Mar 24, 2025
3 min read
Designing Sub-5g Wings
Weight budgets, spar placement, and why Excelobatics outperforms Depron at the micro scale. Includes a worked example for a 400 mm span.
Weight budget for a 400 mm span
| Component | Target g |
|---|---|
| Skin (top) | 0.7 g |
| Skin (bottom) | 0.5 g |
| Spar | 1.2 g |
| Ribs (3) | 0.6 g |
| Glue + finish | 0.5 g |
| Total | 3.5 g |
That leaves 1.5 g of margin before you hit the 5 g ceiling.
Spar placement
35 % chord, single 0.6 mm carbon rod tip-to-tip, glued to the underside of the top skin. The skin is the lower flange — that's the trick.
Why Excelobatics beats Depron at this scale
Depron is too brittle below 0.5 mm. Excelobatics 0.3 mm flexes and recovers; the same impact that craters Depron just dimples Excelobatics.