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How do they do composites.
Just looking for a high level explanation of how manufactures produce the new - light weight - Pattern fuselages. I just haven't figured out how they lay up balsa in the mold without using a ton of resin; or, how they vacuum bag a fuselage without collapsing it.
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RE: How do they do composites.
There have been several threads in here on the subject. I have tried forming balsa by wetting it then forming it around a male plug, using vacuum assist. This preformed 1/16" balsa skin was then layed up over 1 oz fabric in a female mold. This was for a turtle deck that had only one axis of curvature, and was not easy. As far as not crushing foam goes, I have vacuum bagged several foam wings, and this is not an issue since this application does not require more than about 6-8" Hg vacuum. I doubt that a molded composite wing requires much more.
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RE: How do they do composites.
I just haven't figured out how they lay up balsa in the mold without using a ton of resin; or, how they vacuum bag a fuselage without collapsing it.
Imagine a female mold for each half of the fuselage. The resin/cloth is laid in first. The balsa skin is then laid in. The vacuum bag is applied and forces the composite material onto the mold surfaces. When cured the halves arre removed and joined along the seam, maybe in the mold halves clamped together. Ed S |
RE: How do they do composites.
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To give you the idea. This is not a fuselage but the same principle is apply. This is my first attempt doing a mold. Not perfect but I'm happy with the results. There is much more info here. Do a search and you will find lots. In a whole rainy weekend with not much to do I decide to do it. This is the splash of an AW Hawk jet kit flap. I use the original flap as a plug and make a female mold of the LE in order to replicate the Flaps Vanes. Glass stick to the parting board even with 8 coats of wax and PVA. Next time I will use some clear tape or monokote in the parting board. For fuselages after the female molds are made is where it comes what Ed is describing. Wax, PVA, Paint, glass cloth, balsa core and another glass cloth. All this get in to vacuum bag.
Ed thanks for all your tips and posts. Alex |
RE: How do they do composites.
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I'm not a manufacturer but I'll try and explain the process I use. I've made about 5 glass, balsa fuselages and seem to learn something everytime. But here is how I do it.
1. I use 1/32 balsa and glue it together with medium CA then sand the seams to a smooth finish. (wood glue will not hold up to ammonia water) 2. Using a pattern I made off the inside of my mold, I cut the balsa the shape of the fuse. 3. I wet the balsa skins with ammonia water then bag them in the mold to form it, leaving it in the bag for 24 hours. 4. After the balsa skins are dry, I seal the wood with hairspray on both sides so they will not soak up a lot of resin. The hairspray will somewhat relax the formed skins so I lay them back in the mold while the hair spray dries. 5. Wax and PVA the molds, then prime them with PPG epoxy primer 6. First layer in the mold is 2oz cloth from nose ring to tail post and 5oz carbon from nose ring to slightly past the chin cowl 7. next lay the wood then glass it with 1.4 oz cloth to complete the sandwich. 8. Cover with peel ply, then release film and finally breather cloth. ( use the release film so the peel ply doesn't stick to the breather cloth) 9. Put it int he bag for 9 to 10 hours pulling 8 to 9hg. Attached are some pics of my latest 2 meter pattern design. This fuse is quite tall at 14". The total fuse weight is 31oz including canopy and chin. Hope this helps! |
RE: How do they do composites.
Thank you everyone, you've all more than answered my question. I was missing that today's balsa composite fuselages are still formed in half's than joined, just like the fuselages of yesteryear and second the balsa is encapsulated with cloth on both sides. Thanks so much.
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RE: How do they do composites.
ORIGINAL: tschmidt I'm not a manufacturer but I'll try and explain the process I use. I've made about 5 glass, balsa fuselages and seem to learn something everytime. But here is how I do it. 1. I use 1/32 balsa and glue it together with medium CA then sand the seams to a smooth finish. (wood glue will not hold up to ammonia water) 2. Using a pattern I made off the inside of my mold, I cut the balsa the shape of the fuse. 3. I wet the balsa skins with ammonia water then bag them in the mold to form it, leaving it in the bag for 24 hours. 4. After the balsa skins are dry, I seal the wood with hairspray on both sides so they will not soak up a lot of resin. The hairspray will somewhat relax the formed skins so I lay them back in the mold while the hair spray dries. 5. Wax and PVA the molds, then prime them with PPG epoxy primer 6. First layer in the mold is 2oz cloth from nose ring to tail post and 5oz carbon from nose ring to slightly past the chin cowl 7. next lay the wood then glass it with 1.4 oz cloth to complete the sandwich. 8. Cover with peel ply, then release film and finally breather cloth. ( use the release film so the peel ply doesn't stick to the breather cloth) 9. Put it int he bag for 9 to 10 hours pulling 8 to 9hg. Attached are some pics of my latest 2 meter pattern design. This fuse is quite tall at 14''. The total fuse weight is 31oz including canopy and chin. Hope this helps! I like the pattern fuse too. MattK |
RE: How do they do composites.
