Rail gun turned Catapult

[XeroCool]

I just saw a TV show about rollercoaster saying that rollercoasters are trying to get more extreme. They mentioned that the Navy beat coaster designers to the idea of steam, with catapult system on a carrier, but now the Navy is coming back to one of the rollercoaster ideas, Magnetics. Basically the same idea behind a rail gun used to launch aircraft, but it would be exponentially stronger. Anyone else heard of this before or am I just, like the story of my life, a day late and a dollar short?
X

 

[TheBubba]

Never heard that the Navy is looking to roller coaster design to base a catapult system off of, but it wouldn't suprise me one bit.

If you've never been on a coaster that uses linear magnetic induction motors for the initial acceleration, its a pretty awesome ride. Case and point: There is a ride at Hershey Park in PA that uses the induction motors and it gives enough acceleration and momentum for a complete trip around a pretty long track.

That type of propulsion has a very high rate of acceleration for the amount of power being used, i think (not sure of numbers, and going off of what i remember from a Discovery Channel special). Definitely something worth looking into for carrier ops.

From what I understand, the machinery used in the linear induction morots takes up way less space than a steam catapult capable of similar acceleration rates, and is less maintannance intensive.

 

[raptor10]

Magnetic rail guns are one of the big features of CVNX (CVX, CV21, or whatever they are calling it nowadays), With an improved electrical system that is supposed to be able to deliver up to three times the power of a nimitz class carrier, magnetic catapults are only one application of mag lev tech. some of them even suggest rail gun weapons!

 

[HeyJoe]

Emals!

I just saw a TV show about rollercoaster saying that rollercoasters are trying to get more extreme. They mentioned that the Navy beat coaster designers to the idea of steam, with catapult system on a carrier, but now the Navy is coming back to one of the rollercoaster ideas, Magnetics. Basically the same idea behind a rail gun used to launch aircraft, but it would be exponentially stronger. Anyone else heard of this before or am I just, like the story of my life, a day late and a dollar short?
X

Pretty close....big bucks being spent to get rid of steam catapults

Navy Chooses General Atomics for Electromagnetic Aircraft Launcher Program

San Diego, CA, 5 April 2004. General Atomics (GA) announces the award of a 5-year, $145-million contract with the Naval Air Warfare Center Aircraft Division for the System Development and Demonstration (SDD) phase of the Electromagnetic Aircraft Launch System (EMALS).

GA recently completed the 4-year, $80 million Program Definition and Risk Reduction (PDRR) phase of the EMALS program, for which there were two competing contractors. After testing GA's full-scale equipment on a half-length launcher at the Naval Air Warfare Center at Lakehurst, NJ, the Navy selected GA to continue alone with the SDD phase.

EMALS will replace the existing steam-driven catapults, providing a revolutionary advance in carrier launch operations. The GA team's design will provide significant reductions in workload. It will be less stressful to the aircrew and aircraft; and will require significantly less maintenance and onboard personnel, with correspondingly greatly reduced life-cycle costs. The EMALS system's first deployment will be on the next-generation carrier, the CVN-21.

The GA team comprises GA affiliates General Atomics Electronic Systems, Inc. and General Atomics Aeronautical Systems, Inc.; along with John J. McMullen Associates, Inc.; Kato Engineering; Foster-Miller, Inc.; Titan Pulse Sciences Division; STV, Inc.; and the University of Texas, Center for Electromechanics.

The EMALS Program is being carried out in GA's Electromagnetic Systems (EMS) Division, which currently has several projects aimed at increasing electrical functionality aboard Navy ships. These projects include Advanced Arresting Gear (AAG), Integrated Fight-Through Power (IFTP), Superconducting DC Homopolar Motor, and Electromagnetic Guns.

 

[TheBubba]

Magnetic rail guns are one of the big features of CVNX (CVX, CV21, or whatever they are calling it nowadays), With an improved electrical system that is supposed to be able to deliver up to three times the power of a nimitz class carrier, magnetic catapults are only one application of mag lev tech. some of them even suggest rail gun weapons!

The problem with rail guns right now is friction, arcing and the subsequent welding of the projectile to the rail.

Right now, the developers are trying to find a material (or combonation of) that will make friction between the projectile and the rail as cloase to zero as possible as well as withstand the stress of launching a projectile at hypersonic speeds.

Why is this a problem? The slightest little imperfection, whether induced by design, friction or malfunction, can cause an arc in the field (similar to static electricity jumping from one person to another) that has the potential to almost instantaneously weld the projectile to the rail. A bullet travelling at hypersonic speeds coming to an abrupt stop inside of the gun... not good. The potential for damage there is extremely high.

I think the catapults will definitely be around before the rail gun. The technology on rollercoasters, from what I've seen, isn't too far off what would be needed for a catapult.

