Watch the US Navy Test Its Electromagnetic Jet Fighter Catapult 217
An anonymous reader sends word via Engadget that the U.S. Navy has tested its Electromagnetic Aircraft Launch System for the first time with a "dead-load" (a wheeled steel sled that weighs as much as a jet) aboard the Gerald R. Ford carrier. The article goes on to say: "Its advantages over traditional catapults that use steam instead of electromagnetic energy include smoother acceleration and its ability to place less stress on the aircraft — plus, it was designed to work even with more advanced carriers that the military will surely use in the future." You can watch a video of the "dead-load" testing here.
intuitively I would think steam would be better (Score:5, Interesting)
Steam seems like an ideal solution to me. Steam expands so well the dynamic range of it's force curve seems apropos to the task. How much of the EM energy goes into force? surge currents and magneto striction are usually things people find shorten the lifetime of electo devices yet here they are at the extreme in these. Presumably there's no shortage of steam available and it's a great way to store energy.
Re:intuitively I would think steam would be better (Score:4, Informative)
I'm not a practicing engineer, but am one by training. I would imagine that an EM system allows one to "ramp up the power" vs a steam head slamming into a piston and the resulting sudden strain on the plane.
My question is, could you not use something similar for civilian aircraft using a longer ramp up time to lower the amount of fuel on the plane a saving some cost?
Re:intuitively I would think steam would be better (Score:5, Interesting)
Yes to both!
Using a linear motor instead of a steam catapult allows you to configure specific power during any point of the process. goombah99 mentions there's no shortage of steam, but newer carriers are moving away from needing steam to be generated, preferring to take power directly from their generators to the linear motors up top.
Could this be used for civilian airports? Most definitely! Its most likely cost prohibitive though, so unless you're someone leaving a major hub always near takeoff max weight (UPS/Fedex possibly?) or you're at an airport that has a very short runway or a very high altitude runway (both due to geography), it doesn't make sense financially.
Re:intuitively I would think steam would be better (Score:5, Informative)
goombah99 mentions there's no shortage of steam, but newer carriers are moving away from needing steam to be generated, preferring to take power directly from their generators to the linear motors up top.
Aren't they going to have to generate steam at some point to make power with their nuclear reactors? This is an advance nonetheless because steam is a bitch in a way that electricity isn't. A pinhole in your insulation might cause a shock, but it won't cause people to be cut in half. Steam is awful.
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Aren't they going to have to generate steam at some point to make power with their nuclear reactors?
Only if they actually have nuclear reactors. For example, the new generation of UK carriers are not nuclear...
Re: intuitively I would think steam would be bette (Score:2)
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Re: intuitively I would think steam would be bett (Score:2)
Sheesh! Some numbers. (Score:2, Informative)
That's all well and good but surely the power you speak of is allocated for propulsion?
Some numbers: the Nimitz-class carrier generates at least 190MW, a steam catapult on that carrier requires up to 72MJ of energy per launch (at maximum). So a Nimitz-class carrier could launch one airplane per second without using a great deal of its power. In practice, it's rare for a steam catapult to launch more than one aircraft per minute, which means that even with 4 steam catapults going at their maximum rate and hauling a maximum load, the average energy use would be about 18MW, or less than one tent
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something like the QE has: two gas turbines, 4 diesel, and 4 induction motors to the screws. 77,000 tons to 25+kt.
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The UK carriers don't have a catapult. They were designed for jump jets like the Harrier (which they used to have) and a variant of the F-35 which they are getting.
Of course while the UK is building two carriers only the first one is being put into service. The second one is being built and basically mothballed right away because the contract was set up so that it was cheaper to do this than to cancel building it. And to make matters even worse while they have the first carrier now (it could be undergoin
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That old news was overcome by events over half a year ago. Prince of Wales [bbc.com] is not going to be mothballed at infancy after all. 2014 September 5: "The Royal Navy's second new aircraft carrier, the Prince of Wales, is to be brought into service rather than sold off or mothballed, Prime Minister David Cameron has announced. ... Both carriers will not be
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By 2023 they might be able to run them on fuel cells or unicorn farts or whatever the future of alternative energy is supposed to be.
