Navy Prepares to Fire an Electromagnetic Aircraft Catapult on New Carrier

Ford carrierThe Navy is preparing to launch the first ship-board tests of a new Electromagnetic Aircraft Launch System designed to replace steam catapults and propel fighter jets and other aircraft off the deck of an aircraft carrier, service officials said.

“In June, we’ll start shooting dead loads into the James River. The ship is pointed bow out. It will be the first time in 60-years that we have shot something off a ship using something other than a steam catapult,” said Rear Adm. Thomas Moore, Program Executive Officer, Carriers.

The EMALS system, which uses an electromagnetic field to propel aircraft instead of the steam catapult, is slated for the new Ford-class aircraft carriers. The first EMALS system has been under construction for several years aboard the USS Gerald R. Ford, or CVN 78, the first in class of the new carriers expected to deliver to the Navy next year.

“Two of the four catapults are completely built. The other two are almost built,” Moore said.

On the ship, the below-deck EMALS equipment has been installed. This consists of a series of transformers and rectifiers designed to convert and store electrical power through a series of motor generators before brining power to the launch motors on the catapults, Moore explained.

“By having this electrical pulse come down, you are pulling the aircraft down to the catapult to launch it. You can dial in the precise weight of the aircraft. As you accelerate the aircraft down the catapult, you can accelerate it to the precise speed it needs to launch,” Moore said.

Unlike steam catapults, which use pressurized steam, a launch valve and a piston to catapult aircraft, EMALS uses a precisely determined amount of electrical energy. As a result, EMALS is designed to more smoothly launch aircraft while reducing stress and wear and tear on the airframes themselves, he added.

“By the time the aircraft gets to the catapult it is at the right speed. Minimizing stress on the airframe, over time, reduces maintenance,” Moore added.

On the ship, EMALS will be engineered such that any of the ship’s four catapults will be able to draw power from any one of three energy storage groups on the ship, he said.

As the catapult troughs for the USS Ford’s EMALS system were being built and integrated with the overall system, the system’s technology has been in the process of extensive testing at a Naval Air Warfare Center facility in Lakehurst, N.J.

“The testing has allowed us to stay ahead of the curve and identify issues in advance of installing it on the ships,” Moore said.

Ship integration and testing for the EMALS technology will mark a substantial milestone in a program which, until now, has largely been conducting land-based flight tests at the Navy facility in Lakehurst, N.J., Moore explained.

“As things get connected they will increase the number of tests. The first aircraft launch will be after the ship gets to sea. We’ve conducted 452 aircraft launches and just finished up our second phase of aircraft compatibility testing,” Capt. Jim Donnelly, program manager for aircraft launch and recovery equipment, told in a recent interview.

The ground-based EMALS catapult tests have launched EA-18G Growlers, F/A-18 Super Hornets, C-2 Greyhound planes and E2D Advanced Hawkeyes, among others. In fact, EMALS even launched an F-35 Joint Strike Fighter at Lakehurst, Donnelly added.

The USS Ford has been under construction in recent years at Newport News Shipbuilding, a division of Huntington Ingalls.  Equipment for the EMALS system has been in development on board the ship for several years, Navy officials said.

“We’ve been making component deliveries to the ship in Newport News since 2011. It started early because for EMALS, some of the equipment such as the motor-generators are lower in the ship so they had to be part of the super-lift early on,” Donnelly added.

Metal decking is slated to be placed over the trough on the flight deck. Cabling and linear induction motor sections have been installed on board the USS Ford.

The linear motors are engineered to help create a sequentially activated rolling magnetic field or wave able to thrust or propel aircraft forward, Donnelly explained.

“It is the same type of technology that you see in a rollercoaster except this one is designed for critical launch reliability. It has to work every time you press the launch button. You are getting an electromagnetic field by turning on linear motor sequentially so we don’t energize the whole field in one shot,” he explained.

The electromagnetic field acts on a large 22-foot long aluminum plate, he added. The aluminum plate runs in between stationary sections of 12-foot long linear motors. Electricity runs through the two sides of the motors, creating an electromagnetic wave, Donnelly explained.

