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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.
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.
I hope you never buy a diesel powered car.
I want to shoot the messenger!
Former carrier pilot here, so I'm familiar with the output of the old steam systems (having used/lived-and-not-died by them).
You would think that steam is better, and in terms of simplicity of energy supply, it might be: Run a bunch of pipes maintaining the steam energy levels, and hit the button--boom! You're done.
However, reality is hella more complicated. Old catapults were one-shot; you loaded up the steam, and hoped to hell that the spike in acceleration didn't break your aircraft (thus leading to a lot of over engineering of the aircraft and very careful quadruple-checking that you have it set for the right weight/speed/etc.)
Newer catapults were progressive--you add steam along the travel of the ram, and the acceleration was smoother. However, that means that you have to have multiple valves that function exactly right--enough of them go wrong at once, and you're just going to launch a $30+ million aircraft and crew into a minor speedbump in front of the carrier.
The ram itself is very impressive. Carriers have a couple hanging on the walls of the hangar deck, and they are monstrous--I don't have any stats, but they are like 30+ foot long torpedoes that have to be accelerated with the aircraft, then stopped in a very short distance. When carriers launch, you feel the entire ship shake from this massive metal rod hitting the front end of its track.
Then there's maintenance. We're talking live steam here, not the piddling crap that comes from your tea kettle. It's "dry", as in superheated and has to be kept that way. But that means complicated insulation, piping, and constant checking that you're not eating away at your metals in this environment. Not only to you have to keep it at the correct condition before using it, but you have to do something with the used steam--which means an equally complicated recovery system.
All of this adds up to a massive effort to slingshot some dumbass (speaking as one) off the front end of a ship so he can use equally complicated gear to try to stop him after a cycle or two.
Steam works, but only because it was the only medium that could do the job at the time. I don't know the details of the EM rails, but I'm sure that the final design probably uses electric/electronic analogs to the system...but you can replace a bad circuit board or switch a helluva lot easier than you can a bad valve or piping. That, and more refined control of the overall launch makes this an obvious evolution.
Never confuse movement with action. --Hemingway