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Re: intuitively I would think steam would be bett (Score:2)
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The last time they had a plan like that Argentina took advantage of it - however they acted on the announcement and not the actual sale (Invincible) or scrapping (Hermes, Ark Royal) of all the carriers and were caught out.
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Only if they actually have nuclear reactors. For example, the new generation of UK carriers are not nuclear...
I guess they're planning to stay close to home, eh? Fair enough, I guess. But then why dick with carriers?
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The US is the only country with nuclear powered carriers.
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India [wikipedia.org] is also planning to build one or more nuclear powered aircraft carriers, and there has been some information that China [hani.co.kr] also has plans.
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the CDG is the ONLY nuclear powered carrier in service outside the US Navy. Iran have a wooden replica of the Nimitz (seriously!). Citation: http://www.newsmax.com/TheWire... [newsmax.com]
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The US Navy recently just told the Australian government that submarines will be replaced with much cheaper under long range drone and to not invest in expensive major naval vessels. So based on the US navies own recommendation, why, just why?
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The US Navy recommends that the rest of the world do whatever enables the US Navy to continue to have gross superiority, and thanks it for complying. How convenient. It's especially nice when you thank us for the advice.
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Not quite
http://en.wikipedia.org/wiki/F... [wikipedia.org]
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Could this be used for civilian airports? Most definitely!
No it couldn't.
Technically it could be built, of course, but all it will do is save a few metres of runway. It won't affect the amount of fuel an aircraft has to carry nor the thrust its engines have to produce. I don't even want to think about the failure modes....
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...I don't even want to think about the failure modes....
Somewhere at a launch test:
If you'll notice the clean acceleration and graceful arc displayed by the nose of that Airbus now launching...
OK, let's go find the wings and tail!
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For the Rafa
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Most electrical models have mechanical counterparts. While it's not easy to tune on the fly you most definitely can tune a mechanical / steam based system to not simply "slam" into a piston. Have you ever seen a soft-closing kitchen cabinet? The same type of mass-spring-damper systems scale quite well to allow you to control large industrial movement.
But the benefits of EM are that it is configurable on the fly.
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if that were true then we wouldn't have the Flying Scotsman or the Mallard.
Copy/pasting... (Score:5, Informative)
http://en.wikipedia.org/wiki/E... [wikipedia.org]
Advantages
Compared to steam catapults, EMALS weighs less, occupies less space, requires less maintenance and manpower, is more reliable, recharges more quickly, and uses less energy. Steam catapults, which use about 1350 pounds of steam per launch, have extensive mechanical, pneumatic, and hydraulic subsystems.[4] EMALS uses no steam, which makes it suitable for the Navy's planned all-electric ships.[14] The EMALS could be more easily incorporated into a ramp.[4]
Compared to steam catapults, EMALS can control the launch performance with greater precision, allowing it to launch more kinds of aircraft, from heavy fighter jets to light unmanned aircraft.[14] EMALS can also deliver 29 percent more energy than steam's approximately 95 megajoules, increasing the output to 122 megajoules.[4] The EMALS will also be more efficient than the 5-percent efficiency of steam catapults.[2]
Re:Copy/pasting... (Score:5, Insightful)
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Compared to steam catapults, EMALS can control the launch performance with greater precision, allowing it to launch more kinds of aircraft, from heavy fighter jets to light unmanned aircraft.
Do light unmanned aircraft need a catapult?
Just sayin'...
Re: Copy/pasting... (Score:3)
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Re:intuitively I would think steam would be better (Score:4, Funny)
THey claimed selling point, that it's gentler on the aircraft seems questionable. Why? Steam just provides a force, how quickly you change that into momentum should be up to you. It's not like steam is an explosion that can't be accurately regulated. It's just valves.
Here's my guess. When they built the steam system they decided to make it failsafe so that one the acceleration started it completed itself just by physics not by precision timing of valves. That way you didn't huck planes into the ocean due to a stuck valve. Presumably this led to less fine grained control of the force versus velocity curve.
I would guess that the electrical one will not have that desirable characteristic. What happens if one of the capacitor banks fails or the electro magnet blows up right during the discharge process? Nothing good I would bet.
No doubt this thought has not eluded them but it sounds to me like people on a project overselling their good features and ignoring possible showstoppers early in the development process. After all maybe they won't show up down the road as being important.
