Author Topic: Navy to test electromagnetic catapult on carrier  (Read 1658 times)

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Offline Chieftain

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Navy to test electromagnetic catapult on carrier
« on: May 15, 2014, 12:07:36 AM »

Offline Chieftain

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Re: Navy to test electromagnetic catapult on carrier
« Reply #1 on: May 15, 2014, 12:16:00 AM »
This is what I did on active duty in the Navy.  I was on the catapult test team for two Nimitz Class carriers, USS Theodore Roosevelt CVN-71 and USS George Washington CVN-73.  There is little in the world that is more fun than shooting a 100,000 lbs deadload off the flight deck at 150 knots into the river.  It makes the biggest gawd-awful splash you can imagine, then bobs back up to the surface to float, where it is recovered and launched again.  The best part is that there are a whole series of weights of deadloads and you have to shoot all of them multiple times for each catapult certification. 

EMALS is as  big of a technological leap forward as the introduction of the steam catapult was.  The weight of the machinery required for steam catapults in incredible and the savings in space alone will increase the Ford's capabilities substantially.  The nuclear power plants are completely different than any other afloat, as the system needs to produce large loads of electricity instead of hotel steam for the catapults.

I'm pretty sure there will be some amazing video of these deadload tests coming up....

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Online Oceander

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Re: Navy to test electromagnetic catapult on carrier
« Reply #2 on: May 15, 2014, 12:52:35 AM »
This is what I did on active duty in the Navy.  I was on the catapult test team for two Nimitz Class carriers, USS Theodore Roosevelt CVN-71 and USS George Washington CVN-73.  There is little in the world that is more fun than shooting a 100,000 lbs deadload off the flight deck at 150 knots into the river.  It makes the biggest gawd-awful splash you can imagine, then bobs back up to the surface to float, where it is recovered and launched again.  The best part is that there are a whole series of weights of deadloads and you have to shoot all of them multiple times for each catapult certification. 

EMALS is as  big of a technological leap forward as the introduction of the steam catapult was.  The weight of the machinery required for steam catapults in incredible and the savings in space alone will increase the Ford's capabilities substantially.  The nuclear power plants are completely different than any other afloat, as the system needs to produce large loads of electricity instead of hotel steam for the catapults.

I'm pretty sure there will be some amazing video of these deadload tests coming up....

 :beer:

making stuff go "boom" or "smash" is always fun!

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Re: Navy to test electromagnetic catapult on carrier
« Reply #3 on: May 15, 2014, 01:19:33 AM »


EMALS Rail

Offline EC

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Re: Navy to test electromagnetic catapult on carrier
« Reply #4 on: May 15, 2014, 04:51:57 AM »
Idle thought - I mean obviously it works, with so many successful test launches, but how on earth do they stop the magnetic field spike screwing up the flight instruments and computers on the planes?
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Re: Navy to test electromagnetic catapult on carrier
« Reply #5 on: May 15, 2014, 04:44:26 PM »
Idle thought - I mean obviously it works, with so many successful test launches, but how on earth do they stop the magnetic field spike screwing up the flight instruments and computers on the planes?

There is some information here

http://www.foxnews.com/tech/2014/05/14/navy-to-test-electromagnetic-catapult-on-carrier/

Offline Chieftain

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Re: Navy to test electromagnetic catapult on carrier
« Reply #6 on: May 15, 2014, 04:58:28 PM »
making stuff go "boom" or "smash" is always fun!

Boom yes, smash no.  Thankfully I never put a plane in the water on my watch.

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Offline Chieftain

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Re: Navy to test electromagnetic catapult on carrier
« Reply #7 on: May 15, 2014, 10:04:37 PM »
Idle thought - I mean obviously it works, with so many successful test launches, but how on earth do they stop the magnetic field spike screwing up the flight instruments and computers on the planes?



Not sure of the details, but military aircraft are already hardened against EMI, and from the looks of the trough they probably generate a fairly tight field exactly when and where it is needed.  As I understand it, the shuttle assembly is stopped by reversing the electrical field at the end of the catapult, instead of using massive (and heavy) waterbrakes.



That's a picture courtesy of Wiki of the Charles Degaulle's C-11 steam catapult being worked on.  You can see the power cylinders in the trought with the deckplates still installed.  The water brakes and power pistons have been removed, and the round object in the foreground is the back of the aluminum piston on one of the piston assemblies.  It is pointing the opposite direction it would be installed.

I can't stress how big of a departure this is for aircraft launching and carrier design.  In WWII the Navy used hydraulic catapults...the equipment was mounted below the hangar bay and used tensioned cables to run the launching engine.  When jets came along the British Navy had already invented the steam catapult and sold the design to the Yanks, and it had the power needed to get those jets up to minimum flying speed.  The US Navy has improved and enlarged the original C-7 steam cat to the current C-13-2 that is installed on late model Nimitz Class carriers. 

But the increased power has an enormous weight penalty.  Everything on the ship affects "weight and moment", and a steam catapult installation has an enormous impact on how the carrier is designed.  The nuclear reactors on a Nimitz class are designed to produce enormous amounts of hotel steam for the main engines and the steam catapults.  In that trough you are looking at would normally be installed a pair of 18" ID steam cylinders, like a big double barreled shotgun.  It has heavy removable deckplates that are bolted in place over the cylinders.  There is an extensive hydraulic system to operate and control each catapult, and a massive steam receiver tank that is half filled with superheated water and piped to the end of the catapult.

But EMALS is a whole different breed of cat.  As I understand it, the launching engine is powered by a generator/flywheel that is spun up to a particular speed to give "X" amount of energy to the coils, and when the catapult is fired the generator set discharges to the launching engine in the 2-3 seconds it takes to tow the plane down the track 300 feet...

There is no massive steam system, no need for a hydraulically powered retraction engine or water brakes.  That means the ship can carry a lot more beans, bullets, bombs and jet fuel, which means the ship can stay at sea operating well beyond the capabilities of any Nimitz class hull.

Enormous leap forward in Naval technology, and Naval Air Systems.  EMALS will be as revolutionary as the steam catapult was when it was first introduced in the fifties by the British....

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Offline EC

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Re: Navy to test electromagnetic catapult on carrier
« Reply #8 on: May 16, 2014, 05:06:54 AM »
Thank you, Chief!  :beer: :beer: :beer: Figured if anyone would know, it'd be you!  :laugh:

Never actually considered the whole change in weight distribution aspect. They must have to be redesigning next gen carriers from the keel up again. And of course, with less inert mass hanging there just under the flight deck, she's going to be significantly more nimble than the Nimitz class. Maybe not turning on a dime, but certainly on a quarter. Probably a lot more stable as a landing platform too, since most of the heavy stuff can do double duty as ballast.

The other thing I like about this - You have full launch capability with no reduction in available engine power, since they are no longer sharing the steam.
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