origin ally ▁developed ▁for ▁space craft ▁design ) ▁can ▁be ▁used ▁to ▁improve ▁bla de ▁design . ▁ ▁As ▁of ▁ 2 0 1 5 ▁the ▁rot or ▁diam eters ▁of ▁on sh ore ▁wind ▁tur bine ▁bl ades ▁are ▁as ▁large ▁as ▁ 1 3 0 ▁meters , ▁while ▁the ▁diameter ▁of ▁off sh ore ▁tur b ines ▁reach ▁ 1 7 0 ▁meters . ▁In ▁ 2 0 0 1 , ▁an ▁estimated ▁ 5 0 ▁million ▁kil og rams ▁of ▁fib reg lass ▁l amin ate ▁were ▁used ▁in ▁wind ▁tur bine ▁bl ades . ▁ ▁An ▁important ▁goal ▁of ▁larger ▁bla de ▁systems ▁is ▁to ▁control ▁bla de ▁weight . ▁Since ▁bla de ▁mass ▁scales ▁as ▁the ▁cube ▁of ▁the ▁tur bine ▁radius , ▁loading ▁due ▁to ▁gravity ▁const ra ins ▁systems ▁with ▁larger ▁bl ades . ▁Gra v it ational ▁loads ▁include ▁ax ial ▁and ▁tens ile / ▁compress ive ▁loads ▁( top / bottom ▁of ▁rotation ) ▁as ▁well ▁as ▁b ending ▁( l ater al ▁positions ). ▁ ▁The ▁magnitude ▁of ▁these ▁loads ▁fl uct u ates ▁cy clic ally ▁and ▁the ▁edge wise ▁moments ▁( see ▁below ) ▁are ▁revers ed ▁every ▁ 1 8 0 ° ▁of ▁rotation . ▁Typ ical ▁rot or ▁spe eds ▁and ▁design ▁life ▁are ▁~ 1 0 ▁and ▁ 2 0 ▁years , ▁respectively , ▁with ▁the ▁number ▁of ▁lifetime ▁revolution s ▁on ▁the ▁order ▁of ▁ 1 0 ^ 8 . ▁▁ ▁Consider ing ▁wind , ▁it ▁is