Marvin Kaye wrote:

At 09:02 AM 2/16/99 -0800, you wrote:

Not just "bid" Marvin. Carbon fiber bid.

It is your call Marvin. That is the way it should be. Its
your life on the line.

Never-the-less ten total layers of three inch wide
bid carbon fiber all around a five by five inch hole is a lot stronger
and stiffer than 4 layers of glass with one quarter inch of PVC foam.

I know you mentioned cf BID, I parenthesized that in my last post to you.
We also need to remember that the entire structure is designed with a
certain amount of stiffness built into it. (The area in question, BTW, is
_not_ made up of 2-BID / 1/4" foam / 2-BID... the core is 1/4" Nomex
honeycomb.  I know, not that big a difference, but the Lancair structure
uses no foam-coared components.)  By placing a stiffening CF-BID structure
into an area made primarily of e-glass the loads will change in the entire
assembly, with large stress risers where the CF stops and the e-glass
begins.   Doing something like this at the tail is pretty scary, as that's
the last place we need to put an imaginary dotted line that says "break
here".  If you'd like to learn a bit more about the Lancair MKII tail
flutter controversy and whats gone on in that area, I have a flutter page
on my website with postings from Martin Hollmann and Lance Neibauer which
discuss it at some length... I've provided the information so individual
builders can be made aware of the situation and draw their own conclusions
regarding Martin's suggested "fix".  Go to
http://www.olsusa.com/Users/Mkaye/flutter.html.

Anyway, I just wanted it to be known that modifying composite structures
isn't an activity that should be taken lightly, especially with the demands
put on a structure by an airplane that's meant to travel at speeds in
excess of 200mph.  I've already got some strong concerns about the
structure that's going to be needed around the belly scoops to replace
those parts of the original airframe that need to be removed to accommodate
the cooling ducts.  There's lots more going on here than that which first
meets the eye.

   <Marv>

 
The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org