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The side view showing the great circles are reprocented by the letters D. One of the construction advantages of the 4 frequency
icosahedrons is the horizontal great circle at the hemisphere which greatly simplifies the connection to the foundation and eliminates the need for
rectangular riser walls. This diagram shows one row under the hemisphere that may be used for extra interior
height in smaller spherical geodesic structures.
4 V Side View
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The cord lengths are calculated by multiplying the formula X the diameter you wish to build.
Example for 24' diameter dome
A - 1.52 (30 struts) _____1.52 X 24' = 36.48 -- 36"-1/2"
B - 1.79 (30 struts) _____1.79 X 24' = 24.96 -- 25"
C - 1.76 (90 struts) _____1.76 X 24' = 42.24 -- 42"-1/4"
D - 1.88 (70 struts) _____1.88 X 24' = 45.12 -- 45"
E - 1.95 (30 struts) _____1.95 X 24' = 46.8 -- 46"-3/4"
Your measurements are calculated in decimals. If you round them off to the nearest 1/4" you should be fine. The 24' diameter was chosen because the longest strut is the E strut with a final length of 46-3/4". Using cross Tee's with a length of 47-1/4" we could not go much longer. The 30' diameter is ideal for 10' strut material and 4' sheet materials. The 39' diameter optimizes 12' long strut materials. There are connection systems for larger geodesic structures fabricated from steel or wood on the connections
web page of the Spherical Geodesic Structures website.
