Re: Biaxial-traxial vs 7715 Fiberglass #epoxy


One Sky Dog
 

Fat fingered tail number 187CD


On Oct 17, 2020, at 6:16 AM, One Sky Dog via groups.io <Oneskydog@...> wrote:

A roller can help wet the cloth and raise bubbles but the squeegee is the tool to remove excess epoxy. The glass weight is a given the epoxy weight is a huge variable in the final weight of the airplane. Burt Rutan basic course treats it all to get the lightest airframe.

Remember Voyager non-refueled around the world one flight. Burt knows follow his guidance.

I witnessed the fairing of an America’s Cup racing yacht to precision contour. I have incorporated some of that in my method of surfacing composites.

Like Sam the pro’s spread the micro on thick over the 75’ X 20’ hull. But they used trowels with big notches in them and went from keel to gunnels and called it noodling the hull. After it set they use 36 grit long boards to get the contour close to the laminate but not final. Then they used smooth trowels to fill in the gaps in the first layer saving a bunch of material and sanding. Wait a couple of days and 60 grit long board it to contour. Fill scratches with epoxy.

 In my opinion the micro dusting has flaws. First proper squeegeeing along the fiber Just to the point of pullIng air into the laminate (read Burt’s handbook) Is the way to get the fiber/resin ratio. Having extra epoxy on or under the surface and pouring glass bubbles on top will not make the lightest micro or laminate. 

Get it done right for light.

Charlie
Dragonfly 188CD 


On Oct 17, 2020, at 5:13 AM, Mike Dwyer <q200pilot@...> wrote:


I've worked with tri-axel fiber and found it hard to wet out.  I do like the idea of a Teflon roller.  A squeegee pulls on the fibers and I'd expect that it leaves a rougher surface behind.  I don't like your idea of dusting a layup with micro.  I think it will not fill in the valleys at all.  Sams swipe will fill the valleys and give you a smooth surface.  For a one off foam cut, the plans hot wire method is cheap and easy with good results.  Don't waste time with CAD.
Get her done!
Mike Q200 N3QP

On Fri, Oct 16, 2020, 23:04 Cody <cody.craig1985@...> wrote:
Which is actually of more benefit? 3 layers of unidirectional, or a sheet of woven triaxial? Or a sheet of biaxial with a sheet of uni? I was thinking the layup on my wings and canard could be better an lighter with the multilayer sheets instead of 3 individual plys. Sam Hoskins, I just watched your video on epoxy swipe method. I intend on incorporation of this method and another method of dabbing micro powder on a fresh layup to absorb excess epoxy and fill the gaps more efficiently. I also talked to one of the mechanics who work with me and he said the larger composite planes don't use squeegee much anymore. They use Teflon rollers. Has anyone here done that method as well? I'm looking to be efficient with my work and light in the end, mostly because I want a strong airframe. Could I also ask if anyone has an AUTOCAD file of the LS canard with the carbon spar, main wing and tail I could send to Mohr Composites for a final quote? I know at least one other person on here has expressed interest in getting some CNC hotwire work done. I'm hoping they'll help with a bulk discount or something. But if nothing else maybe just more motivation to cut some cores for us. Thanks in advance. 

Join main@Q-List.groups.io to automatically receive all group messages.