fiberglass question
I did a few searches and read a few articles, but could not find any detailed info on this. I presume that wrapping the part would be "stronger", but only if the balsa LE on the control surface was edge glued to the control surface so that the fiberglass cloth covered both the sheeting and LE. As opposed to having the sheeting installed over all the internal pieces (ribs, LE, and TE), in this condition the fiberglass cloth would be epoxied to just sheeting. I hope this makes sense.
I did read one article where the wing TE had the cloth applied after fiberglassing the top and bottom of the wing. I just could not see what the advantage was to applying the cloth using this method. The cloth does not really do anything, it's not wrapped around, just applied to the LE of the wing.
I wouldn't try and glass the TEs either,, not worth the trouble, just epoxy and sand it smooth is what I always do
good luck
after it dry's over night I gently sand the edge to remove the excess glass with 220,the lighter grit only removes the scrap cloth leaving a small layer of resin and cloth at the trailing edge, the leading edge should be round enough to allow the cloth to wrap around the curve, this should allow for a slight overlap at the LE.
I then glass the other side same method, 2 coats, over night dry, lightly remove excess,this leaves a decent amount of resin and cloth at the TE to protect it.
now that the excess cloth is cleaned up I give the object another 3-5 coats of clear WB poly as needed to fill the weave,I use Varathane Diamond finish WB poly so you can do several coats if there done within a hours time for each coat, if left longer then it needs to dry over night and a light sanding of the surface for the next coats is needed, this helps make for a smoother surface with the WBP any way, so I usually do 3 coats then a sanding before applying another couple of coats,I only apply enough to fill the weave and give the surface a smooth feel,usually 6 coats gets the results I am after but +or- a coat is to be expected depending on how well I sand it.
there is usually plenty of material built up on the TE to protect the area and allow for painting, my P 47 wing right after peeling the paint masks and my spit both glassed this way .
yea gray i'll try that out, it makes sense that it would blend in
dan
I've always used polyester resin for glassing (which is a pain to sand and use) but it yields a very durable surface. I happen to have some Deft laquer sanding sealer and am just starting to finish a model and might try the sanding sealer. My question is: does using sanding sealer yield the hard, durable finish that you get with resin? I can see that it would be much faster and easier and certainly doesn't smell any worse than resin.
What really shocked me was how much easier it was to sand - effortless. Definitely lighter than resin too. I'm sure it isn't quite as durable as glass/resin, but I'll gladly spend the time on repairs (if needed) down the road (runway would be more appropriate). It yields a smooth as glass surface too.
I wasn't looking forward to the task of glassing my current project (a .60 sized plane that has almost no flat surfaces). With this technique I can't wait to start. Just a bit of final sanding and I can get the entire plane covered in a couple evenings and get it painted. I'll be done painting sooner than I would have had it glassed and sanded using resin.
Many thanks for the tip. I'll reserve using resin for times when I really need the extra strength or fuel proofing that resin provides. I'll probably do a test to see how much strength resin really provides vs. the added weight. I'll let you know if the results are really significant.
The last plane I glassed had a flame-out at the worst possible time and overshot the runway and hit a tree about a third of the way out from the wings root 8 feet off the ground. This was a heavy .60 size plane and I expected to have nothing left. Imagine my surprise when the only damage was a crushed LE and sheeting. This was partly due to the balsa sheeted foam wing (and the glass/resin bonding everything together). It would have had much worse damage had it been monocoated without the glass/resin and/or a built-up wing.
I started using polyurethane (Gorilla glue) to sheet foam and it really works great. I sheet everything and then cut out the ailerons etc. which perfectly match the wing. Easier and lighter than built-up and faster too. Too bad I love to build, so I'm still building a lot of my wings.
Thanks for the tip, Tom.
My last plane I did was the 80 inch 1/4 scale Sukhoi 29. Pretty big plane. Glassing added almost one pound of weight, about the same as covering. The paint added about one pound too. Not too bad for a plane that size. After the Deft has cured for about 3 days it is every bit as stiff as resin. If you want it to feel like resin does then keep adding the deft. It is thinner then resin, like resin it doesn't chip so you get very little hanger rash. If you crash then just like resin you will have a lot of small parts clinging to the glass. Glassing adds strength to the air frame, it helps a lot against things like vibration but doesn't help at all in a crash.
can i get the deft sealer at lowes or h depot? sounds like its worth a try.
This time I used 3M fiberglass resin from Home Depot. Worked fine, sands easy enough, in fact I sanded right through the cloth in a few places where I guess I had high spots. No biggie, just going to wipe on a coat of resin.
I’m going to try Gray Beards Deft method next time. Only problem is that lacquer is not available in CA, so guess I’m going to have to take a road trip to Vegas. Now there is a new reason to visit Vegas!