Perhaps an ideal system would be a hybrid. You run the steam with 120% of the FxDistance to get the plane in the sky, and then you run the electrical system in opposition, trimming off 20% of the force. That way it fails safe, but it also has the perfect force curve on the airframe.
Re:intuitively I would think steam would be better (Score:5, Informative)
Catapult launches have specific power requirements to get a given mass to a specific acceleration. This has to be exact. To much or to little causes issues to the airframe in question.
Steam has minimum power/ pressure requirements just to get the system moving. That means there is a minimum load that can be launched. For fully fueled jets or cargo planes that isnt a big deal. For a UAV at half the size it means you have launch issues.
Emals always a much larger load range at launch. You can tailor the power requirements for the mass/ acceraltion ratio you want at launch. This means you can launch a quarter size drone and a full sized jet easily. Something steam struggles with.
Seriously this is Slashdot and basic physics.
PIPES! (Score:3)
Re: intuitively I would think steam would be bette (Score:2)
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I would assume the system involves some sort of captive bolt on a rail. This would make the scenario you're describing highly unlikely. For that you would need a pair of parallel copper rails, a source of ridiculous DC current and a small metal (aluminium?) slug (the bit that completes the circuit and your payload). As for the pipedream of approaching relativistic velocities: with a current of over one million amps, the US Navy have managed to propel a seven pound projectile at just over 1.6 miles a second.
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It's just valves.
Tee hee. Steam trains are just valves and pistons and wheels, and you can make them explode just by changing grades too quickly. Water is fascinating stuff. It has a way of taking things apart. Remember the scene in Top Gun (admit it, we've all seen it, except maybe you new people) where they couldn't launch because the steam catapults were out of operation? Most plausible part of the whole movie, besides the rampant homosexuality.
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What happens if one of the capacitor banks fails or the electro magnet blows up right during the discharge process? Nothing good I would bet.
What happens on a steam catapult if a pipe bursts during launch? Nothing good I would bet.
Mechanical systems fail, there's no avoiding that. What they have with EMALS is a system that they've determined to have a lower probability to fail.
I'll answer some of your questions and hopefully point out how an electric system is superior to a steam system. First is that the energy for launch is not stored in capacitors. There are four flywheels on board which are spun up slowly and can drive an alternator to p
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Re: intuitively I would think steam would be bette (Score:2)
Defense Budget (Score:2)
No doubt this thought has not eluded them but it sounds to me like people on a project overselling their good features and ignoring possible showstoppers early in the development process. After all maybe they won't show up down the road as being important.
Yes, it's the defense budget. That's how the procurement process works. To hell with accuracy, every project is someone's darling and must be sold. There was a great comedy about the Bradley fighting vehicle procurement, IIRC, with... maybe Kelsey Grammer and Cary Elwes? It would blow up with soldiers inside and we kept building the damn thing, even when Israel made us redesign the ones they bought because ours weren't safe.
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Take a look at these advanteges [wikipedia.org]
Another main advantage is that the linear accelerator allows change in acceleration (jerk) to be better controlled along the path. Much of the stress on the aircraft is caused by the initial jerk at the beginning of the launch. A steam catapult goes from no acceleration to high acceleration very quickly and uncontrollably. A linear motor can spread out that jerk and still get the aircraft up to the desired velocity.
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Jerk is the change in acceleration.
Re:intuitively I would think steam would be better (Score:5, Informative)
Steam seems like an ideal solution to me. Steam expands so well the dynamic range of it's force curve seems apropos to the task. How much of the EM energy goes into force? surge currents and magneto striction are usually things people find shorten the lifetime of electo devices yet here they are at the extreme in these. Presumably there's no shortage of steam available and it's a great way to store energy.
Really? My intuition is completely the opposite. Steam may expands well in the dynamic range but electricity will do anything it's controlled to. Want an exponential acceleration? Linear? Sinusoidal? You name it.
With sectorization and a few feedback control unit, it seem to me that you could precisely and instantly control the power transmitted into the catapult anywhere along the ramp. You could also drastically change the speed if needed, also something that doesn't seem as easy with steam. You since those carrier are nuclear-powered it take way less space than a whole steam system.
But, since my field is electrical engineering, I guess my opinion is a little biased.
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How is that energy stored initially? Giant capacitor banks, or flywheel to generator?
