glowplugboy

My Feedback: (17)

I have the wing halves prepared and ready to join. The plans indicate 13/16ths of an inch under BOTH wing tips for proper dihedral. This seems like a huge amount of dihedral for a pattern plane. Can someone verify this for me?

Thanks,
Mike

dave pattern

My Feedback: (3)

thats what the plans i have show as well.
i'm sure joe did some trial and error to come up with this number.
we didn't have mixing radios back then and dihedral was one way to fix roll coupling.
Dave.

glowplugboy

My Feedback: (17)

Thank you. I believe I have figured out the issue. The constuction notes have you turn the wing halves onto the designated "top" side and aligning them on a flat surface. Any gap in the wing halves on the bottom is what needs to be sanded at the top of the wing to create the proper dihedral, that is, 13/16ths TOTAL, NOT under both wing tips. This creates a flat wing on top with appropriate dihedral on the bottom. Thank heavens I read the construction notes!

If anyone would mind verifying my conclusion, I would appreciate.

Thanks,
Mike

JeffH

My Feedback: (43)

The easiest way to sand that angle into the root is to jig the wing square and with the proper dihedral(in this case flat on the board upside down) and then use a sanding block against the edge of the workbench...see crude drawing below.
I sand until my hard block is nice and flat on the frame of my workbench. Of course, this also means that your bench frame must be perpendicular to your dihedral angle. In other words if your dihedral angle calls for the top of the wing to be flat, then your bench top and bench frame must be at 90 degrees to one another so that when you sand the angle into the root, it is 90 degrees to the top surface of the wing.
This also works for wings that require 2" of total dihedral, but you have to jig each panel to 1" at the tip.
NOTE: this may not apply to the original poster since he is probably experienced builder, but somebody else might like the idea.

glowplugboy

My Feedback: (17)

Thanks Jeff. It's been a while since I did a foam core wing that did not have a wing tube! Your drawing is exactly as it is supposed to be done. Interestingly, my cores are (were) nearly perfect, mating with very little sanding necessary.

Mike