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  #1  
Old 04-19-2020, 07:56 AM
brick brick is offline
 
Join Date: Oct 2011
Location: Cambridge Ontario Canada
Posts: 30
Smile Wrapping gear leg with Carbon Fiber

Currently working on RV7A gear leg and pant fairings. After reading numerous posts it seems many if not all RV'S have a speed that vibration occurs. That being said it seems many have wrapped gear leg with Carbon Fiber some with two layers some with more that two and apparently with success. My question is do you use direction CF or bi-directional CF. Please note I have not flown this aircraft yet still building but if it makes sense to do this and be done with it I will. I guess that's a second question. Thanks to all who may reply.
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  #2  
Old 04-19-2020, 07:59 AM
David Paule David Paule is online now
 
Join Date: Dec 2009
Location: Boulder, CO
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Don't forget to use a fiberglass layer between teh carbon and the gear leg.

Dave
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  #3  
Old 04-19-2020, 08:42 AM
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Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 997
Default Brick question response

Just my opinion from all I have read on VAF. I have carbon gear leg wraps that replicate the Vans profile and use a carbon plate on the back side of the leg to form a tear shaped beam.
My conclusion from all the wise input here is the whole issue centers around input frequency and sympathetic natural frequency of the gear leg. There are many ingredients to this plot. Tire shape, tire balance, tire pressure, runway surface crack spacing, speed and last but not simple, the harmonic property of the gear leg.
My personal opinion is carbon is more of a constant over time than pine woodwork and glass. Yet, there is no silver bullet ! Most of the time my gear has no vibration, yet, rarely, I sense a little ?unhappiness? at different temps, different speeds, different runways.
Good luck 😊
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RV-3B flying w/7:1 0320 / carb / Pmags / Catto 3b / digital steam
RV-4 fastback w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN
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  #4  
Old 04-19-2020, 11:48 AM
brick brick is offline
 
Join Date: Oct 2011
Location: Cambridge Ontario Canada
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Thanks for the reply, appreciate the knowledge, but can you tell me if directional or bi-directional was used thanks
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  #5  
Old 04-19-2020, 01:11 PM
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Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 997
Default Bidirectional

I used bidirectional because I had some. The layers cross each other, so that would imply it is better than the bias cut fabric ( for tube and rag covering) that conforms with curves. That said, unidirectional is probably better for total stiffness. The question is what direction ? It has not been proven that the problematic input stimulus is fore and aft or vertical.
This is above my pay grade; consult Dan H.
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Larry DeCamp
RV-3B flying w/7:1 0320 / carb / Pmags / Catto 3b / digital steam
RV-4 fastback w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN

Last edited by Larry DeCamp : 04-19-2020 at 01:13 PM.
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  #6  
Old 04-19-2020, 02:14 PM
brick brick is offline
 
Join Date: Oct 2011
Location: Cambridge Ontario Canada
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Thanks Larry that's what I have also. Thanks for your input
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  #7  
Old 04-19-2020, 02:25 PM
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cderk cderk is offline
 
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Location: Park Ridge, NJ
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Or you can save time, and order the gear leg stiffener from here:
http://www.aircraftspecialty.com/rvall1.html
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  #8  
Old 04-19-2020, 02:59 PM
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bjdecker bjdecker is offline
 
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 331
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Save even more time & money...

https://www.homedepot.com/p/Woodgrai...0688/206000894

One on the front, one on the back, use Proseal to bond to gear leg and then wrap top to bottom with 3" fiberglass tape with 1" overlap between wraps.


Cheers,

B
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Brian Decker
Retired Firmware Guy and Airplane Builder

2020 RV-14 QB -- Under construction - Tailcone & Empennage Complete.
2018 RV-7 QB -- Built, Flying
2007 RV-7 QB -- Built, Drowned, Resurrected and flying
1998 RV-8 QB -- Started, Sold
1986 Mooney 205SE
1980 Mooney 231

Aided and abetted building a number of other RV's.
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