Molded composites question...

[NWade]

Not directly related to EZs, but for any of you out there that have experience with such things:

I'm helping someone out with an 8 foot wing made from upper and lower skins.  The wing will be hollow, except for some reinforcing ribs (that do not go all the way to the leading edge).

The problem is, no joggle flange was made for the wing skins - and one won't be made for future layups from this mold.  So the question is how to close out this wing and get an acceptable and structurally-sound bond between the upper and lower skins along the leading edge.

This is for an unmanned vehicle, so FAA / homebuilder concerns aren't an issue - but the plane needs to hold up under gusty and turbulent conditions; so the bond can't be too flimsy.  A simple butt-joint seems to provide too little bonding area for confidence, and the interior of the wing will be accessible after the two skins are put together - but only awkwardly so via the open root and a couple of access holes at the tip.

Any thoughts or suggestions?

Thanks a bunch!

--Noel

[D]

Hi Noel -

If it's a UAV, chances are the "aerodynamic" penalties for simply peel plying an external tape to the LE won't be too costly.  However, if it's a UAV with nice, slick, gel coated wing skins... well... yuck.    :wink:

You can butt the skins together at the LE like an open book and tape the joint externally w/ duct or packing tape (depending on your external surface).  Bond your ribs and such to the inside of the "bottom" skin.  When you're ready to close things out, run a wet fiberglass tape down the length of the internal LE joint overlapping both skins, add flox the top of the ribs, and close the "book" with clamps on the TE.  The external LE tape will serve as your clamps up front.  Make sense?

Another option would be to make a sample wing, run a fiberglass tape down the external LE, and then cut the LE off after it cures to create a fancy, female LE flange tool.  Coat the inside with release agent, lay in your tape, cure it, and then pop it out.  It'll give you a rigid LE shape to bond to your lower skin along with the ribs.  When your're ready to close out, flox the LE flange just like your ribs and clamp away.  The external duct/packing tape trick works as a nice LE clamp here, too.

Good luck!

D