I measured 37.5 oz for a 4x4 sheet. I've looks around for some properties on the web but came up empty

Rick

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From: Kenny <This email address is being protected from spambots. You need JavaScript enabled to view it.>
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Sent: Thursday, June 30, 2011 9:14 PM
Subject: [Carbondragonbuildersandpilots] Re: steve's dragon



there is always a trade-off for stability. Foam gives you more out-of-plane stiffness, but doesn't add to the in-plane strength AND the adhesive to glue it together adds weight. so, you have to balance the weight verses just adding a ply or 2. My guess is that if the plywood is OK at 1/32 thick, then the 3 plies of GR/EP will be OK without the foam or NOMEX.

Russ is all over me asking for weights anybody got a sheet that they can weigh (also tell me what it is and I'll see if I can find some mechanical properties for it so I can make some comparisons)
Kenny

--- In This email address is being protected from spambots. You need JavaScript enabled to view it., Bill Jackson wrote:
>
> The Millennium hang glider is built with a carbon/foam D-tube. The
> leading edge is composite layers consisting of;
> carbon/Kevlar/foam/carbon/Kevlar. When you make a sandwich with foam
> separating the layers you increase the stiffness tremendously. That is
> why plywood is such a great material; it has thickness that helps
> mitigate wavyness and increase stiffness.
> The later production Mills would forgo the Kevlar and be built with a
> carbon/carbon/foam/carbon/carbon sandwich.
>
> Billj3cub
>
> ~~~~~~~~~~~~~__/)_~~~~~~~~~~~~~~
> On 6/29/2011 6:08 PM, russell wilson wrote:
> > hi kenny
> > lets talk about the leading edge skins/part on the dragon and what you
> > wanted to achive.
> > what you were talking about acheving in relation to using modern
> > composites to replace wood was a weight reduction to offset a slightly
> > larger glider/wing/wing area.
> > its been a while since i read a book that had this information,to save
> > me putting the wrong numbers can you please correct the following
> > statement.
> > when you dobble the thikness of a panell/beam/laminate/sheet....
> > .the strenth goes up by how many times?was it 4?
> > and the stiffnes goes up by how many times? was it 8?
> > the point i am trying to get across is if you half the thikness of
> > your leading edge scin you are loosing much much moor than half your
> > strenth and stifness.
> > for the benifit of other people reading this kenny can you please
> > correct me directly under the statement please.
> > water has a density of 1 that is a block of water 1m by 1m by
> > 1m weighs 1000 kg
> > wood varies and ply has glue....ply floats in water....so its
> > lighter...do you have the density of ply?spruse/fenolic resin....for
> > the exersize lets say .8
> > carbon is 1.8
> > epoxy is i think 1.1/1.2/1.3 depending on what you use
> > a laminate done by hand by us ametors ....carbon epoxy....will be
> > close to 50% of each with an estimated density of ....1.5
> > if you were to build a carbon scin/panel/part that was the same weight
> > as a wood scin/panel/part.
> > it would be half the woods thickness.and it will get thinner as you
> > chase your original goal to be lighter using modern materials.
> > the carbon pannel we are talking about is very thin...althogh the
> > material it self is superior in tension and compression to the ply...
> > becaus we have reduced the parts thikness by half and moor in an
> > atempt to be lighter.... the part itself may no longer do its job.due
> > to the large loss in strenth and stifness.
> > also carbon this thin acts like a spring compared to the ply...i say
> > this becaus iv had a small pice of each in my hands.
> > russ.