EMALS is the electromagnetic catapult on the USS Ford, which replaces the steam catapult that has been in use for the last sixty years.
It's not going very well. The EMALS's launch dynamics apparently is oeverstressing the wings of airplanes with external fuel tanks and the system is not capable of operating for extended periods of time.
Without EMALS, the Ford is merely a ten-billion dollar ship that can transport airplanes from one naval base to another (if there is a crane to offload them) and do semi-major repairs to the airplanes while in transit. Without a functioning catapult, the ship is like having a box of ammunition without having a rifle to shoot them with.
Back in the day when responsible adults ran things, they'd have said "OK, this is a new idea and it might not work operationally. So let's put in one of them and three of the things we know that work, and design it so that if it works, we can swap out the old stuff and if it doesn't, we can put in the old stuff."
You might recall, for example, that the Navy didn't stop buying piston-engined airplanes until it was damn sure that those newfangled jets would work.[1] (The Air Force had enough Mustangs left over after the war to run the risk.) A past SecDef ordered the whole-scale switching over to a new rifle in the middle of a war and a lot of men paid the price for that.
NavAir has thrown all of is eggs into EMALS. If it doesn't work and if it can't be kept in working condition, then the USS Ford is a neutered carrier.
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[1] The F4U Corsair was in production until 1953, which was when it was retired from USN frontline service. Corsairs were in use by other nations, especially France, for many years afterwards.
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11 comments:
Weird how those problems are just now cropping up.
The Navy has a land-based EMALS facility.
You'd think they would have worked out the bugs and dealt with those kinds of one would think obvious configurations and resulting problems before rolling it out live on an aircraft carrier.
The Ford could still be used for keel-hauling... but we probably shouldn't do it to more than 3/4 of the Pentagon. Just anyone that ever got involved in any procurement of any kind since about 1980.
why wouldnt it be generating the same dynamics as a steam catapult? same length boat and gas tanks on a known plane?
Two thoughts:
1. We live in an age of governmental incompetence.
2. The fish rots from the head down.
Yours very crankily,
The New York Crank
Aaron, things work differently on a ship. There might be different aerodynamic flows in play.
Anon 3:20, a steam cat has two pistons which throw the catapult shuttle (and the airplane) down the deck. Maximum acceleration is at the beginning as the steam violently expands. The airplane is thrown into the air and the entire cat rig then hits a water brake to stop it.
EMALS can have constant, if not increasing acceleration. Not a violent at the start, stronger at the end. And then the polarity reverses and it stops without a water brake (presumably there's one as a backup).
But the airplanes were engineered for steam cats. Something is going on and I'm not terribly shocked that it showed up at sea.
Beyond that the mean time between failures is supposedly abysmal.
Seeing as how it is, really (and yes, it isn't that simple, I understand), a linear electric motor, I fail to see why they can't adjust the level of acceleration or even change it as the drive moves along it's path. Or, really, why no one thought that having different acceleration curves might not work for older airplanes.
Surely, peak acceleration would be the issue with respect to risk to the planes, regardless of whether it occurred at the beginning or at the end of the catapult travel? It actually sounds like the steam catapult would have more initial jerk (technical term: derivative of acceleration). An electromagnetic drive *should* be programmable to any feasible profile of jerk and acceleration, but no one should be surprised if it turns out that a single, non-adjustable profile was *inadvertently* baked into the design.
Frank, the peak acceleration is one factor to be combined with aerodynamic loads.
The problem with “tailoring” the shot is one of delivering X energy into Y vehicle over Z distance. In this case the variables aren’t, that is X, Y and Z are all known values, the planes weightt Y and need X energy to fly at the end of a cat shot. Z is the usable accelerative length of the cat, period. The only real “variable” is the rate of energy introduction to the vehicle, and that is constrained by the dynamics of the shuttle and the capacity of the system, above and beyond the need to not ball a Hornet into a pile of tinfoil.
As the Comrade suggested, it’s highly likely that the relative wind over the deck has a relationship to the issue, as that would have been much less evident on the land-based EMALS. The dynamic loads on an aircraft starting at 40kts plus are certainly different than starting at perhaps 5-10kts on a runway, perhaps significantly reducing the amount of energy transfer possible safely. That being said, it could easily be as simple as the EMALS not being about to transfer the initial slug of energy as quickly, at which point the additional energy needed cannot be safety transferred within the available run space.
CP88, I had the pleasure of a trip to the TR in 1994, and they didn't steam for any major wind-over-deck during flight ops...maybe 10-15 knots, with only steerageway on.
This sounds like the same idiots who thought "SSN-21" (and DD-21) was the submarine after SSN-20, not the project for the USN's 21st century submarine.
I understand the Enterprise used one of its 8 reactors to provide catapult steam service. Don't know it that's true, but it does suggest the catapults use a lot of energy.
The PRC shills on /k/ have been having fun with the Ford lately.
Deadstick- they may have had a good breeze or lightly loaded aircraft.
It does take a lot of steam to run a cat. EMALS also fits into the NAvy's plan to do away with steam turbines.
Carrier ops are fascinating in complexity. If you steam hard into the wind to create a strong relative wind over the deck, you lessen the catapult force necessary to get an airplane up to flying speed, as well as the force necessary to trap the airplanes on landing. On the other hand, having a 40-kt relative wind makes deck operations much more difficult, as the plane crews are on deck and moving airplanes around in gale-force winds. The risk to them and to the airplanes of being damaged in deck movement is not minimal. Also, the faster you go, the more energy is taken out of the reactor, which hastens the day when the carrier has to go in for refueling, which is done in conjunction with an overhaul and take about three years.
And carriers don't operate alone. The nuc cruisers are gone, so all of a carrier's escorts are oil-burners and if you run them fast, then you need to refuel a lot more often.
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