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Watch the US Navy Test Its Electromagnetic Jet Fighter Catapult
An anonymous reader sends word via Engadget that the U.S. Navy has tested its Electromagnetic Aircraft Launch System for the first time with a "dead-load" (a wheeled steel sled that weighs as much as a jet) aboard the Gerald R. Ford carrier. The article goes on to say: "Its advantages over traditional catapults that use steam instead of electromagnetic energy include smoother acceleration and its ability to place less stress on the aircraft — plus, it was designed to work even with more advanced carriers that the military will surely use in the future." You can watch a video of the "dead-load" testing here.
Steam seems like an ideal solution to me. Steam expands so well the dynamic range of it's force curve seems apropos to the task. How much of the EM energy goes into force? surge currents and magneto striction are usually things people find shorten the lifetime of electo devices yet here they are at the extreme in these. Presumably there's no shortage of steam available and it's a great way to store energy.
Some drink at the fountain of knowledge. Others just gargle.
http://en.wikipedia.org/wiki/E...
Advantages
Compared to steam catapults, EMALS weighs less, occupies less space, requires less maintenance and manpower, is more reliable, recharges more quickly, and uses less energy. Steam catapults, which use about 1350 pounds of steam per launch, have extensive mechanical, pneumatic, and hydraulic subsystems.[4] EMALS uses no steam, which makes it suitable for the Navy's planned all-electric ships.[14] The EMALS could be more easily incorporated into a ramp.[4]
Compared to steam catapults, EMALS can control the launch performance with greater precision, allowing it to launch more kinds of aircraft, from heavy fighter jets to light unmanned aircraft.[14] EMALS can also deliver 29 percent more energy than steam's approximately 95 megajoules, increasing the output to 122 megajoules.[4] The EMALS will also be more efficient than the 5-percent efficiency of steam catapults.[2]
Mit der Dummheit kämpfen Götter selbst vergebens
WHOOSH!
And it's on topic.
Sorry but you didn't do much research before posting.
The carriers are all nuclear which means they boil sea water to turn steam turbines.
Boiling seawater would produce a lot of salt which would clog the boilers.
The EM system means you have high voltage lines running under the decks and I generally think the system is going to be more complicated and harder to repair/maintain than the steam version.
The high voltage lines take up a lot less space than all the pipes an insulation needed for steam. Pipes corrode and need to be replaced and are susceptible to vibration damage. Maintenance on a wire is much less than on a pipe.
Smoother acceleration? That also makes no sense.
Pistons provide maximum acceleration at the beginning of the stroke and less at the end. That is exactly the opposite of what is good for an aircraft. It is difficult to modify where in the stroke to apply thrust for different aircraft types.
We were hearing about them testing robots to go into a nuclear reactor in Japan.
So what? The catapult will not operate in a high radiation environment.
A steam piston is more reliable than some electro magnetic whatever.
There are a lot more to a steam powered catapult than a simple piston. If any of the valves jam the catapult is down.
Saying that you can't do this with finesse ignores that the most advanced robots these days actually make use of pneumatic actuators.
Which are limited in size and power by the difficulty in moving fluids. Sorry buy advanced robots do not accelerate aircraft weighing tons to flight velocity.
The carriers are all nuclear which means they boil sea water to turn steam turbines.
No. Only a very modest amount of seawater gets boiled in a distillation plant heated by the reactor; the resulting freshwater goes into the propulsion engines, which are closed Rankine cycles. Water goes round and round from boiler to turbines, to a seawater-cooled condenser that turns it back into liquid, to the boiler again. Lather, rinse, repeat. If you tried to use seawater in the propulsion plant, it would fill up with salt in a matter of hours. The distillation plant only supplies enough water to the engines to replenish what leaks out; the rest of its output goes to the catapult system.
The EM system means you have high voltage lines running under the decks
Ever been in the same space with a battle-damaged steam line?
such big industrial machines are hydraulic in most cases. They rely on pressure
Steam machines rely on pressure times volume, which is an order of magnitude increase in control problems.
I hope you never buy a diesel powered car.
I want to shoot the messenger!