best way to fill pinholes/weave of glass cowl?
04-13-2006, 07:02 PM
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best way to fill pinholes/weave of glass cowl?
I've got a 35% Aerotech Yak I've been building for the past few months. It's just about finished....I just need to paint the hatch, cowl, and pants and install the electronics.
My problem is the cowl. It was very poorly made......huge bubbles in the finish that required major work to fill and blend into the surrounding areas. (I'm talking bubbles nearly 1/2" in diameter). After fixing all the obvious pinholes and bubbles, I shot a light coat of primer to see what I needed to fix next.
What I found is the entire surface of the cowl covered with pinholes. It's actually more like the weave of the glass isn't filled....so you can imagine the number of very small pinholes that need filled.
My first thought on how to fix this is to just give the entire cowl a very thin skim-coat of spot-filler and sand it all off. I'm pretty confident I can get the finish I'm after going this route, but I'm dreading the time and mess it will make.
Does anybody have any better suggestions on how to fix such a problem?
Thanks,
My problem is the cowl. It was very poorly made......huge bubbles in the finish that required major work to fill and blend into the surrounding areas. (I'm talking bubbles nearly 1/2" in diameter). After fixing all the obvious pinholes and bubbles, I shot a light coat of primer to see what I needed to fix next.
What I found is the entire surface of the cowl covered with pinholes. It's actually more like the weave of the glass isn't filled....so you can imagine the number of very small pinholes that need filled.
My first thought on how to fix this is to just give the entire cowl a very thin skim-coat of spot-filler and sand it all off. I'm pretty confident I can get the finish I'm after going this route, but I'm dreading the time and mess it will make.
Does anybody have any better suggestions on how to fix such a problem?
Thanks,
04-13-2006, 08:27 PM
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RE: best way to fill pinholes/weave of glass cowl?
Thats unusual for an Aerotech product, I know John does his best to put out a quality product. The spot putty route will work and when I go this way I usually squeeze some out in a cup and thin slightly with laquer thinner. Another way would be to spray on primer and with a rubber gloved finger you can rub the primer into the pinholes.
Shawn
Shawn
04-13-2006, 08:34 PM
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RE: best way to fill pinholes/weave of glass cowl?
I just built an Aerotech Extra 300 and the cowl was awesome!
My suggestion would be to mix up some Z-poxy finishing resin and rub it in, then sand smooth.
Good luck!
Ryan
My suggestion would be to mix up some Z-poxy finishing resin and rub it in, then sand smooth.
Good luck!
Ryan
04-13-2006, 08:38 PM
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RE: best way to fill pinholes/weave of glass cowl?
The laquer thinner tip is a good idea.....I'll give that a try tomorrow after the primer has dried throughly. Thanks for the idea!
This was my first Aerotech kit.....and I'm afraid it will be my last.
I've had way too many negative experiences with Aerotech to justify trying another.
I've built a couple of Carden kits and have been thrilled both times......I think I'll stick with what I know.
This was my first Aerotech kit.....and I'm afraid it will be my last.
I've had way too many negative experiences with Aerotech to justify trying another.
I've built a couple of Carden kits and have been thrilled both times......I think I'll stick with what I know.
ORIGINAL: rcblimppro
Thats unusual for an Aerotech product, I know John does his best to put out a quality product. The spot putty route will work and when I go this way I usually squeeze some out in a cup and thin slightly with laquer thinner. Another way would be to spray on primer and with a rubber gloved finger you can rub the primer into the pinholes.
Shawn
Thats unusual for an Aerotech product, I know John does his best to put out a quality product. The spot putty route will work and when I go this way I usually squeeze some out in a cup and thin slightly with laquer thinner. Another way would be to spray on primer and with a rubber gloved finger you can rub the primer into the pinholes.
Shawn
04-13-2006, 08:51 PM
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RE: best way to fill pinholes/weave of glass cowl?