“The aircraft motors are kicked in at the beginning. There’s a hydraulic piston that pushes a shuttle forward. The shuttle is what connects to the aircraft launch bar,” Donnelly said.

The EMALS system can adjust to different aircraft weights and configurations, Donnelly said.  For example, EMALS is configured such that it could launch a lighter weight aircraft, such as an unmanned aircraft system, he added.

This is particularly useful because the amount of thrust needed to launch an aircraft depends upon a range of interwoven factors to include size, shape and weight of the aircraft, wind speed on the carrier deck and the speed of the aircraft carrier in the water, Donnelly explained.

“EMALS better supports the air wing now and in the future. As you may know we’ve changed the make-up of the carrier wing over the years. We’re getting to an air wing that requires higher energy launches and EMALS is much more capable when it comes to higher launch energy requirements,” Donnelly said.

The USS Ford is able to generate 13,800 volts of electrical power, more than three times the 4,160 volts that a Nimitz-class carrier generates, Moore said.

The EMALS system is also engineered to work in tandem with the USS Ford’s new Advanced Arresting Gear, or AAG. Unlike the existing hydraulic system used on current aircraft carriers, AAG is a mechanical electrical system with a cable that spins a water twister, Moore explained.

Similar to EMALS, the AAG is also designed to reduce stress on the airframe during the landing process, Moore explained.

About the Author

Kris Osborn
Kris Osborn is the managing editor of Scout Warrior.
  • Lance

    They tried this last year the new system doesn’t work well in the salt air environment of the sea. Why not prefect it before we put on a carrier first.

    • Guest

      I’ve worked with linear motors since 76. No reason for them to not work in salt air.

    • Curt

      When did they try it? There are only two installations, the one in Lakehurst and the one on the Ford. The Lakehurst one certainly didn’t go to sea nor did the Ford. They have been consucting tests since last June on the Ford without serious issue, certainly no significant saltwater issues. I think you are mistaken.

    • Gary

      False. Salt air would have no effect on any aspect of this system.

    • John

      they placed these linear motors in a chamber, 100% humidity, hosed down with saltwater and pulsed them thousands of time with no issues

    • blight_

      “Why not prefect it before we put on a carrier first.”

      We are, that’s why the UK is not pleased with EMALS progress and is going with STOVL on the QE’s instead.

  • d. kellogg

    In a forum or two elsewhere, some have brought up the notion that they thought there might be an excess amount of “EM field spillage”, excessive spikes in the local electromagnetic field proving too much for aircraft electronics to handle.

    Granted, amusement park rides using EM catapults for roller coasters and some other thrill rides, are much less powerful,
    but early concern was for risks imposed by EM fields on patrons with pacemakers (might be more questionable as to why pacemaker patients desire to be on thrill rides),
    but in all seriousness, when was the last time (if ever?) anyone heard of a pacemaker death in any amusement park due to EM field surges interfering with sensitive electronics (even cell phones don’t “feel” any interruption from EM catapults at amusement parks).

    Just $.02.

    • Curt

      Give it a rest. Maglev trains use the same technology. While they accelerate slower, they also weigh a lot more so the magnetic field is probably pretty similar or even larger. Ever here of a problem with a maglev train from em fields?

      • Fragtastic

        Read the whole comment before posting a response.

  • MikeN

    “USS Ford is able to generate 13,800 volts of electrical power, more than three times the 4,160 volts that a Nimitz-class carrier generates, Moore said”

    Is this a misquote or just a nonsensical statement? Do you mean megawatts?

  • BlackOwl18E

    I am actually really excited to see how this turns out.


    If they find out 2-5 yrs after the ship is on duty that the system isn’t working anywhere near what they thought it would what are the options ?

  • Leo Johnson

    My bet is that it’s going to “Fizzell”.

  • Mabe

    Heck worst thing that could happen is it turns into “The Philadelphia Experiment” only in reverse. They are already at Newport News.

  • Chuckles

    Who makes the emals systems?

    • blight_

      Being developed by General Atomics.

