ves ▁per ▁cyl inder , ▁two ▁in let ▁and ▁two ▁exhaust ; ▁the ▁ball ▁race ▁main ▁bear ings ; ▁and ▁the ▁double ▁ign ition ▁system , ▁with ▁tw in ▁magnet os ▁and ▁two ▁spark ing ▁pl ugs ▁per ▁cyl inder . ▁ ▁Oper ational ▁history ▁The ▁L 1 ▁was ▁largely ▁an ▁experimental ▁engine , ▁but ▁a ▁small ▁production ▁line ▁was ▁set ▁up ▁in ▁ 1 9 2 5 . ▁R eli ability ▁was ▁not ▁high , ▁however ▁and ▁only ▁a ▁few ▁aircraft , ▁themselves ▁built ▁only ▁in ▁small ▁numbers , ▁used ▁the ▁L 1 ▁and ▁its ▁variants . ▁ ▁The ▁large ▁diameter , ▁circular ▁blow er ▁fitted ▁to ▁the ▁L 1 a ▁resulted ▁in ▁a ▁flat ▁front ed , ▁circular ▁cross ▁section ▁cow ling , ▁particularly ▁notice able ▁on ▁the ▁J unk ers ▁T ▁ 1 9 ▁and ▁ 2 6 . ▁ ▁Vari ants ▁L 1 ▁Original ▁version . ▁L 1 a ▁Lar ger ▁bore ▁diameter ▁and ▁a ▁large ▁circular ▁blow er , ▁g ear ▁driven , ▁mounted ▁at ▁the ▁front ▁of ▁the ▁engine ▁to ▁enh ance ▁high ▁alt itude ▁power . ▁L 1 b ▁ ▁App lications ▁ ▁F ock e - W ulf ▁A ▁ 1 6 b ▁ ▁J unk ers ▁T ▁ 1 9 ▁ ▁J unk ers ▁T ▁ 2 6 ▁ ▁J unk ers ▁J ▁ 2 9 ▁ ▁Spec ifications ▁( L 1 a ) ▁ ▁References ▁ ▁Bibli ography ▁ ▁L 1 ▁Category : 1 9 2 0 s ▁aircraft ▁p ist on ▁engines