neoclassical falcate braced guitar as per t gore

[stanleywolf]

I've built 7 Gore style steel string guitars so far. All have turned out wonderfully. I now want to try a neoclassical guitar with the same body shape and falcate bracing. Immediate questions that arise:
1. what should be the target dimensions for the sound hole.
2. How do I modify the frequency analysis spreadsheet for a classical top. I will be using Lutz spruce from Pacific Rim.
Stiffness: 10059
Density: 362
Q: 160
back and sides: myrtle
neck: tbd
3. What modifications (if any) to the bracing should I make to achieve the 2 degree rotation of the bridge under string tension.
4. What other suggestions before I start

[johnparchem]

I have made a handful of falcate classical guitars. Never as large as a Dreadnought. First question I would have is will you have a lower transverse brace? I do not.

If you do not have a lower transverse brace and you have a thinner classical top than your steel strings the falcate braces should be significantly taller than your steel string braces. This seemed counter intuitive to me until I build one with the same size braces. I pitch my classical T(1,1)2 top higher than my steel string; 190 Hz or 200 Hz vs. 180 Hz steel string. So starting with a thinner top for the classical, stiffness needs to be added with either higher falcate braces or a lower transverse brace.

I do not use a lower transverse brace so my main falcate braces are 10.5 mm vs 8 mm on my steel string..

I use a vibrational stiffness of 60 for the top.

What fooled me the first go was the falcate braces being taller than fan braces. I did not include the lengthening of the the braces span without the lower transverse. Just like the height of the brace the span of a brace is also a cubed factor.