Hi Matt,
National Balsa now has contest grade 1/32 balsa. Todd |
RE: How do they do composites.
ORIGINAL: tschmidt Hi Matt, National Balsa now has contest grade 1/32 balsa. Todd I haven't done business with National is about 2 years. This must be fairly new. 1/32" is plenty strong for our application if the socket is extended just a couple inches into the foam so I've been looking for it. Great news MattK |
RE: How do they do composites.
ORIGINAL: avicom To give you the idea. This is not a fuselage but the same principle is apply. This is my first attempt doing a mold. Not perfect but I'm happy with the results. There is much more info here. Do a search and you will find lots. In a whole rainy weekend with not much to do I decide to do it. This is the splash of an AW Hawk jet kit flap. I use the original flap as a plug and make a female mold of the LE in order to replicate the Flaps Vanes. Glass stick to the parting board even with 8 coats of wax and PVA. Next time I will use some clear tape or monokote in the parting board. For fuselages after the female molds are made is where it comes what Ed is describing. Wax, PVA, Paint, glass cloth, balsa core and another glass cloth. All this get in to vacuum bag. Ed thanks for all your tips and posts. Alex If you use PVA properly it will always come apart but PVA "must be sprayed on" in a thick layer like a layer of plastic. Wiping it on is a waste of time. Jim Fox |
RE: How do they do composites.
Jim the sticky problem was only in the parting board. The mold came off the part very easy with no work at all. But yes the walls of the mold that was held on the parting board was different story, They came off with no much effort but they do stick to the parting board. I guess cause I did not seal the parting board prior to wax. For me make the first part I'm very happy with the results. But I'm open to listen all opinions to make it better next time. Thanks for your comments.;)
Alex |
RE: How do they do composites.
I use clear packing tape over Masonite, wax it and will not cause you any problems. I've used the technique for 30+ years in the glass business. PVA after waxing if you like.
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RE: How do they do composites.
ORIGINAL: avicom Jim the sticky problem was only in the parting board. The mold came off the part very easy with no work at all. But yes the walls of the mold that was held on the parting board was different story, They came off with no much effort but they do stick to the parting board. I guess cause I did not seal the parting board prior to wax. For me make the first part I'm very happy with the results. But I'm open to listen all opinions to make it better next time. Thanks for your comments.;) Alex Some of my clam shell molds are backed up with wood. I normally wax the wood adjacent to the mold surfaces,,,there is almost always epoxy squeeze out from the clam shell. Epoxy just peels off plain, upfinished wood as long as Part All is used first |
RE: How do they do composites.
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Nope. This is the one I used. TR Mold Release H-T.
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RE: How do they do composites.
ORIGINAL: MTK ORIGINAL: tschmidt I'm not a manufacturer but I'll try and explain the process I use. I've made about 5 glass, balsa fuselages and seem to learn something everytime. But here is how I do it. 1. I use 1/32 balsa and glue it together with medium CA then sand the seams to a smooth finish. (wood glue will not hold up to ammonia water) 2. Using a pattern I made off the inside of my mold, I cut the balsa the shape of the fuse. 3. I wet the balsa skins with ammonia water then bag them in the mold to form it, leaving it in the bag for 24 hours. 4. After the balsa skins are dry, I seal the wood with hairspray on both sides so they will not soak up a lot of resin. The hairspray will somewhat relax the formed skins so I lay them back in the mold while the hair spray dries. 5. Wax and PVA the molds, then prime them with PPG epoxy primer 6. First layer in the mold is 2oz cloth from nose ring to tail post and 5oz carbon from nose ring to slightly past the chin cowl 7. next lay the wood then glass it with 1.4 oz cloth to complete the sandwich. 8. Cover with peel ply, then release film and finally breather cloth. ( use the release film so the peel ply doesn't stick to the breather cloth) 9. Put it int he bag for 9 to 10 hours pulling 8 to 9hg. Attached are some pics of my latest 2 meter pattern design. This fuse is quite tall at 14''. The total fuse weight is 31oz including canopy and chin. Hope this helps! I like the pattern fuse too. MattK do you guys think this layup would be good for a hollow wing as well? |
RE: How do they do composites.
BTW, I use Part All wax and PVA and I've never had problems with masonite parting planes.
Tim |
RE: How do they do composites.
ORIGINAL: flyingtheoldones do you guys think this layup would be good for a hollow wing as well? The Science Channel did a very quick video review of BVM composite wing construction. A jet wing has much more structure and strength in it than we would need in a pattern wing but the elements of the overall process were well outlined in that review |
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