In ALRE steam catapult systems, what is the function of an accumulator?

• A. To cool hydraulic fluid after launch
• B. To monitor system temperature
• C. To store hydraulic energy and smooth out pressure fluctuations during launch
• D. To guide the aircraft during taxi

Answer: (C)

The accumulator's job is to store hydraulic energy and smooth out pressure fluctuations during launch. In a steam catapult, hydraulic fluid is driven to push a piston with very high demand and rapid change in flow, which creates pressure spikes and dips. An accumulator, typically gas-charged (often with nitrogen) and separated by a piston or bladder, absorbs and then releases hydraulic energy as needed. When pressure starts to rise or fluid flow surges, the compressed gas in the accumulator provides a reservoir of energy that helps maintain a steadier pressure on the launch piston. This buffering reduces shock and pressure transients, leading to a more controlled, reliable launch and protecting both the catapult components and the aircraft.

Other options don’t fit because cooling the hydraulic fluid, monitoring system temperature, or guiding the aircraft during taxi are handled by separate subsystems or sensors, not by the accumulator.