Carbon/Kevlar hybrid Landing gear question  
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Carbon/Kevlar hybrid Landing gear question - 8/31/2003 12:06:49 AM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		Newflee,
I am building a similar sized plane. Wht are the dimensions of the gear you made? Width, height, stance, weight of cloth, etc. They sound strong enough, and stiff enough. Did you use a 2 piece compression mold like I use? The biggest I've ever done were 60-90 sized. This bird will have an MDS 2.18, and I'm making the mold for the props right now.
Thanks,
--Rick


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(in reply to Newflee)
       Post #: 26

Carbon/Kevlar hybrid Landing gear question - 8/31/2003 1:42:54 AM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		For a 35% plane i used 7 strips of 5.8oz cloth plain weave regualar cf, and 15 layers by 4 layers wide of 50k tow spread by 1.75". Aprrox. 3 layers of tow and the a layer of cloth. Turned out really strong. No colered kevlar though.

(in reply to Newflee)
       Post #: 27

Carbon/Kevlar hybrid Landing gear question - 9/1/2003 3:14:25 AM   
Newflee



Posts: 644
Joined: 10/10/2002
From: Calgary, AB, CANADA
Status: offline 		Rick,
My gear is a little unconventional in that I adjusted it's construction as I went.
I made a mold from thin ply wrapped over a chunk of MDF shaped with the proper slight bow in the legs as scale on a Super Decathlon.
Then I layed up at least 15 layers of heavy weight hybrid cloth using west system.
After it had cured somewhat I realized that it would not be stiff enough, I layered on an additional 4-5 layers of heavy CF cloth to the open side. Since at this point the gear was rigid enough to remove from the mold I popped it off and layered another 4-5 layers of cf to the underside. This is not ideal but it worked. If I do it again I will do the opposite and sandwich the cf inside the hybrid.
It worked for me but you can do it right if you plan ahead. I would say the best would be 3 layers hybrid, 14 layers alternating cf and hybrid and then finally 3 layers hybrid.
Vac bagging would be ideal as well but I have no experience with that.


Lee

(in reply to Newflee)
       Post #: 28

Carbon/Kevlar hybrid Landing gear question - 9/1/2003 11:28:37 AM   
filtr-RCU



Posts: 163
Joined: 2/26/2002
From: Moose JawSaskatchewan, CANADA
Status: offline 		Hi David

I looked at your web page. Great info. I was wondering if the expoy you used was west system or another brand. Also is you are making landing gear what are you using for carbon fiber.

(in reply to Newflee)
       Post #: 29

Carbon/Kevlar hybrid Landing gear question - 9/1/2003 12:33:34 PM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Hi there,
Actually, the epoxy I've used most is from a company called Jeffco. I get it at a store (Diversified Materials) about 5 miles from my house, or direct from the company since they are also in town. http://www.diversifiedmaterialscompany.com/ http://www.jeffcoproducts.com/

The carbon gear I helped make was for a school engineering competition plane, so we used whatever was available. We had some heavy carbon fabric, either 6 or 8oz stuff. We used about 6 layers of that. We ended up adding some uni-carbon to the gear to stiffen them up since they were flexing a little bit too much with the plane fully loaded (~16 lbs).

-David

(in reply to Newflee)
       Post #: 30

RE: Carbon/Kevlar hybrid Landing gear question - 9/14/2003 3:07:28 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		rsieminski: Do you make smaller sized landing gear? If so, what do you use instead of formica for the face of the mold? I have had no luck with formica and smaller gear.

(in reply to Newflee)
       Post #: 31

RE: Carbon/Kevlar hybrid Landing gear question - 9/14/2003 3:54:53 PM   
nucmann


 

Posts: 8
Joined: 9/10/2003
From: timbuctoo, USA
Status: offline 		What dimentions do you want to make them? What problems have you had with the formica?

(in reply to scole)
       Post #: 32

RE: Carbon/Kevlar hybrid Landing gear question - 9/14/2003 6:45:37 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		Formica snaps when bent to far, thats the problem. I just need something that bends furthur.

(in reply to scole)
       Post #: 33

RE: Carbon/Kevlar hybrid Landing gear question - 9/14/2003 8:41:57 PM   
rsieminski



Posts: 1406
Joined: 4/24/2002
From: Sarasota, FL, USA
Status: offline 		Heat it up with a heat gun and make it to shape before you apply the contact cement. (BTW)You can remove formica with a heat gun as well. The heat reactivates the cement. If you work it, you can bend it around a sm radius.

(in reply to scole)
       Post #: 34

RE: Carbon/Kevlar hybrid Landing gear question - 9/14/2003 11:30:05 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		Cool, i never thought of that, thanks.

(in reply to scole)
       Post #: 35

Hollow Carbon/Kevlar hybrid Landing gear - 9/15/2003 5:08:39 AM   
3wExtra


 

Posts: 524
Joined: 12/30/2002
From: seattle, WA, USA
Status: offline 		Has anyone made a hollow landing gear?
If so how did you do it?

(in reply to scole)
       Post #: 36

RE: Hollow Carbon/Kevlar hybrid Landing gear - 9/15/2003 5:56:18 AM   
Jim J


 

Posts: 242
Joined: 8/25/2003
From: Midwest City, OK, USA
Status: offline 		Haven't done landing gear, but either of two ways might lend themselves, the foam core with exterior laid up layers then using appropriate vaccum forming techniques just as in
wing making, or possibly the use of two molds , an upper and a lower each former first ( using vaccum bagging if available, then joining after both molds are done. This joined
"biformed method' could then also be layered on the exterior and vaccum bagged with appropriate release layers (films). I am not sure where hollow would be applicable unless it was a very large structure.
Jim J

(in reply to 3wExtra)
       Post #: 37

RE: Carbon/Kevlar hybrid Landing gear question - 9/15/2003 10:09:24 PM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		I am going to try and make my LG like that. If i could just find a router bit that would give me a concave/ convex surface you can make hollow LG. It will be much stiffer and weigh less.

(in reply to scole)
       Post #: 38

RE: Carbon/Kevlar hybrid Landing gear question - 9/16/2003 1:33:50 AM   
Newflee



Posts: 644
Joined: 10/10/2002
From: Calgary, AB, CANADA
Status: offline 		Personally I would be shy about using a router or anything abrasive to cut a CG part. I am under the impression that disturbing the composite matrix will affect its strength.
Sounds like I'm talking about a movie plot.

I really don't see the purpose of making a hollow structure. I made mine solid with a final weight of 9 oz replacing what was a 18 oz 6061-T6 gear.


Lee

(in reply to scole)
       Post #: 39

RE: Carbon/Kevlar hybrid Landing gear question - 9/16/2003 2:11:44 AM   
scole


 

Posts: 652
Joined: 11/30/2002
From: Fairport, NY, USA
Status: offline 		I'm not cutting into the carbon gear, just the mold.

Basically, by making the carbon skins further apart you are increasing strength a lot. There was a thread a little while ago about that.

(in reply to scole)
       Post #: 40