Another Change

I just read the excellent article in the EAA Sport Aviation magazine about Mike Finney's shortwing Wag-Aero Cub.  What a beautiful little airplane. If you are not an EAA member, you can access the EAA online magazine "Experimenter" on the EAA website.  There is an article about Mike Finney's plane there, too.  Just go to the EAA website (via Google), go to the Multimedia tab and click on "Newsletters".  You can handle it from there.

I have corresponded with Mike on the Yahoo Groups site for Wag-Aero plans-built aircraft.  With all that, I got thinking.  One of the aspects of his airplane is that there are not leading edge, or "false" ribs.  He built full ribs for those locations instead.  The Wag Aero Cub wing is essentially identical to the Wag-a-Bond wing.

I also got thinking about the history of the Piper Vagabond.  The Wag Aero Wag-a-Bond is essentially an exact copy of the Vagabond. There are some changes.  The Vagabond was one of the first Piper aircraft to use aluminum wing ribs and spars instead of wood.  The Wag Aero wing is, essentially, an exact copy of a  pre-1947 Piper wood wing. 

Post-war (WW2), Piper was struggling financially.  They were building great airplanes, but they were doing so as economically as possible.  So, in all likelihood, the leading edge ribs were necessary for the leading edge of the wing, but an adequate wing could be built without full ribs in those locations.

However, if full ribs are installed in those locations, the result would be a stronger wing, and with more secure attachment of the fabric.  So, the additional ribs result in making an adequate wing better.  The weight penalty is actually pretty small, maybe three pounds.  Ribs really don't weigh very much. 

The downside is about a 70% increase in the amount of materials used, and probably just about double the fabrication time for the ribs, and a substantial increase in labor stitching the wings.

It just so happens that I blew the material takeoff when I ordered the spruce capstrip.  I have well over half of the capstrip I ordered sitting unused.  I also have sufficient material to cut the gussets and aileron rib tail blocks.  The nose blocks, which are needed for the leading edge ribs, are already cut.

So I could build full ribs instead of leading edge ribs at no additional out of pocket cost.  It would mean I am not finished building full ribs (and I have just shy of 100 hours into ribs now) and when covering time came the stitching would require a great deal more labor, but...no, or very little, out of pocket increase in cost.

For a better wing...

I'm gonna do it!