RV-10 Door Parabeam Wet-Out

[dmjepsen]

Good day all;
For the RV-10, Section 45, Page 5, Step 4, the instructions say to Wet-Out the Parabeam. When it comes to Parabeam, can someone tell me what constitutes "Wet-Out" or more specifically, how many ounces of epoxy should be applied to each of the 5" x 9" rectangles of Parabeam? If I were to wet-out the parabeam like any other fiberglass cloth, I fear I would be adding waaaay too much epoxy that would ultimately be squeezed out during assembly of the door.

 

[rongawer]

By "wet out", they mean that the parabeam should have epoxy throughout the entire structure of material - it should be sticky with epoxy throughout the thickness of the material and on both sides, but not "filled". The webbing of the parabeam adds strength without the weight of a solid block, so don't go crazy filling the internal voids. It works well to apply the mix with a brush to the parabeam on a layer of cling wrap on a flat surface and then transfer to the door.

Mix about 5 ounces of epoxy with fumed silica, often referred to by one brand name "Cabosil" per door. I recommend having the mixture with a ketchup to mayo consistency. The cabosil should keep it from running, but the thinner mixture will help wet the parabeam.

Doing one door at a time, I recommend wetting the parabeam, then applying the mix to the inner and outer door halves. I used the inner door as the "bottom" sitting on sawhorses, and outer as the "top; lay the parabeam in place on the inner half, and then with the door halves fully wetted at all contact locations, put them together and then place on the airframe as a single unit. Work those halves together applying LOTS of pressure. If you're not seeing some epoxy ooze out of the joints, either you're not pressing hard enough or it's not wet enough and you may have voids between the layers. I used a rubber roller on all surfaces against the airframe to ensure good contact and minimize voids from occurring.

Secure in place... clecos all around the outside of the door into the cabin cover and window frame, about every 4 inches, works well, although tape and weights will get the job done.

 

[dmjepsen]

According to Vans instructions (Section 45, Page 5, Step 5), an additional 10 oz of epoxy are to be used to bond the areas of the door beyond the Parabeam (as this was wetted in Step 4). So, using 5 oz of epoxy for the Parabeam, should I be planning for a total of 15 oz per door?

 

[Capflyer]

You need just enough resin to make it like a wet sponge well rung out. Use a short nap non-linting paint roller to make it easier to spread and press firmly so the fabric is saturated. You should not need any filler, the resin will be viscous enough.

Pro-Tips. Lay plastic down on your work surface (a Hi-Density trash bag cut open works great). The Parabeam should be cut a little larger than needed since it frays terribly. Place it on the plastic with the surface that will be placed down in your part facing up. Heavily wet-out your roller then lightly roll fabric with resin to spread then firmly roll to squeeze it through the fabric, being sure to roll all the way to the edges to squeeze out any excess resin. The plastic you laid out on the bottom should be wet. Now trim both the plastic and Parabeam together to exact size you need, this will give you a clean edge and a dry surface to carry and place it. Pre-wet the location you will be putting the Parabeam. Take the Parabeam on the plastic to where you are placing it, lay it in, then remove the plastic and roll firmly for good contact and removing any dry spots, creases and bunching.

 

[rongawer]

According to Vans instructions (Section 45, Page 5, Step 5), an additional 10 oz of epoxy are to be used to bond the areas of the door beyond the Parabeam (as this was wetted in Step 4). So, using 5 oz of epoxy for the Parabeam, should I be planning for a total of 15 oz per door?

No, you won't need that much. If you're using a medium or slow hardener, you'll have plenty of time to work with the door (including the parabeam), so don't get in a hurry. I do not mix more than 5 oz at a time in order to minimize the mix curing in the cup before I have it fully spread out. The linked video at 1:13 shows a fully wetted out parabeam layer.

The larger the volume, the hotter the mix will get and the faster it will harden in your mixing container. Mix 5oz, wet your parabeam, and continue on applying to the door contact surfaced, doing only one door at a time. If you find you need more epoxy, you will have plenty of time to go mix more and spread that. Just ensure you have a couple hours of time set aside to do the job; repeating myself... do one door at a time.

It's much better to mix more and add to the epoxy you've already applied than to over mix a single amount and have it cook in your cup.

Also, if you use a rotary cutter on a smooth board surface you will minimize fraying of the cloth.