Looking at Fiberglassing my first plane. Looking for feedback before I move forward.

Ducky84

Member
So as much as I love building and repairing my planes, I love flying them about 10x more than that. One of my favorite planes is the Explorer. It's super smooth, and easy to fly, very forgiving, it's just one I really enjoy.

I'm planning on building a second for an FPV setup, but I'm going to really make this one nice. I want to paint it, and also reinforce certain areas of the plane with Fiberglass. The purpose of the fiberglassing is to add strength to sensitive areas, and increase the life of the plane. I wasn't planning on fiberglass the entire plane. I'm going to glass the underbody (Since it's a belly lander) the Front and tips of the wings, the nose, and the tail section. Basically any potential impact area.

So I've seen many posts on here, and I think I have a good idea of what I'm going to do, but before I buy the stuff and get to work, I wanted to run past some of these ideas as I think I still have questions.

First thing is I was going to pick up some Polycrylic: https://www.lowes.com/pd/Minwax-Polycrylic-32-fl-oz-Semi-gloss-Water-based-Polyurethane/999913685
I have some Polyurethane at home I wast testing with, but it left this yellowish tint behind, and I was hoping Polycrylic might avoid that.

Second thing is Fiberglass. My local Hobbytown has some 1oz glass here: https://www.hobbytown.com/deluxe-ma...rglass-cloth-1.0oz-dlmbd12/p-xuyqs4fqwqqbg4yz

But there's also a local supplier that has 3/4 oz Fiberglass for much less: https://www.plasticareinc.com/cloth-3-4-oz-38.html

Not sure which to go with. The 1oz would add more strength, but I also like getting more for less.

Last thing is painting. I was just going to pick up an Airbrush kit from Harbor Freight since I already have a compressor.

So here's my questions...

1. If I'm planning on Airbrushing, should I paint first, then Poly over the paint, or do it the other way around? Ideally I'd protect the bottom part of the craft from skids and such.

2. Will the combination of 3/4oz or 1oz Glass + Polycrylic provide a bit more impact resistance, or would I really need to consider an Epoxy setup? I'm not looking to slam this thing into a tree and for it to come out unscathed or anything, I'm just looking for low impact resistance. If I hit a twig, or branch or something, I don't want to replace the entire wing or tail section.

3. Anything else I'm missing here? It seems straight forward, but there's also a lot of conflicting info about Poly this, water-based that, oil-based this, etc. It's the finish I think I'm more concerned about.
 

FoamyDM

Building Fool-Flying Noob
I don't know the answers... Most people paint after. By I want to know the answers too.
 

Baron VonHelton

Elite member
I painted mine BEFORE assembly, due to the fact that painting the interior would be a real PITA after it's glued together. The Halberstadt may be a little of both. Paint the interior, assemble it, then paint the exterior.
(y)
 

foamboardflyer

Active member
I would recommend testing out the polycrylic fiberglass on a scrap piece of foam board to see if it works. And definitely use the lighter glass cloth. If you’re scratch building with DTFB you could probably paint it first, but if you’re using Flite Test FB I definitely would painting it AFTER you glass it.
 

Baron VonHelton

Elite member
I would recommend testing out the polycrylic fiberglass on a scrap piece of foam board to see if it works. And definitely use the lighter glass cloth. If you’re scratch building with DTFB you could probably paint it first, but if you’re using Flite Test FB I definitely would painting it AFTER you glass it.

Doesn't fiberglass make you itch??

:unsure::unsure::unsure::unsure::unsure::unsure::unsure:
 

Ducky84

Member
I would recommend testing out the polycrylic fiberglass on a scrap piece of foam board to see if it works. And definitely use the lighter glass cloth. If you’re scratch building with DTFB you could probably paint it first, but if you’re using Flite Test FB I definitely would painting it AFTER you glass it.

Thanks,

I'm using DTFB, so I'll try to paint first.

I'm assuming for the parts that I'm glassing, I should glass, coat, paint, then coat again to protect the pain?
 

earthsciteach

Moderator
Moderator
I have a good amount of experience with fiberglassing foam board and XPS.

Let's start with #3. Either water-based or oil-based poly is compatible with foamboard, but each has a different purpose. There is no need for oil based if you are using water resistant foam board. Actually, there is no need for oil based if you are glassing. If you are glassing, remove the paper. The paper is the heaviest part of foamboard.

#2: You are building with foamboard. You really can't reinforce it enough to make it handle a hard impact without making it too heavy unless you are scaling an FT design up significantly. The upside to this is, you can replace any component for a dollar or two. I use 0.56 oz/yd glass cloth on foamboard. I buy it from Thayercraft. Link: https://thayercraft.com/0.56-oz-104-volan.html

#1: You will have a better looking paint job if you paint over the finished result. Lay the glass on the foamboard (after removing the paper), spread on polycrylic just enough to wet the cloth (do not apply enough such that runs occur. Use plastic spreader or similar to remove excess poly). Allow to dry. Lightly sand with 220 grit. Clean the surface. If you are looking for a glass smooth finish, keep doing this until the weave is almost full. (Don't go to this trouble with an Explorer.) The last coat is a 50/50 mix of polycrylic and baking soda. This results in a hard surface finish. Paint as desired.
 

Ducky84

Member
I have a good amount of experience with fiberglassing foam board and XPS.

Let's start with #3. Either water-based or oil-based poly is compatible with foamboard, but each has a different purpose. There is no need for oil based if you are using water resistant foam board. Actually, there is no need for oil based if you are glassing. If you are glassing, remove the paper. The paper is the heaviest part of foamboard.

#2: You are building with foamboard. You really can't reinforce it enough to make it handle a hard impact without making it too heavy unless you are scaling an FT design up significantly. The upside to this is, you can replace any component for a dollar or two. I use 0.56 oz/yd glass cloth on foamboard. I buy it from Thayercraft. Link: https://thayercraft.com/0.56-oz-104-volan.html

#1: You will have a better looking paint job if you paint over the finished result. Lay the glass on the foamboard (after removing the paper), spread on polycrylic just enough to wet the cloth (do not apply enough such that runs occur. Use plastic spreader or similar to remove excess poly). Allow to dry. Lightly sand with 220 grit. Clean the surface. If you are looking for a glass smooth finish, keep doing this until the weave is almost full. (Don't go to this trouble with an Explorer.) The last coat is a 50/50 mix of polycrylic and baking soda. This results in a hard surface finish. Paint as desired.

Awesome, thanks for the feedback.

One last question is around the control surfaces. Ailerons, rudder, etc. If I'm removing the paper, should I still coat, or glass those sections? How would I do that without stiffening up those areas where they no longer work?