by 115-1172523331 » Thu Mar 22, 2007 1:50 pm
Here's how I would do it (in the English system of measurements)!
1. Calculate the force on the panel: worst case wind is directly on the face.
Drag= Cd (Drag Coeff) x q (dynamic pressure) x S (area).
Flat plate Cd = 1.29 (lots of references).
q (dynamic pressure) = 1/2 x rho (air density) x velocity of wind squared. I'll use 60mph ~ 90fps (actually 88, but use 1.5 to convert mph to fps and you will be "close enough for Government work". LOL)
S (reference area) = h x w of your panel (sq ft)
Drag=1.29 x 1/2 x .002378 (sea level) x 90^2 x 12.9 = 160 lb
2. Calculate the moment trying to tip the panel over
M = Drag x moment arm (use 1/2 the "h" dimension - slightly less due to spillage at the top, but OK)
M = 160 x 3 ft = 480 lb - ft
3. Calculate the resistive moment
Mr = Wt x resistive arm
The resistive arm is the distance from the panel to the edge of the base you don't show dimensions on.
You want the Mr to be more than the M, so calculate W = M / rest.arm! Unless this thing is going to fly, double the weight. If that isn't possible leave the weight and double the base dimensions! When you are calculating the weight, don't forget to add in the weight of the base.
Hope this helps! -- Doug