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  #1  
Old 02-02-2017, 04:53 PM
rvtestpilot rvtestpilot is offline
 
Join Date: Jul 2016
Location: Lewistown
Posts: 18
Default My attempt at a carbon FWD baggage door

It's a good start. The idea is to have 1/4 turn fasteners on the lower corners instead of the key lock and monkey motion.

Noel Simmons
4063664638


[IMG][/IMG]
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  #2  
Old 02-02-2017, 11:19 PM
greghughespdx's Avatar
greghughespdx greghughespdx is offline
 
Join Date: Nov 2011
Location: Aurora, OR
Posts: 1,168
Default

Cool. Any more pics and details? Any special technique?
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Building RV-8A since Sept 2014
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  #3  
Old 02-03-2017, 09:13 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,258
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Vacuum bagging might help with those bubbles and voids.

The general technique isn't hard. This shows the basic plan. The fabric and core are your part, the rest is the process:



Here's my vacuum pump and my plumbing:



The stub vertical pipe below the gauge is a trap.

I take the pvc pipe up to the part and put it under the outer bag. That section of pipe has several holes in it, and I lay some bleeder/breather mat under and over those. Here in Boulder we typically see about 12.5 psi of air and I can recover about 9 psi of vacuum with my simple and cheap set-up, so pvc is fine.

I use heavy but common plastic sheet for my outer bag and duct tape it down. That's adequate. The bleeder/breather mat is common padding from a fabric store, an inch or so thick. ACS sells the release film and the peel ply is polyester aircraft covering (the cheaper non-certified stuff). The pump came from McMaster and is rated for continuous use; I had it run for a week on my boat once to dewater a section of core. It was as good after that as before.

Dave
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  #4  
Old 02-03-2017, 08:12 PM
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GHRoss3 GHRoss3 is offline
 
Join Date: Feb 2009
Location: Niceville, FL
Posts: 46
Default Carbon fiber Galvanic Corrosion & Aluminum

I'm surprised this hasn't already been brought up with this thread. Carbon fiber reinforced composites (CFRC) and aluminum causes galvanic corrosion.

Carbon Composites' Drawbacks

Despite all of the excellent properties of CFRCs, there are issues with using CFRC and metals together. Carbon fibers in CFRPs cause this material to become electrically conductive. The carbon fibers are electrically conductive and electrochemically very noble. Therefore, when a metal is electrically connected to a CFRP, it is more susceptible to galvanic corrosion. This situation becomes worse when a large surface area of carbon composite components is coupled to small metallic parts (such as fasteners, bolts and nuts). In these circumstances, the rate of galvanic corrosion is extremely high due to the high cathode to anode surface area ratio (Ac/Aa). . . Aluminum alloys are extremely vulnerable when they are coupled to a carbon composite.

This was copied from https://www.corrosionpedia.com/2/155...orced-polymers

Hopefully the composite master DanH will pipe in on how to isolate the carbon fiber from the aluminum.
Cheers
George
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  #5  
Old 02-03-2017, 10:40 PM
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DanH DanH is offline
 
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Location: 08A
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Quote:
Originally Posted by GHRoss3 View Post
...how to isolate the carbon fiber from the aluminum.
The usual approach is a ply of ordinary fiberglass to isolate the carbon. Alternate approach is two coats of epoxy primer and two coats of paint, then hope it doesn't wear though.

If aluminum rivets are used, they too must be isolated from the carbon somehow. Minimum is to wet-set in a moisture proof sealant. Proseal might do.

Good luck finding a titanium lock assembly.

This is not a great application for carbon.

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Last edited by DanH : 02-03-2017 at 10:46 PM.
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  #6  
Old 02-05-2017, 11:13 AM
rvtestpilot rvtestpilot is offline
 
Join Date: Jul 2016
Location: Lewistown
Posts: 18
Default More picture

Did the bonding of the foam reinforcing yesterday. And it turned out really nice. The curve of the door needed to be slightly modified as my quick mold was slightly relaxed. But today the door fits really nice! I need to clean up some edges.


And let me add, there is fiberglass on the surface so the carbon won't corrode the aluminum that has been primed, painted, and clear coated.

And vacuum molding only works if you have a proper mold that will not deflect, inside curves require a very very strong mold!!

This particular door along with airplane will be wrapped

In conclusion: this is the "perfect" and proper size part to make a vacuum mold from. Any takers?



[IMG][/IMG]

[IMG][/IMG]
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  #7  
Old 02-05-2017, 11:16 AM
A2022 A2022 is offline
 
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Posts: 2,425
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that is truly impressive.
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  #8  
Old 02-05-2017, 12:45 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,258
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Quote:
Originally Posted by rvtestpilot View Post
....And vacuum molding only works if you have a proper mold that will not deflect, inside curves require a very very strong mold!! ....
Actually, they don't, if the part is sealed to the side (typically an extension of the side) that it's up against, and the back side is at ambient air pressure.

Dave
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  #9  
Old 02-05-2017, 02:09 PM
Chkaharyer99 Chkaharyer99 is offline
 
Join Date: Oct 2011
Location: Pilot Hill, CA
Posts: 864
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Quote:
Originally Posted by rvtestpilot View Post
Did the bonding of the foam reinforcing yesterday. And it turned out really nice. The curve of the door needed to be slightly modified as my quick mold was slightly relaxed. But today the door fits really nice! I need to clean up some edges.


And let me add, there is fiberglass on the surface so the carbon won't corrode the aluminum that has been primed, painted, and clear coated.

And vacuum molding only works if you have a proper mold that will not deflect, inside curves require a very very strong mold!!

This particular door along with airplane will be wrapped

In conclusion: this is the "perfect" and proper size part to make a vacuum mold from. Any takers?



[IMG][/IMG]

[IMG][/IMG]

Does the carbon fiber door weigh less or more than the stock Vans baggage door? It looks really cool BTW.
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  #10  
Old 02-05-2017, 03:52 PM
rvtestpilot rvtestpilot is offline
 
Join Date: Jul 2016
Location: Lewistown
Posts: 18
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I'm going for lighter. And I don't like the modified lock and pins of the stock door so just going with to 1/4 turn fasteners from sky bolt.
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