sticking with the demensions of the original 10.5 gallon tank, but I will be using the straps to hold it in place.

Here is a photo of what I have cut out so far. I used an air cut off disk to trim close to my lines and then filed up to them. I'll be cutting out the top and bottom pieces next. Another thing I am doing different from the plans is putting all the flanges on the top and bottom pieces instead of this piece (which I call "the box"). I discussed this with Dave as well and he seemed to think this was a good idea.

Finished work on rudder pedals and brakes

2010-03-11T10:40:00.000-08:00

Painted and mounted the master brake cylinders on the rudder pedals.

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More work on my rudder pedals

2010-03-03T18:55:00.000-08:00

I just kept wondering how I was going to lubricate my rudder pedals. After some thought I drilled a couple of #40 holes in the tubing that the pedals hang from so I can put drops of oil in them.

Click on image to enlarge

I did the same on the back side of the foot pedal itself.

Not shown in the photo is another change I made to the assembly that I bought from Dave Thatcher. He used a rivet in the sleeve he used to hold the foot pedal in place. I drilled this hole clean through to the other side so I could hold the sleeve in place with a cotter pin. This way I could easily remove the sleeve if there was ever a need to without having to drill a rivet out.

Reinforcing my hanging rudder pedals

2010-02-21T06:07:00.000-08:00

I came full circle on which rudder pedal setup to use. I had bought hanging rudder pedals from Dave early on in my build process. Then came the discussion of why they wouldn't be approved in Europe. The concern is that being attached to the hanging mechanism from only one side at the top and bottom is weak due to the twisting forces introduced when using them. I discussed this issue with my local EAA Chapter 80 Tech Counselor and he agreed that over time there might be a problem of the weld breaking due to the design. He related a story about another local Chapter 80 member and his RV6. The early RV6's had a similar hanging design. The twisting side loads from using the pedals eventually broke the weld and near disaster happened. Our fellow chapter member was on take off roll when the pedal broke. He did manage to stay on the ground, but did significant damaged his aircraft. Van's actually changed the rudder pedal design because of this incident. They added another vertical tube to the other side of the rudder pedal to make a "box" frame that evenly distributed the loads when using the pedal.

So, after I heard this story I went about trying to "fix" my hanging pedals in the same way. However, after a conversation with Dave Thatcher, it was determined that I could not use the "box" design because the additional vertical tube would interfere with the fuel tank that sits just in front of the pedals in the CX4. Darn!

By this time Dave had come up with his floor mounted rudder pedal setup and I was headed in that direction. But I’m a little hard headed when it hits my pocket book and I kept coming back to the hanging pedals I had already had purchased. Why throw away good hard money when some of the early builders who have the hanging pedals say they like them and don’t intend to switch. So, after further discussion with my Tech Counselor, we came up with a plan to reinforce my hanging pedals.

Click on image to enlarge

You can see in the photo’s that we welded a couple of triangles to both sides of the upper joint and welded a strap to the lower joint to help take the twisting forces that will be applied when using these pedals.

Are these necessary? Maybe not, but now I personally have more confidence in them. As they say; “It’s my butt in there”. Be assured, checking these welds will still be on my annual inspection list!

That took longer than I thought it would!

2010-02-07T19:58:00.000-08:00

I finally finished my forward access panels. It took longer than I thought it would. Mainly because it is tedious work.

Once I got the flange made and shaped the way I wanted it, I then needed to rivet it to the forward side skin. I postioned it on my workbench near the edge and clamped it in place. I marked the position of the holes and drilled through both the skin and the flange at the same time. After drilling the first hole I used a cleco as another way to hold everything in position. I used a 2nd cleco in the second hole and then drilled the rest of the holes.

Click on image to enlarge

I used a similar method for drilling the holes for the cover panel and the flange. For instance, after the first hole was drilled, I used a screw and a nut to hold the position of this hole while I drilled the second hole and used another screw and nut while I drilled the remaining holes.

The nut plates were way to tight, so after a call to my friend and technical counselor, I used a tap and carefully opened them up slightly. If you over do it and make the nut plate too loose, just simply use pliers to squeeze it back to the tightness needed.

