Gentlemen:
Can Someone verify my wind loading calculations for my quad? I think I must be
doing something wrong.
3 elements on 15M and 20M with 4 elements on 10M. Boom is 3 inch at 18 ft long.
Calculations:
Spreaders are 1.5 inches Dia X 312 inches long (26 ft;tip to tip)= 468 square
inches each
468 X 2 for each large element = 936 square inches.
936 x 3 elements is 2808 square inches.
10 meter dedicated element spreader is .75 dia X 144 (12 ft;tip to tip) = 108
inches square
108 X 2 for the total 10M element is 216 square inches.
2808 + 216 for all spreaders is 3024 square inches.
Boom: 3 inches dia X 216 (18 feet long) = Boom 648 square inces.
Mast 2 inches X 96 (8 fee)t = Mast 192 square inches
Mast Plate 6 X 10 = Plate 60 square inches.
Wire = .1" Dia X 5904 (492 feet (3band) = Wire 590 square inches.
Adding all this up = 3024 +648 + 192 + 60 + 590 = 4514 square inches!
Since a square foot is 144 square inces (12 X 12), I divided 4514 by 144 to get
a total of 31 square feet.
If I mutiply by .66 for the round surfaces, I now get 20.7 square feet. Does
this seem heavy? The quad weighs about 75 lbs and is on top of a 51 foot triex
crankup tower.
What about the rotor? about 1 square foot? Cables?
I would have "thrown a number of" 10 feet st the beast, but now that seems
crazy also. Most quad manufacturers list this type of arrangemaent at 9 to 10
square feet. Who's right? Any Ideas??? I have been keeping the tower cranked
down at 40 feet during 25 MPH+ wind. When I get nervous, I drop it to 30 feet.
AT 35 feet and 45MPH a few weeks ago, I had no problems (except HAM4 brake
slipping), but I'm not sure if it would have survived if at full height!
Thanks
George AB2KC
