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Old Jun 03, 2009, 06:17 AM
TROUT OR THERMALS
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Eureka, Ca
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Fiberglass Layup on a large fuse question... OR...Making big 2 piece sailplane fuses

Howdy all-

I'm just pricing out some materials and was wondering what others use as a layup schedule for a large TD fuselage.

I was just thinking about the layup schedule on big old fuses like the Constellation and the Catalina verses the newer fuses and the like.

I'm getting ready to do a layup on an XC fuse and got to wondering what was typical on an open class TD ship.

Thanks!

Dean
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Old Jun 05, 2009, 08:09 AM
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United States, CO, Denver
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Layup schedule

It really depends on how you designed the fuselage. If it's a minimum sized TD fuselage then you're likely going to need the stiffness of carbon fiber to keep it from flexing all over. How big is it behind the wing trailing edge ? How big is it at the end of the fuselage ?
I add up the weight of the plies and use around 10 oz of glass for the TD ships that I've done plus local reinforcements for the nose and wing carry through area. So that would be three plies of 3 oz fabric plus a top ply of 1 1/2 which is for a fine finish. Since it's intended use is XC and is significantly larger then you may want to use the equivalent of 15-20 oz or so and can consider heavier fabric to get there.
If it's a T-tail then the boom will be under a lot greater load torsionally and you'll have to compensate accordingly. Keep in mind that orienting the fibers linearly 0-90 will give you bending strength and 45-45 will give you the torsional strength. For the tailboom area, at least one of the plies of bidirectional fabric should be laid up 45-45 otherwise known as "a bias layup" .
I'm going to layup a tailboom for my XC ship this weekend. I'll let you know how it goes.

Mike

Quote:
Originally Posted by steelhead

.....I'm just pricing out some materials and was wondering what others use as a layup schedule for a large TD fuselage.....

Dean
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Old Jun 05, 2009, 12:25 PM
yyz
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Dean & Mike,

Can you guys please post some photos of your fuselage work? I'm doing a similar build right now and would love to see some photos.

Mike
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Old Jun 05, 2009, 01:43 PM
Father of Fr3aK, DLG Pilot
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USA, OH, Worthington
Joined May 2002
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I did some repairs (replaced about an 8" section of the boom) on my old constellation and I used three layers of 5.7oz glass. I don't believe the original had any carbon in it but I could be mistaken. The repaired area seemed every bit as stiff as the original. Since it's XC, I'd err on the side of more rather than less.

Tom Siler
Columbus, OH
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Old Jun 05, 2009, 02:04 PM
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Eureka, Ca
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ThermalSeeker-
What are you using for making a tailboom? I'm trying to find a large tapered cylinder to use for a boom mold, but I'm just not finding one. I'm thinking about rolling some plywood and then just glassing and sanding, but seem like so much room for error.

The big Catalina, to me, looked like only 2 layers of 6 ounce and tons of epoxy with a couple pieces of Carbon Tow in them. There was a nose cone, so I know that how a lot of strength was put into the nose. I'm trying to figure out how to make a shippable, 2 piece boom.

Just really interested in what those really large TD ships used for glass and layup.

YYZ-
I should be popping a fuse out tomorrow, I'll post a pic for ya.

For XC, I'm going with 1 ounce skin, and three layers of 6 ounce nose to tail with some extra in the nose for landing stength. The fuse is 80 inches long though. That would give me 19 ounces from nose to tail.

The Catalina is 65 inches long.

Dean
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Old Jun 06, 2009, 12:18 AM
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Dean,
I use the .014 mylar that I bag wings with. Roll it up in the cone shape you want and tape it together. That'll leave a tiny step where the mylar starts or ends depending on your viewpoint. That's the basic shape. Then I roll some thin mylar up over the top of that cone, creating a totally new cone which also bridges that step. That mylar is .0015 thick if memory serves me correctly. Lay the whole mess down on the fabric that you want. Mark a starting point for rolling the fabric on top of the mylar. Roll the mylar across the fabric how ever many times you intend to get the number of wraps you want. Then mark the end point on the fabric where you'll stop rolling to get your 2 or 3 wraps or whatever you want. Cut the fabric on your marks. Wet the fabric out with epoxy. Lay the mylar(s) back at your start point and roll the fabric up on the mylar. Use some scrap mylar, credit card or old hotel key to squeegee out the air bubbles and delaminations and set aside to cure. Once cured you can slide the glass and outside mylar right off the inside mylar. Then comes the bad part, peeling and pulling the inside mylar off your new boom tube. It's never easy.

