05-06-2008, 23:52 PM
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#3 (permalink)
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Administrator
Join Date: 09-03-03
Location: Fort Myers FL
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Quote:
Originally Posted by Sea Toby
With nuclear propulsion, using steam to power the ship, I do not see the need to change. The Bush will have four C13-2 catapults.
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No need to change from steam?
Why do you say that? 
This summary is from Wikipedia, but it's drawn from the links provided at the bottom. (Bold added by me)
Quote:
The EMALS has a number of significant advantages over the conventional steam driven catapult system, including reduced weight, volume, and maintenance, and increased controllability, availability, reliability, and efficiency.
One of the most important advantages of the EMALS is its simplicity, compared to the existing catapult system. The steam catapult system, which uses about 614 kg of steam per launch, requires extensive mechanical, pneumatic, and hydraulic subsystems that complicate the launch system as a whole. With the EMALS, launching, braking, and retraction would be performed by the linear induction motor, eliminating a substantial amount of auxiliary components. The EMALS is an entirely stand alone electric system, requiring no steam to be pumped around the ship. This characteristic makes the EMALS easily suitable for integration into the all-electric ships the Navy is currently researching. Its simplicity also reduces the manpower necessary to operate and maintain the system.
The EMALS is also a much more flexible system. Its feedback control system allows operators to control the launch performance with greater precision. This ability makes the EMALS capable of launching a wide variety of aircraft, from heavy fighter jets to lightweight unmanned aircraft. The EMALS could also be easily incorporated into a ramp, which would reduce the aircraft’s required end speed and consequently the launch energy.
The EMALS offers the increased energy capability necessary to launch the next generation of carrier based aircraft. The current steam catapult system can deliver about 95 MJ of energy, while the EMALS is capable of 122 MJ, a 29% increase. The EMALS is also being designed to be much more efficient than the current system, which is only about 5% efficient. With a cycle time of only 45 seconds, the EMALS can launch planes much more quickly than the conventional launch system.
Defense Tech: EMALS: Next Gen Catapult
http://www.lakehurst.navy.mil/nlweb/ieeerevc.pdf
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