Spar cutting and bending...

[DesertBearhawk]

Guys,

Getting ready to cut and bend my spar webs this week. Was doing some figuring in the shop and reading everything I can get my hands on. The formula I have (its in the book, THE book) is flange X2 + bend radius + rib hight to get the cut size of the spar. the question I have is do use the rib hight of an un-joggled rib or a joggled rib?

Thoughts and suggestions welcomed!

[bestbearhawk1231]

Hi Dave, I didn't joggle my ribs. I measured across the end of the rib to get the height, used the formula flange x2 + flange height + 1/16", and they turned out spot on. My thoughts on the rib joggling is that it is one extra step that could cause problems (ie screwing up and having to rebuild ribs) so I decided not to joggle them and will watch my rivet spacing so the skin will "drape" across the slight gap.

[Enewton57]

I made a couple of test bends using a short 6" length of .032 material before actually commiting to the full length spar pieces. Helps you get the sight picture of the angles correct and allows you to see if your calculations for the web hight are correct. The flange width is not as critical as the flange angles and the spar web height. Bend up a couple of samples first and test fit them to the rib. I didn't joggle either, and my wings came out beautiful.

[DesertBearhawk]

Sigh.... Somehow I got convinced that the Joggle was a requirement...I guess I will work the bends to fit my ribs now....no Joggle would have saved a lot of work....

[Bradrock]

Everyone using 1/16" bend radius for spars, or 1/8"?

[marcusofcotton]

Plans pages 3 & 4 say .10" bend radius typical.

Mark J