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Building Tips and technical articles. => Building techniques => Topic started by: roger gebhart on April 11, 2007, 06:19:51 PM
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I'm thinking of using CF to stiffen the trailing edge on a Ringmaster. I see it comes in .004 and .007 strips 2" wide. Can I and how do I cut it down to 1/4" strips. I would like to sandwich it between upper and lower trailing edge at the rear. rog
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Cut it just like cutting silk span, knife,scissors.
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You can slice it with a knife, but that's a really "fussy" job. Why not just buy the ¼"-wide CF Tape?
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cut it with a sharp blade but insrtead of sandwiching it between the TE (which adds very little strength, Put one strip on top. and one below.
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I didn't see it listed in 1/4 but I'll look for that. I guess as thin as it is it won't show a lot on top and bottom? rog
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CST and Aerospace Composites both sell CF strips in varying thicknesses and widths.
Here's CSTs website:
http://www.cstsales.com/
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Cutting is very easy as has been noted but please keep in mind that CF is similar to fiberglass in that you need to handle it very carefully. n1 You don't want to get a tiny sliver, splinter or strand lodged into any skin, or more importantly your eyes. HB~> Please wear protective goggles when cutting sanding grinding this great stuff!!! y1
As long as you never have a problem, CF seems really like no big deal. Like seatbelts, many people just don't bother but let that one awkward moment happen and you will be a believer the rest of your life.
CF, as has been pointed out, comes in a huge variety of widths, lengths, thickness and of course shapes, both solid, and hollow. It is in your best interest to buy the closest possible size and shape in order to keep cutting, sanding or grinding to a bare minimum. This in itself will be your best protection.
Robert
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I cut my CF just like I do balsa - use a straight edge and a number 11 blade Exacto. A light sanding with a block afterwards and iut's fine. As far as using CF on the top and bottom, that's not the most effective way to go. The advantage of the light strength available from CF is more easily used by placing the strip verticle. One strip does more that way than two placed horizantal. for my last 6 stunters I have made my wing trailing edges and the LE and TE of my stabs by sandwiching 1/4" x 1/2"extremely light balsa over .007 CF placed verticaly. I've dropped close to 1/2 ounce from each uncovered system this way on a 675 square stunter. The strength is fine with many 100's of flights on each ship and no stress cracks.
Blessings,
Will #^ y1
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I'm thinking of using CF to stiffen the trailing edge on a Ringmaster. I see it comes in .004 and .007 strips 2" wide. Can I and how do I cut it down to 1/4" strips. I would like to sandwich it between upper and lower trailing edge at the rear. rog
Roger,
I do not think that there is anything to be gained by using carbon fiber to stiffen the trailing edge of a Ringmaster. The application of tissue and dope will stiffen up the wing a lot. Even without the tissue and using plastic flims, you should not have any trouble. Further, gluing it between the upper and lower trailing edge ( I am assuming laid flat horizontally) will not add any stifness. Think of the top and bottom plates of an "I" beam and understand that you would need both plates to be made of carbon fiber and held apart vertically to achieve maximum strength. If the trailing edge of your wing is built up, finish off the boxes formed by the inside edges of the two ribs and the top and bottom trailing edge sheeting by enclosing the front of of the box as well. (make a piece of balsa to fit just inside the cavity) This WILL add stiffness to the trailing edge.
Hope this helps,
Kim.