How is a bladder-type fuel cell typically supported?

A bladder-type fuel cell is typically supported by being made of rubber or nylon because these materials have the necessary flexibility and durability to accommodate changes in fuel volume and pressure. The bladder allows for expansion and contraction as fuel is added or consumed, which helps to prevent damage to the fuel cell and ensures proper fuel containment.

Rubber and nylon also provide the necessary resistance to fuel permeation, ensuring that the fuel remains contained within the bladder while resisting degradation over time. This is crucial for maintaining the structural integrity and functionality of the fuel cell in various operating conditions.

The other options involve methods of support that do not align with the design principle of bladder-type fuel cells. For example, while external metal supports and rigid plastic structures might be used in other types of fuel cells or components, they do not conform to the functional requirements that define bladder-type fuel cells. Mounting directly into the wings is also not an accurate description, as the bladder is designed to be free-floating within the wing structure, allowing it to function effectively under varying conditions.