IMHO, it'll depend on many things. How much weight or space is an issue for carrier? What's the hazard if that storage is hit? How many backup is needed? Is operating life or ease to replace important? And we're not talking military grade equipment neither which I'm not very familiar with.
Whenever they think of, I guess it's gonna be a similar tech the navy have developed for their railgun : https://www.youtube.com/watch?... [youtube.com]. And, according to my quick google search, it seem they are using Lithium Iron Phos
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The key drawback of steam is that building a steam catapult that can vary its power output well enough to launch both large manned planes and (much more fragile) small drones is rather hard. And people _really_ want to launch drones from carriers.
Re:intuitively I would think steam would be better (Score:5, Informative)
Former carrier pilot here, so I'm familiar with the output of the old steam systems (having used/lived-and-not-died by them).
You would think that steam is better, and in terms of simplicity of energy supply, it might be: Run a bunch of pipes maintaining the steam energy levels, and hit the button--boom! You're done.
However, reality is hella more complicated. Old catapults were one-shot; you loaded up the steam, and hoped to hell that the spike in acceleration didn't break your aircraft (thus leading to a lot of over engineering of the aircraft and very careful quadruple-checking that you have it set for the right weight/speed/etc.)
Newer catapults were progressive--you add steam along the travel of the ram, and the acceleration was smoother. However, that means that you have to have multiple valves that function exactly right--enough of them go wrong at once, and you're just going to launch a $30+ million aircraft and crew into a minor speedbump in front of the carrier.
The ram itself is very impressive. Carriers have a couple hanging on the walls of the hangar deck, and they are monstrous--I don't have any stats, but they are like 30+ foot long torpedoes that have to be accelerated with the aircraft, then stopped in a very short distance. When carriers launch, you feel the entire ship shake from this massive metal rod hitting the front end of its track.
Then there's maintenance. We're talking live steam here, not the piddling crap that comes from your tea kettle. It's "dry", as in superheated and has to be kept that way. But that means complicated insulation, piping, and constant checking that you're not eating away at your metals in this environment. Not only to you have to keep it at the correct condition before using it, but you have to do something with the used steam--which means an equally complicated recovery system.
All of this adds up to a massive effort to slingshot some dumbass (speaking as one) off the front end of a ship so he can use equally complicated gear to try to stop him after a cycle or two.
Steam works, but only because it was the only medium that could do the job at the time. I don't know the details of the EM rails, but I'm sure that the final design probably uses electric/electronic analogs to the system...but you can replace a bad circuit board or switch a helluva lot easier than you can a bad valve or piping. That, and more refined control of the overall launch makes this an obvious evolution.
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thanks!
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For once, I can say, (Score:5, Funny)
WHOOSH!
And it's on topic.
Drones! (Score:2)
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You can already vary the power, it's called a valve. As for the complexity... How is an EM railgun system ANY less complex than a (at its core) a tube with a valve and a hook on a slug?
Mechanical systems are always more complex to build and maintain than electrical systems.
Also not that this not a rail gun, it is a linear motor.
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Mechanical systems are always more complex to build and maintain than electrical systems.
Of course. That's why when the electric window died on my Cadillac it proved cheaper to replace the entire door than to have them swap or fix the failed component.
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Of course. That's why when the electric window died on my Cadillac it proved cheaper to replace the entire door than to have them swap or fix the failed component.
No, that was because you were too lazy to track down replacement brushes, bushings, whatever, and install them. I don't blame you; me too, much of the time. But you can actually buy brushes (e.g. from carbonbrush.com, I've never bought from them but I know someone who has... for the blower motor in their Audi A8) and replace them, if the comms aren't trashed. Or whatever the problem is. Rewind the motors? Re-bush? Or it was because there's a lot of your car in the pick-and-pulls. But then that only undersco
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Of course. That's why when the electric window died on my Cadillac it proved cheaper to replace the entire door than to have them swap or fix the failed component.
No, that was because you were too lazy to track down replacement brushes, bushings, whatever, and install them. I don't blame you; me too, much of the time.
I'm not going to track down parts, that's the dealership's problem. If they decide that it's more cost-effective to replace the door than to spend tons of man-hour fixing the failed component, it's up to them, I`m not the one paying either way.