Your layup sounds like a great starting point. Since you have this earmarked as an inexpensive entry level XC ship will it be rudder and elevator only ? Or do you plan on having some means of glide path too ?

YYZ ,
I may do a thread on alternatives to the lost foam technique, but I'm reluctant to post anything until I'm completely through with my build. I don't get much time to build and the entire process is likely to take many months. So pics at the moment aren't likely to happen.

Mike
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Old Jun 06, 2009, 02:39 AM
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Eureka, Ca
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Fuse layed up, bagged and in the box tonight. This one is a single piece fuse.

3/4 ounce skin
6
6
12K Carbon Tow
6 Ounce inside

Rudder/ Elevator. So far, that combo has worked well. Spoilers would be great for a landing aid, but it weakens the wing and requires more spar and materials.

I still have not settled on a fuse for two pieces for shipping ease, but we will see after this one piece comes out and is flexed. I think the only way to keep shipping costs low will be to have it be a two piece glass fuse.

Mike- thanks for the info on how you do booms. I'm trying to decide what to do on the fuse for 2 pieces. So far, I might try and get a guy to lathe one up for me. We'll see. I like the idea of rolling plywood or sheet plastic. I think I could do that, then fill with expanding foam and make a mold from it.

Fun stuff. Laying up a fuse this big really does take 2 people.

Right now, The 4 mil sheet plastic is holding 10 in HG and it's 118 degrees

Carbon fiber in there sure is sexy!
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Old Jun 06, 2009, 01:13 PM
yyz
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Mike,

This is a great idea. I'm going to try this before going through the expense and trouble of having a huge mandrel built. Excellent tip!

Thanks,

Mike



Quote:
Originally Posted by ThermalSeeker
Dean,
I use the .014 mylar that I bag wings with. Roll it up in the cone shape you want and tape it together. That'll leave a tiny step where the mylar starts or ends depending on your viewpoint. That's the basic shape. Then I roll some thin mylar up over the top of that cone, creating a totally new cone which also bridges that step. That mylar is .0015 thick if memory serves me correctly. Lay the whole mess down on the fabric that you want. Mark a starting point for rolling the fabric on top of the mylar. Roll the mylar across the fabric how ever many times you intend to get the number of wraps you want. Then mark the end point on the fabric where you'll stop rolling to get your 2 or 3 wraps or whatever you want. Cut the fabric on your marks. Wet the fabric out with epoxy. Lay the mylar(s) back at your start point and roll the fabric up on the mylar. Use some scrap mylar, credit card or old hotel key to squeegee out the air bubbles and delaminations and set aside to cure. Once cured you can slide the glass and outside mylar right off the inside mylar. Then comes the bad part, peeling and pulling the inside mylar off your new boom tube. It's never easy.

Your layup sounds like a great starting point. Since you have this earmarked as an inexpensive entry level XC ship will it be rudder and elevator only ? Or do you plan on having some means of glide path too ?

YYZ ,
I may do a thread on alternatives to the lost foam technique, but I'm reluctant to post anything until I'm completely through with my build. I don't get much time to build and the entire process is likely to take many months. So pics at the moment aren't likely to happen.

Mike
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Old Jun 06, 2009, 10:19 PM
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Mike,
You're welcome. The neat part is that you can use the .014 mylar over and over again. So once you've fussed with making the cone the exact size that you want it's there for next time too.

Dean,
I changed gears slightly this weekend and have decided to make my fuse in one piece. So there were no tailbooms made this weekend. If carving the full fuse doesn't work out as I'd like, I can always cut it in half and go back to pod and boom. How did your project progress this weekend ?

Mike


Quote:
Originally Posted by yyz
Mike,

This is a great idea. I'm going to try this before going through the expense and trouble of having a huge mandrel built. Excellent tip!

