Step 8.4, Bulkheads galore

This is bulkhead F706 and the Border Collie at 1 o'clock is Roxy, my ever faithful tech inspector.  The keen observer may detect a slightly incredulous look on her face as she looks on.  It seems that she is concerned with F706 being too flimsy to be considered airworthy.  My canine companion would be correct were we not building in the semi-monocoque fashion.  As you will recall from our previous discussion in step 8.1, when using monocoque design the strength is mostly in the skin not the frame.

On this bulkhead the aluminum is very thin and will be an interesting test of the theory.  The edges are dressed and the mating pieces are match drilled.  Then the corners are fluted in an attempt to get the hoop to lay flat.  Only partially successful, I would say.  The material is so light weight that too aggressive manipulations will only distort the metal.  So I go as far as I dare and will let the skin's pre punched holes line everything up.

Up next is the elevator bellcrank assembly, sans bellcrank which will be assembled later.  This assembly mounts the bellcrank centered in the fuselage tube at the bottom of bulkhead F706 pictured above.

The next two bulkheads are assembled without much fanfare.  The corners require a signifcant amount of fluting to get them to lay flat, but at least these bulkheads are made from somewhat thicker material.

After the fluting, match drilling and priming they're pretty much done.

The next bulkheads are the F711 and F712 which both require some pieces to be fabricated from aluminum stock.  On the F711, 1/8" bar stock is trimmed down as pictured below before riveting.

At right, the F712 is riveted together.  The tie-down for the tail is trimmed to fit next.










Carol took care of this part for me.

And while she was at it, Carol also assembled the elevator bell crank.  Shown below with the hardware already pulled and ready to install.

The last bulkhead I did was the F710 which only requires a piece of angle stiffener to be attached at the top.

And here they are all lined up in order.

The next section will be bending of the F718 longerons.  I've heard that this step can be a maddening experience as the aluminum angle becomes quite obstinate and unpredictable when asked to bend.  No worries here as I've been taking some profanity lessons and feel ready to meet this challenge head on.