I happened to find this interesting video of the EMALS being tested: https://www.youtube.com/watch?v=T1Icd3MFmWc
This is a real U.S. Navy railgun.[1] One big energy burst energizes the rails, and the projectile comes out at Mach 7.
The first is already physically built and is starting sea trials this summer.
> and they want to use the EMALS launcher on some of the ships (maybe)
They've got ski-jumps, not catapults.
[1] http://www.theregister.co.uk/2013/02/06/defence_committee_ca...
Adding EMALS to the UK carriers would only be useful for future naval UAVs. The UK really doesn't want to have to keep pilots current at doing conventional deck landings, it is too expensive and you can't rapidly change the mix of F-35 and helicopters on each carrier.
The expectation is that if the new carriers were ever full of F-35s then a fair number would have USMC markings.
Here's a big ultracapacitor bank, from Maxwell. This one is intended for temporary energy storage for buses, trucks, and trains, so it can take some banging around.[2] Capacity is 144 Watt-hours, or about half a megajoule. Weighs 64Kg, not including fans. So it would take about 250 of those units to equal one flywheel unit, for a weight of 16 metric tons.
The flywheel unit weighs about 11 metric tons. So using ultracapacitors increases weight, but it's not out of the question. Might be simpler. If the system were being designed today, it might well be capacitor-powered. No moving parts, unit-replaceable if damaged, and low-maintenance.
The EMALS system doesn't actually need 121MJ to launch.[3] Each launch uses maybe a quarter of that. Apparently the idea is to have enough energy stored for several launches on several catapults.
(A Marx generator is a setup for getting a high voltage at low current, by charging capacitors in parallel and then switching them to series. They're useful for powering some physics experiments and for making big sparks. The Museum of Science and Industry in Chicago used to have a big one, their old "Million Volt Lightning Generator". Not useful in this application.)
[1] http://www.globalsecurity.org/military/systems/ship/systems/... [2] http://www.maxwell.com/images/documents/125vmodule_ds_101469... [3] http://vtb.ee.sc.edu/vtbwebsite/downloads/publications/emals...
from arleigh burke wikipedia
"He usually pushed his destroyers to just under boiler-bursting speed, but while en route to a rendezvous prior to the Battle of Cape St. George, a boiler casualty to USS Spence (DD-512) (a jammed boiler tube brush used for cleaning) limited his squadron to 31 knots, rather than the 34+ they were otherwise capable of. Thereafter, his nickname was "31-knot Burke," originally a taunt, later a popular symbol of his hard-charging nature.[2]"
That has to create huge stresses on the windings. You wind up the flywheel, and then suddenly apply field current to activate the generator. They may be trying to ramp up field current slowly to reduce the stress. Some articles mention problems with a voltage regulator causing machine damage. Maybe the rotating machinery can't take a full-power turn-on.
Details on the system seem rather vague. Some published articles say there are four motor-generator-flywheel sets; others say only two. Isolating failed units electrically for maintenance is apparently difficult. Unclear why.
This unit "passed factory acceptance testing" in 2008.[1] These problems should have been discovered and fixed years ago. The manufacturer is Kato Engineering, part of Emerson Electric, acting as a subcontractor to General Atomic. They make a range of generators for various applications. So this is coming from a company with a long history of making generators. But generators are usually continuous-duty, not something that experiences shock loads like this flywheel rig. Apparently nobody insisted on some serious testing like running this thing through 50,000 cycles into a dummy load.
The linear motor of the catapult itself seems to be working OK.
The new arresting gear shouldn't have been a problem. That's mostly a paddles-in-water brake, something that's centuries old. How did that get screwed up?
Overall, the Ford series of carriers uses electricity for functions that, on other carriers, involve piping steam around. Most newer Naval ships are Diesel or gas turbine powered, and don't generate steam as a by-product. Nuclear plants do generate steam, which has been convenient for carrier catapults. The new British carrier series (if it gets built) is to be non-nuclear, and they want to use the EMALS launcher on some of the ships (maybe). That's part of a big mess - without a catapult, they have to buy the VTOL/STOL version of the F-35, which has its own problems.
There's an amusing book, "Ships, Machinery, and Mossbacks", by H.G. Bowen, from WWII. Bowen was a U.S. Navy engineering officer and eventually was in charge of most Naval propulsion systems during WWII. He was a real hard-ass on contractors, and often sent back large, expensive items like final drive gears back as rejects. Admiral Arleigh Burke ("31 knot Burke") wrote that his ships wouldn't have been able to go 31 knots without Bowen's work. When it really has to work, you need people like that who can say no.
[1] http://www.ga.com/emals-motor-generator-passes-acceptance-te...