Step 8.9, Center section to tailcone assembly

Now that the center section bottom skin is riveted on the baggage compartment floors are temporarily attached (foreground) as well and the seat skins (background).  The F-705 bulkhead is in the middle of the picture below.  Recall that the 705 bulkhead supports the seat backs.

The next step is to insert the upper longerons into the tailcone.  Here one can see the curve that was so lovingly bludgeoned into the aluminum angle in Step 8.5.  There is a slot cut into the bulkheads such that the longerons may pass by on their way to the tail and its depth just allows the outer surface of the longeron to be flush with the bulkhead flange, allowing the skin to lay flat across both.

Now the big step is flipping the center section and tail cone upside down and setting them on saw horses. Naturally, this does not go as smoothly as it seems it should.  First I discover that the center section is too wide for the saw horses.  If I had taken 2 seconds to think about this before it lifted the piece up it wouldn't have been any big deal.  But I didn't, and now I have to find a way to wrestle this thing safely to the ground.  I am the master of empirical discovery.  Did I mention that I was attempting to do this by myself?

OK. Now I've got some wood on top of the saw horses to make them wider and once again I gather my strength and undiminished resolve to lift the center section into place.  It's really not all that heavy, it's just a bit wobbly.  From underneath, the two spar verticals have to set on the sawhorse in front while the middle sawhorse holds the forward most bit of the tail cone.  The only thing holding the center section up is that it is leaning on the front of the tailcone.  It sets there very precariously until the center and tailcone can be clecoed together. 

At this time I would like to point out that the tailcone and the center section have no intention of being joined. There are overlapping skins, and baggage ribs, and various other points of contention.  One by one they must each be addressed before the two will join.  In order to get to that point, however, the whole assembly must be alternately pushed and pulled, and jostled about while at the same time keeping it from falling off the the sawhorses.  Some profanity may have been emitted.

As soon as the center section skin is clecoed to the bottom of the tailcone the side skins are temporarily applied.  I say temporarily because as soon as they are clecoed on, the build manual has you taking them right back off to bend the lower curved section that meets the center section skin. 

And so the curved bit is a cone shaped affair that turns 90 degrees to meet the bottom skin. A piece of angle is match drilled to the tab to keep the end straight and then a good deal of force is applied.  Eventually, a nice smooth curve will appear.  Stop bending when the curve is a right angle at the small end and sweeping 90 degree turn on the other.

When the curve is satisfactory, the skin is returned to the airframe.  At this point the side skins can be match drilled to the bulkhead and spar center section.   In addition, the longerons are drilled to match the side skins. 

Meanwhile Carol has been working diligently to fabricate the myriad of small flanges, spacers, and attachment straps that are used in the fuselage assembly.  

She was hoping to avoid the paparazzi.

In the next posting we attach the steps.