Three New Bulkhead Shapes

So here they are, the three bulkheads. The largest one is simply the baggage bulkhead that has been enlarged so that it will fully encompass the sides and bottom skin for added strength. The middle bulkhead is "D", with its appropriate shape, and the smallest is what I call "D-prime" and will give added strength to the tail in the vicinity of the tail wheel box. More on that later. The shapes will need to be tweaked a small amount, I am sure, but the shapes are good and give me some idea of what the final structure will be like. The tape is askew but that is more an artifact of my taping than the shape of the bulkheads, which are symmetric.

As the pictures show, I am now working in my apartment. This is a living situation I have to deal with for the upcoming months and is putting the brakes on my build process. So lately it has been busy-work for me. What you see here could (and probably should) be done with the actual airplane, thus saving a step and several hours of labor. But for me, it keeps the project in my mind and lets me think I am making some sort of progress. "Virtual Progress."

Poster Board and Tape

The process is slow, but it gives much better results. A straight edge is placed from bulkheads "C" and "E" and the intersection with the posterboard strip is marked. The frame is canted aft 20 degrees, parallel to the "C" bulkhead, and "E" as well.

Two New Bulkheads

I tried to get the dimensions for the bulkheads using string tied from bulkhead "C" to "E", but this did not work. The string is just too slack and the measurements are very inaccurate. So I will build a frame to hold strips of posterboard to get the correct measurements. The string looks interesting though and it gives me a sense of what the skin would look like. Er, if it was made of aluminum and was not see-through and flimsy.

Botched Firewall

I couldn't make the firewall work the way I wanted it to. I didn't want to change the firewall or the two rear bulkheads but that is going to happen now. As I sat in my cardboard airplane, winging over the Sierra Estrellas, I realized my feet were binding on the rudder bar. The lower side rail was pushing my feet together and squishing them up against the fuel feed line.

And if that wasn't bad enough my toes kept pushing against the cut out I had to make to accomodate the rear mounted mag. The thermals were gettting a little uncomfortable and my rudder work was making me wish for a bigger firewall.

I sat back, reached outside and picked my beer gingerly off the wing root. Cardboard airplanes make a lot of sense. I need to stretch that firewall 2 inches wider to conform with the 2 inch stretch at the cabin seatback. This will make my size 12 boats a little less claustrophobic and less likely to put me into an unwanted rudder throw.

I sure wish I hadn't cut the plywood form blocks for the plans-sized firewall though! I was premature on that but I can use the wood for something else, nothing goes to waste here. The good news is that the side rails won't have to bend as much because the firewall will be scaled up appropriately.