Navy Fixes Carrier Catapult to Launch Jets with External Fuel Tanks

Ford carrierThe Navy plans to fix the software on its new carrier-based electromagnetic catapult system so that it can launching F/A-18s and Growlers carrying additional external fuel tanks under the wings, service officials said.

The changes will be finished on the Navy’s Electro Magnetic Aircraft Launch System, or EMALS, in time for operational testing aboard the Navy’s first Ford-class carrier — the USS Gerald R. Ford — in 2017, said Navy Cmdr. Thurraya Kent.

In April 2014, the Navy discovered an issue during testing at its facility in Lakehurst, N.J., that prevents the system from launching F/A-18 Super Hornets and EA-18 Growlers that are configured with external wing tanks, service officials said.

“The Navy understands the issue and will address it with a software modification well before any planned operational launch and recovery of aircraft.  The fix will only involve a software change and will be completed well before any planned operational launch and recovery of aircraft,” she said.

The external fuel tanks, positioned beneath the wings on the E/A-18G Growler electronic jamming aircraft and F/A-18s, add additional stress to the aircraft when launched by EMALS, an issue which could wind up shortening the operational life of the aircraft.

The software updates are anticipated to begin by March of next year.

“No additional hardware or hardware changes to equipment already installed onboard CVN 78 are required, and there are no modifications required for any of the aircraft affected,” Kent explained.

EMALS is a next-generation carrier-deck launch systems engineered to replace existing steam catapults and go on the services’ new Ford-class 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.

The USS Ford has been heavily criticized by lawmakers and government watchdog groups for cost overruns and delays with the new technologies. The ship is on track to come in under its congressionally-mandated cost cap of $12.9 billion.

“Two of the four catapults are completely built. The other two are almost built,” said Rear Adm. Thomas Moore, Program Executive Officer, Carriers.

The system is part of a new series of carrier-based technologies designed to significantly increase the sortie rate and engineer a tailorable catapult that can achieve the desired amount of power for a an aircraft’s dimensions and weight – all while reducing wear and tear on airframes.

“EMALS gives the Navy the flexibility to make adjustments based on aircraft weight and configuration to accommodate a wider range of aircraft, including lightweight unmanned aerial vehicles that cannot be launched with a steam catapult,” Kent said. “EMALS can be adjusted more optimally and rapidly than a steam catapult could accommodate, providing the Navy with the ability to increase sortie generation rate for our entire inventory of combat aircraft.”

Additional laboratory testing of the software glitches will be performed this year before control algorithms and fine-tuning can take place, Kent added.

“This will be followed by dead load launches, comparative steam catapult launches and aircraft launches at Lakehurst next fiscal year,” she said.

The fixes are designed to build upon how EMALS is engineered to adjust power and thrust depending upon the weight of the aircraft.  As a result, Navy officials say the system can be adjusted to accommodate the aircraft loaded with extra fuel tanks under the wings.

“EMALS will allow us to do the fine-tuning as necessary,” Kent said. “The resolution of this issue is straight-forward because the Navy will leverage this inherent capability of the system to tune the catapult forces for these wing tank configurations. There is no impact to ongoing shipboard installation or shipboard testing and this will not delay any CVN 78 milestones,” Kent said.

On the USS Ford, 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.

— Kris Osborn can be reached at Kris.Osborn@military.com

About the Author

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

    Question is they “fixed” on dry dock and land test like it faltered already will it work in the salty sea air of the open ocean??

    • t1oracle

      What are you talking about? The EMALS was putting too much stress on planes with fuel tanks and other large external payloads, so they tweaked the software to be a bit more gentle with those aircraft. Salty sea air doesn’t even come into the equation.

      Regardless, radar already works in salty sea air, this isn’t the first electronic system put on a Navy ship. It is 2015 if you remember…

  • Rob Crawford

    Go Navy (I ike)

  • ghostwhowalksnz

    No sure how can just having full fuel tanks can damage the airframe with an Emals launch, compared to a steam launch ? The force is applied via the nosewheel launch bar as before. If anything the force applied is less than before for planes under the max takeoff weight of the system. Full tanks on the wings are weights away from the centre line as before. Emals can give higher top speeds , about 30kts more , up to 180kts. And 4 catapults are not cheap, installed price on Ford is $750m.

    My guess is the electromagnets in the under deck launcher rail is trying to pull the tanks off the wings

    • IronV

      Uh, no.

    • bucky

      Electromagnets don’t attract aluminum.

      • Dale

        But they do create drag on aluminum (or anything else conductive) that moves through their magnetic field, through a phenomenon called eddy currents. https://www.youtube.com/watch?v=Yu1uRvErM80

    • JJMurray

      The stress imposed during the launch still affects the wings, especially at the wing root and when those wings have more weight hanging on them then there is more stress.

