Carbon/Kevlar hybrid Landing gear question  
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Carbon/Kevlar hybrid Landing gear question - 7/3/2003 3:39:08 AM   
Newflee



Posts: 644
Joined: 10/10/2002
From: Calgary, AB, CANADA
Status: offline 		Does anyone have experience with this hybrid cloth in making landing gears.
I have to make one for a 33% decathlon that weighs 35 lbs. The original gear was 1/4" 6061-T6. My question is if I should lay it up entirely of CF/Kevlar cloth or alternate layers of glass and the hybrid? I don't want to make it entirely from the hybrid if I don't have to for cost and waste reasons. I want to retain the 1/4" thickness but wonder if a solid 1/4" of the good stuff will be required.

Any experience will be great.

BTW I have made one from carbon and it is very strong but I think maybe too brittle, thus the carbon/ Kevlar hybrid.

Thanks
Lee
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Carbon/Kevlar hybrid Landing gear question - 7/3/2003 11:23:34 AM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Rather than alternating glass and cf/kevlar, use a few layers of the hybrid on the outsides and make a glass "core." This way the stiff fibers are on the outside where they will do the most good. As for the brittleness, remember that the carbon will most likely snap before the kevlar "sees" any real load. So this hybrid looks really cool... but engineering it's use is rather challenging.

-David

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Carbon/Kevlar hybrid Landing gear question - 7/4/2003 9:57:08 AM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		On a 35# plane, I don't think I'd use glass at all. I made some out of glass that were way too flexable. All the other sets I've made were carbon/kevlar cloth, carbon tow, carbon/kevlar cloth. I used the kevlar going in the same direction as the gear long ways.
Here's the details:
http://mywebpages.comcast.net/webmaster01/composite/cf-gear.html
and a picture of the finished product:

and another:


I mostly go with the arch shape, because of strength. That top corner, like on conventional gear, takes a lot of stress. They could be done that way, but you'd ned to add extra layers on the corner radius. Take your time, and they'll come out nice!


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Carbon/Kevlar hybrid Landing gear question - 7/6/2003 1:45:13 AM   
Ghostrider FIN



Posts: 89
Joined: 3/30/2003
From: Oulu, FINLAND
Status: offline 		Looks great! Do you use one direction carbon inside the landing gear to fibers set same direction as the gear long ways? Do you have picture about that carbon used in side of a gear? I think i make this kind a landing gear to my CG Sukhoi Su-26 because it original aluminum gear weights way too much.

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Carbon/Kevlar hybrid Landing gear question - 7/6/2003 5:49:44 AM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		Yes, it's uni-directional fiber called Tow. All the fibers inside run the long direction. It's cool looking stuff. It's flat, with a thread every 2 inches or so to keep all the fibers in line. The completed gear, suitable for a .90 sized plane, weighs around 2 oz. The carbon/Kevlar is really just for the outside layer, for looks, in this case.


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Your landing gear - 8/28/2003 2:57:50 AM   
mogles


 

Posts: 144
Joined: 2/5/2002
From: Glenwood SpringsPicket County, USA
Status: offline 		I am hoping to do the same as your gear looks really cool. However, I am confused. Plastic mold baked at 150 degress? wouldn't it melt?

Can you post some pics? I would love to see the mold.

Thanks much.

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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 6:09:46 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		What i use is particle board cut up and glued together about 1/2" wider than the gear itself. You then cut the shape of the landing gear from the block, and sand it smooth. The buy a formica sheet about 2'x4' and cut 2 strips the width of the mold and use contact cement to glue them on the face of the mold. Put a layer of PVA mold release on the formica and your set. I like this alot better than the foam mold because you can really crank down the vacuum in the bag to get lighter landing gear.

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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 6:11:25 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		Here is the mold

Attachments
Click to see fullsize image.
Click for fullsize

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       Post #: 8

Carbon/Kevlar hybrid Landing gear question - 8/28/2003 9:33:55 PM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		I broke the 1/2 the mold for the gear pictured, but have since been working on a mold exactly like scole has described. I used MDF in place of the particle board. It's a little harder, more like compacted dust, but really anything will work. Get gloss Formica, and get some nice uniform coats of PVA on the mating surfaces. I have switched my process a little. I now put a thin layer of epoxy on the surface, and wait for it to gel up, then make my layup on a piece of glass. Epoxy, CF, squeegee, epoxy, CF, squeegee, epoxy, CF, squeegee, ..... Let it sit for a bit, until it's almost at the tack stage, then put it in the mold, compress and bake. If you can catch it in time, it gets to an almost hard phase, that allows for easy trimming. It's really got to be an experience 1st hand kinda thing. You can practice on cheap glass a couple of times, to get a feel for it.
Try it, it's fun to do. I've been making CF props lately. I'm working on a big one right now, 22x8. CF parts look so cool when they're done.
--Rick


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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 9:48:38 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		Hey Rick, how do you make your props?

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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 10:37:53 PM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		I make a temp 1/2 mold out of clay 1st then pour epoxy over it, peel out the clay, pva, and more epoxy. I'll try to post a pic when I get home tonight.


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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 10:49:55 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		Thats cool, i'd like to see a pic also when you get home. I want to try this!

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Carbon/Kevlar hybrid Landing gear question - 8/28/2003 11:22:12 PM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Here are some pics/instructions on making small carbon props.
http://members.cox.net/davidfee/PROPS.html

Making large ones would require slightly different techniques.

-David

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Carbon/Kevlar hybrid Landing gear question - 8/29/2003 3:46:12 AM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		That's exactly how I do it!


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Carbon/Kevlar hybrid Landing gear question - 8/29/2003 6:59:55 AM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		I got a Q. with that. Do you put clay on the left side of the prop before you put the epoxy in? And how do you make the other half of the mold? I'm exited! I want one!

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