I took everything over to my friend's house and used his dimple die and rivet squeezer to put everything together.

I was not pleased with the gap around my cover plate, so I made them over again. My second attempt is better, but I won't be winning any Lindy awards with them either. It certainly looks hand made to me.

I'm glad I made these access panels and I'm glad the work is done.

Continued work on forward access panels

2010-01-25T07:54:00.000-08:00

I continued work on my forward access panels. This is tendious work as you have a lot of cutting, filing, shaping, trial fitting and more filing & shaping until you like what you see.

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I first used the fuselage side panels to draw the shape of my panel. I cut it out on my band saw and then filed it down to shape. I left a gap of aproximately .032 all a way around the side panel opening and my access panel edge to allow for paint thickness.

Next it was time to make the mounting flange. I found a large washer that had a width of 5/8" from the center hole to the edge. I used this to trace an outline around my panel. I placed my access panel on top of the material I was making my flange from and placed the washer directly up against the edge of it. I simply used a Sharpie pen and placed it in the washer hole and rotated the washer all a way around the edge of my access panel to get an outline of what will be the outside edge of my mounting flange. Then I cut this out and filed the edge smooth.

To get the outline of the inside edge of the mounting flange I measured in from the outside edge 1.25" (2 x 5/8") and drew lines that intersected on all four sides. I then drew rounded corners to my liking. I drilled holes near these corners to provide access for my jigsaw blade and carefully cut the inside out.

Filing the inside is a challenge and requires patients to get a nice finish. On my second one (I have panels on both sides), I used a hole sander in the corners first to remove most of the material and then finished with the file.

The next step will be to mate everything.

Creating an access hole

2010-01-18T08:50:00.000-08:00

Click on image to enlarged

After seeing Dave Thatcher's plane at last year's Sun 'N Fun, I knew I wanted to incorporate an access panel to gain access to the rudder pedals and brakes. This is what I worked on over the last few days.

I decided to put one on each side. I had received a couple of photos from Dave with dimensions I could use, but I also asked Peter Beck for his views on the size and location of this hole since he has had access to Dave's plane. Peter said that he is shipping kits with a larger hole than Dave used. I finally settled on a size that was between the two at about 10" long x 8" high at one end and 5" high at the other with 3/4" radius in the corners. I then drew this up on a software package I use to create sign layouts called Corel Draw, and printed it out for a pattern. I drilled holes in the corners and used a jig saw to cut out the larger access hole. I then used files to finish the shaping. Now I could used this hole as a pattern for the cover plate which I cut out using my band saw.

I called a local, more experinced RV6 builder to see how close of a fit I should try to achieve between the cover and the access hole. He cautioned against too close of a fit, because once you paint the peices they may fit too tightly and chip the paint. He suggested I use some scrap .032 material and maintain this gap distance all away around the cover plate. Then I filed the cover plate down to this tolerance. I'll include pictures of this cover in the next update when I have completed the creation and installation of the mounting plate and cover.

Here is what she looks like with both forward skins temporarily attached together.

Forward Side Panels

2010-01-10T18:56:00.000-08:00

Click on image to enlarge

I continued to work on the forward fuselage side panels. I decided to create one piece instead of two that attach from the firewall back to F5. Seemed easier and Dave Thatcher said it would actually be better. Again, once I had one side fitted, I used it as a pattern for the other side. I won't be ready to drill rivet holes for a while, but the panels are cut. Next to do item is to cut an access door in both side panels so you can get at the rudder pedals and brake assemblies.

Just trying to keep moving forward.

2010-01-03T18:33:00.000-08:00

I need to finish skinning the bottom of the rear fuselage, but I want to take the skins to our EAA chapter's metal brake to bend the flanges in my 3 skin pieces. However, the brake is in an unheated shed at a small urban farm and we have at least 2 feet of snow on the ground and it is cold. Gaining access to the brake is not in the near future. So, I'm cutting & fitting the forward skin pieces.

Click on image to enlarge

I cut and fit one side of the cockpit side skin and used it as a pattern to cut the 2nd side. No big deal, but progress was made.