    • timbrwolf

      I would imagine it is due to EMALS accelerating the aircraft differently than what they were built to handle. They probably just had to adjust launch software to accommodate the extra weight, as well as the position of the tanks on the aircraft.

    • RunsWithScissors

      Fuel tanks =mass. Mass x acceleration=force. As you mentioned EMALS produce higher top speeds and since the run out is the same that means higher acceleration. Acceleration to high = force to high on wings. This isn’t complicated when you understand the physics.

      • ghostwhowalksnz

        That is the physics, but the point is EMALs is ‘dial in’ the top speed and weight. Most planes dont need a higher launch speed, yet.
        Increasing the launch acceleration for no real reason will create problems for the whole airframe, not only the relatively expendable fuel tanks.
        I was speculating about the magnetic field but nothing else really stacks up yet

        • AO1 Ret. John Mooney

          ghostwhowalksnz, I’m assuming you were/are an ABE? You sure talk like one. You know the physics of a cat shot, fer sher. As a retired AO, I have seen a few bad ones. I saw an A-4 dribble off the bow, and I saw an A-7 shot too hot. The stress at the wing root pretty-well did the plane in. He had to land on the beach, because we had no idea if it could take an arrested landing. I agree with your logic 100%. It’s easy to spot those who have never been on the roof here.

  • Derek

    I assume the software they need to “fix” is that they basically will have someone enter in the correct info, like: F-18/E/external tanks/ect So that way it will launch something with more weight, with more force.

    • LPF

      This!!! of course if the was Lockheed , they’d charge $4 Million for a fix that takes 3 mintues lol

    • Dylan

      I assume the fix is slightly more complicated, because the weight is on the wings, meaning the same acceleration curve would produce different stresses on the airframe than, say, if that extra weight was slung under the centerline instead. So now you have to develop a different acceleration curve to keep stresses in the wing root to acceptable levels. (Which will probably be much better than steam cat shots, too!)

      Exciting stuff. I look forward to seeing the long-term benefits of these new catapults.

  • guest

    Can the Navy now launch and recovery aircraft from drydock?

    • ghostwhowalksnz

      It was a requirement for the A5 Vigilante to be launched with no wind over deck, ie at anchor

      • CDR ow prawl ret

        Where did that come from! No Viggies for many years!
        A vigil sailor 1960-1964 Heavy Attack Squadron Seven

      • UAVGeek

        That doesn’t even pass the basic sniff test. Show us a NATOPS page and we’ll believe you.

        • ghostwhowalksnz

          You are both right, However in the very early stages when it was called NABPAW inside North American, zero wind over deck was an ‘early’ requirement.
          AS you have pointed out that changed in production

          “The original NAGPAW proposal called for a low-altitude penetrator which dictated an aircraft with a small wing area with a high loading to give an acceptable low-altitude ride at high speeds. However, the Navy wanted the aircraft to have the ability to launch from a carrier even in a (ridicules) zero wind conditions, which requires a larger wing area, for it had decided that it would be a better idea to abandon the low-altitude penetrator mission in favour of better carrier landing and takeoff characteristics. …..”

          Also discussed here :http://librarun.org/book/35210/6

  • GI dude

    “Software upgrades” The golden goose that keeps giving and giving. Defense contractors have been playing that fiddle since the early 1980’s.

  • JJMurray

    “The fixes are designed to build upon how EMALS is engineered to adjust power and thrust depending upon the weight of the aircraft. As a result, Navy officials say the system can be adjusted to accommodate the aircraft loaded with extra fuel tanks under the wings.”
    Actually what they described sounds more like an acceleration issue than a weight issue. If the launch is over stressing the wings when they have fuel tanks on them then it seems like you have to alter the acceleration profile not just amp it up because the jet is heavier.

    • TTotten

      Agreed. Additionally, earlier reporting seemed to make this an EMALS issue. Really, this is the very reason EMALS is better. With a steam system, there’d be nowhere near this level of control. While coding can take time and be costly, it can be done relatively easily compared to hardware replacement for something located in the flight deck. The system, once properly calibrated is a marked improvement over steam. Binary to digital.

      • t1oracle

        “coding can take time and be costly”
        Tweaking the launch variables can’t be that time consuming, and the only real costs in software is time.

      • blight_

        Every parameter change you make (which doesn’t necessarily require going into the source and re-compiling, bug testing et al) is likely associated with a theoretical model to simulate the consequences of such parameter change in silico before those changes are tested at Lakehurst. And then changes tested at Lakehurst find their way to the fleet.