    • OldFedVet1941

      Let’s hope it isn’t Lockheed Martin!



    • Dr. Horrible

      SO DO I!

    • blight_

      Thanks for the historical perspective. People seem to think steam cats arrived in a day, but were part of a long lineage of systems designed to launch aircraft.

    • davew

      Those electrical impulses are going to play hell with the watches, computers and gadgets used by the junior officers in the J.O. bunk room on the 0-3 level. And remember, the first nuc powered ac carrier, the Enterprise, came out of the yard with continuous reeve catapults to replace steam. They didn’t work and they had to fast rework the cats back to steam. Of course the space allowed for continuous reeve was a lot less than that required for steam cats and they had to literally cram everything in. Result was a crappy system. But who knows maybe the engineer who worked on Continuous Reeve catapults retired before the electric cat was designed.
      If they go back to steam, tell them I told you so. USS Kitty Hawk Cat officer 1967-1969, Big Dave

  • Rich

    Having had a few hydraulic shots and a couple hundred steam shots, this looks really like a good thing. I hope they incorporate something like the 2 man rule for maintence.

  • NDInReadytogo

    Very cool stuff, I have been waiting a long time to see this technology being used with a practical application. i.e.

  • Noname

    The EM fields wouldn’t be a problem for military aircraft because they are electromagnetically shielded! And if there was an over abundance of EM field the aircraft are grounded by the launch mechanizim, making them able to absorb and redirect the field back into the ship! Also I find it hard to believe that the ships reactors only put out 13,800 volts!

    • Dr. Horribl

      Why? 13.8 KV is more than an insignificant voltage. Did you read GilbertC, above?

    • lightingguy

      Ships electrical puts out 104 meg watts. 104 million watts of power @ 13,800 volts

      The higher the voltage the smaller the wire size required at a given load. Makes it efficient if dangerous.

      I saw a Con-Ed (NY) 3 phase, 13,800 feeder fuse together across all 3 phases once. Impressive friggin explosion in which I was about 40 ft. From.

      • Curt

        Since transmission loss goes up at the square of the amperage, increasing bus voltage by 4 times should reduce transmission loss 16 times. Of course, you have to deal with 13.8kV which comes with it’s own challenges as you point out. Given the power required for EMALS, it probably helps keep the transmission losses and resultant heat build up reasonable.

        • Craigpv2d

          Also the higher the voltage, the smaller the motors and generators for a similar HP rating. Conductor size is rated in amps at a certain temp. Insulation is rated in volts at a certain temp, but insulation is cheaper and lighter than conductors. If you are a utility you can even forgo the insulation even at 500kv.

    • Gary

      Voltage is only one side of a power equation (V*A=W) it is impossible to determine power (watts) from just ONE value. 104 meg watts is a pretty significant amount of power.

      • Lightingguy

        Correct. The delivery voltage is only one side of the equation and we have no idea what the ship systems demand load is currently. But as stated in an earlier post, the electrical system has significantly more generating and delivery capacity the the Nimitz it is replacing so as to power up all the new toys as well as future proof as much as possible

  • ABEC Buxtor Hanning

    I’d sure like to know who’s gonna operate and maintain these cats. I spent a career on those old steam bastards and it was a helluva Lotta work with very little sleep. Are we going to need a lot more Em’s now and are they going to operate it as well? Cats have always been maintained by AIR Dept. ABs. If the EMs maintain them, the ABE rating’s gonna all but go the way of the Tradevsman in the next 20 or so years.

  • Robert

    Instead of aircraft they should try supplies to our troops on the ground

    • Chief

      When the troops call in an airstrike, who’s there? The Air Force a thousand miles away? The best supplies are 2 thousand pounds of ordinance on the enemy’s head…

  • hibeam

    Does anyone else see a rather stern and Demonic face when they look at the front end of that carrier? I wasn’t trying to see it… just kind of jumps out at me…

    • Born Skeptic

      I see an Angry Birds cartoon character, myself. Pareidolia, anyone?