There are two products developed in the full scale aircraft industry for this problem. When building a Glassair or plane using 6 oz fiberglass cloth Superfil is used to fill the weave. it's an epoxy based product and is extremely lightweight and sands well. After sanding and inspecting for pinholes there are two products designed to fill and not bridge across the pinholes, FC-900 is a solvent based filler and Smooth Prime is a water borne product designed to fill pinholes.
They both act like a primer and are sprayed or brushed on, then painted. Being solvent based, do not used a solvent paint over the FC-900 except for Poly Tone. Any two part or catalyzed paint will work fine.
Smooth Prime is catalyzed and works well with anything.
They are all three available on http://www.stits.com
I know someone will inevitably post alternate places to purchase these products but FC-900 is only produced for modelers and only available from F&M Enterprises.
They both act like a primer and are sprayed or brushed on, then painted. Being solvent based, do not used a solvent paint over the FC-900 except for Poly Tone. Any two part or catalyzed paint will work fine.
Smooth Prime is catalyzed and works well with anything.
They are all three available on http://www.stits.com
I know someone will inevitably post alternate places to purchase these products but FC-900 is only produced for modelers and only available from F&M Enterprises.
04-13-2006, 09:41 PM
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RE: best way to fill pinholes/weave of glass cowl?
This seems to actually be a big problem with aerotech fiberglass. I am getting ready to fill in lots of large holes in a cowl for a customer's plane. I have heard of many others, too
I am with you on this JMIRACLE.......this is the last aerotech that I do. It would take some real convincing to get me to believe that the average aerotech kit is a good kit. Now don't get me wrong, after being built and finished well, it will be a good flying plane. It just takes so much more work to get it right. The foam was horrible. The top hatch wasn't even close to symmetrical when viewed from the front. The turtle deck had a flat spot on the top center, wings weren't very smooth at all, I did have John replace the stabs due to the tube holes not being the same (meaning the lateral angle in respect to the fuse would be different on both), I ended up using quite a bit of my own balsa for the skins as the wood supplied was hard and heavy...... Again, the final product will fly fine, but as for what you save financially by buying an aerotech, you can save in labor with a better designed kit.....like a carden
I literally had to walk away from this kit many times because so much of it was so very frustrating....and I love a challange. Thing of it is, I nearly felt like I scratch built a plane when I finally finished this one. On more than one occasion, I was tempted to burn it and give the guy his money back for the kit cost.
I am with you on this JMIRACLE.......this is the last aerotech that I do. It would take some real convincing to get me to believe that the average aerotech kit is a good kit. Now don't get me wrong, after being built and finished well, it will be a good flying plane. It just takes so much more work to get it right. The foam was horrible. The top hatch wasn't even close to symmetrical when viewed from the front. The turtle deck had a flat spot on the top center, wings weren't very smooth at all, I did have John replace the stabs due to the tube holes not being the same (meaning the lateral angle in respect to the fuse would be different on both), I ended up using quite a bit of my own balsa for the skins as the wood supplied was hard and heavy...... Again, the final product will fly fine, but as for what you save financially by buying an aerotech, you can save in labor with a better designed kit.....like a carden
I literally had to walk away from this kit many times because so much of it was so very frustrating....and I love a challange. Thing of it is, I nearly felt like I scratch built a plane when I finally finished this one. On more than one occasion, I was tempted to burn it and give the guy his money back for the kit cost.
04-13-2006, 09:46 PM
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RE: best way to fill pinholes/weave of glass cowl?
I asked John about a replacement shortly after I received the kit, but never received a response to my question. To be fair, I asked about the cowl along with a laundry list of missing parts. He eventually took care of the missing parts, but never mentioned the cowl. I took his silence on the matter to mean a replacement was not likely to be better than the cowl I currently have.
....and honestly, I've had enough problems with this project.....it's to the point where I'm just glad i HAVE the parts to finish the plane.
....and honestly, I've had enough problems with this project.....it's to the point where I'm just glad i HAVE the parts to finish the plane.
04-13-2006, 09:57 PM
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RE: best way to fill pinholes/weave of glass cowl?
This sounds EXACTLY like my kit.
