The newly-named USS Gerald R. Ford (CVN 78) is the first of the next generation of U.S. Navy aircraft carriers, and with these ships are plans for the incorporation of radical new technology.
The most basic mission of an aircraft carrier is to launch and recover … duh … aircraft. The Electro-magnetic Aircraft Launch System is being fielded to take care of what we call the “shooting off the pointy end” or launch part.
In very basic terms, the legacy steam catapult system uses energy to “push” the shuttle down the track to launch aircraft. EMALS uses magnetic fields to “pull” the shuttle to affect the same end.
EMALS consists of four major subsystems:
Linear Induction Motor (LIM)
The LIM, developed in a configuration for the flight deck, is a compact, modular, integrated structure. The motor design will tolerate the range of conditions experienced in the flight deck environment and operating scenarios. The simple moving shuttle will interface with the aircraft in the same manner as the existing catapults.
Power Conversion Electronics
The power conversion electronics derive power from the energy store and convert this power to constant-current ac with increasing frequency and voltage to drive the shuttle along the launch stroke. Based on solid-state technology that GA uses in its line of commercial power equipment, the power electronics are packaged as compact modules in cabinets that are located below-deck in the carrier.
Shipboard Energy Store
The shipboard energy store consists of rotating energy storage machines connected to the power trains and LIM.
Control System
The EMALS achieves a peak-to-mean force ratio much lower than those of steam catapults by using a state-of-the-art control system to control the current into the LIM. (Source: General Atomics)
So what are the basic advantages of EMALS over the time-tested steam catapults? “We don’t have all that steam piping running all over the ship,” Capt. Steven Rorke, NAVAIR’s program manager for shipboard launch and recovery systems, explained during a recent interview with DT. “The steam stays in the plant generating electricity and then the electricity runs around the ship.”
The second major attribute is the growth potential of the system in terms of dealing with what Capt. Rorke called “the air wing of the future” including unmanned vehicles. “We can control the launch sequence much more precisely.”
And lastly, Rorke claimed EMALS will require fewer Sailors to operate and maintain.
“The technology is proven,” said Rorke. “We developed a full-scale but about half-length track that we tested at the Naval Engineering Station at Lakehurst to prove the control theory and the logic. We’re in the phase now of building shipboard representative equipment.”
But although “the technology is proven,” like all good acquistions programs, issues remain unresolved. For EMALS the main issue is non-trivial: Will it fit on the carrier? “We’re not the only customer on the ship,” Rorke said. “Finding real estate to put everything in is a challenge.”
And as with most aircraft development programs, keeping the weight of the system under control is a challenge.
In any case, the folks at General Atomics, NAVAIR, and NAVSEA have some time to figure it out. CVN 78 isn’t scheduled to sail into harm’s way until 2015.
And speaking of catapults:
(Remember that guy from “Fargo”?)
– Ward
Pull vs. Push? I take it there arent many engineering majors contributing to this site. You may also want to reconsider “contant current ac”. AC stands for alternative current, which cant very well be constant. I know what you guys meant, but the terminology is lacking.
In essence this is the same technology that launches the newer roller coasters. There is nothing particulalry complex about it. It should weight considerably less than the steam piping it replaces, and take up less room as well.
Damn, good catch, Vash. My political science roots are showing. I’m not clear on your point, though. Are you saying it’s not valid to state that the EM system “pulls” the shuttle down the track vice “pushing” it like steam cats do?
And there are a lot of things it “should” do, but guess what: So far it ain’t doing it. And that’s why the systems commands exist. As you flagged the fact we aren’t engineers (I am an Academy grad, though. I did take a lot of engineering courses in college … under protest), I’m guessing you never spent much time working with a procurement program.
Thanks for reading.
Something like this might be appropriate:
Wtf -> Lol @ vid.. :p
As reference, the VW commercial uses a trebuchet, not a catapult.
Then again, the catapult on a carrier is more like a ballista…
I hate those VW commercials but even I can’t resist the pull of a trebuchet. Gotta love those machines
Btw. you said CVN-78 was the first of the next-gen aircraft carriers but weren’t EM catapults one of the improvements planned for 77 already?
Or was that cancelled?
According to Capt. Rorke, CVN 78 will be the first for both EMALS and the new arresting gear system.
Uh Vash, that’s Alternating Current.
I know this is off the point…but. They are naming a carrier after Ford?!?! WTF. Does nixon get one named after him to? Or maybe Rumsfeld or cheney? geeez.
I was lucky enough to occupy the top bunk directly under the starboard bow catapult on CVN 69 (Ike — V4 berthing). It was hissing steam release coupled with an F-14A at full after burn, followed by an enormous BANG as the shuttle hit the bow plate. Kinda like the unstoppable force meets the immovable object dozens of times a day. But it happens so often you don’t even notice it.
The EMALS will be quieter than the steam cat at the launch, but your still gonna get the enormous BANG as it releases the plane.
Greg, Ford was a Navy man, served on carriers in WWII. Not a flyer like GHWB, but still a Navy man. Reagan got one named after, I believe his service was in Hollywood making war info films (AAF commission? anyone? help me out here). Carter got a Sub named after him, apropo considering his exp. Nixon was also in the Navy, but on a Tin can I think. JFK was a PT guy but got a carrier named after him. It doesn’t seem to me naming one after Ford is out of line at all.
I asked 4 years ago what the effects of the EMP from each magnet firing would be on the avionics package from many engineers and all that could be figured out was that they would have to be shielded. Now I find out that the Navy is about to pull the plug on this system because noone can seem to get a full scale model to work. How can you design and start construction of a $10 billion ship based around a launch system that has never been proven. The steam generating capacity has been changed on the Ford on the belief steam catipults would not be used. I have to wonder how much it will cost for this ship if the power plant on up the the flight deck needs to be redisgned.
I’m actually writing a Wikipedia article about the EMALS (http://en.wikipedia.org/wiki/Electromagnetic_Aircraft_Launch_System). You guys seem to have more knowledge on the topic than I do, so if you feel motivated enough to check it out, you should post any comments on the “Discussion” page or just edit the article yourself. Any feedback would be great, thanks!
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