Fuse Bagging
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Fuse Bagging
Not sure if this is an appropiate thread title or not, but I have been doing a little experimenting with fuse bagging and wanted to share.
Basically, I am fiberglassing, and adding a little carbon to the inside of both fuse sides on my Q500 Seekers. My first attempt came out quite heavy, as I used a lot of carbon 2.4 oz fabric.
This go around I tried to go as light as possible. I started with a solid 1" thick, straight board which I wrapped with Coated freezer paper (please test your epoxy with the coated freezer paper, some will stick, most will not). I took both inside fuse halves and laid up 3/4 oz fiberglass to each half on top of the freezer paper (epoxy and glass up). After the glass was wet out and scraped nearly dry, I added some CF laminate (.007) to the rear just in front of the tail for strength. I then lined up the 1/64" ply doublers and carefully placed them perfectly over each fuse half. Once everything was scraped and lined up well, I put down a layer of perforated peel ply, and then some breather cloth. The perforated peel ply allows the epoxy to be pulled through the holes into the breather sucking up nearly all of your excess epoxy.
Try to use as little epoxy as possible, if you use too much near the alignment slots or edges it takes more time to clean up the halves after everything is dry.
I then placed (in this order) the wood board, with coated freezer paper, the wood fuse sides, glass, epoxy, doublers, CF, Peel Ply, and breather, into the bag and sucked as much pressure as my pump could pull (about 20" of mercury). If you want to save your breather cloth for future use, you could substitue any of the "better/thicker" paper towels available.
Basically, I am fiberglassing, and adding a little carbon to the inside of both fuse sides on my Q500 Seekers. My first attempt came out quite heavy, as I used a lot of carbon 2.4 oz fabric.
This go around I tried to go as light as possible. I started with a solid 1" thick, straight board which I wrapped with Coated freezer paper (please test your epoxy with the coated freezer paper, some will stick, most will not). I took both inside fuse halves and laid up 3/4 oz fiberglass to each half on top of the freezer paper (epoxy and glass up). After the glass was wet out and scraped nearly dry, I added some CF laminate (.007) to the rear just in front of the tail for strength. I then lined up the 1/64" ply doublers and carefully placed them perfectly over each fuse half. Once everything was scraped and lined up well, I put down a layer of perforated peel ply, and then some breather cloth. The perforated peel ply allows the epoxy to be pulled through the holes into the breather sucking up nearly all of your excess epoxy.
Try to use as little epoxy as possible, if you use too much near the alignment slots or edges it takes more time to clean up the halves after everything is dry.
I then placed (in this order) the wood board, with coated freezer paper, the wood fuse sides, glass, epoxy, doublers, CF, Peel Ply, and breather, into the bag and sucked as much pressure as my pump could pull (about 20" of mercury). If you want to save your breather cloth for future use, you could substitue any of the "better/thicker" paper towels available.
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RE: Fuse Bagging
After I cleaned up the edges with sandpaper, and cut out the alignment tabs with a xacto, I put them on the scale and measured in grams.
This is both fuse sides after glassing at 54 grams.
The second picture is two fuse sides and doublers not glassed. I weighed 3 differenet sets of fuse sides and doublers, and all unglassed kit sides came in between 46-48 grams.
Bottom line is that I added no more than 6-8 grams and SIGNIFICANTLY added to the stiffness of the fuse sides. Well worth it in my opinion.
Thoughts???
This is both fuse sides after glassing at 54 grams.
The second picture is two fuse sides and doublers not glassed. I weighed 3 differenet sets of fuse sides and doublers, and all unglassed kit sides came in between 46-48 grams.
Bottom line is that I added no more than 6-8 grams and SIGNIFICANTLY added to the stiffness of the fuse sides. Well worth it in my opinion.
Thoughts???
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RE: Fuse Bagging
Here is the final product.
Alot stronger, with not much work. I originally was just looking for a way to get away from using CA to glue the doublers down because of bad allergies I have to it. I am quite pleased with this fuse, just wish it was for me.
Alot stronger, with not much work. I originally was just looking for a way to get away from using CA to glue the doublers down because of bad allergies I have to it. I am quite pleased with this fuse, just wish it was for me.
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RE: Fuse Bagging
ORIGINAL: daven
I am quite pleased with this fuse, just wish it was for me.
I am quite pleased with this fuse, just wish it was for me.
