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  • U. S. Navy Electromagnetic Aircraft Launcher

    http://www.youtube.com/watch?v=euLsg_viWW0

  • #2
    Whats wrong with the steam catapults they use now?

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    • #3
      Originally posted by RB211
      Whats wrong with the steam catapults they use now?
      When I toured the USS Intrepid in NY harbor several years ago there was a display of the "future US Navy aircraft carrier" which included the electromagnetic catapult. If my memory is correct they should be more energy efficient, more reliable, and can cycle faster than the current steam cats. It is anticipated it will be an improvement comparable to the change from hydraulic to steam cats.

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      • #4
        catapult

        Nothing wrong with steam, however electric catapults could potentially have many benefits:

        No plumbing (gotta have wires though, of course)
        VERY adjustable (with keystrokes instead of valves moving)
        Probably a much lighter shuttle assembly which is easier to stop
        Cleaner
        Potentially less maintenance
        etc.

        ..... and without the steam, think how much better you'd be able to see the aircraft than this:



        :-)
        Last edited by precisionmetal; 12-21-2010, 10:18 PM. Reason: addition of photo

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        • #5
          This didn't seem as energetic as the I remember the steam catapaults being. Probably more precisely controlled, though.
          Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
          ~Practitioner of the Electromechanical Arts~

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          • #6
            linear electric motors were developed by Eric Laithwaite
            1950 onwards.

            Another application HERE @18sec & 50secs

            john
            John

            I used to be indecisive. Now I'm not so sure , but I'm not a complete idiot - some bits are still missing

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            • #7
              Originally posted by MFolks
              If anyone wants 2 minutes of their life back, skip to 1:50 of the video

              Interesting concept, but like Wes says, it doesn't seem anywhere near as powerful as the steam catapults.
              I wonder if the EM pulse from the linear rail affects the avionics?
              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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              • #8
                I am guessing that it is a linear motor rather than a railgun. So I doubt that there are any significant fields by the time you are a few feet away from the track.

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                • #9
                  Originally posted by RB211
                  Whats wrong with the steam catapults they use now?

                  According to the description, clipped from the youtube video:

                  "Newer, heavier and faster aircraft will result in launch energy requirements approaching the limits of the steam catapult, increasing maintenance on the system. The system's technology allows for a smooth acceleration at both high and low speeds, increasing the carrier's ability to launch aircraft in support of the warfighter. EMALS will provide the capability for launching all current and future carrier air wing platforms from lightweight unmanned aerial vehicles to heavy strike fighters."

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                  • #10
                    This didn't seem as energetic as the I remember the steam catapaults being. Probably more precisely controlled, though.
                    Very much more precisely controlled. The acceleration profile is entirely different. They have been testing it on land for some years now. The steam system produces a massive initial surge and then tails off as the cylinder volume grows and the pressure drops. The linear motors provides a smooth intitial pull and then ramp up the force exponentially. It is probably a much smoother ride and will make for better control. Normally the pilots don't even have their hands on the controls during the launch. With this system they may be able to keep hands on.

                    The steam system has a dedicated reactor just to produce steam for the catapult and a backup as well. The electric system will be able to use ship's power instead. I will guess that they are using flywheels to store energy that is then dumped via alternators to the linear motors. I also suspect that it will allow the ship to steam into the wind faster than before and that will reduce the amount of kick needed for launch.
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                    • #11
                      Big boat that one
                      Precision takes time.

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                      • #12
                        Originally posted by Evan
                        Very much more precisely controlled. The acceleration profile is entirely different. They have been testing it on land for some years now. The steam system produces a massive initial surge and then tails off as the cylinder volume grows and the pressure drops. The linear motors provides a smooth intitial pull and then ramp up the force exponentially. It is probably a much smoother ride and will make for better control. Normally the pilots don't even have their hands on the controls during the launch. With this system they may be able to keep hands on.

                        The steam system has a dedicated reactor just to produce steam for the catapult and a backup as well. The electric system will be able to use ship's power instead. I will guess that they are using flywheels to store energy that is then dumped via alternators to the linear motors. I also suspect that it will allow the ship to steam into the wind faster than before and that will reduce the amount of kick needed for launch.
                        Having been stationed on both the USS America (oil powered) and the USS Enterprise (massively overpowered nuclear), I can say that I saw no difference in catapault or steaming performance - both could steam effortlessly at 30 knots for days - except that the America needed to refuel. The aircraft needed 30 knots of headwind down the deck for launch, so the ships had to be capable of 30 knots in a dead calm for air ops.

                        The cats made use of superheated steam that, in addition to the initial surge from opening the valve, continued to expand as the shuttle advanced. The result was a force proportional to the needed load while increasing in velocity.

                        As to pilots launching with hands off the controls, I don't think so. The planes don't fly themselves. The second most critical time of flight is launch (the first most critical being landing) and the idea of groping for a flailing stick on launch is, well, silly. Indeed there are g-forces to be contended with, but the pilots train for such things, and the usual position for the stick is full back for maximum nose up rotation immediately off the cat with quick correction after leaving the deck. Excessive delay in correcting or inadvertent aileron movement could be disasterous.

                        The pilot (and other aircrew) does, however plant his head firmly against the headrest during the catapault launch.

                        The g-forces are similar during an arrested landing but in the opposite direction. THe launch and recovery (velocity change from 0 to 150 or 150 to 0knots) take place in about the same space. The pilot does not let go of the stick during these g-forces, as he must be in full control of the aircraft in the event of a bolter. (missed cable)


                        While on the ships I watched literally hundreds of launches and landings. Although I never had the personal experience of a catapault launch or arrested landing, I did have a flight in an RA-5C, and was impressed with the skill and stamina of the pilot. I found the flight strenuous just as a passenger.
                        Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                        ~Practitioner of the Electromechanical Arts~

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                        • #13
                          As to pilots launching with hands off the controls, I don't think so. The planes don't fly themselves.
                          The planes do indeed fly themselves. This is an excerpt from the launch operations sequence for the F-18.

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                          • #14
                            Originally posted by Evan
                            The planes do indeed fly themselves. This is an excerpt from the launch operations sequence for the F-18.

                            Are those instructions from a flight sim?

                            "Salute (shift g)"?
                            Gene

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                            • #15
                              It is for a flight sim but the instructions are from the flight manual for the F-18. I was watching a video about carrier operations recently and they pointed out specifically that the pilot has a grab bar on some aircraft that he hangs onto to ensure he doesn't touch the controls.
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