▁References ▁ ▁External ▁links ▁ ▁Bo oster ▁Engine ▁Pro totype ▁Project : ▁TR 1 0 7 ▁Engine ▁Component ▁Techn ologies ▁ ▁TR - 1 0 7 ▁Render ing ▁with ▁explan ations ▁ ▁Category : R ocket ▁engines ▁using ▁k eros ene ▁prop ell ant ▁Category : R ocket ▁engines ▁using ▁the ▁st aged ▁comb ust ion ▁cycle <0x0A> </s> ▁David ▁Y el ld ell ▁( born ▁October ▁ 1 , ▁ 1 9 8 1 ) ▁is ▁a ▁retired ▁American ▁s occer ▁player ▁who ▁played ▁as ▁a ▁goal keeper ▁and ▁currently ▁serves ▁as ▁an ▁assistant ▁coach ▁for ▁S onnen hof ▁Groß asp ach . ▁Although ▁he ▁was ▁born ▁in ▁Stuttgart , ▁Germany , ▁he ▁was ▁c apped ▁for ▁the ▁United ▁States ▁national ▁team . ▁ ▁Club ▁career ▁Y el ld ell ▁was ▁the ▁first ▁choice ▁goal keeper ▁for ▁Tu S ▁Kob len z ▁until ▁suffering ▁a ▁kne e ▁lig ament ▁injury ▁which ▁kept ▁him ▁out ▁of ▁the ▁final ▁four ▁matches ▁of ▁the ▁ 2 0 0 9 – 1 0 ▁ 2 . ▁Bundes liga ▁season , ▁when ▁the ▁club ▁were ▁re leg ated ▁to ▁the ▁ 3 . ▁Liga . ▁ ▁He ▁signed ▁with ▁M SV ▁D uis burg ▁before ▁the ▁ 2 0 1 0 – 1 1 ▁season ▁and ▁made ▁his ▁compet itive ▁debut ▁for ▁the ▁club ▁in ▁a ▁first ▁round ▁D FB - P okal ▁match ▁against ▁V f B ▁Lü beck ▁on ▁August ▁ 1 3 , ▁ 2 0 1 0 . ▁ ▁The ▁next ▁season ▁saw