Work continues on skinning the fuselage belly.

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

Click on image to enlarge

 

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

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

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.

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"

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

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

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

Click on image to enlarge

More work on my rudder pedals

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

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!

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

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.

Click on image to enlarge

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

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

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.

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.