  • David

    I retired from Puget Sound Naval Shipyard two years ago, and the electrical group was briefed on this somewhere around the 2000/2003 time frame by a Navy Captain (don’t remember his name). the 13.8 KV was of particular interest to me as I worked in the Breaker section of the shop. We were curious about the circuit breakers and just what the breaker frames would look like. Never got to see any of it before I retired.
    The electrical group apprentice class was tasked to build a working proto type of the EMALS. The class designed and built a table top working model that operated on 110 VAC. The whole concept was quite interesting. Hope everything works well when put into actual working conditions.

    • Lightingguy

      13,800 volts is an electrical industry standard voltage. It’s often the voltage on the top of residential supply poles and is the voltage transformed down to 120/240 residential and 120/208 commercial and others. This is not new stuff (equipment) it’s been in use for decades.

      • David

        It may be the industry standard for buildings and such, but I believe this is a first for shipboard use.4160 had its own set of challenges, and I’m sure 13,800 will have its own set of challenges as well.

    • Craigpv2d

      Electrical power plants output in the range between 2kV and 30kV with about 20k amps. This voltage is stepped up for transmission from 115 kV to 765 kV and then back down again for the customers. There is no limit on the theoretical voltage of the generator but the higher you go the more insulation you need and you reach a point of diminishing returns. Best operation is to run generators at a constant speed just around max power, so they only build them as big as they need. Any larger and it’s a waste of money.

  • ColdWarVet75

    With the joint strike fighter why not use the ski jump like the Brit’s did?

    • Dr. Horrible

      The aircraft launch rate of the ship would be limited, legacy aircraft would be incompatible with the configuration, significant deck storage space and storage options would be lost, and aircraft payloads would be relatively smaller.

    • blight_

      Look at the QE2 carriers. With the loss of the catapult system they are now STOVL-only carriers. Correspondingly the only fast-moving jets they can launch are the F-35B, with AEW and the like performed by helicopters. If we forfeited catapults we would no longer have fixed wing COD and AEW, which would all have to be performed by helicopters.

      In principle, designing systems to perform delivery and AEW duties via helicopters will provide the ability to perform these capabilities without requiring the presence of a carrier (or it will allow shuttle-hopping those helicopters to the periphery of the fleet from a carrier, without requiring one to be in the operational radius of the carrier at a given moment).

  • Jack

    What about Vtol jets. How would it work with the Electromagnetic field?

    • Dr. Horrible


  • Craigpv2d

    The “stator” part of the inductive linear motor in an EMALS system would be exposed in the flight deck track, but should be no more susceptible to corrosion than any other motor exposed to the elements. The “rotor/shuttle” is the only moving part topside in an EMALS system. This should be easily replaceable during an inport period. Both the old and new catapults will still have to deal with heat, salt water intrusion, fod, etc. but the EMALS will not have to deal with steam. The EMALS does generate a significant amount of heat because of the high currents involved, but this can be dealt with by active cooling, (water/glycol), similar to cooling the jet blast deflectors. Inductive furnaces in the steel industry actually use liquid cooled wiring to reduce the size of the conductors by carrying away heat to a outdoor heat transfer radiator. Electrical power plants use cooling towers or lake/sea water to dissipate heat from the boiler/reactor. A ship could transfer the heat to seawater.

  • Eddie

    New technology is awesome, but what about the possibility of EMP weapons or other advanced technology that can bring down our technology, hollywood style? You know what I mean, we really don’t know what’s out there and we should be keeping old analog and reliable technology as backup incase of whatever. We are relying so much on technology that it can doom us, just a thought.. New technology along side with old as backup would be more ideal.. I know many my think I’m krazy or stuck in Hollywood SciFi fantasy.. The facts are we just don’t know? Better to be prepared than sorry right?

    • Guest

      EMP? On this? Nope. All the control circuitry is below decks and shielded. This is a tight system. The energy levels required for this are pretty high so the conductors will be quite large.