    • timbrwolf

      Exactly! Most people do not understand the differences between a steam catapult and EMALS. It is like apples and oranges. When power is applied EMALS, being a magnetic system would receive instantaneous thrust.. I’m would venture to say EMALS could rip the nose wheel off without even moving the aircraft.

    • Dylan

      That’s exactly what I assumed, too. Rather than one lump ‘dial a weight’, they have to program all sorts of acceleration curves depending on where the weight is on the airframe. This ‘fix’ is to improve something that is already well beyond the performance of a steam cat shot.

    • Djaeger

      EXACTLY JJ The EMALS starts at full speed whereas a steam cat takes a little bit to fully accelerate. with the weight of the tanks on the wing it causes stresses on the wing and pylons. I’m sure it the change is a smoother acceleration curve with the same speed achieved at the end of the stroke.

  • Chuck Stable

    If only everything could so easily be fixed with only a simple software tweak…

  • CPTCHUCK

    It is interesting that this problem has existed with be steam catapults for years, the problem being the G force exerted at the instant of launch. Can not go full up fuel and ordnance.

  • EdC

    Software related…great. Imagine not being able to launch aircraft, losing a battle or a war because of a computer virus no one understands how to fix? We’re becoming WAY too dependent on these delicate things.

    • Fatman

      Becoming? We already are dependent on software for much of our advanced military abilities. And it’s been a good thing.

      • ghostwhowalksnz

        And everything else. The plane you fly in is highly dependent on computers. Same goes for cars and washing machines. Viruses are only a problem when changes arent locked down, which you can do by the file permissions and so on.

    • John

      these systems wont be on the internet, They also are running on Linux or a custom os… either way you have to build a virus specifically for the vulnerabilities of it then find a way to physical get the virus to the machine… its just not going to happen.

      the real risk the navy faces with electromagnetic computer controlled launch systems is in the event that a nuclear device is detonated close enough for the EMP portion to hit the carrier, even if your people inside survived, your launch system is now worthless.

  • rob

    Bad ass cat;

  • Leo Johnson

    I wonder how much Microwave activity this system will create and what injury will it cause to the people iwho operate it.

    • mule

      Um… none. How many electric motors (in this case linear induction motors) have you encountered that directly generate microwaves?

    • John Mooney USN Ret.

      No problem, guy. Those antennas on the island and those big long whip antennas hanging off the sides of the ship are not making us sterile yet. More than once I tried to tape a message to my family aboard ship, and you can hear the Zzzzz of the antennas on the recordings.

      • john

        mainly because a microphone is designed to convert motion into electromagnetic pulses which are then read… so the big ass radar and coms antennas putting off large pulses are easily picked up on something that operates using similar energies.

        If tune my hand held ham radio to 145.45 Mhz and key up the mic with 5watts of out put power next to a stereo system, i can make that stereo make all kinds of funky sounds, ive even seen some sound systems that will cut out when i key up.

        doesnt mean that 5w is particularly dangerous to me, but again for equipment operating on similar signals, it doesnt always deal with it well.

    • Ray

      And how many debit cards and cell phones it will wipe slick!!!

  • Lurker

    All things considered, a software update is much easier to deal with than if they had to physically reengineer the device itself. This shouldn’t be a cause for too much concern.

  • Fatman

    There’s no doubt this system passes the ‘cool tech’ test along with operational ability and endurance. My real worry with this system is long term maintenance. The material these electromagnets are made from is relatively rare and expensive. Replacing them will cost a pretty penny.

    As an aside, what sort of effect would an EMP have on this system? My uneducated guess is not good…

    • Dfens

      nobody is developing an emp, let alone even trying to develop one. why focus on a threat in the far future. that’s the biggest problem with our military. is that we focus on threats that either don’t exist or nobody has them for instance we should be focusing on china’s anti ship ballistic missile. the df21. or Russia’s ever growing presence an the arctic.

      • Fatman

        I was thinking if they were in the proximity of a nuclear blast. While it may be a far off possibility a carrier group is a good target for even an inaccurate nuke.

      • ghostwhowalksnz

        The latest E3D Hawkeye can track ballistic incoming and pass on data to an Aegis ship.

        Its a bit like why the harpoon was first required, the Soviet cruise missile subs launched from the surface, and the then US air launched torpedo wasn’t capable of engaging a target on the surface ( it was designed for subs underwater). The USN is far more capable then you think.

        • Fatman

          I don’t believe I ever questioned the capabilities of the Navy, just posed a question that has yet to be answered.

