, ▁single - eng ined ▁bi plane ▁with ▁a ▁w eld ed ▁steel ▁framework , ▁covered ▁with ▁fabric . ▁ 3 0 ▁were ▁produced ▁for ▁the ▁Finn ish ▁Air ▁Force ▁and ▁served ▁from ▁ 1 9 3 5 ▁to ▁ 1 9 4 9 . ▁ ▁Design ▁and ▁development ▁Ar vo ▁Y lin en , ▁who ▁was ▁the ▁chief ▁designer ▁at ▁the ▁State ▁A ircraft ▁Factory ▁( Val tion ▁l ent ok on ete hd as , ▁abbre vi ated ▁V L ) ▁led ▁a ▁project ▁to ▁create ▁a ▁new ▁tra iner ▁aircraft ▁for ▁the ▁Finn ish ▁Air ▁Force . ▁A ▁prototype ▁was ▁built ▁in ▁ 1 9 3 3 ▁and ▁it ▁was ▁first ▁flow n ▁on ▁January ▁ 1 0 , ▁ 1 9 3 4 ▁by ▁lieutenant ▁U . E . ▁M ä kel ä . ▁Series ▁production ▁began ▁one ▁year ▁later ▁in ▁ 1 9 3 5 ▁- ▁ 3 0 ▁aircraft ▁were ▁built ▁over ▁a ▁period ▁of ▁two ▁years . ▁ ▁Oper ational ▁history ▁Three ▁different ▁versions ▁of ▁the ▁aircraft ▁were ▁made : ▁a ▁mar itime , ▁a ▁pilot ▁training ▁and ▁a ▁reconna issance ▁training ▁version . ▁Ex amples ▁were ▁attached ▁to ▁all ▁Finn ish ▁Air ▁Force ▁squad rons ▁until ▁ 1 9 4 9 , ▁with ▁the ▁identification ▁codes ▁T U - 1 4 9 ▁to ▁T U - 1 7 9 . ▁ ▁A ircraft ▁on ▁display ▁One ▁T uis ku , ▁named ▁" S ok eri - S irk ku " ▁( T U - 1