5V 1/2 sphere geodesic dome
Class I icosahedral breakdown, cut snapped to the nearest vertex ring (achieved portion 55.4%). 425 struts in 9 lengths, 151 hubs, 275 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 | 0.19815 | 1' 2 1/4" | 1' 7" | 1' 11 3/4" | 2' 4 9/16" | 2' 11 11/16" | 3' 11 9/16" |
| B | 60 | 0.22569 | 1' 4 1/4" | 1' 9 11/16" | 2' 3 1/16" | 2' 8 1/2" | 3' 4 5/8" | 4' 6 3/16" |
| C | 30 | 0.23160 | 1' 4 11/16" | 1' 10 1/4" | 2' 3 13/16" | 2' 9 3/8" | 3' 5 11/16" | 4' 7 9/16" |
| D | 30 | 0.23179 | 1' 4 11/16" | 1' 10 1/4" | 2' 3 13/16" | 2' 9 3/8" | 3' 5 3/4" | 4' 7 5/8" |
| E | 80 | 0.24509 | 1' 5 5/8" | 1' 11 1/2" | 2' 5 7/16" | 2' 11 5/16" | 3' 8 1/8" | 4' 10 13/16" |
| F | 20 | 0.24535 | 1' 5 11/16" | 1' 11 9/16" | 2' 5 7/16" | 2' 11 5/16" | 3' 8 3/16" | 4' 10 7/8" |
| G | 70 | 0.24724 | 1' 5 13/16" | 1' 11 3/4" | 2' 5 11/16" | 2' 11 5/8" | 3' 8 1/2" | 4' 11 5/16" |
| H | 70 | 0.25517 | 1' 6 3/8" | 2' 0 1/2" | 2' 6 5/8" | 3' 0 3/4" | 3' 9 15/16" | 5' 1 1/4" |
| I | 35 | 0.26160 | 1' 6 13/16" | 2' 1 1/8" | 2' 7 3/8" | 3' 1 11/16" | 3' 11 1/16" | 5' 2 13/16" |
| Total | 425 | 613 lin ft | 818 lin ft | 1,022 lin ft | 1,227 lin ft | 1,533 lin ft | 2,045 lin ft |
Cut lengths are hub-centre to hub-centre; subtract your hub's offset at each end.
Hubs
| Valence | Qty |
|---|---|
| 6-way | 120 |
| 5-way | 6 |
| 4-way (base) | 25 |
| Total | 151 |
Panels
| Signature | Qty | Area (unit R) |
|---|---|---|
| AAD | 30 | 0.0186 |
| BBD | 30 | 0.0224 |
| BCG | 60 | 0.0238 |
| EEF | 40 | 0.0260 |
| EGH | 70 | 0.0269 |
| HHI | 35 | 0.0287 |
| III | 10 | 0.0296 |
| Total | 275 | 6.879 |
Proportions (per foot of radius)
- Height 1.108 × R · floor diameter 1.988 × R
- Surface 6.879 × R² · floor 3.105 × R²
- Base ring is not flat: hubs differ by 0.0069 × R — plan a stepped base plate or trim the base struts.
Computed by DomeSketch from the icosahedral geometry; the 2V/3V/4V values match the published tables and the test suite asserts it.