  • Lightingguy

    What baffles me is that this system has “theoretically” been put thru it’s paces at NAS Lakehurst, NJ for many years. One would think that prior to installing on the carrier, they would have tested ALL the aircraft current and planned in the inventory, with their entire range of payload configurations, so as to get this figured out along ago.

    How did they only now determine there was a problem ? which possibly has a software only fix available.

  • flomerdr

    What ever happened to the stories about the launch failures every 230 shots. I don’t think microwave radiation would be an issue with a magnetic launcher., however emf protection might depending on the voltages involved.

    • john

      you do realize 1000s of civilians have been sitting on top of systems like EMALS for years right? google Launched roller coaster. sure EMALS is more powerful but a pilot and his planes computers are also further from it (by nature of the landing gear lifting the plane) Its important to remember that the intensity of an EM field follows an inverse square curve with relation to distance. aka every time you double your distance to the source, its 1/4th as powerful

  • oblatt22

    Yet another corrupt program where a litany of design flaws and poor construction is being “managed” with PR.

    Ford is going to be launched unable to launch aircraft. Which is fine since it would be able to recover them either.

    • William_C1

      It will never be able to launch or recover aircraft. Just like that F-35C which you said would never take off or land on a carrier.

      • oblatt22

        One specially modified F-35 lands on a carrier and the losers are singing hallaluha. Meanwhile 30 odd F-35C and increasing sit unable to ever land because they were designed and built for failure.

  • donbacon

    “Navy Fixes Carrier Catapult” becomes “The Navy plans to fix the software…The changes will be finished …in 2017.”
    Who writes headlines?

  • CE Abernathy ABCS

    The V-2 Division, the long bearer of the responsibility of the steam catapult and arresting gear for a long time. I’m a dinosaur that watched the birth of the steam catapult and MK 7 Arresting gear.
    AB’s are pretty flexible, but this seems a step into the beyond. Who will operate and maintain these ststems

    • John Mooney, AO1 Ret

      Aw Come on, Chief…They’ll dump it on the Blue Shirts, like anything else. ;-) I agree with you. On one hand, this will save a lot of water; But on a “nuke boat”, that was never a problem. Last time I saw water hours was on an old 27-C Carrier back in ’69. If they iron this out, it will be fantastic.

  • flash

    The steam cat has been so reliable in the past, I wonder if there is a way to have a steam redundant systen side by side, piggyback, etc., with the EMALS? Just in case the EMALS system should fail in a time of urgent need. I mean, software glitch, computer re-boot, i just hope the system works as designed. I would hate to lose a carrier or ground units, depending on air defense, due to a failure to be able to cat.

    • blight_

      Having two systems will make the Ford twice as complicated. If it doesn’t work on the Ford, they’ll just rip the EMALS out, then delay completion of the next Ford to fix it up.

  • sol acres at choa chu kang

    I was able to find good ingo from your bog articles.

  • Super Tex

    That is ever so thoughtful……………I’ll bet those pilots just want, to give hugs and kisses. To those reprogramming the cats, so they can carry extra stores.

  • Blah blah

    I’m guessing that the steam catapult either produces slightly less pulling force due to the mechanical nature of it’d function OR produces the same pulling force but leads to slower acceleration of the aircraft at the moment of first trigger (due to static friction being greater than dynamic friction possibly?). The effect of either of these means the aircraft is accelerated marginally slower at the moment of trigger. This would place less shear stress or greater stress on any structure on the plane that experiences a load that is a vector of horizontal acceleration and downward force due to the weight on the wings. As the plane accelerate down the ramp, building air speed generates lift under the wings and the fuel tanks essentially ‘lightening’ the weight of the wing and fuel tanks and reducing shear forces and the downward component of the vector. Thus, even with higher pulling force of the catapult towards the end of the ramp, the stress created remain the same. With EMALS, a uniform pulling force from start to finish will still give the plane the same final velocity at the end of the ramp but the greater acceleration at the start of the run would produce higher stresses on the wing structures. Programming an acceleration profile which eases up on the initial pull and adds some extra towards the end of the run will solve the problem. (just a guess, I could of course be completely wrong about this)

    • John

      i think you are spot on, as electric motors are capable of 100% of their torque from the instant they turn on.

  • DennisJP

    Sick of hearing negativity.
    The same process happened hen they started building large carriers and the steam catapult. there here adjustments and fixes that needed to be made. It will all be figured out and the Ford will be operational soon and it ill all be the Navy saying I told you so.
    Also the past has to be left behind. If we cam make new tech that helps with maintenance on ship and aircraft as well as allows the ship to operate in a way that it could not with steam cats it is always better.
    Always hard to let go of what your used to to move to something better.