Attached Flange on the back of the Firewall

2009-12-27T08:20:00.000-08:00

Click to enlarge

I did find some time on Christmas eve to go back and create and attach the flange on the back side of the firewall. I was looking at some other builders' photos and discovered that I had forgotten to do this. This process was very easy to do. I stuck the .75"x.75"x.0625" angle up to the back side of the firewall and marked the places on this angle where the firewall had flange cuts. Then, using a #40 drill bit, I drilled holes at these locations on the mounting side of the angle. I then used my band saw to cut slots up to these holes so I could bend the angle to match the contour of the firewall edge. Be careful not to take too much material out of the mounting side of the angle. You don't need to, as you do not bend the angle much to get it to take the shape of the firewall edge.

Finishing Touches on Top Skin

2009-12-09T14:04:00.000-08:00

I did work on the airplane this past weekend, but didn't take any pictures. I pulled the rivets on the top skin. Before I did, I remembered that I will be putting the side skin under the top skin, which is not what the plans call for. So, before pulling the rivets I had to go back and crease the edge so it will make a nice fit when I do pull the rivets along the rear stringer. I also may make my temporary angles which are holding the F8 & F9 bulkheads tops in place permanent. They seem to be holding everything in place nicely. I still have time to decide.

I also started cutting the lower skin. I think I will do it in 3 parts.

I am having knee surgery this Friday, so building will come to a stop for a while.

Fitting the rear fuselage top skin. - Part2

2009-11-27T07:16:00.000-08:00

While my wife toiled away at preparing a great Thanksgiving meal, I worked on my CX4 project. It was time to put the trimmed top skin back on and drill the holes in the stringer. Before I put the skin back on, I marked out the hole locations in the stringer and then drilled them with a #40 drill. This way I could replace the skin and hold it tight to the stringer with the straps and 1"x2" boards, reach up underneath and use the previously drilled holes as guides for drilling the skin. This technique worked great.

Click on image to enlarge

I occassionally drilled a little deeper into the 1"x2" board and used a cleco to temporarily secure things.

One of my concerns leading into drilling these holes was how to secure the stringer where it butts against the forward longeron. If you remember, I chose to do my splice differently than the plans call for. I'm doing this splice from the outside with screws instead of the inside with consunk rivets. So, at this point I have to undo my splice to drill my holes. This means that nothing is holding the two peices together where the stringer butts against the forward longeron. So, I carefully held the stringer and skin in place with a clamp and twisted it inward (because the top skin wants to bow outward) until everything lined up and then drill the first hole nearest my splice and installed a cleco. I also used a couple of wood clamps after this first hole was drilled to twist everything into alignment. This really wasn't as hard has it sounds. Just take care and drill that first hole carefully. Everything else falls into place after that.

So, once all the holes are drilled, you can remove the clecos from the underside, loosen the straps and clamps carefully and install clecos on the outside. It is one of those times you can look at your project and see that you have accomplished something of significance.

By this time, the turkey was done and I had one more thing to be thankful for!

Fitting the rear fuselage top skin.

2009-11-22T16:53:00.000-08:00

With the rear bulkheads in place, it was time to start fitting the rear top skin. The key is to pre-drill the bulk heads where you want the rivets to go. Once the holes were drilled in the bulkheads, I used my Dremel tool and drilled the skin from underneath using the bulkhead holes as guides. I started with just the centerline holes and put cleco's in them.

Click on image to enlarge

Then I clamped a 1"x2" board to each side edge and then use some straps to pull the skin down tight. Looking underneath, I was concerned about the gaps I saw near the top of the bulkheads. After a conversation with Dave Thatcher, I proceded with drilling holes and installing cleco's. What I did was, I loosened the straps until the skin laid nicely near the tops of the bulkheads and drilled the holes and installed more cleco's. Then I would draw the straps tighter and repeat the process.

I am pleased with the outcome as the gaps I was concerned with just went away using this procedure. As I tighten the strap closer to the stringer, I then used the clamps holding the 1"x2" board in place to clap it to the stringer.

Once all the holes were drilled, I then drilled them to 1/8" size and marked the oversized skin for trimming along the stringer and the F6 & F10 bulkheads. I have now removed the skin for trimming and while it is off, I will predrill the holes in the stringer. I will also debur all the holes. Hopefully, I will be able to finish the installation over the Thanksgiving weekend.

