Yet Another Fiberglass Question

On my -8, I have the Grove streamlined landing gear. Today I fitted the Fairings, Etc. fairings between the wheel pants and the gear leg, and bonded them on using flox. My question is, after I apply some epoxy/cabo to smooth the transition between the fairing and the wheel pant, do I need to apply glass cloth over this joint? The cloth would not really be structural and would only be there to prevent a future surface crack. Or is the flox and epoxy/cabo strong and flexible enough so that a crack in the joint area won't later appear at the transition if there is no cloth applied? Thanks

Fiberglass Joints

Jim -

I believe you'll get a stronger joint if you put a few plies of glass directly over the joint, then use epoxy/micro/cab-o-sil to smooth things out.

cloth

Jim,
Good Question. I realize the part is not structural, as if it was, you would surely
want to install some cloth. But what would it hurt to install some cloth now? It would really be hard to re-do later if a crack developed after you have a beautiful paint job done!
Another place to consider cloth is on the inside. Cut away excess wheel pant material under the fairing until the two parts line up and you can install glass cloth there as well to further strengthen the part.
BTW......isn't it too hot to work in the hangar ????
Supposed to feel like 110 in shade today!
You might think we lived in Texas!

Bob Martin said:

BTW......isn't it too hot to work in the hangar ????
Supposed to feel like 110 in shade today!:

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Reason for the question is I HATE fiberglass work, but I guess I already knew the answer.....

Wasn't too bad yesterday...relatively dry air with a little breeze. That plus my fan made it decent until late in the day when the sun started coming in the hangar. That's when I left....

Don't plan to work on it today...

You want to install the glass cloth directly to the fiberglass parts, not to your filler. The glass doesn't stick very well and may eventually come unglued from the filler if the joint is subject to much flexing. If you don't cover it with glass, IT WILL crack. You can use a little flox underneath the cloth to prevent an airbuble where the two parts joggle together.

Just lay the glass up on a piece of aluminum foil first and wet it out. Then cut it to shape foil and all. Lay it upside down on your part and peel the aluminum foil off. Works like a charm, cuts down on the mess, and makes for a straight and strong layup.

flickroll said:

My question is, after I apply some epoxy/cabo to smooth the transition between the fairing and the wheel pant, do I need to apply glass cloth over this joint? The cloth would not really be structural and would only be there to prevent a future surface crack. Or is the flox and epoxy/cabo strong and flexible enough so that a crack in the joint area won't later appear at the transition if there is no cloth applied? Thanks

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Jim, wheelpants take a lot of abuse, so some extra care now is worthwhile.

Epoxy joints have poor toughness in peel, and I assume you plan to split the fairings planar to the wheelpant split. Consider the nature of the joint at the split.

As you go, sand all glass surfaces in the work area to a coarse finish prior to bonding.

Filet the transition between outer surfaces with flox/epoxy (always preferable for structure, but micro/epoxy or cabo/epoxy paste would do here). Blade it smooth, and while it is still wet lay on glass plies. Allow to cure.

Carefully make your split cut and separate the halves.

Now cut out the excess wheelpant shell on the inside. Again blade a filet into the joint and lay up more glass. See the drawing.



The end result will look like this:

DanH said:

Jim, wheelpants take a lot of abuse, so some extra care now is worthwhile.

Epoxy joints have poor toughness in peel, and I assume you plan to split the fairings planar to the wheelpant split. Consider the nature of the joint at the split.

As you go, sand all glass surfaces in the work area to a coarse finish prior to bonding.

Filet the transition between outer surfaces with flox/epoxy (always preferable for structure, but micro/epoxy or cabo/epoxy paste would do here). Blade it smooth, and while it is still wet lay on glass plies. Allow to cure.

Carefully make your split cut and separate the halves.

Now cut out the excess wheelpant shell on the inside. Again blade a filet into the joint and lay up more glass.

Click to expand...

Dan, thanks so much for the thoughtful and thorough response. My wheel pants are split just like yours. I'll use the technique that you described as I work on them. Thanks again.