|Dec 21, 2012, 12:46 AM|
Joined Jun 2009
Is it possible to wet-out some of the fabrics outside of the mold, blot dry to desired resin content, then lay into mold?
I can appreciate some fabrics will not tolerate this approach such as .75 glass or 1oz Kevlar. Perhaps the difficult to handle fabrics can layered in in some way.
Could this be an approach to solving an excess resin content issue? Flame suit on
BTW I really admire the work you have been putting into this project.
|Dec 21, 2012, 01:15 AM|
Paul, the challenge is knowing how much resin to remove and still not leave any air voids. This is the great thing about bladders on parts like this. The fabric is put into the mold while the fabric is "full" of resin and in it's relaxed state. The bladder then presses the fibers closer together leaving less space for resin. As the fibers are pressed together the excess resin migrates out of the mold along the flange. My DLG fuses would have been 16 to 18 grams heavier without the fiber compression. If the fibers don't get compressed then the open spaces between them need to filled with resin to transfer the load from fiber to fiber.
|Dec 23, 2012, 09:28 PM|
United States, MD, Lusby
Joined Nov 2003
It is possible to wet out outside the mold, this is a typical technique employed on dlg wings. However, it is difficult to avoid air bubbles as Adam mentioned but you can weigh the fabric to get exact weights. Unfortunately this really only works when you aren't distorting the fabric in the mold, as you need more epoxy in the mold to avoid bubbles.
One trick is to layer the fabrics before placing them into the mold with 3M77. This way you can wet the fabric outside the mold as one clump, place some extra resin in the mold, then drop the wet fabric into the mold and add a little more epoxy to help get it to conform. This saves you time wetting individual pieces of fabric out in the mold, and time is weight.
Reality is the layup schedule on a DLG is a science but in practice it is an artform to achieve light weights. It has become easier in the last 2 years as lighter materials are now available, but you pay a steep price to get those materials.
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