Thanks,

Mike
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Old Jun 07, 2009, 11:10 PM
The Truth is Not Forgotten
Hotchkiss Co.
Joined Feb 2008
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I'm in the process of building a BoT +2ft on the wing and will go with pod an boom ,boom is the bottom end of a deep sea fishing pole 3\4in od way stout and lite too, other wise, I was going to go lost foam with a golf shaft sandwiched between 1in foam to keep the fuse straight as I shapped it, might do that next
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Old Jun 08, 2009, 06:02 AM
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Eureka, Ca
Joined Sep 2002
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Mike-

I taped up the seems, assembled the mold halves and hot boxed the fuse for several hours and POP! Out comes a nice glass fuse. I still have not removed all the flashing or washed off the PVA, but everything looks great.

So far, the fuse seems more than strong enough with the 3/4 ounce skin and three layers of 6 ounce with some carbon tow sandwiched in. None of the layers were angled. I am very please with the stiffness (seems stronger than needed) and we will see how it did on weight tomorrow.

Pete- Excellent! there seems to always be another use for golf shafts. Would love to see how it turns out.


I might have photos tomorrow. I love the way the carbon looks in there

Dean
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Old Jun 08, 2009, 08:30 AM
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Seam during layup or secondary ?

Did you layup the fuse halves with an overlap for the seams and assembled it all wet or did you cure each fuse half independently and then wet seam them to connect them after the first cure ?

Congrats on finding a layup schedule that you like and for getting a good fuselage out of the mold.

I epoxied a couple boards together to start carving my XC fuselage but it will be a couple weeks before I can get back to it again. Hopefully the boards I chose will stay straight after carving.

Mike


Quote:
Originally Posted by steelhead

.......I taped up the seems, assembled the mold halves and ...........
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Old Jun 09, 2009, 12:59 AM
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Mike-

Cured each side separate, then used pieces of 1 inch wide glass to tape the seams. Did the "slide" method, just like if I had used the overlap method. On one side of the fuse I taped the bottom, on the other side of the fuse I taped the top, then slid the two together making sure the seem was in position with a popsicle stick between the two halves before final lowering. Screws were loosley tightened. Then the seems were pressed down with a long, rounded stick. Finally, the screws were tightened down all the way.

I actually used 2 layers of glass for the seams with a little thickener and some microballoons to fill gaps. The base of the nose has 2 extra layers of 2 inch wide glass for landing strength and for the towhook.

These pics are what the fuse looks like just out of the molds, havent even cleaned off the PVA yet. I will wash after I sand down the mold line.

Fun stuff!

Dean
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Old Jun 09, 2009, 04:34 AM
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I found this info on the Houston Hawk site-

1.5 oz fiberglass used the entire length,
6 oz fiberglass used from nose to the middle of the wing,
6 oz fiberglass used in the wing area,
6 oz fiberglass around wing saddle area
strip of Kevlar used from the wing TE to just past the fin LE
6 oz fiberglass used the entire length

http://www.houstonhawks.org/Projects.../FuseLayUp.htm

The Condor Fuse is a small, thin TD fuse, but interesting to see that it uses a Kevlar strip and 6 ounce for the tailboom.

Dean
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Old Jun 09, 2009, 06:30 PM
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That's a beautiful fuselage ! Congrats !

I like the sub fin idea too. If you're doing a flying stab it'll have plenty of strength yet you can do a light built up Vertical fin above it and have a built up rudder. You'll have strength where you need it and lightness everywhere else. An ounce saved back there will save you four more in the nose.

Kevlar is a strange critter. It's better than carbon fiber in tensile strength yet as bad as fiberglass in compressive strength. Modulus (stiffness) is better than fiberglass but not much. Toughness is as good as it gets. So my guess is that the kevlar is there to stop tears in the fiberglass at the wing junction in case of ground loops.

Mike



Quote:
Originally Posted by steelhead
....The Condor Fuse is a small, thin TD fuse, but interesting to see that it uses a Kevlar strip and 6 ounce for the tailboom.....

Dean
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