Just one question: Do you find that the pre-laminated fuselage sides are hard to bend when gluing them to the formers? Seems like to really pre-fab them, you'd want to use a form that presses them into their final shape as the epoxy is curing ... especially if you're trying for that "Coke bottle" effect in the aft section.
But, notwithstanding any of that ... looks great! Thanks for sharing!
Duane Gall
RCPRO
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RE: Fuse Bagging
Duane, I don't use a "coke" bottle design like many others, it pretty much shapes itself on the location and width of the formers. I don't remember the last one being an issue, the tabs on the formers and tray pretty much straighten everything out. I haven't built a "banana" since I started using the tabs and slots.
I really like your idea of baggin it against a form in the exact shape of the fuse. However, that would be a little trickier. I'll have to noodle that one over.
I really like your idea of baggin it against a form in the exact shape of the fuse. However, that would be a little trickier. I'll have to noodle that one over.
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RE: Fuse Bagging
This is much easier than building a hollow composite wing, but that is where the building idea came from. I've been building hollow composite wings for a couple years, and really find little enjoyment in that process. I have one started that I hope to finish in a week or so where I used no PVA and tried a little painting in the mold with wax only. Actually, molded wings would be funner if you weren't constantly trying to cut weight.
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RE: Fuse Bagging
Thinking out loud here. Why not use a little heavier glass - 3 oz or so - and leave the 1/64 ply stiffeners off the sides. Seems like
it would be one less step, maybe a few grams less weight and have the same end result. The end result being a stiff
fuselage. Put the glass on the bias. I make spars for wings out of 1/8" vertical grain balsa, bag with 2 layers of glass on
each side of the balsa. 1 layer on the warp & weave, the 2nd layer on the bias. With using peel ply to soak up the excess
resin, it gains very little weight and makes an amazingly strong piece of lumber.
brad
it would be one less step, maybe a few grams less weight and have the same end result. The end result being a stiff
fuselage. Put the glass on the bias. I make spars for wings out of 1/8" vertical grain balsa, bag with 2 layers of glass on
each side of the balsa. 1 layer on the warp & weave, the 2nd layer on the bias. With using peel ply to soak up the excess
resin, it gains very little weight and makes an amazingly strong piece of lumber.
brad
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RE: Fuse Bagging
Not a bad idea at all Brad. Dropping the 1/64" would be fine with me, its one of the more expensive cut parts of the kit.
I fit the formers and servo tray tonight and cracked the fuse at the rear former squeezing it all together. I'm really not sure if I can use the right side, pics to come shortly.
I fit the formers and servo tray tonight and cracked the fuse at the rear former squeezing it all together. I'm really not sure if I can use the right side, pics to come shortly.
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RE: Fuse Bagging
Heres the damage, not sure I can save this fuse side. It doesn't want to bend properly with the crack.
Here are some pictures. I'm going to try and glue the crack with alphatic resin and try to rebend in the morning.
Here are some pictures. I'm going to try and glue the crack with alphatic resin and try to rebend in the morning.
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RE: Fuse Bagging
Actually, it may be ok. It looks crooked as hell without the wing hold down blocks in place. Although, with them in, it straightens up very nice.
I think it is ok.
I think it is ok.
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RE: Fuse Bagging
Dave,
Dumb question, but has anyone ever attempted to create a reverse mold and just lay it up? Or do you need to have wood in the mix?
Sorry, still learning here.
Dumb question, but has anyone ever attempted to create a reverse mold and just lay it up? Or do you need to have wood in the mix?
Sorry, still learning here.
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RE: Fuse Bagging
I have done this a few times after Dave and talked about it over some cocktails one night in his shop.. I don't pull anywhere near the 20" does but still the end weight seems minimal.. I have also seen the cracking issue a couple times with and without the inside glass.. I have started to think that it has more to do with the particular piece of wood than it does the glassing..It is amazing how stiff the assembly gets even before the top and bottom sheeting is applied...
For 2006, only one of my Seekers doesn't have the inside glass/CF.. First race is a little more than a week away and I was in a hurry
For 2006, only one of my Seekers doesn't have the inside glass/CF.. First race is a little more than a week away and I was in a hurry
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RE: Fuse Bagging
I think this fuse is ok, but I will take precautions going forward.
All I really needed to do was spray the balsa with a little water/alchohol mixture a bit before bending. The air is quite dry this time of year and I think that had a lot to do with the cracking.
Basically I rushed it, I still think this is a good idea......
