Sunday, October 10, 2010

And before I knew it....

It's North meets South day. The pointy end of the airplane is attached to the tail cone. This is a process that I definitely thought to be a two man job, so I asked Co-pilot Rick if he'd be able to come by and assist. He agreed, but he had morning errands to run and wouldn't be available until the afternoon. That met my schedule perfectly; I had another brace to paint and install, and once that was done the hangar would need some serious rearranging in order to liberate the long dormant tail cone from its place of repose behind the wing spars.

As expected, that stuff took a good hour and a half. I like to have everything ready to go by the time the help shows up, so I went ahead and started on the first few pages of section 25. It didn't start auspiciously. The first page was one of those that I am half convinced are intended as very dry jokes by the folks at Van's. If that's not the case, then I anxiously await someone from Van's telling me with a straight face that they believe that we can actually bend things down to an accuracy of one degree.

It reminds me of an apocryphal story I read recently. Back in the days when airliners had navigators of the human variety, it was practice for the navigator to pass heading corrections up to the pilot on a slip of paper. A very precise navigator once passed forward a note instructing the pilot to change heading one degree to the right. The irked pilot sent the note back with an added note telling the navigator that there was no way that he could fly to within one degree of heading. The navigator replied by sending a note up front telling the pilot to turn to an alternative heading of ten degrees to the right. The pilot turned around in his seat and gave the navigator a thumbs-up, as if to say "That's more like it."

Two minutes later the navigator sent up another note: "Turn nine degrees to the left."

Yeah, I think this is like that.

The way I translated these instructions was "bend these a little bit. Bend those a little bit more."


The idea of those bends is to open the top edge skins of the tail cone so that they will slide over the aft bulkhead flanges of the upper fuselage. With the tail cone positioned just behind the fuselage, I could see how much bending would be required to clear the bulkhead.


It was pretty easy to bend the tabs up. And yes, that's dust on the tail cone. It's been sitting in the back of the hangar since February.


I inched the tail cone closer to the fuselage by sliding it forward on the sawhorses supporting it. The tail cone is very light and it was easy to get it into position. The process of joining starts with the bottom skins. The front of the tail cone bottom skin has to slide between the back edge of the fuselage belly skin. I moved the tail cone skin higher and lower in relation to the fuselage belly skin by moving one of the sawhorses supporting the tail cone further forward or backward until it looked about right.


I incrementally moved the tail cone closer until the skins started to mesh.


I wasn't too surprised when I finally met resistance. I was a little surprised at the source of it, though. This was never going to work! Somehow I'd have to hold those tail cone skins down while simultaneously moving the tail cone forward.


I had to reach into the tail cone through the baggage bulkheads to push the skin down with one had while using the other two (Yeah, I know. That's what the whole job was like - one hand short) to move the tail cone forward. It wasn't long before I ran into a similar problem with the side skins. I addressed that through the clever use of a cleco.


Then I encountered a real problem. The book says that skins should overlap from front-to-rear and from top-to-bottom. It says nothing about a tie-breaker in the case where either could be accomplished, but not both. Fortunately there is a pretty good drawing on a later page that shows that the correct way is to give primacy to a front-to-rear overlap.


Then, yet another problem. I couldn't figure out how to get this skin to stay outside the flange on the bulkhead.


That too was accomplished with the use of three hands and a cleco.


Clecos also came in handy when three pieces of skin had to be meshed together.


Finally, after what seemed like hours of making tiny little adjustments (because it was hours of making tiny little adjustments) and incremental progress, I crawled underneath and put in the first cleco.


Followed by a whole lot more!


For a change of pace, the plans then had me install the should harness mount. That was easy!


Unfortunately, while I was up on the top clecoing in the should harness mounts I couldn't help but notice that I had what looked to be an insurmountable problem with the top brace. It had pulled the baggage bulkhead forward when it was riveted in and it looked like there was going to be no possible way to move the bulkhead back enough for the holes to align with the tail cone.


I figured I had to try, though. I got up on a stool and stepped into the fuselage (for the first time!!) to hold it in place while I yanked on the roll bar as hard as I could.


Amazingly, I was able to pull it far enough to get the corner of a cleco in one of the holes and use my patented Cleco Coercion(tm) method to get the holes aligned.

And before I know it, the tail cone was joined to the fuselage. I guess it was a one man job after all!

Here's the victory pose.


That was enough for the day, so I pushed Papa back in and prepared to head home. It's getting pretty crowded in the Schmetterling hangar!


And the RV-12 is starting to look a lot like an airplane!


I may still have Rick come over to help. There are a lot of rivets to install yet and it might go easier if the newly embiggened fuselage can be rolled on its side for better access to the bottom.

3 comments:

bobmueller said...

Excellent news, Dave! Congratulations!

Tony_T said...

Nice work. I also did the tailcone joining by myself, I rather like to work alone.
Tony

Vieille Burette said...

Great description Dave, I'm not there yet but I anticipate as much fun as you had when time comes... with the advantage of having this great step by step document at hand. VANs should pay you for doing such a helpful illustration of the builder's issues and solutions.
Keep it up Buddy, the rewards will come!
Jean-Pierre/aka Vieille Burette/aka Wingedfrop

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