Sunday, January 17, 2010

The last steps, for now

Saturday dawned with the type of weather that would have essentially ruined the day for me back when actual flying was the desire of the day. But here I am with an airplane to build, perfectly happy with a day that isn't so cold that my dog refuses to go out for his morning business.

It was with mixed emotions that I went over to the hangar for a day's work. I'm thrilled that the tail cone is very nearly done because it indicates a milestone in the building of the airplane, but I'm also sorry to see the work end, even if it is just for a few weeks while I await the arrival of the fuselage kit. The fact is that I truly enjoy the work. So much so, in fact, that I feel the need to find a word for it other than "work." There are too many negative connotations to "work" for it to adequately describe what I'm doing as I assemble my new airplane.

I briefly discussed the next step at the end of the last installment of this series when I went on a frantic search for the F-1210B plate which was to be guided through the slot in the F-1278 Top Skin. Having eventually determined that the part in question was already attached to the existing airframe, I called it a day.

Today was a new day, and it was a simple matter to do just that. The top skin was easily put into position and clecoed in place:

With the top skin in place, we are to look for deformations in the skin caused by a bracket that rests just under the skin. These deformations would come from not getting enough bend in the bracket back when we fluted it to match the curvature of the frame; that happened so long ago (way back on page 10-02) that I had forgotten about it! If there is any deformation showing, the skin is removed and a file is used to shape the bracket into a more compliant form. I had no deformation showing, so I proceeded with the next step. That step is a simple two hole match drilling:

After that is a step that looks like it's going to be pretty complicated, but that complexity is a simple illusion coming from the fact that the plans tell you to do it twice:

I suppose it is a testament to the overall superior quality of the plans that little things like this are so notable, but it never fails to amuse me to see something like this still remaining on a page that has had at least one revision.

As I clecoed the very back end of the skin, I was somewhat concerned about the gaps that were appearing under the edges of the skin:

Clecos don't hold nearly as tightly as rivets do so I figured there was some chance that the gaps would disappear once riveted, but I wasn't sure I wanted to take that chance. Conversely, using the edge breaking tool to increase the "break" on those edges was rife with risk. As it was, those edges already had a sharper break than the rest of the edges. I was afraid that more break would be too much. In the end, I decided to go ahead and rivet:

It turned out fine. The rivets were enough to close the gaps.

All that was left was to install the half rib that will be the lower attach point for the fairing on the front of the vertical stab:

A couple of the rivet locations on that part were pretty hard to get at. I had to use the little angled wedge and a hand puller to get at them. One of the holes in the corner needed a little touch with the #30 bit, but I couldn't get it to reach. Somewhat ironically, I had to use the extended length #30 bit that I didn't need for the step that actually called for it.

The top skin is the only tail skin that doesn't have a J-stiffener already molded into it (although there are two that need extensions to the molded J-stiffeners) so one has be riveted on. The drawing on the plan is extremely detailed, but the text tells us that the notched end goes towards the rear:

It gets completely riveted in; it is an exception to the "don't rivet any of the holes in the forward seven inches" rule.

Everything else gets riveted. I found that I needed to turn the tail cone a couple of times to get good access, but fortunately it is still light enough to just lift if I need to:

The riveting went well enough, but it left a bad taste in my mouth. That's probably because at any given time I had a dozen or so rivets in my mouth:

I doubt if that's an OSHA approved method of holding rivets when you only have two hands, but... I only have two hands.

I haven't yet decided if I will go ahead and attach the stabs and rudder; it will be easier to store without those big parts attached. The only reason to do it now is that I have no more work to do and I might get bored. That said, the RV-6 still has some open jobs to be performed, so I will probably shift focus to that.

Here's the more-or-less completed cone:

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