written by Rene K. Mueller, Copyright (c) 2005, 2006, 2007, last updated Tue, January 29, 2019
The Icosahedron
Icosahedron
Uniform Polyhedron: U22
Platonic Solid
Platonic Element: Water
Vertices: 12
Edges: 30
Faces: 20
Wythoff symbol: 5|2 3
Symmetry Group: icosahedral
Vertex Configuration: {3, 3, 3, 3, 3}
Dual: dodecahedron
V: s3 * 5/12 * (3 + √5)
A: s2 * 20 / 4 * √3
rinner: s / 12 * (3 * √3 + √15)
router: s / 4 * √(10 + 2 * √5)
1V/L1 2/3 Icosahedron Dome
Geodesic 1V 2/3 Icosahedron Dome (front view)
Geodesic 1V 2/3 Icosahedron Dome (bird view)
vertices/connectors: 11
5 x 4-way
6 x 5-way
1V 2/3 Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 25: 1.05146 (31.72°)
faces: 15 (3-sided)
A-A-A x 15 (60.00°, 60.00°, 60.00°)
diameter: 2.000, radius: 1.000
height: 1.447 or 72.36% of diameter
1V 2/3 Icosahedron Dome Calculator
Geodesic 1V 2/3 Icosahedron Dome (Human is 170cm/5'7")
2V/L2 Icosahedron Dome
Geodesic 2V Icosahedron Dome (front view)
Geodesic 2V Icosahedron Dome (bird view)
vertices/connectors: 26
10 x 4-way
6 x 5-way
10 x 6-way
2V Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 30: 0.54653 (15.86°)
B x 35: 0.61803 (18.00°)
total 65 struts (2 kinds)1)
strut variance 13.1%
faces: 40 (3-sided)
A-A-B x 30 (55.57°, 55.57°, 68.86°)
B-B-B x 10 (60.00°, 60.00°, 60.00°)
2 kinds of faces2)
diameter: 2.000, radius: 1.000
height: 1.000 or 50.00% of diameter
1) strut lengths sorted by 1/10'000th or +/-0.00005 exact
2) clock wise (cw) and counter clock wise (ccw) orientation neglected
2V Icosahedron Dome Calculator
Geodesic 2V Icosahedron Dome (Human is 170cm/5'7")
3V 4/9 Icosahedron Dome
In some literature this variant is also called "3V 3/8 Dome".
Geodesic 3V 4/9 Icosahedron Dome (front view)
Geodesic 3V 4/9 Icosahedron Dome (bird view)
vertices/connectors: 46
15 x 4-way
6 x 5-way
25 x 6-way
3V 4/9 Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 30: 0.34862 (10.04°)
B x 40: 0.40355 (11.64°)
C x 50: 0.41241 (11.90°)
total 120 struts (3 kinds)1)
strut variance 18.3%
faces: 75 (3-sided)
A-A-B x 30 (54.63°, 54.63°, 70.74°)
B-C-C x 45 (58.59°, 60.70°, 60.70°)
2 kinds of faces2)
diameter: 2.000, radius: 1.000
height: 0.828 or 41.42% of diameter
1) strut lengths sorted by 1/10'000th or +/-0.00005 exact
2) clock wise (cw) and counter clock wise (ccw) orientation neglected
3V 4/9 Icosahedron Dome Calculator
Geodesic 3V 4/9 Icosahedron Dome (Human is 170cm/5'7")
As you see the bottom isn't entirely even, for heavy construction you have to level them.
3V 5/9 Icosahedron Dome
In some literature this variant is also called "3V 5/8 Dome".
Geodesic 3V 5/9 Icosahedron Dome (front view)
Geodesic 3V 5/9 Icosahedron Dome (bird view)
vertices/connectors: 61
15 x 4-way
6 x 5-way
40 x 6-way
3V 5/9 Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 30: 0.34862 (10.04°)
B x 55: 0.40355 (11.64°)
C x 80: 0.41241 (11.90°)
total 165 struts (3 kinds)1)
strut variance 18.3%
faces: 105 (3-sided)
A-A-B x 30 (54.63°, 54.63°, 70.74°)
B-C-C x 75 (58.59°, 60.70°, 60.70°)
2 kinds of faces2)
diameter: 2.000, radius: 1.000
height: 1.188 or 59.38% of diameter
1) strut lengths sorted by 1/10'000th or +/-0.00005 exact
2) clock wise (cw) and counter clock wise (ccw) orientation neglected
3V 5/9 Icosahedron Dome Calculator
Geodesic 3V 5/9 Icosahedron Dome (Human is 170cm/5'7")
As you see here as well that the bottom isn't entirely even, for heavy construction you have to level them.
4V Icosahedron Dome
Geodesic 4V Icosahedron Dome (front view)
Geodesic 4V Icosahedron Dome (bird view)
vertices/connectors: 91
20 x 4-way
6 x 5-way
65 x 6-way
4V Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 30: 0.25318 (7.27°)
B x 60: 0.29453 (8.47°)
C x 30: 0.29524 (8.49°)
D x 30: 0.29859 (8.59°)
E x 70: 0.31287 (9.00°)
F x 30: 0.32492 (9.35°)
total 250 struts (6 kinds)1)
strut variance 28.3%
faces: 160 (3-sided)
A-A-C x 30 (54.34°, 54.34°, 71.32°)
B-B-C x 30 (59.92°, 59.92°, 60.16°)
B-D-E x 60 (57.52°, 58.80°, 63.68°)
E-E-F x 30 (58.72°, 58.72°, 62.55°)
F-F-F x 10 (60.00°, 60.00°, 60.00°)
5 kinds of faces2)
diameter: 2.000, radius: 1.000
height: 1.000 or 50.00% of diameter
1) strut lengths sorted by 1/10'000th or +/-0.00005 exact
2) clock wise (cw) and counter clock wise (ccw) orientation neglected
4V Icosahedron Dome Calculator
Geodesic 4V Icosahedron Dome (Human is 170cm/5'7")
The 4V looks very attractive, yet, I would recommend using the L3 version instead with less strut lengths and less strut variance.
L3 Icosahedron Dome
Geodesic L3 Icosahedron Dome (front view)
Geodesic L3 Icosahedron Dome (bird view)
vertices/connectors: 91
20 x 4-way
6 x 5-way
65 x 6-way
L3 Icosahedron Dome Construction Map
edges/struts & bending angles (αstrut):
A x 60: 0.27590 (7.93°)
B x 60: 0.28547 (8.21°)
C x 70: 0.31287 (9.00°)
D x 30: 0.32124 (9.24°)
E x 30: 0.32492 (9.35°)
total 250 struts (5 kinds)1)
strut variance 17.8%
faces: 160 (3-sided)
A-A-D x 30 (54.40°, 54.40°, 71.20°)
A-B-C x 60 (54.68°, 57.60°, 67.72°)
B-B-D x 30 (55.77°, 55.77°, 68.46°)
C-C-E x 30 (58.72°, 58.72°, 62.55°)
E-E-E x 10 (60.00°, 60.00°, 60.00°)
5 kinds of faces2)
diameter: 2.000, radius: 1.000
height: 1.000 or 50.00% of diameter
1) strut lengths sorted by 1/10'000th or +/-0.00005 exact
2) clock wise (cw) and counter clock wise (ccw) orientation neglected
L3 Icosahedron Dome Calculator
Geodesic L3 Icosahedron Dome (Human is 170cm/5'7")
The L3 might be a better choice for a 250 strut dome than the 4V variant: the L3 provides less strut variance 17.8% (5 kinds of struts) instead of 28.3% (6 kinds of struts).