A system. The system includes one or more self-sealing panels and a cap member. The one or more self-sealing panels substantially cover an exterior surface of a liquid container. The cap member covers at least one of the following: one or more portions of the exterior surface of the liquid container; and an exterior surface of at least one of the one or more self-sealing panels.

A system. The system includes a liquid container and an energy absorbing system positioned. The liquid container includes a wall which defines an interior volume of the liquid container. The energy absorbing system is within an interior volume of the liquid container. The energy absorbing system is configured such that if an object passes through the wall of the liquid container and impacts the energy absorbing system, an amount of energy absorbed by the energy absorbing system is at least 18% greater than an amount of energy absorbed by the wall of the liquid container. The energy absorbing system includes one or more energy absorbing members, wherein at least one of the one or more energy absorbing members comprises a metal and has a Brinell hardness of at least 150.

In an embodiment, an aircraft includes a fuselage; a propulsion system powered by a fuel; and a fuel cell configured to store the fuel, the fuel cell including an inner layer configured to contact the fuel; an outer layer; and a self-sealing fabric structure formed from ultra-high molecular weight polyethylene (UHMWPE), the self-sealing fabric structure being between the inner layer and the outer layer, the self-sealing fabric structure being configured to self-seal a hole formed in the inner layer and the outer layer by a projectile.