Hangarskip - Det har vært stille omkring EMALS i USN - Her en oppdatering - AW&ST

Despite Trump’s Ire, Electromagnetic Launch System Is Full Steam Ahead Lee Hudson and Steve Trimble Shortly after his 2017 inauguration, U.S. President Donald J. Trump landed aboard the USS Gerald R. Ford (CVN 78) in a Sikorsky VH-3 helicopter for a pre-commissioning ceremony.   Touring the aircraft carrier’s below-deck compartments, a particular subsystem decades in the making drew his fury. As a sailor explained how the new Electromagnetic Aircraft Launching System (EMALS) would replace steam-powered catapults, Trump erupted: “No you’re not. You’re going to goddamned steam. The digital [alternative] costs hundreds of millions of dollars more money, and it’s no good.”  U.S. Navy’s EMALS still misses critical reliability metric Upgrades necessary for Ford-class carriers to meet goals The memory of that encounter stayed with Trump almost two years later, as he riffed on technology during normally pleasant, morale-boosting phone calls with sailors serving overseas on Thanksgiving Day.   “Steam is very reliable, and the electromagnetic, I mean, unfortunately you have to be Albert Einstein to really work it properly,” Trump said. Trump’s blunt criticism adds another challenge for General Atomics Electromagnetic Systems’ struggling EMALS program. Although not quite as complicated as Einstein’s views on relativity, EMALS’ reliability still compares poorly to the steam-powered system being replaced. Twenty years after entering preliminary design stage, the EMALS remains a maintenance headache and an operational speed-bump as the Gerald R. Ford prepares for a maiden deployment in 2020. For instance, in June 2017, the subsystem averaged 455 cycles between critical failures, which is drastically fewer than the Navy’s objective of over 4,000. During the 2018 calendar year, there was an uptick of an average of 747 catapults and traps before failing, Navy acquisition executive James Geurts told the Senate Armed Services seapower subcommittee in November. “We’re feeling pretty confident on both those systems, both on catapults and the arresting gear,” Geurts said.

Credit: General Atomics and Colin Throm/AW&ST

Subcommittee Chairman Roger Wicker (R-Miss.) asked if the Navy believed investing in EMALS was the correct decision despite technical challenges. “For the carriers of the future to be able to launch everything from fairly heavy fighter aircraft and some of the others to very light systems like the MQ-25 [unmanned refueling tanker], you need these systems to have the range of capability you need to launch that different airwing of the future,”  Geurts replied. The era of steam on aircraft carriers began in 1950, with the British Royal Navy trialing the technology on the HMS Perseus (R51). The ship’s boilers generated steam from desalinated seawater, pumped the resulting vapor into dry receivers or wet accumulators and then released it through a set of valves to drive steam pistons. The piston stroke functions as the catapult, as it flings an aircraft loaded into a deck shuttle off the ship. In many ways, steam is an ideal energy source for a ship as large as a carrier, with an inexhaustible supply of water from the ocean and enough size to contain all of the equipment. But steam technology also poses limitations. In the same amount of space in which EMALS generates 121 megajoules (MJ), the steam catapult produces a maximum of 95 MJ. Steam power also cannot be tailored to fit the weight of the aircraft, so lighter aircraft are ejected with the same force as heavier machines. The Navy has been aware of the theoretical advantages of an electromagnetic alternative to steam for decades. Westinghouse tested the Electropult for an aircraft carrier in 1946, but the limitations of power electronics doomed such technology from full-scale development for nearly six more decades. A new source of voltage and rising frequency for the launch motor finally made it possible to consider an electromagnetic system for aircraft carriers: the cycloconverter. In a process not unlike a steam catapult (except using electric power), the EMALS feeds power into energy storage devices, which in this case involve a set of rotors on flywheel alternators. When the alternators release that power in 2-3-sec. pulses, the cycloconverter efficiently amplifies voltage and frequency of the current to the launch motor. The cycloconverter allows the launch motor to vary the voltage and frequency, depending on the need. The technology behind EMALS is 150 years old. The idea of moving a projectile using an electronic field is not new, Bryan McGrath, deputy director for the Center of American Seapower at the Hudson Institute and a retired Navy commander tells Aviation Week. “This technology has been known and understood for a long time,” McGrath says. “The suggestion that somehow this is splitting the atom or one of the great leaps forward of technology is just misplaced, and I think the president overdoes that.”

Trump blasted EMALS during his March 2017 visit to carrier CVN 78. Credit: Mass Communication Specialist 3rd Class Cathrine Mae O. Campbell/U.S. Navy

Critics say Trump does not understand the benefits of working through EMALS and advanced arresting gear engineering challenges. The problems are not insurmountable, and McGrath is confident the Navy and General Atomics will figure it out. “Thirty years from now, other navies will build these ships with electromagnetic launch-and-recovery systems,” McGrath says. “We’re far from throwing in the towel on this, and the suggestion from the commander-in-chief that we [do so] . . . is unwise, and it is sort of reminiscent of this impetuous nature in general.” The service is completing launch bulletins for a variety of aircraft, Navy Capt. Kenneth Sterbenz, aircraft launch and recovery equipment program manager at Naval Air Systems Command, tells Aviation Week. “For shipboard operations, those launch bulletins will tell the ship at a very high level what’s required wind over deck—in other words, how much headwind is needed for the specific aircraft at that specific weight of launch,” Sterbenz says. An advantage of EMALS over the steam catapult is that the Navy can more precisely manage all those factors to launch an aircraft from the flight deck. The recovery bulletins are the inverse to arrest an aircraft, he says. Sterbenz’s team is incorporating the lessons learned from the at-sea test period conducted by the service roughly one year ago. When asked about failures between cycle times, he says the at-sea sample set is much smaller compared to the 3,800 launches and more than 2,000 arrestments the Navy has conducted at its land-based test site in New Jersey. In the fourth quarter of this calendar year, the Ford will have the launch bulletins and the latest software and hardware, he says. “The main difference I’m getting to appreciate between the two systems is with the EMALS, you start with a known condition at 0 kt., and you know where to get that aircraft to, whatever its speed,” Sterbenz says. The Navy reached an agreement in December with Huntington Ingalls Industries Newport News Shipbuilding to purchase two aircraft carriers at the same time—the USS Enterprise (CVN 80) and CVN 81. This is an opportunity for the service to make modifications to subsystem design because the Enterprise will not begin construction until 2020.