Re: Quickie Q1 Canard and wing foam cut
|
Robert Cringely
That may all be true, but the nature of composite aircraft is that they are vastly overbuilt simply because building to the strength requirements alone yields a structure that is too fragile -- too susceptible to hangar rash. A ply is a ply and while it would be ideal to use 0.8 plies or 1.2 plies, in the end we use two or three. So your fiber may be superior to my fiber, but they are both good enough. Here I have locally-sourced pre-preg that has good (not great) characteristics plus the very real advantage of 45 percent resin content. Build it from your stuff and it won't be any stronger or lighter by the time it gets in service. Thirty years ago I worked with Martin Hollmann who did the structural designs of all the Lancairs up through the L-IVP. A guy wanted to fly his Lancair 320 around the world so he asked Martin to take as much weight out of the kit as possible. This meant moving to S-glass and changing both ply schedules and core materials. We took more than 200 lbs out of that L-320. The service limits were lowered a little but it was still plenty strong. But the builder decided against it when we explained typical hangar rash could compromise his fuel tanks. REAL WORLD composite design comes down to such things and in that real world high-crystalline cellulose or flax don't make a difference.
On Thu, Sep 16, 2021 at 2:18 PM David J. Gall <David@...> wrote: Flax is inferior to highly-crystalline cellulose fiber for exactly the reasons mentioned below. Highly-crystalline cellulose fiber is nearly equivalent to E-glass in all respects except weight -- glass is much heavier -- and in sanding -- glass is itchier. Highly-crystalline cellulose fiber is mechanically derived from what would otherwise be wastes generated in lumber processing industries and is marketed worldwide under the trade name BioMid by Gordon Shank consulting. The roving is used as twine (you know it must be inexpensive!) in the hydroponics industry so availability will persist for a long time for numerous reasons. BioMid is available woven into cloth in the US from Absecon Mills and in Europe from FRP Services & Co (France).
|
|
|