Installing F8 & F9 Bulkheads

2009-11-02T09:45:00.000-08:00

I finally spent time working on my project yesterday. I worked on locating and installing the F8 & F9 bulkheads. I used an 8 foot piece of 1"x2" square alum. tubing as a straight edge and placed it on top of F6 & F10 bulkheads to determine the height of F8 & F9 bulkheads. I had already used this square tubing to make sure F10 was level with F6.

Click on image to enlarge

The photo above shows the assembled bulkheads, but I assembled them after the next step I'm about to describe. I had to figure out a way to get the tops of the bulkheads to stay in position while I attached the skin. I had assembled my bulkheads by laying them on the plans. I temporarily assembled them with cleco's, but found that they were too tall to fit between the square tubing and the 2"x4". So what I did was I disassembled the top of the bulkheads and clamped them to the underside of the square tubing. I located them in a postion where the top skin would transition nicely onto the side stringer (I use a scrap peice of .020 alum. for this). I then used some scrap 1/16"x3/4" angle as temporary "holders" to keep the top bulkhead piece in place where I wanted it. Once I had drilled holes and cleco'd everything in place, I could disassemble everything and begin to figure out how to attach the remaining side and bottom bulkhead pieces, which I kept assembled.

I had to trim my side pieces so I could raise the bottoms to the correct height. I slid them between the temporary mounting angle and the face of the bulkhead and then aligned everything the way I wanted it. Then drilled holes and cleco'd things together.

Take note of the hole in the left side piece. This is the hole that the elevator push rod tube is suppose to go through. Again, I drilled this hole by placing this piece on the plans and locating it's position. As I said before, the bulkheads didn't fit until they were trimmed down. I only trimmed from the top on both side pieces on both the F8 & F10 bulkhead (instead of trimming a little off the top and a little off the bottom of these pieces), so at this point, I don't know if this hole is in the correct position. I'll let you know when we get to installing this push rod tube. If I had to do it over, it might be better to drill this hole later on.

I did try to pull the top skin down over the top pieces before attaching the side and bottom pieces, but I didn't feel comfortable in doing so. I'm now ready to try this again. Till next time...

Too much football

2009-10-12T10:06:00.000-07:00

Between watching football, and my son playing football, I haven't had much time to work on my CX4 project. I did pull some rivets to finish my rear stringer lengthening and it's installation, but that's about all. I ordered some screws for the forward splice between the forward longeron and the rear stringer. I think I'm ready to start the installation of the top rear skin. I'll do a trial fit soon.

Get that seat back height correct!

2009-09-15T07:14:00.000-07:00

For many of you, this is your first project. This is mine as well. Mistakes happen. Here's another example of one I made and corrected.

I assembled the section between the firewall to F6 (seatback) and then started on assembling the fuselage. I didn't pay close attention to the height of the seat back. I had assembled it by placing it on the plans. But the builder needs to keep in mind that there are many areas of adjustment before proceeding. My seat back height was too high, but I didn't realize it. I proceeded to set up my 2x4 on my work bench by locating the F10 bulkhead position and then leveling the top of F10 to the top of F6. Thinking I had things where they ought to be, I notched F10 for the 3/4" stringer angle. I did the port side 1st. But when I got to the starboard side I could see that I was going to cut into the large hole that F10 has for which the elevator control passes through. Since I bought my bulkheads from Peter Beck, I called him to discuss this hole location. He immediately recognized that I had an issue with my set up. After some discussion and measuring, we determined that I had not set my F6 top to 6" above the forward longerons.

So what I had to do is lower the seatback top and reposition my 2x4 so I could relevel my F10 top with the lowered height of F6 top. Now everything was where it needed to be. In the photos below you can see I simply repaired the 1st notch I had cut on the port side of F10 and continued with my building.

Click on photos to enlarge

Tool for bending forward upper longeron.

2009-09-15T06:51:00.000-07:00

I need to take a couple of steps back to show you how I bent the upper longeron to match the angle of the rear stringer that runs from behind F6, all the way back to F12. You can't really bend the upper longeron until it is mounted in place because you don't know the angle to which to bend it. Here is the tool I made to bend mine.

