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In a modern U.S. Navy catapult, high-pressure steam ( , admitted through the launch valve (7), propels a piston (6) to which the shuttle that pulls the tow rope (3) is attached. When the plane reaches the end of the runway (2) and leaves the flight deck (1), a water-brake (5) stops the piston, and bring-back mechanisms (4, 9) reset the catapult for the next launch.
STEAM CATAPULTS Steam catapults are steam powered and direct drive. In this chapter we describe the basic design of the steam catapult, while presenting some of the major differences in the various modifications of the steam catapult. When you complete this chapter you should be able to do the following: · State the functions of the various catapult systems and their controls. · Describe the operation of the integrated catapult control station (ICCS) monitor control console. • Explain the operation and functions of the C-13/C-13-1 hydraulic charging panel. • Describe procedures for operating and monitoring the linear and rotary retraction engines. STEAM-POWERED CATAPULTS Steam is the principal source of energy and is supplied to the catapults by the ship’s boilers, The steam is drawn from the ship’s boilers to the catapult steam receivers or accumulator, where it is stored at the desired pressure. From the receivers/accumulator, it is directed to the launching valves, and provides the energy to launch aircraft. The most significant differences between the various types of steam catapults are the length and capacity. See table 4-1 for the differences. DESCRIPTION OF OPERATION A steam fill-valve system controls the amount of steam from the ship’s boilers to either the dry-steam receivers or the wet-steam accumulator, depending on your ship’s catapult steam system. Steam from the steam receivers/accumulator is then released into the launching engine cylinders through a set of launch valves (the amount of steam used is varied by a capacity selector valve [CSV] assembly that controls the launch valve opening rate). This surge of steam acts on a set of steam pistons inside the launching engine cylinders. These pistons are connected to a shuttle that is attached to an aircraft (see fig. 4-1). The force of the steam being released from the steam receivers/accumulator pushes the pistons forward, towing the shuttle and aircraft at an increasing speed until aircraft take-off is accomplished. The shuttle and steam pistons are stopped at the end of their “power stroke” as a tapered spear (figs. 4-1 and 4-2) enters a set of water-filled cylinders, forcing the water to be “metered” out of the cylinders as the tapered spear moves into them. After the shuttle and pistons have been stopped, a grab is advanced forward along the catapult trough covers by means of the retraction engine, and attaches to the shuttle assembly. The retraction engine is then reversed and returns the grab, shuttle, and piston assembly to the battery position in preparation for the next aircraft launch.
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Dopuna: 28 Okt 2008 22:05
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