All that having been said, the predicted specs on the ril gun are quite impressive: "muzzle velocity" of about Mach 8-10 and an on-target velocity of about Mach 8 or so. Pure kenetic energy round... no explosives. Also in development: a "cluster bomb" anti-personnel variant... the projectile is hollow with ball bearings inside.

Pretty awesome stuff.

 

[A4sForever]

*Sigh* ... there goes the thrill of 0 to 160 KIAS in 2 seconds and catapult "demonstrations".

 

[TheBubba]

^Great pic!!!

 

[Chubby]

*Sigh* ... there goes the thrill of 0 to 160 KIAS in 2 seconds and catapult "demonstrations".

Why? There will still be a catapult, it will just be powered by a different source. The jet has to reach end speed somehow ... or am I missing something?

 

[UMichfly]

Seeing A4's picture reminded me of a movie I got off netflix last week. It was called "City of Steel: Carrier". It was definitely one of the coolest things I've ever seen watching them weight test the catapults using wheeled sleds. There's something about watching a multi-ton brick flying across the water at 100+ knots that brings a tear to my eye.

/end shameless plug

 

[A4sForever]

... or am I missing something?

I dunno .... maybe. 'Cause Joe quoted:

......EMALS will replace the existing steam-driven catapults, providing a revolutionary advance in carrier launch operations. The GA team's design will provide significant reductions in workload. It will be less stressful to the aircrew and aircraft; and will require significantly less maintenance and onboard personnel, with correspondingly greatly reduced life-cycle costs. .....

Soooooooooo ... I'm assuming .... "less stressful to the aircrew and aircraft"?? Sounds like something's "different". Besides ... I just wanted to say it.

Homework assignment: You find out and report back to us.....

 

[Chubby]

Roger ... that'll give me a break from all this squeezing of li.....I mean studying NATOPS.

 

[Chubby]

Ok, so here is what I can garner ...

Due to the inherent high level of elegant control of electronic equipment, it is possible to reduce the stresses imparted to the aircraft. The present steam catapult has relatively high peak-tomean acceleration profiles (nominally 1.25, with excursions up to 2.0). This results in high stresses in the airframe and generally poor performance. With an electromagnetic system it would be possible to correct for deviations in the acceleration profile in typically hundreds of milliseconds, which would result in low peak-tomeans. A simulation was conducted that analyzed the level of controllability of the proposed design. The acceleration profile is smooth and flat, compared with a typical steam catapult profile. The simulation shows that for various load conditions, the EMALS is capable of operating within the 1.05 max peak-to-mean acceleration requirement. The result of this reduced peak-to-mean is reduced stress on the airframe. To quantify the effects of a reduced peak-to-mean, a Fracture Mechanics analysis was conducted on the airframe [4] with both the steam catapult and EMALS peak-to-means. The results from this analysis show a peak airframe life extension of 31% due to the reduced stresses on the airframe. This is becoming more important as tight budgets are forcing the Navy to procure fewer aircraft. This also has the benefit of a safer operational environment, since when the EMALS experiences any unforeseen problems during a launch, it has the capability to quickly adjust and correct for them, even if a component fails during the launch.

Now I was a graduation major in college, so I have no clue what all that means, but I think that the reduced stress to the aircraft has less to do with 0-160 KIAS in 2 seconds and more to do with how smooth the acceleration is. Which is good because I am really looking forward to launching off the front of the boat in the quasi-near future.

For those of you who are more techno savvy than I, here is the link I got that from ... maybe you can make more sense of the mumbo jumbo ...
http://www.globalsecurity.org/military/systems/ship/systems/emals.htm

 

[A4sForever]

I see you've found a picture of the US Navy's new "catch and release" terrorist detention policy.

Yeah ..... actually ..... it was taken aboard USS Enterprise in the '90's .... taken during a dependents' day cruise. Dependents, dog and pony shows galore ...

 

[TheBubba]

So was that CAG's car or the Skipper's car?

 

[kmac]

For those of you who are more techno savvy than I, here is the link I got that from ... maybe you can make more sense of the mumbo jumbo ...
http://www.globalsecurity.org/military/systems/ship/systems/emals.htm

Not a Shooter here, but...
Even on the nukes the acceleration is never the same. You can feel the difference on the cats. Now the end speeds are the same, but sometimes the initial push is a bit harder or weaker. Actually I'm not even sure if the end speeds are really the same. I've settled off a cat (relatively speaking, not a cold or soft cat or anything) and I've sailed off like a rocket before (well over calculated endspeed). Basically instead of steam valves, computers would make millisecond decisions on how much "push" to give the shuttle. Basically you've created an accurate feedback control system into the equation, even while the shuttle is running down the cat. Who knows if it will be precise, or safer in practice. If you want to hear about real fun cat shots, talk to the guys that used to shoot off the smaller decks.