[NSRCA-discussion] Firewall Material

[rcmaster199 at aol.com]

Plain weave 3K is fine Anthony. I have both types of cloth and use the plain more for all kinds of apps, including propellers and landing gear (high perf requirements). But twill is fine for flats and they say is actually a little stronger. I find it more difficult to work with

I've been getting mine from Fiberglast lately but most any sources with good pricing will work. I wait for the 20% off coupons from Fiberglast (at least once a month) and get a couple yards. It is expensive material but worth the price. BTW, forget about using 1K cloth for structural things....it's nice and light and looks good but that's about it. It has little guts...if you want it, use it as top coat after you reinforced the structure with the stronger grade.

Please let me know the ebay sources. Always looking for less expensive materials that are appropriate to use.

MattK





-----Original Message-----
From: Anthony Romano <anthonyr105 at hotmail.com>
To: nsrca-discussion at lists.nsrca.org
Sent: Fri, Feb 5, 2010 5:23 pm
Subject: Re: [NSRCA-discussion] Firewall Material


Hi Matt,
 Twill or plain weave? Anyone have a favorite source? Found some sellers on ebay who seem to have good prices.
 
Anthony
 
To: nsrca-discussion at lists.nsrca.org
Date: Thu, 28 Jan 2010 10:47:40 -0500
From: rcmaster199 at aol.com
Subject: Re: [NSRCA-discussion] Firewall Material


Tim,
 
You can build up cross grained balsa and carbon firewalls your self. It's easy.
 
Aircraft ply. 1/8", will weight almost double what a carbon balsa laminate will at 5/16" thickness.
 
Ed Alt discussed this technique some time ago in the KFactor. We first built up his firewall shape in cross grained light balsa and installed as many hardpoints as needed for the mount...hard points are simple maple blocks (lighter) or aircrfat ply squares (heavier), maybe 3/8" square. It requires some prep as you can see.
 
Lamination is straightforward. I use 3K carbon cloth, 1 layer each side, and epoxy such as ProSet, West Systems or the newest discovery JGreer, which is half the cost of the others. The assembly is inserted in a vacuum bag such as a Food Saver, and closed up. I place it on a flat surface and use a 10 lb weight on it to keep it flat.The vacuum is great because, besides the fact that you get the best contact possible between the layers, it draws epoxy into the grain and really stiffens the structure. Nonteless, before insertion into the bag, I use paper towels to remove as much of the excess as practical. You can't remove too much.
 
I think Ed said the weight of his Integral FW was around 40 grams. I am using the same type in my new design that has a rather large FW, and is designed for a gasoline engine. I took weights of the light ply FW I removed from my fuse and the new Carbon/balsa. Original weighed around 85 grams, and new 42grams.
 
MattK






-----Original Message-----
From: Pascoe,Tim [Burlington] <Tim.Pascoe at ec.gc.ca>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Thu, Jan 28, 2010 10:29 am
Subject: [NSRCA-discussion] Firewall Material



I’m working on a pair of Genesis’ for next season. In the past, most of my airplanes have been wood, and while I have some experience with composite airframes, I’m far from being an expert. I’m ready to put in the firewalls, and I’d like some suggestions as to what the best material will be for this. I’d like to keep the weight down (don’t we all), and was wondering if laminated carbon/balsa panels such as those available at the Composites Store (http://www.cstsales.com/carbon_sandwich_panel.html)  are worth it, difficult to work with, etc. Also, do panels like this require some special reinforcement where the bolts go through? Special epoxies for adhering to the fuse, etc.? Or should I just be using aircraft grade plywood?
 
Any suggestions would be great.
 
Tim Pascoe
 


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