Now that the airframe is built, I'm satisfied with the results.....but it took a LOT more work to get to this point than the Carden kits I've built in the past. Early on in the project, I stacked up all the parts I would not use or would replace.......and did the same with the replacement materials. I then weighed both stacks. The stock parts were 1.5 POUNDS heavier than the replacement.
In fact, I gave up on the plans when it came to the hatch and just scratch-built my own. When I was finished, the completed hatch frame with dash/instrument panels and speckle-paint finish was 10oz. lighter than the stock hatch-plate/foam block.
Even with all the weight savings, i think I'll be lucky to come in at 28lbs. I originally started the project with a goal of a RTF weight of under 27. The plane is advertised as coming in at 26-28.....but I haven't read of one yet coming in under 29lbs.
I agree with you though....it should be a good flying plane when it's finished.....but getting it finished has tested the limits of my patience!!
Here's a couple pics of my "problem child"
Now that the airframe is built, I'm satisfied with the results.....but it took a LOT more work to get to this point than the Carden kits I've built in the past. Early on in the project, I stacked up all the parts I would not use or would replace.......and did the same with the replacement materials. I then weighed both stacks. The stock parts were 1.5 POUNDS heavier than the replacement.
In fact, I gave up on the plans when it came to the hatch and just scratch-built my own. When I was finished, the completed hatch frame with dash/instrument panels and speckle-paint finish was 10oz. lighter than the stock hatch-plate/foam block.
Even with all the weight savings, i think I'll be lucky to come in at 28lbs. I originally started the project with a goal of a RTF weight of under 27. The plane is advertised as coming in at 26-28.....but I haven't read of one yet coming in under 29lbs.
I agree with you though....it should be a good flying plane when it's finished.....but getting it finished has tested the limits of my patience!!
Here's a couple pics of my "problem child"
ORIGINAL: CAPtain232
This seems to actually be a big problem with aerotech fiberglass. I am getting ready to fill in lots of large holes in a cowl for a customer's plane. I have heard of many others, too
I am with you on this JMIRACLE.......this is the last aerotech that I do. It would take some real convincing to get me to believe that the average aerotech kit is a good kit. Now don't get me wrong, after being built and finished well, it will be a good flying plane. It just takes so much more work to get it right. The foam was horrible. The top hatch wasn't even close to symmetrical when viewed from the front. The turtle deck had a flat spot on the top center, wings weren't very smooth at all, I did have John replace the stabs due to the tube holes not being the same (meaning the lateral angle in respect to the fuse would be different on both), I ended up using quite a bit of my own balsa for the skins as the wood supplied was hard and heavy...... Again, the final product will fly fine, but as for what you save financially by buying an aerotech, you can save in labor with a better designed kit.....like a carden
I literally had to walk away from this kit many times because so much of it was so very frustrating....and I love a challange. Thing of it is, I nearly felt like I scratch built a plane when I finally finished this one. On more than one occasion, I was tempted to burn it and give the guy his money back for the kit cost.
This seems to actually be a big problem with aerotech fiberglass. I am getting ready to fill in lots of large holes in a cowl for a customer's plane. I have heard of many others, too
I am with you on this JMIRACLE.......this is the last aerotech that I do. It would take some real convincing to get me to believe that the average aerotech kit is a good kit. Now don't get me wrong, after being built and finished well, it will be a good flying plane. It just takes so much more work to get it right. The foam was horrible. The top hatch wasn't even close to symmetrical when viewed from the front. The turtle deck had a flat spot on the top center, wings weren't very smooth at all, I did have John replace the stabs due to the tube holes not being the same (meaning the lateral angle in respect to the fuse would be different on both), I ended up using quite a bit of my own balsa for the skins as the wood supplied was hard and heavy...... Again, the final product will fly fine, but as for what you save financially by buying an aerotech, you can save in labor with a better designed kit.....like a carden
I literally had to walk away from this kit many times because so much of it was so very frustrating....and I love a challange. Thing of it is, I nearly felt like I scratch built a plane when I finally finished this one. On more than one occasion, I was tempted to burn it and give the guy his money back for the kit cost.
