aeberl wrote:It turned out to be stiffer than expected. Usually I use a total of 18oz of glass per side on a 11mm balsa core, which results in just the right flex.
The 8oz carbon + 4oz glass resuts in about half the flex of the all 18oz all glass (good for a stiff freestyl board, but oo stiff for an all round freeride board). I would suggest to reduce core thickness to 8 or 9mm or use lighter carbon fabric.
sounds like a good test
matweb is still a good place for material properties:
density : 1.8
modulus: 33.5 million psi
max strength : 600, 000 psi
density : 2.5
modulus: 10.5 million psi
max strength : 250, 000 psi
so comparing 8 oz carbon to 18 oz glass
equivalent weight of carbon has approx 30% more volume than glass and 3 times the stiffness
so 8oz carbon x 1.3 x 3 = 31 + 4 oz glass = 35 oz glass
remarkably close to twice the overall stiffness of 18 oz glass
stiffness and strength are not the same thing.
if you look up S glass, you will find it has similar modulus (stiffness) to e-glass
but strength comparable to carbon
perhaps a better way to keep the flex you are looking for.
carbon is lighter, but you'll need much better acounting to get significant benefits.
the resin and core make up so much of the totals that the carbon numbers get diluted.
science in action,