The G132 and G135 groups sit between the main S90 run and the S138 evolution. Their different gun arrangements suggest trials for the later S138 design, although that connection is an interpretation. One group carried four 52 mm guns, while the other combined an 88 mm gun with lighter pieces. Both retained three 450 mm torpedo tubes, so the changes explored greater gun power within a design still centered on torpedo attack.
Notable Point · 32:18-33:38
G132 and G135 explored different gun batteries
The G132 and G135 groups retained three 450 mm torpedo tubes while trying different gun batteries, suggesting a bridge between the S90 and S138 designs.