flybyjohn

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I am new to spad design and I know the key ingredient is to keep it simple, however I have not run across a plan yet that utilized a double yardstick spar to its full potential. It may be out there, I just have not seen it yet and have searched a bit for it. I was thinking that if two yardsticks were to be used, then it would be the best configeration to have one stick vertical and rip the other stick lengthwise and glue it to the top and bottom of the vertical one to make a I beam out of it. this would put much more of the yardstick material in the tension/compression areas. Is this commonly practiced?

flybyjohn

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I had another idea the other day also that some may be able to answer. Someone sugested using a dremel as a router or even a router to cut across one layer and through the flutes on the inside of the leading edge to make folding it much better with less stress on the plastic. I was wondering if you used this same technique to cut one layer on the inside of the wing off in squares, rectangles or circles with the router. Leave enought 2 layer material to make the wing ridgid but cut out uneccessary material out. This would save a bit of weight in the wing. I might try to do this with a flying wing I plan to make and see if the structure strength is still there.

jimgee1

My Feedback: (3)

John,

The early Debonair had a two yardstick wing. Nobody builds them that way anymore. Go to spadtothebone.com and look at all the free plans. You'll learn a lot just by browsing that site.

Craftman1 has a series of videos available on-line for spad construction. Look at norcalspads.com, too.

There's plenty of help on-line. Good luck..

Jim Gallagher

jimgee1

My Feedback: (3)

John,

I'm sorry. It's draftman1 who has the excelent videos, not craftman1 as I misstated in teh above post..

jimgee1

Lnewqban

Your thinking is correct; however, the plastic skin carries the tension / compression stresses.

The yardstick functions as a web or separator of both skins, and also to make the compressed skin more stable, preventing buckling.

In other words, the spar may or not be stronger than the plastic skin under stress by itself, but it would add weight and work for sure.

Clean

USS uses that exact method, Yardstick center with top and bottom, though he uses trim strips instead, at the time we were getting terrible yardsticks that were spliced together scraps every couple inches. Stripped hardwood doesn't have that problem.

http://www.spadtothebone.com/SPAD/ul...34/page34.html

AND, they're excellant airplanes too.