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Old 04-27-2019, 05:11 PM
Join Date: Jul 2006
Location: , MD
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Originally Posted by speedracerntrixie View Post
The practice of running fiber orientation is a good one however you need to know what your reference point is. The fiber orientation on a plain weave fabric runs in two directions the " Warp " fiber runs the length of the roll and the " fill " fiber runs at 90 degrees to the roll. When fiber orientation is specified it is in relationship to the warp.

From personal experience, I was reprimanded for taking too long to cut some cloth for a project. Boss sez: "What took you so long? - I was getting ready to send out a search party." Me: "Oh, I was cleaning up the area after cutting materials, putting some things away, and then I was talking with someone in the hallway." Boss: "Geez, I didn't ask you to weave cloth, did I? We don't have all day! This task should have taken minutes, not hours! Please don't tell me you're cutting one piece of cloth at a time." Fact of the matter is, I spent an enormous amount of time deliberating how to keep fiber orientation while cutting cloth off the roll. After much head scratching, I had to draw some arrows on both sides of the pattern and turn it over several times to help me see what happens here.

1) Stacking two pieces of plain weave cloth while using care to maintain orientation coming off the roll and cutting both with a pattern at the same time gives identical pieces - two rights or two lefts and both pieces will have warp and fill fibers running exactly alike. For this example, slashes can represent the fibers running the length of the roll. [//>] [//>] 2) Using care to turn only one of the pieces over now gives a left and a right with fiber orientation in a mirrored or balanced manner. [//>] []

Also from experience, early AMA 428 class Q-500s were shown to be having wing failures in compression, not tension - so strength was commonly achieved by concentrating on reinforcement to the top of the wing, not the bottom. Glass coverage on the top of the wing usually extended out further than the bottom to avoid stress concentration - especially at the LE. In other words, not simply a single wrap of narrow, constant-width cloth around the wing panel joint which may have been fine for 424.

Last edited by H5606; 04-27-2019 at 05:52 PM.