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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.
My first thought was, "Since when are aircraft magnetic?" Yeah, really, that was my first thought. Then, I wondered why they didn't just fire the damned things from a rail gun. Oh - wait - in essence, that's what this is. The EM force is acting on the launcher mechanism itself, rather than the payload. Hmmm - wonder why I never thought of that before? It isn't necessary to launch your ferrous accelerator thingamabob. Next up - space launches? Yeah, I realize it would require a bigger launcher, bigger by a few orders of magnitude. It sure would save a lot of rocket fuel though!
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I did some model ship tow tank testing at DTRC. The wave generators there were air bladders inflated/deflated by pneumatic pumps. I suspect the main reason they want to get away from steam for the catapults is the same reason air bladders for wave generators suck: The exact performance varies depending on the ambient air pressure and temperature. Over decades of trial and error and experience, they had built up tables allowing you to set the controls based on the air temperature and pressure so you sorta kinda got the same waves as you got yesterday. But it was never exact, and your test results were never fully reproducible.
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.