The guy who did the job told me that more and more they do this kind of thing, replacing entire sections instead of fixing small parts because the electronics are too sensitive or something like that. I asked if the door was refurbished, he said no, they don`t send th
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The guy who did the job told me that more and more they do this kind of thing, replacing entire sections instead of fixing small parts because the electronics are too sensitive or something like that.
Well, I haven't been into the workings of a modern Cadillac at all, so I don't know how they're put together. If I had to dick with the window regulators in a typical Chevy, I would throw the door away, because it's easier than drilling out the fucking gigantic steel rivets they put it in with, those cocks. The new caddys are made out of aluminum, though, so they're going to have to stop doing that. Probably they will have used a decent fastening technology, anyway; at worst, the rivets will be Aluminum.
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And that's the problem with parts which cost pennies (or dollars) to make. It's cheaper to replace than repair. If you lose a coil on an aircraft carrier, you're probably not going to replace the whole deck. For one, these things are made to be repairable (it's generally part of the specification, though exceptions do exist). Two, there's a surplus of labor on any ship.
If you're paying $0 extra per hour of labor, as you are with an aircraft carrier, and your budget for operation and maintenance is in the ra
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the window was "electric", whatever that is
According to Wikipedia: "Power window or electric window lifts(American English) as well as power or electric windows (British English) are automobile windows which can be raised and lowered by depressing a button or switch, as opposed to using a hand-turned crank handle."
See, you can learn amazing stuff on internet!
Took a few seconds (Score:2, Insightful)
My first thought was, "Since when are aircraft magnetic?" Yeah, really, that was my first thought. Then, I wondered why they didn't just fire the damned things from a rail gun. Oh - wait - in essence, that's what this is. The EM force is acting on the launcher mechanism itself, rather than the payload. Hmmm - wonder why I never thought of that before? It isn't necessary to launch your ferrous accelerator thingamabob. Next up - space launches? Yeah, I realize it would require a bigger launcher, bigge
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Think "really long run", rather than hard acceleration. As in, a ramp from the bottom of Kilimanjaro to the top. Even IF that long a run can't accelerate the ship to orbital velocity, it won't take very much of a burn to finish the job, will it? Of course, for unmanned launches, they can ram the craft into orbit at any launch speed desired.
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You're not the first guy to think of this stuff. I think I became aware of it through Rodent (yes...), a former housemate who's into space stuff, sometime in the early 1990s. For unmanned launches, it has more recently been suggested that you would get the craft up to speed in a circle [newscientist.com] before it hit the ramp. That requires a lot less real estate and a lot less track, making the concept somewhat more feasible.
For manned launches, it's pretty much a non-starter due to the amount of track you would need. But y
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It requires a vacuum equipped rail gun of quite an incredible length, designed to tolerate spacecraft zipping down it and out of the end of the tube about Mach 25. We don't have anything built or even tested at Mach 1 that can even approach those launch velocities, or be cacuum sealed effectively along its entire launch length. And when it leaves the launch tube at Mach 1, the sonic boom is likely to _destroy_ the end of any launching tube as it reverbates back.
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This isn't a particle accelerator. You're accelerating your launch vehicle with the very same magnets which are levitating it around that curved track. If they can bend it around a 1km radius, they can accelerate it linearly in a shorter distance than that.
There's also the minor issue with all launch rails, linear or circular, that your orbital inclination is basically fixed by the installation. You're not going to have the energy to perform any significant plane change at 8km/s, especially with a kick m
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range OK, bearing off? (Score:2, Funny)
They totally missed that white boat! Looks like about 30 degrees to starboard and they'd have nailed it. Bad aiming there.
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They totally missed that white boat! Looks like about 30 degrees to starboard and they'd have nailed it. Bad aiming there.
That thing is accurate. It's the guy with the hard hat and sunglasses that pointed wrong. I guess he was too busy trying to look cool with his ninja stance to fully focus on the target.
I don't get the point of this thing... (Score:2)
The carriers are all nuclear which means they boil sea water to turn steam turbines.
That means they have lots of steam. Stupid amounts of steam. Always.
The EM system means you have high voltage lines running under the decks and I generally think the system is going to be more complicated and harder to repair/maintain than the steam version.
