In Chapter 6, you assemble your fuselage. First, you dry fit everything together, make sure everything fits the way you want and make any last minute tweaking. You then flox everything in place and apply BID tape to all bulkhead sides. Lastly, you contour the fuselage bottom and install it.
Here is a screenshot of what you want to end up with when you complete Chapter 6.
A close-up of the F22 bulkhead installed. Notice how the fuselage sides sandwich the F22 doubler (Oh! THAT's why the doubler didn't extend all the way across... it's ALL making sense now!!).
Another thing to note, the F22 is the only bulkhead that extends below
the lower longeron waterline. This is because the fuselage floor later
butts up against the F22 bulkhead.
Showing how the floor later butts up against the F22 bulkhead.
A close up of the F28 bulkhead. Notice the wooden doubler that goes on just aft of the F28 bulkhead. This provides extra reinforcement.
Here is a forward shot of the F28. Notice how the fuselage longerons are later blended to form the shape of the F28. I hope this helps explain what is shown in upper portion of the 2D full-scale drawing (A7).