Stringers

The fuselage sides, top and bottom would be very flat and square (like a Zenith 750) without stringers.  The stringers simply shape the fuselage giving it a more rounded, pleasant appearance. The stringers can be made from wood or aluminum channel material (like a screen door frame).  Avipro carries the aluminum channel which is a rectangular in shape and 1" wide by 1/4" thick. It comes in 20' long pieces.  Per the plans, there are two bottom stringers on the fuselage, two on each side and one on the top of the fuselage right down the center.

Use some steel "U" shaped clips made from .030" thick steel to attach the stringer material to the fuselage.  Here are some of the clips ready to weld to the fuselage:

Starting with the bottom, there will be two stringers that run from the bottom former at station "C" all the way back to the tail. To get better access to the fuselage bottom, we turned the fuselage onto it's side.  Two of the steel  "U" clips were welded to the bottom former, right where it bends:

Here the stringers have been inserted into the clips until they are aligned with the bottom of the former. They were drilled and clecoed in place:

The bottom stringers must be located to achieve good clearance from the control stick assembly which hangs underneath the fuselage.  To hold the stringers off the bottom about 4" or so, some stand-offs must be made using the "U" shaped clips and a 1/4" steel tube. Here is one of the stand-offs ready to weld to the fuselage:

Here are two of the standoffs welded to the fuselage bottom at station "D":

What you are trying to achieve is a nice smooth, rounded transition from the fuselage former at station "C" to the tail, When the stringers reach the tail they should be flush with the bottom longerons. Therefore as you progress aft with the stringers, the standoffs get sorter and shorter and each station.

Here are the standoffs at station "E":

When you get back to station "H" the stringers are up against the bottom cross tube and no standoffs are needed.  Just two clips are welded to the tube.:

At the tail, we have welded a 3/4" wide strip of .040" steel to contain the stringers at their end:

This is kind of hard to photograph because the picture is so "busy" but here is the basic shape you are looking for:

Next we will stand the fuselage back upright and and install the side stringers.

Click here to go to Stringers page 2