Smoother acceleration? That also makes no sense. You can make a steam piston VERY smooth. As smooth as an electromagnetic whatever?... probably not but who cares... you w
Re:I don't get the point of this thing... (Score:5, Insightful)
Sorry but you didn't do much research before posting.
The carriers are all nuclear which means they boil sea water to turn steam turbines.
Boiling seawater would produce a lot of salt which would clog the boilers.
The EM system means you have high voltage lines running under the decks and I generally think the system is going to be more complicated and harder to repair/maintain than the steam version.
The high voltage lines take up a lot less space than all the pipes an insulation needed for steam. Pipes corrode and need to be replaced and are susceptible to vibration damage. Maintenance on a wire is much less than on a pipe.
Smoother acceleration? That also makes no sense.
Pistons provide maximum acceleration at the beginning of the stroke and less at the end. That is exactly the opposite of what is good for an aircraft. It is difficult to modify where in the stroke to apply thrust for different aircraft types.
We were hearing about them testing robots to go into a nuclear reactor in Japan.
So what? The catapult will not operate in a high radiation environment.
A steam piston is more reliable than some electro magnetic whatever.
There are a lot more [globalsecurity.org] to a steam powered catapult than a simple piston. If any of the valves jam the catapult is down.
Saying that you can't do this with finesse ignores that the most advanced robots these days actually make use of pneumatic actuators.
Which are limited in size and power by the difficulty in moving fluids. Sorry buy advanced robots do not accelerate aircraft weighing tons to flight velocity.
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The nature of the piston is more configurable than that.
You can have multiple inlets for steam that trigger as the piston goes forward, thus causing an increase in the amount of steam as the piston expands. If configured properly, the stroke can be as uniform in force as anyone will notice.
You'd probably be surprised what you can do with mechanical parts.
keep in mind that the Apollo rockets were mostly mechanical. A lot of the things in them that we'd do today with mirco controllers, they did with valves an
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You can have multiple inlets for steam that trigger as the piston goes forward, thus causing an increase in the amount of steam as the piston expands.
How do you tune the acceleration curve to handle different aircraft? Wouldn't each of those ports need to be a valve and each valve becoming a point of failure?
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You don't get it because your first sentence is wrong.
The Navy is moving to all-electric propulsion. So they won't have steam turbines.
Also, you seem to think the steam is teleported to the catapult. High pressure steam pipe versus high voltage cable? I'll take the cable every time.
As for smoother acceleration, you can't do that with a launch catapult on an aircraft carrier. There isn't enough time for nice, smooth acceleration. Instead, steam pressure builds up in the piston until it literally breaks
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The carriers are moving to all electric? What are you talking about?
Furthermore, I don't think you know what all electric means.
The carriers already use electric motors. They are however supplied with power from nuclear reactors and those reactors produce power with STEAM.
now if we go with a destroyer or smaller craft that has electric propulsion, what you'll find is that they all have diesel generators in them. That is they burn GASOLINE... and the gasoline produces electricity and that electricity then dr
Re:I don't get the point of this thing... (Score:5, Funny)
I hope you never buy a diesel powered car.
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The carriers already use electric motors. They are however supplied with power from nuclear reactors and those reactors produce power with STEAM.
This is true, but if you're going to transmit that power to other parts of the ship, I'm guessing that the Navy has concluded that electricity is better. A pipe that can carry enough steam to power the catapult must be pretty beefy. If a pipe fitting gets beat up when they're under attack, you have to depressurize the pipe so guys can fix it. With electricity,
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You're correct, though... I'm actually looking through the literature and it doesn't appear the nuclear ships are going electric in their drive drain. Correct me if I'm wrong. But the Ford class carriers appear to be using gear boxes still. I'm not sure what the subs are doing.
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A distinction without relevance to this discussion. The point is that the "electric" drive trains are ultimately powered by a hydrocarbon fuel or nuclear fission.
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Even if that happens, if they are deriving the electricity from nuclear power (as they certainly will for aircraft carriers), they certainly will have steam turbines to drive the generators. Whether the turbines drive the propellers through reduction gears, or by running generators which in turn drive electric motors, is a mere detail of power transmission.
Yes, in theory you could run a gas turbine using a gas-cooled nuclear re
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... okay but all our carriers are nuclear. And will remain so for the next hundred years or so at least. The Ford Class carriers are slated to be in service for another 90 years.
