Monday, June 15, 2009

Rudder lay up

I layed up one half of my new rudder strut today. I’m using John Zseleczky’s mold for the Eppler 836 section (4.5” chord). This was the strut that generated the lowest drag coefficient of the five Bill had tested in the tank. (Available from the class website as a downloadable document: Bill is sure that’s because it was the thinnest tested. John had commented that the thin section was a little whippy when compared to the BR or FC rudders and he recommended that I beef up the laminate schedule. Here’s what I used:

2 layers of ± 45˚ 5.7 oz carbon cloth, full width
4 layers of 9 oz uni-carbon full width.
6 layers of 9 oz uni carbon strips, varying in width between 1 and 3 inches, centered around the fat part of the foil
1 layer of ± 45˚ 5.7 oz carbon cloth, full width
Core of maple, except the last 4 inches which is composed of all glass cloth (for the bottom of the rudder that will form the tang that fits into the horizontal’s socket.

Pics to follow tomorrow after I release it from the mold.
While I was laying up the rudder I was listening to Clapton. Enjoy.

Lay Down Sally by Eric Clapton, Marcy Levy and George Terry (1977)

There is nothing that is wrong
In wanting you to stay here with me.
I know you’ve got somewhere to go,
But won’t you make yourself at home and stay with me?
And don’t you ever leave.

Lay down, sally, and rest you in my arms.
Don’t you think you want someone to talk to?
Lay down, sally, no need to leave so soon.
I’ve been trying all night long just to talk to you.

The sun ain’t nearly on the rise
And we still got the moon and stars above.
Underneath the velvet skies,
Love is all that matters. Won’t you stay with me?
And don’t you ever leave.


I long to see the morning light
Coloring your face so dreamily.
So don’t you go and say goodbye,
You can lay your worries down and stay with me.
And don’t you ever leave.

Chorus, repeat


Karl said...

The core is more important for stiffness than the amount of carbon. If it isn't tied together in shear it gets wobbly.

Joe Bousquet said...

For my previous struts I simply glued the two halves together. Do you think an intervening layer of +-45 cloth would be of benefit (obviously not contributing to stiffness since it's on the centerline, but of keeping the two haves of the core together)?

Karl said...

Um, no. But it will give you a nice trailing
Edge. I usually run uni down the middle.