Sunday, August 22, 2010

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.

No comments:

Post a Comment