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New technology to give Navy planes a big push
Goal is to make old steam catapults obsolete
Friday, July 3, 2009
 Click here to enlarge this photo Artwork courtesy of General Atomics
A drawing of the EMALS system on a ship shows how the new catapults will give Navy planes a boost off carriers.
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Images of planes launching from an aircraft carrier, for many people, come from the movie "Top Gun," with its view of planes sitting on a flight deck, surrounded by billowing steam, as they get ready to launch from the ship's catapult.
That image is gradually going to be changing, according to Capt. Randy Mahr, program manager for PMA 251, the Navy's aircraft launch and recovery equipment program. His program is working on a system called EMALS — the Electro-Magnetic Aircraft Launch System.
"The Navy's goal is to get steam catapults off the ships," Mahr said. "We settled on steam for the last 50 years and now it is time to go to the next level."
Mahr explained that steam catapults are maintenance intensive, because steam has to be moved up to the flight deck. EMALS requires less maintenance, because it is all electricity and wires. And, because there are fewer moving parts, it requires less manpower.
In fiscal year 2008, according to Mahr's office, the steam catapult systems required nearly seven man-hours of maintenance for every sortie flown. Navy analysis predicts EMALS will reduce that maintenance time by 30 to 40 percent, based on reliability objectives for the individual system components. As the system goes through testing, these reliability objectives will be verified.
According to an article in the Smithsonian's Air and Space magazine, the amount of steam needed to launch an aircraft depends on the weight of the aircraft. With steam, once a launch has begun, adjustments can no longer be made. And, according to the article, if too much steam is used, the nose-wheel landing gear, which attaches to the catapult, could be ripped off during the launch. If too little steam is used, there is a chance the aircraft won't reach takeoff speed, but instead will shoot off the deck and into the water. With EMALS, the launch control system will know what speed an aircraft should have during the launch sequence. And, it will be able to make adjustments throughout the process.
Mahr said EMALS puts out less of a heat signature than does the steam catapult, which is useful in a war zone.
"One of the nice things for people working on it is that it is not as hot as steam," Mahr said. "Steam is safe and we know to operate it. But, the maintenance involves manpower and there is a lot of maintenance on steam."
The new system will also be easier on the structure of an aircraft, according to Mahr. When a steam catapult gets ready to launch an aircraft, there is a lot of push that includes noise, steam and shaking of the aircraft. With EMALS, there should be a smooth acceleration. There will still be noise from the jets, but the launch itself should be quieter.
Anyone who has ever magnetized a credit card, making it unusable, could wonder whether using electro-magnetics on a ship or an aircraft would magnetize the computers or the compass.
Mahr said that is not an issue.
"Based on the data we have so far, the magnetic field dissipates about a half-inch above flight deck," he said. "The field basically disappears so this won't have any impact on compasses or computers on the ship."
Once EMALS becomes the catapult, there will be some training for pilots and crew members, but Mahr's said he expects it to be a smooth transition. "The pilots and the folks on the flight deck will see no difference," Mahr said. "Right down to the launch station itself, the hand signals — everything is the same. The differences are contained within the system itself."
The idea of an electro-magnetic catapult is based on simple electronics. Already, some high-speed trains and roller coasters throughout the world operate with an electro-magnetic system. A motor generator is the power driver for the catapult, according to Mahr, providing the energy for catapult.
The decision to go with EMALS came after a review of the system's cost, performance and delivery timetables, said Lt. Clay Doss, a Navy spokesman.
"The Navy is committed to ensure adequate management is in place to manage risk, maintain the current schedule for the program … and to provide adequate oversight for General Atomics, who will be building the EMALS and delivering EMALS to the ship and for Northrop Grumman, who is the shipbuilder," Doss said.
Major testing of the catapult system is going on in Lakehurst, N.J., and Tupelo, Miss. Mahr noted that there are usually four catapults on a ship, which use a shared power distribution system.
"We are putting a full system in Lakehurst," Mahr said, "where we will do all of our testing. As EMALS move to the new carriers, we will eventually replace the steam catapult down here at Pax River. But that won't happen until around 2017."
In September 2008, Northrop Grumman Corporation received a $5.1 billion, seven-year contract for detail, design and construction of the Gerald R. Ford (CVN 78) nuclear-powered aircraft carrier, with delivery expected in 2015.
"Pax River and Lakehurst N.J., are changing what the Navy is doing with ships," Mahr said. "The generation of sailors who are now operating the catapults have gone beyond steam. We want to give them what they are used to — the GameBoys and the Wiis — and, at the same time, save the taxpayers money, because they are paying for it."
Steam catapults are not going to disappear anytime soon, since the current fleet of aircraft carriers still uses steam and these ships cannot be retrofitted. But on Tuesday, General Atomics, located in San Diego, was awarded a $573 million contract action for the production of EMALS for the CVN-78 class of aircraft carriers. Work on the system is expected to be completed in September 2015.