Been away from my computer for a few days. Thanks for the responses. I did just cut away most of the fiberglass, and then sand it down to the edge. This is my second fiberglass job, but the first time with resin. My first attempt I used the WB poly, and for some reason it bubbled up in a few places when the plane sat out in the hot sun. This has been discussed a few times on here, and in my case the plane sat for almost a year after I fiberglassed it until I painted it, so it had plenty of time to out gas. I think the sanding sealer that I used to seal the balsa just couldn’t handle the heat.
This time I used 3M fiberglass resin from Home Depot. Worked fine, sands easy enough, in fact I sanded right through the cloth in a few places where I guess I had high spots. No biggie, just going to wipe on a coat of resin.
I’m going to try Gray Beards Deft method next time. Only problem is that lacquer is not available in CA, so guess I’m going to have to take a road trip to Vegas. Now there is a new reason to visit Vegas!
How long did you let the model sit, after the sanding searler, before the poly ?
If you could still smell the sanding sealer, it wasn't dry. If your poly was applied over it, bubbles would occur when you place the model in the sun.
The sanding sealer will handle the sun, but make sure that it is completely dry before you apply anything over it.
The same is true with the poly. Give it plenty of time to dry before you put anything over it.
Been away from my computer for a few days. Thanks for the responses. I did just cut away most of the fiberglass, and then sand it down to the edge. This is my second fiberglass job, but the first time with resin. My first attempt I used the WB poly, and for some reason it bubbled up in a few places when the plane sat out in the hot sun. This has been discussed a few times on here, and in my case the plane sat for almost a year after I fiberglassed it until I painted it, so it had plenty of time to out gas. I think the sanding sealer that I used to seal the balsa just couldn’t handle the heat.
This time I used 3M fiberglass resin from Home Depot. Worked fine, sands easy enough, in fact I sanded right through the cloth in a few places where I guess I had high spots. No biggie, just going to wipe on a coat of resin.
I’m going to try Gray Beards Deft method next time. Only problem is that lacquer is not available in CA, so guess I’m going to have to take a road trip to Vegas. Now there is a new reason to visit Vegas!
How long did you let the model sit, after the sanding searler, before the poly ?
If you could still smell the sanding sealer, it wasn't dry. If your poly was applied over it, bubbles would occur when you place the model in the sun.
The sanding sealer will handle the sun, but make sure that it is completely dry before you apply anything over it.
The same is true with the poly. Give it plenty of time to dry before you put anything over it.
One thing though, at first it only blistered where the surfaces are sealed on the other side, or were solid/thick surfaces. For example, it blistered on top of the wing where the split flaps are painted on the other side of the top of the wing, and at the wing tips where the is a solid block of balsa. It was this way for a long time, but now there are several very small blisters appearing in other places.
I cut away one of the blisters, and everything (paint, primer, fiberglass, and sealer maybe?) pealed away from the wood in one big solid paint chip.
The "silver lining" is that when I scrape the wing tips on landing, I don't feel so bad . It's a heavy plane and hard to land, but it makes for a good "warbird trainer".
can i get the deft sealer at lowes or h depot? sounds like its worth a try.
Read and copied your instructions above, but just wanted to verify one thing. You use just the sanding lacquer sealer for all of the coats, including the last coats mixed with talc or baby powder? You do not use the sanding lacquer at all? Is that correct?
I did some experiments with the light glass/deft technique and my old glass/resin to determine strength and weight. I also compared them to monocoat for a frame of reference.
I used a powder scale that measures in grains because my 4” X 4” test pieces were so light I couldn’t get significant measurements on the electronic scale. I converted to ounces but I’m just going to give relative values. My paint could have been lighter too. This was 4 coats of lacquer. I think the resin would also be heavier in practice since I was able to sand it down farther than might be practical on curved surfaces. The deft is faster, easier and you don’t have to worry about pot life.
These are not meant to be absolute values. I just wanted to get an idea of what to expect.
These numbers are for materials only (no wood) for a single test piece. Due to different amounts and materials (or math errors) the results could differ.
Monocoat = .22 oz per square foot.
Glass/deft = .36 oz per square foot. With paint = .67 oz per square foot.
Glass/resin = .78 oz per square foot. With paint = 1.09 oz per square foot.
I knew the deft would be lighter than resin. Half the weight is not bad. Since you can’t paint over monocoat that number is meaningless really. I’ll have to try silkspan/dope sometime just for grins.
I tested the strength by dropping lead weights from various heights. The resin is definitely stronger (perhaps as much as twice as resistant), but the glass/deft protects well too. Another coat or two might help, but I’m not sure it’s worth the weight.
Unless I really need the protection or fuel proofing that resin provides I will never use it for glassing again – the deft is so much easier to work with and lighter too. My thanks to Gray Beard for this tip.