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Old Feb 05, 2013, 04:39 AM
Flying Low
cbarnes0061's Avatar
United States, VA, Petersburg
Joined Mar 2012
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Help designing a profile fuse.

Ok guys I need a little help over past couple of months I have aquirred to crashed 50cc size airframes. Both of them the fuse is destroyed. The wings are from a sukhoi su26 and the tail feathers are off of one of the Carden Yak54 by hanger 9. What I'm looking to do is use the wings and tail feathers to build a profile plane. All I would have to do is fix minor damage on the LE of one of the su26 wings and build me a fuse but I'm unsure as to the size the fuse would need to be. I'm thinking loosing the wieght of the full fuse I could power it with either the DLE30 or 35RA. I'm not looking for anything to do crazy 3D just something fun to burn up the sky with. Each wing panel is 40" long so that is putting the wingspan I would say in the 82" range. Let me know what you think. How thick should the fuse be? How long?
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Old Feb 06, 2013, 08:32 PM
Rob H
rph1225's Avatar
United States, MD, Rosedale
Joined Jul 2011
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Quote:
Originally Posted by cbarnes0061 View Post
Ok guys I need a little help over past couple of months I have aquirred to crashed 50cc size airframes. Both of them the fuse is destroyed. The wings are from a sukhoi su26 and the tail feathers are off of one of the Carden Yak54 by hanger 9. What I'm looking to do is use the wings and tail feathers to build a profile plane. All I would have to do is fix minor damage on the LE of one of the su26 wings and build me a fuse but I'm unsure as to the size the fuse would need to be. I'm thinking loosing the wieght of the full fuse I could power it with either the DLE30 or 35RA. I'm not looking for anything to do crazy 3D just something fun to burn up the sky with. Each wing panel is 40" long so that is putting the wingspan I would say in the 82" range. Let me know what you think. How thick should the fuse be? How long?
As an opinion, I would start with a fuse length (Including rudder) of about 65"-70" long. This should be a good length, but won't be too elevator sensitive and should balance pretty well.

For the structure, I would suggest making the first third of the fuse out of laminating (2) layers of 1/4" ply to make it 1/2" then complete the rest with a truss design of 1/2" square stock. After framed then sheeting the whole structure with 1/8" balsa sheet. I have done this process in smaller scale on a few smaller profiles with great success. It makes for a rigid fuse.

Best of luck and post pics of the process.
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Old Feb 06, 2013, 08:55 PM
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Australia, WA, Kalgoorlie
Joined Apr 2011
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FWIW, here's a 3 view of an Extra 300. Maybe you can extrapolate the fuselage dimensions from the wing root chord? Should get you somewhere in the neighbourhood of the proverbial ball park!
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Old Feb 06, 2013, 09:55 PM
Flying Low
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United States, VA, Petersburg
Joined Mar 2012
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Thanks for the input guys. I actually posted the same thread over on flying giants as well and got some good input. I'm thinking I will be going with the 2" pink foam from Lowes. I will come up with some sort of shape and for length I think I am going to fall in the 70 to 80 inch long range. I will core and sheet the foam to keep it as light as possible and to give it good strength I will add either Fiberglas or carbon fiber tube running the length of the fuse.
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Old Feb 06, 2013, 09:56 PM
Flying Low
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United States, VA, Petersburg
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Also it will be a while before I start this build as I have to finish a few other projects I have on the table. Namely my 30% cap 232 I really want to see it in the air this summer.
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Old Feb 17, 2013, 07:47 AM
Chess club geek with wings
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Brainerd, MN
Joined Aug 2008
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I would take a well known design and scale it up to your needs - sometihing like one of the "Skeeter" profiles would be a great place to start...the plans are free and they are a great flying airplane. If your not going to fly 3D with it then feel free to strech the fuse a little so it's more pleasing to your eye.

I'd also look into incorporating 2, CF tubes into the fuse. They are light and would stiffen up your fuse considerably - run them from the motor mount through the wing and all the way to the horizontal stab.

Here are the plans for the Skeeter 30:
http://www.rcgroups.com/forums/showt...ght=skeeter+36

Quicker used to have a web site with plans for most of his designs but it looks like he's taken it down. I have plans for his Skeeter 36 so if your intrested I could give you those measurements - if you doubbled those it would be close

If your into composite fabrication a vacuum bagged fuse would be ideal- I've made one for a 36" profile and it's fantastic
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Old Feb 18, 2013, 07:01 PM
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Joined Jan 2009
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I'm not at all familiar with planes that large, but I've built a couple of Skeeters and a Mojo 40. I'm guessing with 80" wingspan the main slab (fuselage) needs to be made of balsa stock with at least a 3/4" or maybe 1" thickness. The 30" Skeeter slab is 1/4" thick and it has a flying weight of a pound or less. Obviously the slab isn't solid balsa, but trussed up sections, like the Skeeter and most similar aircraft.

Check out SwanysHouse.com for profile kits up to 60 size -- it might give you some ideas. Here's a link to photos on that site of the Mojo build.

http://swanyshouse.com/primo/construction.aspx
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Old Feb 18, 2013, 11:27 PM
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United States, VA, Petersburg
Joined Mar 2012
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Thanks for the links. I'm pretty sure I will be going the route of foam core with either fiberglass or carbon fiber tubes running the length of the fuse. My plan is to make the fuse a little longer than traditional profiles just to keep it from being short coupled. Also I want lots of surface area because I want it to knife edge without even trying hard.
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Old Feb 24, 2013, 07:55 AM
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Gee, those parts look familiar.
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Old Feb 24, 2013, 08:45 AM
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Canada, ON, Cottam
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Gee Bee has a nice fat fuselage for knife edge.
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Old Mar 01, 2013, 07:08 AM
Flying Low
cbarnes0061's Avatar
United States, VA, Petersburg
Joined Mar 2012
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Well while I was waiting for some glue to dry last night I decided start drawing what I think will work. Whenever I actually start building this I plan to laminate two pieces of 1" thick foam together. I will use a router to cut two groves in the foam so I can embed two 3/4" fiberglass or carbon fiber tubes for plenty of strength. Then I start to remove lots of foam to cut some weight and sheet the whole thing. I think the chin of the plane will get chopped away like BamBam did on his WWRC so I can keep the motor inverted. What thickness sheeting do you all think I should use on her? Any other suggestions are more than welcome.
The fuse is 75" long from tip to tip without the spinner.
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Old Mar 01, 2013, 02:35 PM
Rob H
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United States, MD, Rosedale
Joined Jul 2011
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I actually would suggest glassing the foam the standard f/g cloth from home depot/Lowes and resin (or even polyurethane). Much like the DLG guys use. It works very well and is very strong. Just a thought though.
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