4V 1/2 sphere geodesic dome
Class I icosahedral breakdown, cut snapped to the nearest vertex ring (achieved portion 50%). 250 struts in 6 lengths, 91 hubs, 160 panels. Strut length = chord factor × sphere radius.
Open this geometry in the studio
Struts
| Strut | Qty | Chord factor | 12 ft dome | 16 ft dome | 20 ft dome | 24 ft dome | 30 ft dome | 40 ft dome |
|---|---|---|---|---|---|---|---|---|
| A | 30 | 0.25318 | 1' 6 1/4" | 2' 0 5/16" | 2' 6 3/8" | 3' 0 7/16" | 3' 9 9/16" | 5' 0 3/4" |
| B | 60 | 0.29453 | 1' 9 3/16" | 2' 4 1/4" | 2' 11 5/16" | 3' 6 7/16" | 4' 5" | 5' 10 11/16" |
| C | 30 | 0.29524 | 1' 9 1/4" | 2' 4 5/16" | 2' 11 7/16" | 3' 6 1/2" | 4' 5 1/8" | 5' 10 7/8" |
| D | 30 | 0.29859 | 1' 9 1/2" | 2' 4 11/16" | 2' 11 13/16" | 3' 7" | 4' 5 3/4" | 5' 11 11/16" |
| E | 70 | 0.31287 | 1' 10 1/2" | 2' 6 1/16" | 3' 1 9/16" | 3' 9 1/16" | 4' 8 5/16" | 6' 3 1/16" |
| F | 30 | 0.32492 | 1' 11 3/8" | 2' 7 3/16" | 3' 3" | 3' 10 13/16" | 4' 10 1/2" | 6' 6" |
| Total | 250 | 448 lin ft | 598 lin ft | 747 lin ft | 897 lin ft | 1,121 lin ft | 1,495 lin ft |
Cut lengths are hub-centre to hub-centre; subtract your hub's offset at each end.
Hubs
| Valence | Qty |
|---|---|
| 6-way | 65 |
| 5-way | 6 |
| 4-way (base) | 20 |
| Total | 91 |
Panels
| Signature | Qty | Area (unit R) |
|---|---|---|
| AAC | 30 | 0.0304 |
| BBC | 30 | 0.0376 |
| BDE | 60 | 0.0394 |
| EEF | 30 | 0.0434 |
| FFF | 10 | 0.0457 |
| Total | 160 | 6.165 |
Proportions (per foot of radius)
- Height 1.000 × R · floor diameter 2.000 × R
- Surface 6.165 × R² · floor 3.142 × R²
Computed by DomeSketch from the icosahedral geometry; the 2V/3V/4V values match the published tables and the test suite asserts it.