ohogain
Airman
When did armor protection and self-sealing tanks become standard on fighter aircraft? For instance, the Gloster Gladiator did not have either, if I'm not mistaken, nor did the Seversky P-35, and I'm not sure, but I don't think the Curtiss P-36 did, either, so it looks like it was immediately before WW2 that both became common. The P-38, P-40 and P-51 all started out without armor or self-sealing tanks. In rough numbers, what kind of weight penalty did armor and self-sealing tanks impose on the aircraft?