Patriot

Has anyone ever laminated a few layers of 2-3oz cf cloth to make some custom lightweight I-struts for a biplane? Specifically aerobatic, like or a pitts or ultimate? Just wondering, as I am tinkering with an idea.

Patriot

Mel Francis

Sounds like a good idea. But I wonder about the upper and lower tip strength for hardware attachments.

How about forming some thin piano-wire 'backbones', that run the length of the strut and then wrap around, forming the locations for the upper and lower bolt holes.

Then laminate the carbon layers over each side of the wire to form the I-struts, as you intended.

First laminate over the pre-formed wire on a piece of waxed flat-stock, then release and laminate over the back side, entrapping the wire in the center. Then trim the leading, trailing edges and sand-shape the sides.

The wire will give the needed resistance to tension pullout of the hardware, and the carbon laminations will provide the compression resistance, to eliminate side-bowing.

This same technique might work well for reinforcing built-up C/F landing gear struts.

Patriot

Aren't some I-struts made from birch ply? And no internal wires? Just wondering. My guess is that laminated cf would be as strong or stronger than plywood.

Patriot

Mel Francis

If you're bonding the ends of the struts to tabs sticking up and down from the wing surfaces, no problem.

But if this is a larger scale plane, that bolts together at these ponts, you might experience hardware pullout, unless that area on the strut is reinforced.

Just a thought. Sounds like you should proceed with your first idea.

Patriot

I was thinking of attaching the metal brackets to the wing so they stick out of the wing vertically and then the struts would have a bolt going through the sides of them to hold everything in place. The struts would have blind nuts in them for the bolts.

I am thinking even glassed birch ply would work well.

Patriot

nichanderson

My Feedback: (4)

Sounds like this might interest you:

http://www.biteam.com/i-beam.htm

Comes in a variety of fibers, materials and weights..

Probably a pretty hefty min order, unless you can get them to send you some rejects.

Nick Anderson
http://www.calpolydbf.com