Click on photos to enlarge

I used a scrap 2x4 and cut a slot at one end of it just wide and deep enough to fit the upper longeron into. My 2x4 just happened to be 27" long, but it gave me enough leverage to bend the forward longeron inward.

It is important to have bulkhead F10 in place and notched for the 3/4"x1/16" angles, making sure they are level with the top of the forward longeron. Then temporarily mount the 3/4"x1/16" stringer and bend the forward longeron inward until the angle matches the stringer. A second pair of hands is nice to hold the stringer while you bend the longeron, but not required.

Mounted F12 to Stringers

2009-09-13T20:15:00.000-07:00

Click on photos to enlarge

I continued work on attaching the stringers today. This is tedious work because it requires you to assemble and then unassemble the peices several times before you have what you want. I used a scrap peice of the 1/16" angle as a shelf to attach the stringers to. I attached this to the front side of F10 as shown in the photo above. The angle makes it easy to level the stringers at F10 side to side. The stringers will be held in place with one 1/8" rivet attached vertically through this shelf. Due to lack of space to drill the vertical rivet hole, I figured out the appropriate location of the vertical rivet hole and dismounted the angle and drilled it 1st. Then I remounted it and put the stringer back in place and used a Sharpie to transfer where the hole was to the stringer. Then unassembled everything and carefully drilled the hole in the stringer. Then I went to the other side and did the same thing. Very tedious!

Next I attached F12 to the stringers. I was having trouble figuring out the horizontal distance F12 is from F10. The plans have the distance from F10 as it is laid out on your 2x4, but I had to cut the end of the board off because it interfered with F12. So my measurement was gone also. I finally found it on Sheet #3 (Rudder & Fin Assembly) where it indicates "about" 17 3/4" between the front and rear fin spars. Well, these spars mount to bulkheads F10 and F12 respectfully. Not very clear if you ask me. I trimmed my stringers so that I achieved this distance. In lue of a countersunk rivet to mount F12 to the stringer, I will leave the cleco in place until it is time to put the side skin on where I will use a "hole finder" and use this hole to attach the skin as well. I have to remember to use a long rivet here.

It might be time to replace some clecos for rivets and then some top skin.

Stringer splice to go beyond 8 foot stock length.

2009-09-08T08:28:00.001-07:00

Click on images to enlarge.

I didn't get much done this Labor Day weekend. We had a family wedding to attend. I wanted to get something done so I worked on lengthening the stringer past the standard shipping length of 8 feet. I cut off 36" and added 41" which puts the splice between F9 & F 10. I'll let you know what my final length is when I install F12. I'm leaving the cleco's in place until I know for sure I have enough length to work with.

I used a 5" piece of 3/4" x 1/16" aluminum angle (same material as the stringer) for the splice. You have to round off the outside corner edge to get it to fit inside the 6061-T6 aluminum angle due to the inside radius. I used an aggressive file to knock off the corner edge and then used sand paper to give a nice radius until it matched perfectly with the inside radius. I will use 1/8" rivets to secure from the top only, so as to save the side rail for attaching the skin to.

While talking to Dave Thatcher on the phone on "what I do next", he reminded me that there are two anchor nuts that hold the front fin spar to F10 which get mounted later on to the front side of F10. He said not to rivet the side skin on until I have mounted these nut plates. I leave little notes like the one above to help remind me of these things!

2009-09-07T11:21:00.000-07:00

Click on photos to enlarge.

Because C3 thru C6 protruded out the bottom slightly, I had to modify my bottom skin flange just outside of ribs C3 & C6 as you see in the photo above. Basically I cut a small wedge out of the flange so I could get the skin to angle upward towards ribs C1 & C2 on one side and ribs C7 & C8 on the other side.

Then I attached a piece of bent aluminum to extend the C2 & C7 rib flange down to the skin as shown in this photo.

Other ways to fix the problem were discussed, like tearing out the seat pan & ribs C3 thru C6 and redoing them, but I opted for this fix. I discussed with Peter Beck why ribs C3 thru C6 might have been longer in the rear and he was going to review his forms. There are some trimming involved with these ribs anyway and, had I followed the plans and laid the wings directly on the floor, or placed a flat piece of plywood between the 2x4's I used to raise my structure off the floor, I would have just had to trim the ribs C3 thru C6 from the top side to make the seat pan fit correctly. Had I known what was happening, I would have chosen to do this.

