djmrozinski

I am working on my first composite wing. I have been reading all the threads. I have found some info on how to set up hinges for a composite wing. I am just wondering if this thread could generate more discussion on the subject.

It appears that fiberglass skin hinges are the method of choice, but I really am hoping that I could get move details (pictures) on how to actually set them up. I am really not clear on what happens on the bottom of the wing when skin hinges are used. Is there just a gap cut in the bottom of the wing? You get the idea.

Thanks
Dave Mrozinski

Ollie

The shell of a hollow molded wing usually consists of a foam or balsa core about 1/16 of an inch thick with a layer of lite glass cloth in epoxy on the inside and outside. An integral skin hinge is made by leaving out the foam core along the hing line for a width of about 1/8 inch. The foam core is beveled on the inside on either side of the gap so that the two glass skin come together along the gap in the core material. On the side of the airfoil away from the hinge, the shell must be cut away enough so that the control surface can move through the desired range of deflection. The result is that the outer contour of the airfoil in uninterrupted when the control surface isn't deflected. When the control surface is deflected, the skin along the gap in the core bends through a smooth arc somewhat like a tiny leaf spring. The ease of bending can be adjusted by the thickness of the skin and the width of the core gap. The ease of bending can also be adjusted by the angle that the warp and fill of the glass cloth makes with the hinge line. If a bias cut strip of cloth is stretched before lay up, the angle between the warp and fill is reduced and a more flexible hinge results.

Two layers of 3/4 ounce glass cloth with a 1/8 inch gap make a fairly flexible hinge. If heavier cloth is used, a wider gap may be necessary for sufficient flrxibility.

SCALECRAFT

My Feedback: (13)

Hi

We use a hollow glass only wing. It is hinged at the aileron by a robart pin hinge and balsa cap placed in the wing aprox 1/8" back to allow for a fairing to minimize the gap and give a clean look.

The hinge pin is placed with the "pin" part in the flying surface that moves, and the LE of the flying surface in "bullnosed accordingly.

This is what we do on our composite warbirds. May not apply to your model. Tried to post pic on your topic, but don't get that yet.

Steve