Tail Spars

From "Construction Notes" Falco Builders Letter, September 1992

On the plans, each side of the rudder spar is shown with a bevel sanded on the forward edge of the spar as clearance for the elevator. Many builders have reported that this is not necessary, or at least to the extent shown on the drawings. I'm not sure what the history on this is, but it's certainly not necessary to cut any more than you need for clearance. So I'd suggest you just sand on it as necessary when you put the rudder in place.

From "Construction Notes" Falco Builders Letter, March 1986

A recent builder question: "On the original drawing for the forward fin spar, the spar was shown with no particular grain direction for the 1.2mm plywood. However, when we received the new set of drawings, the grain is specified at 45°. Is this necessary on a vertical component? And what is the action for my friend who has already completed this component. I notice that the ribs in these new drawings imply 45° grain direction but is not annotated as such."

Sorry to have caused some panic. The original production drawings did not specify the grain direction nor did our first drawings. When I was drawing the latest set, I specified 45° out of habit. Thus, it is not essential but 45° is stronger and a good idea. As for the ribs, the grain direction depended on where my right elbow was when I drew the drawing.

From "Construction Notes" Falco Builders Letter, March/June 2002

The tailplane main spar-the section on the drawing appears to indicate a 12.5 thick timber over a 10mm pieces in both top and bottom booms. The main view does not show this 'split'. Do I have to laminate two pieces for each boom? The material that I have from Western Aircraft is over 12.5mm thick by 40mm plus, it seems a shame to run it through a saw just to stick it back together again!

Mike Aherne

The main stabilizer spars have the spar caps made in laminations so that the wood can more easily be bent into the very slight bend at the center. It doesn't make any difference if you use 12.5 or 10mm laminations. We use two 12.5mm laminations, and taper the outside one.