On Mar 20, 12:12*pm, Fred the Red Shirt
wrote:
On Mar 19, 5:15 pm, "
wrote:

See * * * *http://www.eng-tips.com/viewthread.cfm?qid=103139

Thanks.

While we're discussing this, any idea as to what unit weight
is typical for 1.7 oz dacron finished with latex paint?

Would the same weight of paint also seal the heavier cloths?
(My guess would be 'almost').

I've been wondering the same thing. Its on my list of experiments for
this summer. Octave Chanute used a baloon fabric that I believe was
silk impregnated with latex.

I conducted a few interesting (and historical) experiments using 2.3
oz cotton a few years ago. In one of Wilbur Wright's 1899 letters to
Octave Chanute, he asks about several things including a source for
spruce and the type of dope used on Chanute's gliders (1896-97)
stating that "hitherto we have used shellac". Based on the date of the
letter, this would have referred to the Wrights' experiments with the
1899 kite. Wilbur's purpose in asking for materials soruces appears to
have been for the 1900 glider. As we know from the notebooks, the
Wrights did not dope the wings of the 1900-1908 machines. Why not?
Good question! Here's what I found:

Assuming a 3-pound cut, I used 7 coats of orange shellac to fill the
weave (might be a little less for them since their fabric was about
1.8 oz.) That roughly trippled the weight of the fabric alone. By my
rough calculations, this would have equated to an additional 8 pounds
for the 1902 glider (317 sq, ft total surface). Considering the lift
limitations of their technology and the ultra-slow launch speeds, the
gains from ruduced porisity (sp?) did not equal the loss from the
added weight.

Unfortunately, that means that early Wright machines are made from
great expances of unshrunk cotton just waiting for that passing cloud
to turn them into giant parallelograms. (Yep, it happened, but not to
me thank God.)

Harry Frey