This calculator allows you to compare spars and determine their relative scaling factor. Your reference spar's deflection is the distance it bends when a 908
gram weight is hung from the center of a 26 inch lengh of spar. Note the elasticity moduli used for 'carbon' (17.7634892268) and 'fiberglass' (7.2686776573) vary. Future versions of this page will include a way to enter your own value for E. Use this calculator as a guide together with field testing with
a critical eye.
This page is written in PHP by Jesse Gersenson (see his other kite calculators) based on equations from Dave Lord's Scale Factor and
a spreadsheet by Simon Craft.
| Calculated spar (O.D/I.D) | weight (g/m) | deflection (in.) | scale factor |
| mm / mm carbon | 0.00 | ||
| mm / mm carbon | 0.00 | ||
| mm / mm fiberglass | 0.00 | ||
| mm / mm fiberglass | 0.00 | ||
| mm / mm ramen | 0.00 |
2mm carbon rod 21.85 -100% 2.5mm carbon rod (9.1) -100% 3mm carbon rod 4.316 -100% 4mm carbon rod 1.366 -100% 4/2.5mm carbon (jino) 1.711 -100% 5/3mm carbon tube -100% 6/4mm carbon tube -100% Skyshark P 90 -100% (deflection: 0.565) Skyshark P 100 -100% (deflection: 0.413) Skyshark P 400 -100% (deflection: 0.302) Excel 6 fg tube blue -100% (1.079) 24.67 g/m Excel 8 fg tube grey -100% (0.272) 38.18 g/m Excel 9 fg tube red -100% (0.118) 51.2 g/m Excel 10 fg tube white -100% (0.047) 54 g/m 3mm Wood (35.3288) 5mm Wood (4.5786) 6mm Wood (2.2081) 8mm Wood (0.6986) 1/8" Wood (28.1604) 3/16" Wood (5.5626) 1/4" wood (1.7600) 5/16" wood (0.7209)