How did self-sealing tanks on ww2 aircraft work (ie on what design principle)? Did only US fighters have this feature or did other nations adopt this feature for their aircraft? Any drawbacks? Are self sealing tanks still used on newer planes?
The tank was lined with two layers of rubber. The inner layer was vulcanized to resist and hold fuel, and the outer layer was untreated so it absorbed and expanded when fuel contacted it, sealing any punctures. Theoretically. Drawbacks were, it added weight, and reduced fuel capacity, as all these extra layers had to fit inside the same space.
Most US planes had them standard, and most other countries had them as well. Japan’s utilization was limited earlier in the war but had mostly been adopted in the later years. France had spotty adoption.
Most modern military aircraft still have them, if not the same design. Commercial aircraft generally do not.
Self-sealing tanks work fairly well against small flak shrapnel and non-exploding solid bullets such as WW-II 0.50 cal machine guns or foreign euquivalents.
They’re not real effective at dealing with explosive cannon shells which became commonplace by the end of WW-II and are universal aircraft armament today. They’re also not much good at the huge slashing wounds that modern air-to-air or surface-to-air missiles produce.
This post answers the OP, but to addd to this point, Japan chose to not utilize self sealing tanks (and armor) for range and performance, and it cost them dearly once Allied pilots figured that out.
For example, the Imperial Japanese Navy’s land-based medium / torpedo bomber, the Mitsubishi G4 was nicknamed the Flying Lighter from its tendency to catch on fire easily.