Saturday, August 25, 2012

Breaking The Edges On Tail Cone Skins – Plans F-1279 L&R Omission

The seemingly easy task of breaking the edges on the tail cone skins ultimately turned out to be an all day chore … nothing hard mind you, just time consuming. Before breaking the edges on the skins, a soldering iron was used to remove the blue plastic from the top and bottom area of the skins to be broken. While at it, the blue plastic coating was also removed from those areas where there will be an overlap so they can be primed. That added up to over 160 feet of plastic that needed to be removed. After the plastic coating was removed, the rivet holes that were punched into the skins at the factory needed to be deburred, thus assuring the rollers on the edge breaking tool would not get hung up on the burrs …. figure 9 skins at well over 100 holes per skin needing deburring, it takes time.
                            Melting the plastic for removal with a soldering iron. Gee, that pool noodle came in handy yet again.
                                             Deburring the holes so the edge tool rolls over the holes smoothly.

While preparing the skins, I quickly realized the plans omitted mentioning anything about breaking the edges of the F-1279 L&R skins. Looking at the plans, it appeared to me as though the edges of the F-1279 L&R skins should also be broken. I spent quite a bit of time looking at the plans and could see no good reason why not to break the edges on the F-1279 skins … so made up my mind I was going to do so. However, it was getting late so set those two skins to the side and got on the computer just to make sure breaking the edges would not cause a problem. I went to the Van’s Forums and did a little research and discovered another builder had wondered the same thing and called Van’s about it, he was told to go ahead and break the edges of the F-1279 L&R skins … it was just an omission from the plans. The omission is really no big deal, at the end of the day it is purely cosmetic.

Breaking the edges went smooth without any problems. I did follow another builder’s tip I read about and sprayed a little WD-40 on a paper towel and rubbed down the edges before using the Cleaveland edge tool. I think it made the process easier. Holding onto the bolt for the top roller in addition to the handle helps keep the tool in proper alignment, plus aids in pulling the tool down the length of the skin.
                                          Breaking the edge with the Cleaveland edge tool was smooth and easy.
                                       Top tailcone skin after breaking both edges … it is like a big soft noodle.

Return from the future: The portion of the top skin between the F-1210 far aft fuselage frame and the aft bulkhead the plans say to add extra break really needs it … especially the last 12” to 14”. If you are planning on dimpling your RV-12 for flush rivets as I am doing, hold off on dimpling the F-1278 top skin until the top skin is test fit onto the tail cone assembly. Once dimpled, you can not add more break.