Squaring the Fuselage
BY JOE NORRIS
WHEN BUILDING A TUBE and fabric aircraft project you do a lot of
measuring. The old adage is “measure twice, cut once.” There are
hundreds of measurements you need to make, check, and check
again. While you’ll run into lots of places on the fuselage where
tubes come together at an angle, you will often find that the fuselage
is square in the cockpit area. Sure, you can take a bunch of cross
measurements to make sure the fuselage is square and true, but
there’s a quicker and easier way!
All you need is two large carpenter squares and three or four
small C-clamps or some Clecos to hold the two squares together.
When you’re ready to square up your fuselage simply lay the two
carpenter squares together with the shorter arm of each square
overlapping. You’ll need to know two things to set your squares up
correctly—the diameter of the tubing used
for your fuselage longerons, and the dimen-
sions of the cockpit area. Make sure you
know whether your cockpit dimension is an
“inside” measurement or a “center to cen-
ter” measurement. Most often the plans will
call out the dimensions referencing the cen-
terline of the tubing, so you’ll need to adjust
the distance between the outside edges of
your squares accordingly. For example, if
your cockpit area is 24 inches center to cen-
ter, and your longeron tubing is 3/4-inch
outside diameter, your actual inside
