Wednesday, April 29, 2015

Its Been a Long Long time....

.......since my last post on this blog. Greetings fellow builders and followers. Contrary to what you may have heard I am not dead, nor have I sold my RV-8 project or anything silly like that. I'll just sum it up as I have done many many times in the past - life just got in the way. Kids, school, weather, work, etc.

I have spent the past few weeks cleaning up the shop after a long winter. I did my best to organize everything so I could continue where I left off last August. Specifically I needed to fabricate two small flanges for each side of the modified 408 rib that I was working on. One of the issues I had when I stopped last August was that I needed to determine the bend radius that Vans used to bend the rear rib flanges of the 408 rib. I needed to make sure that the new fabricated flanges are bent to the same radius as the existing rear rib flange so that any stresses on this part of the rib are consistently handled by the entire part.

Turns out that trying to determine the bend radius of an already-bent part is not an easy thing to do. All I knew for sure is that the radius was greater than 1/8 of an inch but less than 1/4 of an inch. I determined this by taking some drill bits with long shanks of different sizes and basically set it in the radius of the rear flange and eyeballed the fit. It was easy to tell if the drill bit was too big because a gap would appear between the drill bit edge and the bend of the flange. The problem is that all drill bits with sizes that are equal to or less than the actual end radius will obviously fit next to the bend radius. SO I started with smaller bits and continued to increase the bit size until I reached the largest size bit that seemed to sit flush inside the bend radius of the rear rib flange. This occurred with a 3/16th of an inch drill bit.

SO off I went to the local HD aircraft supply store to buy a piece of smooth 3/16th inch rod that I intend to use to form flanges of the 2 parts that I need to fabricate. Hopefully once I figure out how to position the rod to make the bends to the .032 scrap aluminum I am using to make the parts, the new flanges will be completed and then I can proceed with riveting them to the rib web. More on that in tomorrow's post. AC 43.13 provided the answers as to how many rivets I will need to use. I provide more info in the next post about the formula that was used and how this was determined.

I'm back!