Repairing ZFoam

I dearly love flying my Radian and have had occaision to repair damage to the wing. Once I hit an electric wire and most recently I was attacked by an evil Slow Stick. These two incidents left large gouges and missing chunks.

The Slow Stick prop made several slices through the wing (the Radian eventually broke the prop and landed).

We luckily found the missing chunk -

I believe this type of wing is made from what they call ZFoam. It's like a rubbery styrofoam. It does not react well to hot glue. The challenge is to fill in the gaps and glue it together. I decided to try polyurethane glue. Gorilla now make a white version that seemed like a good fit. For a gouge that didn't have any pieces missing I wet the surface and put a few drops of glue on it. Next I covered the glued up gouge with some clear packing tape. I was careful to stretch it tight and stick it down securely arount the edges of the gouge.

The trick is to get the tape to follow the contours as closely as possible - keeping it smooth and even.

After a few minute the glue starts to foam up and fill the gap.

Before long it should be filled completely. To prevent it from blowing out the tape I punctured it with a pin to allow it to expand as much as needed.

Allow it to set for a while and then you can remove the excess. It doesn't stick to the top of the tape.

For the the big gouge, I glued the chunk back in and added some additional glue arount the gaps. This required a couple of relief holes.

Here is the finished repair -

The Glue dries much harder than the ZFoam, but it's very strong and looks great (at least on white foam). It's very smooth and perfectly follows the original contours. I just leave the tape on. You can easily trim it back on the ZFoam, but it sticks very well to the glue.

Here is the electric wire repair -

Best Regards,
PCH