▁ ▁In ▁ 1 9 1 9 ▁Gö sta ▁von ▁Por at ▁was ▁comple ting ▁an ▁advanced ▁aer onaut ics ▁course ▁in ▁France , ▁part ▁of ▁which ▁was ▁a ▁design ▁study ▁for ▁an ▁ 8 0   hp ▁( 6 0   k W ) ▁single ▁engine ▁bi plane . ▁He ▁returned ▁to ▁his ▁native ▁Sweden ▁to ▁lead ▁the ▁Swedish ▁Army ▁Te legraph ▁Corps ' ▁A viation ▁Department , ▁based ▁near ▁Link ö ping ▁which ▁had ▁F VM ▁as ▁its ▁work shop ▁and ▁passed ▁on ▁the ▁rather ▁incomplete ▁set ▁of ▁diag rams ▁and ▁calculations ▁to ▁Henry ▁K j ell son , ▁an ▁engineer ▁there . ▁Von ▁Por at ▁also ▁made ▁several ▁ 9 0   hp ▁( 6 7   k W ) ▁Le - R h one - Th ul in ▁rot ary ▁engines , ▁bought ▁after ▁the ▁bank rupt cy ▁of ▁the ▁Th ul in ▁concern , ▁available ▁to ▁K j ell son . ▁ ▁The ▁result ▁was ▁the ▁E . 1 , ▁the ▁factory ▁name . ▁The ▁nick name ▁T um mel isa , ▁after ▁the ▁female ▁partner ▁of ▁Tom ▁Th umb , ▁was ▁widely ▁used , ▁though ▁often ▁short ened ▁to ▁Lisa . ▁After ▁the ▁formation ▁of ▁the ▁Swedish ▁Air ▁Force ▁in ▁ 1 9 2 6 ▁the ▁aircraft ▁became ▁officially ▁known ▁as ▁the ▁Ö ▁ 1 . ▁It ▁is ▁an ▁all - wood ▁single ▁bay ▁bi plane , ▁with ▁equal ▁span ▁wings ▁without ▁st agger . ▁The ▁wings ▁have ▁simple ▁parallel , ▁fa ired ▁inter plane ▁str uts