All I really needed to do was spray the balsa with a little water/alchohol mixture a bit before bending. The air is quite dry this time of year and I think that had a lot to do with the cracking.
Basically I rushed it, I still think this is a good idea......
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RE: Fuse Bagging
Dave,
A comment on that fuse crack. From the picture you can see the crack(s) propagating from sharp corner to sharp corner of the bulkhead tab cutouts. The fact that those cutouts have sharp 90ΒΊ corners has introduced large stress concentrations at each corner. If your "laser cut guy" could put the smallest radius in those corners that fuse section would be much less susceptible to cracking and or a failure. In general, from a structural stand point, sharp corner should be avoided when possible.
Tom Hegland
37c
A comment on that fuse crack. From the picture you can see the crack(s) propagating from sharp corner to sharp corner of the bulkhead tab cutouts. The fact that those cutouts have sharp 90ΒΊ corners has introduced large stress concentrations at each corner. If your "laser cut guy" could put the smallest radius in those corners that fuse section would be much less susceptible to cracking and or a failure. In general, from a structural stand point, sharp corner should be avoided when possible.
Tom Hegland
37c
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RE: Fuse Bagging
Good point Tom, thats something I can do myself pretty easily, rather than paying the cutter to do it.
Reno,
I'm not sure I really understand your question about a reverse mold. There are plenty of people molding fiberglass fuses for quickie, I personally find the wood (normally) easier to work with, especially with the jigsaw pieces. Still fiberglass the plane and paint though, just easier for me to do it that way than making a mold. I hate plugs.
Reno,
I'm not sure I really understand your question about a reverse mold. There are plenty of people molding fiberglass fuses for quickie, I personally find the wood (normally) easier to work with, especially with the jigsaw pieces. Still fiberglass the plane and paint though, just easier for me to do it that way than making a mold. I hate plugs.
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RE: Fuse Bagging
Dave,
Another thing you might want to try, even though it will add a little weight is to put down some 3/4 ounce cloth on the board before you put the sides down. You will want to use minimal epoxy, as it will not get sucked out. But you will equalize the surface properties of the inside and outside. Since you are glassing and painting anyway, you could probably avoid having to glass the sides, just the top and bottom. A little filler at the tab notches since you wouldn't be glassing over them. You would have a really stiff fuselage.
If you are going to continue experiementing, you may want to put some .014 mylar down on your 1" board so you don't have to mess with wax paper. Another option is to find a piece of 1'-2' x 3'-4' untempered glass in .375" to .5". It makes a great flat molding surface. I found a 2'x4' piece at Michaels craft shop for $25. A lot of glass houses have cut-offs or blemishes. A potential problem with the glass in your application is the weight and getting it into the bag.
Got the last coat of primer on the Seeker tail parting plate tonight. I know the plug was a lot of work, but I'm excited about how it should turn out.
Another thing you might want to try, even though it will add a little weight is to put down some 3/4 ounce cloth on the board before you put the sides down. You will want to use minimal epoxy, as it will not get sucked out. But you will equalize the surface properties of the inside and outside. Since you are glassing and painting anyway, you could probably avoid having to glass the sides, just the top and bottom. A little filler at the tab notches since you wouldn't be glassing over them. You would have a really stiff fuselage.
If you are going to continue experiementing, you may want to put some .014 mylar down on your 1" board so you don't have to mess with wax paper. Another option is to find a piece of 1'-2' x 3'-4' untempered glass in .375" to .5". It makes a great flat molding surface. I found a 2'x4' piece at Michaels craft shop for $25. A lot of glass houses have cut-offs or blemishes. A potential problem with the glass in your application is the weight and getting it into the bag.
Got the last coat of primer on the Seeker tail parting plate tonight. I know the plug was a lot of work, but I'm excited about how it should turn out.
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RE: Fuse Bagging
Glassing both sides is a good option, I think I will give it a try on the next go around. Considering I don't bag the outside when glassing, laying it up on Mylar wouldn't add any extra weight.
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RE: Fuse Bagging
I'm going to use the mylar and epoxy system on my seeker fuselages- I still have my press from my teamrace days- worked very successfully on those teamracer components and will certainly do the same on the fuselage items- I had always used CIBA GEIGA k36 but may revert back to the WEST resin for this time. I'll use .75 oz glass cloth and will be more than adequate as long as the penetration of the epoxy is good. Highly stressed areas will be double layered. kind regards trevor henderson, nz[8D]