How Aircraft Carrier’s Arresting Gear Works

Understanding the Arresting Gear System

Overview of the Arresting Gear System

• The arresting gear system is crucial for aircraft carriers, enabling high-speed aircraft to land within a limited distance by absorbing kinetic energy during landing.

• The system was pioneered by Hugh Robinson and Eugene Ely, with Ely's historic landing on January 18, 1911, marking its first use in aviation history.

Historical Development

• World War I saw significant advancements with hydraulic arresting systems that improved safety and adaptability for various aircraft weights and speeds.

• Modern U.S. Navy carriers utilize Mark 7 Mod 3 arresting gear capable of handling aircraft weighing up to 50,000 pounds.

Key Components of the System

• Cross-deck pendants (arresting cables) are flexible steel cables engaged by an aircraft's tailhook; typically three or four cables are used on carriers.

• Each cable is constructed from wire rope with a core designed for cushioning and lubrication; they require replacement after every 125 landings.

Mechanism of Operation

• Wire supports elevate deck pendants to facilitate engagement by landing aircraft while allowing them to taxi over without obstruction.

• The system includes a hydro-pneumatic engine weighing 43 tons, which utilizes sheaves and purchase cables connected through dampers for effective operation.

Hydraulic System Functionality

• The entire mechanism operates using pressurized hydraulic fluid (ethylene glycol), essential for managing vibrations during landings.

• Upon engagement, the purchase cable withdrawal initiates vibration control via damper sheave installations to stabilize the system during deceleration.

Control Mechanisms

• The Constant Runout Control Valve (CROV), integral to the system, ensures consistent stopping distances regardless of varying aircraft weights and speeds.

Aircraft Stopping Mechanism

Overview of the Controlled Retraction and Operation Valve (CROV)

• The CROV is crucial for slowing down aircraft, effectively shutting off fluid flow from the engine cylinder to the accumulator, which helps bring the aircraft to a controlled stop.

• The valve's operation can be adjusted based on aircraft weight; withdrawing a screw reduces the valve's cross-section, increasing resistance for heavier aircraft.

• For lighter aircraft, the operator performs an opposite action. Hydraulic fluid flows into the accumulator, where pressure builds from an initial 400 psi to approximately 650 psi during arrestment.

• Upon completion of arrestment, the tail hook disengages from the deck pendant, which is returned to its ready position by operating a retracting valve.

Retracting Mechanism Functionality

• When pulling down on the retracting lever at the deck edge control station, it transmits force through a cable that lifts one end of the lever connected to a return spring and tie rod.