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Old Sep 23, 2011, 11:34 AM
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Inexpensive carbon booms

Has anybody tried to make arms out of this stuff. any input is appreciated.

http://www.cstsales.com/carbon_braid.html
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Old Sep 23, 2011, 12:18 PM
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Has anybody tried to make arms out of this stuff. any input is appreciated.

http://www.cstsales.com/carbon_braid.html
Those are sleeves to pull over a fuselage mold to make sail plane fuselages. I would imagine it will work as arm if you pull them over a round tube mold. You may have to use a couple of layers to get the stiffness needed.

Most posters here buy pre-made tubes. I have yet to see anyone molding their own carbon fiber parts.
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Old Sep 23, 2011, 12:42 PM
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looks like you could make some nice streamline section arms with that stuff laminated over a foam former/core as wet layup , although it might be difficult to get it as stiff/light as normal pultruded/pullwound tube, unless you've got vacuum bagging equipment. Have you got access to hot wire for foam cutting for the cores? I could definitely see some advantages to streamline/airfoil section arms in terms of stiffness and vibration reduction from propwash & the only way of getting those is laying it up yourself.
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Old Sep 23, 2011, 01:00 PM
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The usual way to make stuff with that CF braid is to wrap it with heat-shrink tape and bung it in an oven. Definitely not easy.
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Old Sep 23, 2011, 01:07 PM
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I don't mind hard if it saves me some money what do typical braided carbon arms sell for? I see the ones in Dragonplate and their expensive
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Old Sep 23, 2011, 01:09 PM
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goodwinds.com extruded carbon rods....

Paid $60 for 15"x6 rods
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Old Sep 23, 2011, 02:08 PM
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Ya extruded not braided
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Old Sep 23, 2011, 03:35 PM
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I don't mind hard if it saves me some money what do typical braided carbon arms sell for? I see the ones in Dragonplate and their expensive
You cannot compare some simple carbon weave sleeves to the Dragon plate stuff. They are expensive but they are very well made.

By the time you finish making three, four or six perfectly matched arms from these carbon weave material you will realize you may have spent just as much money if not more than if you buy small quantity from Dragan plate.

Don't forget to count your time spent as costs also.
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Old Sep 23, 2011, 03:56 PM
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Good point
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Old Sep 23, 2011, 05:03 PM
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On the other hand if you are looking for exotic aerodynamic shaped arms you may have to use those carbon weave sleeves. Now you really got me thinking. The big question will be the transition from a nice shape on the arm to the attachment points for the motors and center plates. It will be nice to have a vertical airfoil shape through out the entire arm with a flat area to mount the motor and center plate.
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Old Sep 23, 2011, 05:19 PM
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I think you would need to make the airfoil small im afraid the wind would pitch it around more unless you only did the foil out to the prop diameter
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Old Sep 23, 2011, 05:39 PM
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I think you would need to make the airfoil small im afraid the wind would pitch it around more unless you only did the foil out to the prop diameter
Hmmmm.....that will be a nightmare to pull the sleeve off after the epoxy has cured. The reason why the sail plane fuselage works is because they melt away the plug after the epoxy cures. Or we can make a female mold and inflate a bladder on the inside to push the weave against the mold.
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Old Sep 23, 2011, 06:46 PM
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you could have a 2 stage airfoil shape for the arms, vertical out to just past the edge of the prop disc then transition to 15 -20 degree or so (off horizontal) angle of attack for the arms - would be nice & aerodynamic for forward flight - you might even get a bit of extra lift off them & save a bit of battery if you get your angles right.
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Old Sep 23, 2011, 06:59 PM
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Looks like im going to have to brush up on my Blender modeling skills again I haven't used it for at least 3years
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Old Sep 23, 2011, 07:55 PM
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Originally Posted by jonnyc67 View Post
you could have a 2 stage airfoil shape for the arms, vertical out to just past the edge of the prop disc then transition to 15 -20 degree or so (off horizontal) angle of attack for the arms - would be nice & aerodynamic for forward flight - you might even get a bit of extra lift off them & save a bit of battery if you get your angles right.
I am not going to be that optimistic and expect any lift from the arms. I just want them to look cool and may be a bit less draggy on the prop wash.
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