All in all, if I had not mentioned this to you, you would never have known about this mistake as it is on the bottom of the airplane where no one will see it.

Seat Pan Mistake & Correction

2009-09-07T11:07:00.000-07:00

Another mistake I made that I would like to communicate had to do with the center section. The plans say to lay the center section spar on a flat level surface and attach the wings and create the rear center section spar. Then you are to attach the ribs C1 thru C8. Well, my garage floor in flat and level so I used it. However, what I did next sort of got me in trouble. I was having trouble working with a wrench when everything was laying flat on the floor, so I placed two 2x4's under the wings to raise everything up off the floor so the wrench would work better. When I went to install my ribs, I made them fit the top of the front & rear spars. Well, ribs C3 thru C6 were slightly taller in the rear than ribs C1 & C2 and C7 & C8. This made ribs C3 thru C6 protrude out the bottom by about 3/16". I didn't discover this until I flip the center section over to put on the bottom skin.

See next post for how I corrected for this mistake.

2009-09-03T10:46:00.000-07:00

Here is the reworked wing tip.

2009-09-03T10:41:00.000-07:00

Click on photo to enlarge

As you can see from this photo, my first attempt at the leading edge of my left wing tip did not have a satisfactory result. What I decide to do is to start on my right wing and try to figure out how to do it correctly. Then I came back and redid this wing tip. The trick is to roll this with a different radius at each end.

2009-09-03T10:35:00.000-07:00

Trying to get the wing tip skin to mate well with the wing skin was a bugger as well. I had a neighbor help me with this process. He held things in place while I drilled the holes. This was truely a trial an error process for me. I hope filler will hide my poor workmanship. Most who have seen these corners say I'm being too hard on myself. You be the judge.

2009-09-03T10:29:00.000-07:00

Next came the center wing tip rib. I had to reshape it to get it to fit properly. I was concerned that the other wing tip was going to be different from this wing tip, but as it turned out, I had to make these changes on both wing tip structures. So, whether they are different from the plans, the important thing is, THEY ARE A LIKE!

Wing tips were a problem

2009-09-03T10:03:00.000-07:00

Click on photo to enlarge

I have now uploaded my CX4 build photos for everyone to review and since I'm starting this blog after I have started, I will try to pick a couple of issues that gave me trouble. One of these was the wing tip structure. I had several issues that challenged my building abilities.

First was fitting the rear wing tip spar. I should point out that I bought Peter Beck's spars/center section and his bulkhead and rib kits. I personally thing Peter has a good product and if this is how you want to get a head start on your project, I would recommend his kits. As you can see in this photo, the rear spar had to be positioned in a different position than called for in the plans. No big deal really, just do it. I have found this similar issues throughout the build process. I guess it's just part of "scratch building" from plans. Dave Thatcher has been a great help with dealing with these types of things.

First Post

2009-09-02T14:23:00.000-07:00

Why blog? Well, I have been the editor of the Quickie Builders Association newsletter, Q-Talk, for nearly 5 years now and the newsletter seems to be as relevant today as a typewriter in the age of computers and the Internet. After 20 plus years and 5 editors, the Q-Talk newsletter will come to an end this December. I believe the Internet has replaced it. Yahoo Groups allows you to discuss any subject or ask any question to other like minded people and get a response almost instantly. The newsletter used to be the means by which this type of information got communicated. By the time I publish the newsletter now, a topic is old. The newsletter used to be the archive of all the information that was known about our little airplanes. It was always strongly suggested that you buy all the back copies to inform yourself about what had come & gone with this particular airplane design, before you started your project. Now you are asked to search the Yahoo Groups email archive to get yourself up to speed. Searching the Yahoo Groups archives is way easier than trying to remember what issue a brake mount modification was in.

Also, instead of writing an article about an issue you have overcome with your project and then sending it to the newsletter editor, guys started their own blogs to record their journey with their airplane. And this is the reason I started this blog. Not only for me to record my journey, but to document my build process for those future builders.