, ▁which ▁were ▁laid ▁out ▁with ▁a ▁horizontal ▁c rank sh aft , ▁this ▁new ▁engine ▁had ▁a ▁vertical ▁c rank sh aft , ▁and ▁the ▁cyl ind ers ▁were ▁arranged ▁radial ly ▁like ▁an ▁aircraft ▁engine . ▁Four ▁of ▁these ▁, ▁, ▁eight - ton ▁engines ▁could ▁be ▁installed ▁in ▁a ▁single ▁engine ▁room , ▁thus ▁deleting ▁an ▁entire ▁compart ment ▁from ▁the ▁sub marine ' s ▁design . ▁The ▁goal ▁was ▁to ▁reduce ▁overall ▁length , ▁as ▁testing ▁had ▁shown ▁that ▁shorter ▁sub mar ines ▁were ▁more ▁man eu ver able , ▁especially ▁in ▁depth , ▁and ▁had ▁less ▁sub mer ged ▁drag . ▁Four ▁compact ▁Gu ppy - type ▁ 1 2 6 - cell ▁lead – ac id ▁batter ies ▁were ▁installed ▁to ▁provide ▁a ▁high ▁sust ained ▁sub mer ged ▁speed . ▁The ▁overall ▁design ▁allowed ▁for ▁a ▁ ▁top ▁speed ▁and ▁possible ▁future ▁prop ulsion ▁replacement ▁with ▁a ▁Type ▁XVII ▁U - bo at - der ived ▁hydro gen ▁per ox ide ▁tur bine , ▁closed - cycle ▁dies el ▁system , ▁or ▁even ▁a ▁nuclear ▁power ▁plant . ▁However , ▁attempts ▁to ▁develop ▁the ▁first ▁two ▁systems ▁were ▁un success ful , ▁and ▁nuclear ▁power ▁plants ▁proved ▁too ▁large ▁to ▁be ▁accommod ated ▁in ▁the ▁Tang - class ▁h ull . ▁ ▁When ▁the ▁boats ▁went ▁to ▁sea ▁in ▁the ▁early ▁ 1 9 5 0 s , ▁the ▁new ▁engines ▁did ▁not ▁work ▁well . ▁ ▁Their ▁compact , ▁high - speed ▁design ▁made ▁them