      • Craigpv2d

        The high amperage conductors, (wires or buss bars) will be fairly short as they will only be from the cyclo-convertors to the linear motors. Since they are used only 2-3 seconds for every cat shot the conductors and motors will have time to cool. I would think there could be a few minutes at least between cat shots at each position when you figure the time to reposition another aircraft and do the checks and runup. I would assume there will be at least two separate complete systems with two cats each for redundancy. They are also actively cooled with a liquid jacket like mig welders and many induction furnaces in a foundry, (I’ve worked on those). Water cooled conductors can handle a tremendous amount of current compared to air cooled conductors.

    • t1oracle

      The only viable EMP weapon is a nuke. No one is going to waste a nuke just to fry some electronics. Especially given the unpredictability of the results even with a nuclear EMP.

  • Patrick Laframboise

    cool stuff some folks don’t like moving a head i think its cool

  • Brian B. Mulholland

    Craig, I gather that energy for EMALS is not stored in some massive bank of capacitors, as I had visualized. Launch depends on that “massive spinning alternator.” Is that also true of current railguns?

    That’s got to be one big, impressive alternator, the sort of thing I’d otherwise visualize inside a dam.

    • Craigpv2d

      Basically they’ll use a large flywheel to store energy. They’ll spin up the flywheel gradually, (45sec.), with the same motor/generator but running on ships power. When the flywheel disks are running at full speed, the motor will switch to generator mode. When the launch button is pressed, the cyclo-convertor will supply all that energy in a shorter burst, (2-3sec), of high power to the linear motor. At this time the rotor setup has a higher energy density and is cheaper than a bank of capacitors with the same output. Flywheels can store tremendous amounts of kinetic energy. Think of the flywheel starter on the ME-109 or the flywheel on an old hit and miss engine.

    • xXTomcatXx

      The rail guns use large capacitor banks.

  • Brian B. Mulholland

    Perhaps when the Ford reaches her midlife overhaul we’ll be able to install laser systems that can tap into the EMALS powertrain for a really impressive short-range point defense system.

    • hibeam

      Now your cooking with gas!… that’s were this is headed..

  • david mcleod

    maybe the electric magnetic field will make the ship invisible and go too another dimension just a thought

  • Jerry SM1(SS/SW) Ret.

    You Wan’t Be Left Standing In The Shower,All Soaped Up & The Fresh
    Water All Of A Sudden Is Shut Off Due To Flight OpS. I Slept Right
    Under # 1 Cat On the U.S.S. Ranger ( CVA~61 ) 70 ~ 71 Cruise.

    • Bob Kauth

      Jerry, Perhaps you can tell me if a new way of sealing the cat track plates was a success! In Jan 1964′ I was an asst. ships supt at San Fran Navy Shipyard. At that time, the plates, 18″ x 60″. X 1″ thick were fastened down with about. 50 1″ bolts , and sealed with canvas and lots of red lead. I proposed…. And we tried on the starboard bow cat… Sealing them down with silicone seal around all the edges and all the bolt holes, waiting til the silicone had partially set up, and then heavy greasing the bottom of the deck plates and bolting them down. In Feb,, 1964, I returned to civilian life, and never did find out fit the new way was successful, and applied to other carriers. Perhaps you know the result ? Would you please let me know??
      I am now an Iowa farmer….. But still love the Ranger….
      Even as she is towed to Texas.

  • Peter

    That carrier does look kind of angry.

  • realist

    the catapult won’t make any difference to the status of US carriers as sitting ducks in view of latest Russian and Chinese submarines and anti-ship missiles.

    The more money you sink into the white elephant, the bigger the loss in a real naval conflict.

    Now even countries like Iran and Syria has acquired weapon systems capable of wiping out US/NATO warships.

    The way things are going, the US can’t even afford to fight a war anymore. Jingoistic rhetorics and postures aside, there have been nothing but failures and defeats on every front - Ukraine, Syria, Saudi Arabia, Iraq, Iran, Afghanistan, Venezuela, …

    European and Asian countries are now openly ignoring US pressures, and applying to join the Chinese led AIIB. Even IMF’s Christine Lagarde is speaking in favor of the new challenger to US dominated global financial institutions.

    How fast the tides have turned!

    • blight_

      It’s a pity we don’t have any long ranged aircraft. Defeating enemy anti-ship missiles that you know about relies on having long-ranged platforms delivering long-ranged weapon systems.