So... where do I care about gas turbines when I'm fitting my ships with nuclear reactors and steam turbines?
As to managing the piping and seals on the catapult being a PITA... I'll take your word for it. But we don't really know if the electromagnetic ones are going to be better until they've been in service for awhile.
You could be
Re:I don't get the point of this thing... (Score:5, Interesting)
The carriers are all nuclear which means they boil sea water to turn steam turbines.
No. Only a very modest amount of seawater gets boiled in a distillation plant heated by the reactor; the resulting freshwater goes into the propulsion engines, which are closed Rankine cycles. Water goes round and round from boiler to turbines, to a seawater-cooled condenser that turns it back into liquid, to the boiler again. Lather, rinse, repeat. If you tried to use seawater in the propulsion plant, it would fill up with salt in a matter of hours. The distillation plant only supplies enough water to the engines to replenish what leaks out; the rest of its output goes to the catapult system.
The EM system means you have high voltage lines running under the decks
Ever been in the same space with a battle-damaged steam line?
such big industrial machines are hydraulic in most cases. They rely on pressure
Steam machines rely on pressure times volume, which is an order of magnitude increase in control problems.
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We've hundreds of years of experience with live steam... in battle and in peace.
I also know how dangerous live steam is... I keep hearing people ask me this question as if of course I wouldn't have any idea what live steam was like. Give me a break.
Any well designed steam system is going to have pressure safety valves. Which means explosions are not likely especially when engineers are watching the boiler. The steam that is in the pipes is going to be within spec for those pipes and applications.
If a pipe i
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I'm not sure if their main boiler runs entirely on that. They could and recycle filtered water.
However, when there were the big typhoons in east Asia that caused something of a survival problem for millions of people, the US dispatched a couple of its carriers to the region to provide clean drinking water.
The carriers can produce huge amounts of clean drinking water and I believe they do have large desalination plants inside of them. Whether they must be used for the reactor or not is not known to me. But I
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I am very aware of the dangers of "live steam"... however, a pipe is easier to repair than god knows what kind of electromagnetic whatever the fuck they embed under the decks.
Something that I don't think a lot of people get about naval ships is that most of the maintenance happens at sea. They only send the ship in to a yard or dry dock if they have to and they try to limit what a ship goes into a dock for to things that can only be done in a dock.
A steam catapult is much more likely to be repairable at sea
Using steam. (Score:2)
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The coolant on the nuke power plant is NOT likely to be water
It certainly isn't, but it transfers its heat to distilled water that ultimately serves as the working fluid in the propulsion engines. It also heats the distillation plant that provides that distilled water for the engines and all the other water users aboard.
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The coolant used in all US Navy nuclear power plants is pressurized water, with the secondary circuit being a separate water/steam loop. The experiment using sodium cooling in USS Seawolf SSN-575 [wikipedia.org] was (predictably) a miserable failure and was never repeated. The Soviet Alfa class [wikipedia.org] used lead-bismuth cooling. In operation they were very problematic. They could not even be refueled. They could never be shut down without elaborate port installations to keep the coolant liquified. All of them were retired early.
Ye
how much longer will jet fighters be relevant? (Score:2, Interesting)
when nations or even non-state groups can put up swarms of, say, 1000 drones for $1M. or 10,000 drones for $10M.
aside from the economics (using $1M+ missiles to shoot down $1000 drones) can a jet fighter even cope with swarms of cheap drones ramming its jet intakes, with or without small explosive charges?
can jet fighters even shoot other targets if there's a huge swarm of drones in the way, programmed to intercept missiles and blow them up before they hit?
and as they get smaller, can a jet and/or its pilo
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Swarms of drones would likely be susceptible to concussive explosives or flak. The nice thing about the bigger planes is they have some toughness to them.
Still, I imagine a swarm of terrain-hugging mesh-netted drones carrying small bombs would be a massively useful tool in some circumstances.
Flinging a Weighted Car off the Deck - Awesome! (Score:2)
That is a strangely satisfying thing to see, launching a car off the deck like that. A bus loaded with politicians would have been better, but they probably can't do that.
The 13-year-old me in my brain says there is a lot of play potential in this. "Gee, I wonder if it can launch $THIS off the deck? Let's do it!". Something like the Red Bull Flugtag [youtube.com]