      I am somewhat concerned about the ability of aircraft to detect enemy AShipM launchers, radar systems etc from the Navy. It would be Navy Hawkeyes, or depending on the quality of JSF’s gizmos, JSF. Or waiting for other intelligence-gathring assets.

      For sure, we will no longer be able to simply park a CVN close to a target and bomb it with impunity. But it doesn’t rule the carrier out completely. They may devolve to the role of the WW2 battleship, but it’s hard to imagine what else the Navy could use to replace the carrier. The Russian solution of a pile of missiles isn’t particularly great. At best it is built around throwing a sucker punch at the Navy carrier. They don’t really have land attack missiles the way we do.

  • Brian B. Mulholland

    If the CV concept was really dead, neither China nor Russia would show any interest in building one.

    You can reasonably argue that the CV is of declining relevance in a confrontation with China or Russia. In such case, there is no single platform that will take its’ place; the war will be fought between competing Networks of Everything, so to speak.

  • galloglas

    And here is Commander Dunsel the first US Navy pilot to launch from the whizbang EMLS.
    “Yes, what is that little brown ring on his nose?”
    Oh, That’s his anus.

  • OldFedVet1941

    I thought the Navy had already done this, shooting weights off of the bow.

  • Brian B. Mulholland

    The Navy’s been firing weights with the catapult, in a dry-land test installation, for some time. Now we’ll do it on a ship being prepared for service. Ultimately we’ll need a few thousand launches and traps in service to be content that the system is trustworthy for future CVs without major modification.

  • Rob C.

    I hope they worked out the problems with the EMALS , there concern about the Hornets and Growler’s having trouble with their external fuel tanks being able handle the stress of the system.

  • Justin

    Can someone explain to me the advantage of EM over hydraulic?

    • Craigpv2d

      Historically, the steam catapult was more reliable and more powerful than the hydraulic catapult. Space and weight is a big factor for designing any ships system. On a carrier, any time you can reduce weight and space needs means you can carry more aircraft and fuel and ordnance. Reliability and repeatability are also high on the list of design considerations. Cost is usually farther down the list. With a steam catapult system, generating a large number of launches in a short period of time can tax the feed water system so much as to actually reduce the amount available to the propulsion turbines. Any system with fluids, (hydraulic/water/steam), will eventually leak and repair/replacement of these systems is difficult and time consuming. Having worked on coal/nuclear power plants myself I can tell you that steam is very abrasive and will scour the inside of pipes until they are paper thin and blow out, usually at an elbow first. The Navy is moving to an all electric ship design as much as possible for reliability, space and weight savings. The EMALS system will have many fewer moving parts to wear out. The current steam systems cannot grow to accept heavier aircraft and also cannot be dialed down enough to launch really light aircraft like a UAV. An EMALS system can. The Navy is also trying to reduce the operating costs of ships by reducing the number of sailors onboard. The EMALS system will require far fewer sailors to operate and maintain. The biggest problem for an EMALS system is removing the heat generated in the linear motors and conductors after each launch. Liquid cooling will be used to remove this heat and could be recycled to the ships steam system as a bonus. I’m confident that the Navy will work out any bugs in the system before too long.

      • Justin

        Thanks Craig! Very insightful.

        • Craigpv2d

          Your welcome. Hydraulics were used from the 20s until the mid 50s. All the WWII carriers that served after the war were converted to steam and new carriers after that all had steam. Unfortunately the lack of extra electrical power in the Nimitz class will prevent these ships from being converted entirely. There has been some talk of converting one of the cats on the Nimitz class to an EMALS for drones and large aircraft, but I doubt it will happen.

  • Mark

    Maybe just me, but something about using systems that require massive amounts of electricity on a water based force seems like an accident waiting to happen.

  • dblj

    think of all the under ground high voltage wire in a large city ..wet environment ..temp. extremes. all in sealed conduit with circuit breakers .. think of miles pipe carrying 1000 psi 900 degree steam . Ill go for the rewire if there is a problem

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